rev 10520 : 8055723[client]: Replace concat String to append in StringBuilder parameters
Contributed-by: Otavio Santana <otaviojava@java.net>

   1 /*
   2  * Copyright (c) 2006, 2013, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 package javax.swing;
  26 
  27 import java.awt.Component;
  28 import java.awt.Container;
  29 import java.awt.Dimension;
  30 import java.awt.Insets;
  31 import java.awt.LayoutManager2;
  32 import java.util.*;
  33 import static java.awt.Component.BaselineResizeBehavior;
  34 import static javax.swing.LayoutStyle.ComponentPlacement;
  35 import static javax.swing.SwingConstants.HORIZONTAL;
  36 import static javax.swing.SwingConstants.VERTICAL;
  37 
  38 /**
  39  * {@code GroupLayout} is a {@code LayoutManager} that hierarchically
  40  * groups components in order to position them in a {@code Container}.
  41  * {@code GroupLayout} is intended for use by builders, but may be
  42  * hand-coded as well.
  43  * Grouping is done by instances of the {@link Group Group} class. {@code
  44  * GroupLayout} supports two types of groups. A sequential group
  45  * positions its child elements sequentially, one after another. A
  46  * parallel group aligns its child elements in one of four ways.
  47  * <p>
  48  * Each group may contain any number of elements, where an element is
  49  * a {@code Group}, {@code Component}, or gap. A gap can be thought
  50  * of as an invisible component with a minimum, preferred and maximum
  51  * size. In addition {@code GroupLayout} supports a preferred gap,
  52  * whose value comes from {@code LayoutStyle}.
  53  * <p>
  54  * Elements are similar to a spring. Each element has a range as
  55  * specified by a minimum, preferred and maximum.  Gaps have either a
  56  * developer-specified range, or a range determined by {@code
  57  * LayoutStyle}. The range for {@code Component}s is determined from
  58  * the {@code Component}'s {@code getMinimumSize}, {@code
  59  * getPreferredSize} and {@code getMaximumSize} methods. In addition,
  60  * when adding {@code Component}s you may specify a particular range
  61  * to use instead of that from the component. The range for a {@code
  62  * Group} is determined by the type of group. A {@code ParallelGroup}'s
  63  * range is the maximum of the ranges of its elements. A {@code
  64  * SequentialGroup}'s range is the sum of the ranges of its elements.
  65  * <p>
  66  * {@code GroupLayout} treats each axis independently.  That is, there
  67  * is a group representing the horizontal axis, and a group
  68  * representing the vertical axis.  The horizontal group is
  69  * responsible for determining the minimum, preferred and maximum size
  70  * along the horizontal axis as well as setting the x and width of the
  71  * components contained in it. The vertical group is responsible for
  72  * determining the minimum, preferred and maximum size along the
  73  * vertical axis as well as setting the y and height of the
  74  * components contained in it. Each {@code Component} must exist in both
  75  * a horizontal and vertical group, otherwise an {@code IllegalStateException}
  76  * is thrown during layout, or when the minimum, preferred or
  77  * maximum size is requested.
  78  * <p>
  79  * The following diagram shows a sequential group along the horizontal
  80  * axis. The sequential group contains three components. A parallel group
  81  * was used along the vertical axis.
  82  * <p style="text-align:center">
  83  * <img src="doc-files/groupLayout.1.gif" alt="Sequential group along the horizontal axis in three components">
  84  * <p>
  85  * To reinforce that each axis is treated independently the diagram shows
  86  * the range of each group and element along each axis. The
  87  * range of each component has been projected onto the axes,
  88  * and the groups are rendered in blue (horizontal) and red (vertical).
  89  * For readability there is a gap between each of the elements in the
  90  * sequential group.
  91  * <p>
  92  * The sequential group along the horizontal axis is rendered as a solid
  93  * blue line. Notice the sequential group is the sum of the children elements
  94  * it contains.
  95  * <p>
  96  * Along the vertical axis the parallel group is the maximum of the height
  97  * of each of the components. As all three components have the same height,
  98  * the parallel group has the same height.
  99  * <p>
 100  * The following diagram shows the same three components, but with the
 101  * parallel group along the horizontal axis and the sequential group along
 102  * the vertical axis.
 103  *
 104  * <p style="text-align:center">
 105  * <img src="doc-files/groupLayout.2.gif" alt="Sequential group along the vertical axis in three components">
 106  * <p>
 107  * As {@code c1} is the largest of the three components, the parallel
 108  * group is sized to {@code c1}. As {@code c2} and {@code c3} are smaller
 109  * than {@code c1} they are aligned based on the alignment specified
 110  * for the component (if specified) or the default alignment of the
 111  * parallel group. In the diagram {@code c2} and {@code c3} were created
 112  * with an alignment of {@code LEADING}. If the component orientation were
 113  * right-to-left then {@code c2} and {@code c3} would be positioned on
 114  * the opposite side.
 115  * <p>
 116  * The following diagram shows a sequential group along both the horizontal
 117  * and vertical axis.
 118  * <p style="text-align:center">
 119  * <img src="doc-files/groupLayout.3.gif" alt="Sequential group along both the horizontal and vertical axis in three components">
 120  * <p>
 121  * {@code GroupLayout} provides the ability to insert gaps between
 122  * {@code Component}s. The size of the gap is determined by an
 123  * instance of {@code LayoutStyle}. This may be turned on using the
 124  * {@code setAutoCreateGaps} method.  Similarly, you may use
 125  * the {@code setAutoCreateContainerGaps} method to insert gaps
 126  * between components that touch the edge of the parent container and the
 127  * container.
 128  * <p>
 129  * The following builds a panel consisting of two labels in
 130  * one column, followed by two textfields in the next column:
 131  * <pre>
 132  *   JComponent panel = ...;
 133  *   GroupLayout layout = new GroupLayout(panel);
 134  *   panel.setLayout(layout);
 135  *
 136  *   // Turn on automatically adding gaps between components
 137  *   layout.setAutoCreateGaps(true);
 138  *
 139  *   // Turn on automatically creating gaps between components that touch
 140  *   // the edge of the container and the container.
 141  *   layout.setAutoCreateContainerGaps(true);
 142  *
 143  *   // Create a sequential group for the horizontal axis.
 144  *
 145  *   GroupLayout.SequentialGroup hGroup = layout.createSequentialGroup();
 146  *
 147  *   // The sequential group in turn contains two parallel groups.
 148  *   // One parallel group contains the labels, the other the text fields.
 149  *   // Putting the labels in a parallel group along the horizontal axis
 150  *   // positions them at the same x location.
 151  *   //
 152  *   // Variable indentation is used to reinforce the level of grouping.
 153  *   hGroup.addGroup(layout.createParallelGroup().
 154  *            addComponent(label1).addComponent(label2));
 155  *   hGroup.addGroup(layout.createParallelGroup().
 156  *            addComponent(tf1).addComponent(tf2));
 157  *   layout.setHorizontalGroup(hGroup);
 158  *
 159  *   // Create a sequential group for the vertical axis.
 160  *   GroupLayout.SequentialGroup vGroup = layout.createSequentialGroup();
 161  *
 162  *   // The sequential group contains two parallel groups that align
 163  *   // the contents along the baseline. The first parallel group contains
 164  *   // the first label and text field, and the second parallel group contains
 165  *   // the second label and text field. By using a sequential group
 166  *   // the labels and text fields are positioned vertically after one another.
 167  *   vGroup.addGroup(layout.createParallelGroup(Alignment.BASELINE).
 168  *            addComponent(label1).addComponent(tf1));
 169  *   vGroup.addGroup(layout.createParallelGroup(Alignment.BASELINE).
 170  *            addComponent(label2).addComponent(tf2));
 171  *   layout.setVerticalGroup(vGroup);
 172  * </pre>
 173  * <p>
 174  * When run the following is produced.
 175  * <p style="text-align:center">
 176  * <img src="doc-files/groupLayout.example.png" alt="Produced horizontal/vertical form">
 177  * <p>
 178  * This layout consists of the following.
 179  * <ul><li>The horizontal axis consists of a sequential group containing two
 180  *         parallel groups.  The first parallel group contains the labels,
 181  *         and the second parallel group contains the text fields.
 182  *     <li>The vertical axis consists of a sequential group
 183  *         containing two parallel groups.  The parallel groups are configured
 184  *         to align their components along the baseline. The first parallel
 185  *         group contains the first label and first text field, and
 186  *         the second group consists of the second label and second
 187  *         text field.
 188  * </ul>
 189  * There are a couple of things to notice in this code:
 190  * <ul>
 191  *   <li>You need not explicitly add the components to the container; this
 192  *       is indirectly done by using one of the {@code add} methods of
 193  *       {@code Group}.
 194  *   <li>The various {@code add} methods return
 195  *       the caller.  This allows for easy chaining of invocations.  For
 196  *       example, {@code group.addComponent(label1).addComponent(label2);} is
 197  *       equivalent to
 198  *       {@code group.addComponent(label1); group.addComponent(label2);}.
 199  *   <li>There are no public constructors for {@code Group}s; instead
 200  *       use the create methods of {@code GroupLayout}.
 201  * </ul>
 202  *
 203  * @author Tomas Pavek
 204  * @author Jan Stola
 205  * @author Scott Violet
 206  * @since 1.6
 207  */
 208 public class GroupLayout implements LayoutManager2 {
 209     // Used in size calculations
 210     private static final int MIN_SIZE = 0;
 211 
 212     private static final int PREF_SIZE = 1;
 213 
 214     private static final int MAX_SIZE = 2;
 215 
 216     // Used by prepare, indicates min, pref or max isn't going to be used.
 217     private static final int SPECIFIC_SIZE = 3;
 218 
 219     private static final int UNSET = Integer.MIN_VALUE;
 220 
 221     /**
 222      * Indicates the size from the component or gap should be used for a
 223      * particular range value.
 224      *
 225      * @see Group
 226      */
 227     public static final int DEFAULT_SIZE = -1;
 228 
 229     /**
 230      * Indicates the preferred size from the component or gap should
 231      * be used for a particular range value.
 232      *
 233      * @see Group
 234      */
 235     public static final int PREFERRED_SIZE = -2;
 236 
 237     // Whether or not we automatically try and create the preferred
 238     // padding between components.
 239     private boolean autocreatePadding;
 240 
 241     // Whether or not we automatically try and create the preferred
 242     // padding between components the touch the edge of the container and
 243     // the container.
 244     private boolean autocreateContainerPadding;
 245 
 246     /**
 247      * Group responsible for layout along the horizontal axis.  This is NOT
 248      * the user specified group, use getHorizontalGroup to dig that out.
 249      */
 250     private Group horizontalGroup;
 251 
 252     /**
 253      * Group responsible for layout along the vertical axis.  This is NOT
 254      * the user specified group, use getVerticalGroup to dig that out.
 255      */
 256     private Group verticalGroup;
 257 
 258     // Maps from Component to ComponentInfo.  This is used for tracking
 259     // information specific to a Component.
 260     private Map<Component,ComponentInfo> componentInfos;
 261 
 262     // Container we're doing layout for.
 263     private Container host;
 264 
 265     // Used by areParallelSiblings, cached to avoid excessive garbage.
 266     private Set<Spring> tmpParallelSet;
 267 
 268     // Indicates Springs have changed in some way since last change.
 269     private boolean springsChanged;
 270 
 271     // Indicates invalidateLayout has been invoked.
 272     private boolean isValid;
 273 
 274     // Whether or not any preferred padding (or container padding) springs
 275     // exist
 276     private boolean hasPreferredPaddingSprings;
 277 
 278     /**
 279      * The LayoutStyle instance to use, if null the sharedInstance is used.
 280      */
 281     private LayoutStyle layoutStyle;
 282 
 283     /**
 284      * If true, components that are not visible are treated as though they
 285      * aren't there.
 286      */
 287     private boolean honorsVisibility;
 288 
 289 
 290     /**
 291      * Enumeration of the possible ways {@code ParallelGroup} can align
 292      * its children.
 293      *
 294      * @see #createParallelGroup(Alignment)
 295      * @since 1.6
 296      */
 297     public enum Alignment {
 298         /**
 299          * Indicates the elements should be
 300          * aligned to the origin.  For the horizontal axis with a left to
 301          * right orientation this means aligned to the left edge. For the
 302          * vertical axis leading means aligned to the top edge.
 303          *
 304          * @see #createParallelGroup(Alignment)
 305          */
 306         LEADING,
 307 
 308         /**
 309          * Indicates the elements should be aligned to the end of the
 310          * region.  For the horizontal axis with a left to right
 311          * orientation this means aligned to the right edge. For the
 312          * vertical axis trailing means aligned to the bottom edge.
 313          *
 314          * @see #createParallelGroup(Alignment)
 315          */
 316         TRAILING,
 317 
 318         /**
 319          * Indicates the elements should be centered in
 320          * the region.
 321          *
 322          * @see #createParallelGroup(Alignment)
 323          */
 324         CENTER,
 325 
 326         /**
 327          * Indicates the elements should be aligned along
 328          * their baseline.
 329          *
 330          * @see #createParallelGroup(Alignment)
 331          * @see #createBaselineGroup(boolean,boolean)
 332          */
 333         BASELINE
 334     }
 335 
 336 
 337     private static void checkSize(int min, int pref, int max,
 338             boolean isComponentSpring) {
 339         checkResizeType(min, isComponentSpring);
 340         if (!isComponentSpring && pref < 0) {
 341             throw new IllegalArgumentException("Pref must be >= 0");
 342         } else if (isComponentSpring) {
 343             checkResizeType(pref, true);
 344         }
 345         checkResizeType(max, isComponentSpring);
 346         checkLessThan(min, pref);
 347         checkLessThan(pref, max);
 348     }
 349 
 350     private static void checkResizeType(int type, boolean isComponentSpring) {
 351         if (type < 0 && ((isComponentSpring && type != DEFAULT_SIZE &&
 352                 type != PREFERRED_SIZE) ||
 353                 (!isComponentSpring && type != PREFERRED_SIZE))) {
 354             throw new IllegalArgumentException("Invalid size");
 355         }
 356     }
 357 
 358     private static void checkLessThan(int min, int max) {
 359         if (min >= 0 && max >= 0 && min > max) {
 360             throw new IllegalArgumentException(
 361                     "Following is not met: min<=pref<=max");
 362         }
 363     }
 364 
 365     /**
 366      * Creates a {@code GroupLayout} for the specified {@code Container}.
 367      *
 368      * @param host the {@code Container} the {@code GroupLayout} is
 369      *        the {@code LayoutManager} for
 370      * @throws IllegalArgumentException if host is {@code null}
 371      */
 372     public GroupLayout(Container host) {
 373         if (host == null) {
 374             throw new IllegalArgumentException("Container must be non-null");
 375         }
 376         honorsVisibility = true;
 377         this.host = host;
 378         setHorizontalGroup(createParallelGroup(Alignment.LEADING, true));
 379         setVerticalGroup(createParallelGroup(Alignment.LEADING, true));
 380         componentInfos = new HashMap<Component,ComponentInfo>();
 381         tmpParallelSet = new HashSet<Spring>();
 382     }
 383 
 384     /**
 385      * Sets whether component visibility is considered when sizing and
 386      * positioning components. A value of {@code true} indicates that
 387      * non-visible components should not be treated as part of the
 388      * layout. A value of {@code false} indicates that components should be
 389      * positioned and sized regardless of visibility.
 390      * <p>
 391      * A value of {@code false} is useful when the visibility of components
 392      * is dynamically adjusted and you don't want surrounding components and
 393      * the sizing to change.
 394      * <p>
 395      * The specified value is used for components that do not have an
 396      * explicit visibility specified.
 397      * <p>
 398      * The default is {@code true}.
 399      *
 400      * @param honorsVisibility whether component visibility is considered when
 401      *                         sizing and positioning components
 402      * @see #setHonorsVisibility(Component,Boolean)
 403      */
 404     public void setHonorsVisibility(boolean honorsVisibility) {
 405         if (this.honorsVisibility != honorsVisibility) {
 406             this.honorsVisibility = honorsVisibility;
 407             springsChanged = true;
 408             isValid = false;
 409             invalidateHost();
 410         }
 411     }
 412 
 413     /**
 414      * Returns whether component visibility is considered when sizing and
 415      * positioning components.
 416      *
 417      * @return whether component visibility is considered when sizing and
 418      *         positioning components
 419      */
 420     public boolean getHonorsVisibility() {
 421         return honorsVisibility;
 422     }
 423 
 424     /**
 425      * Sets whether the component's visibility is considered for
 426      * sizing and positioning. A value of {@code Boolean.TRUE}
 427      * indicates that if {@code component} is not visible it should
 428      * not be treated as part of the layout. A value of {@code false}
 429      * indicates that {@code component} is positioned and sized
 430      * regardless of it's visibility.  A value of {@code null}
 431      * indicates the value specified by the single argument method {@code
 432      * setHonorsVisibility} should be used.
 433      * <p>
 434      * If {@code component} is not a child of the {@code Container} this
 435      * {@code GroupLayout} is managing, it will be added to the
 436      * {@code Container}.
 437      *
 438      * @param component the component
 439      * @param honorsVisibility whether visibility of this {@code component} should be
 440      *              considered for sizing and positioning
 441      * @throws IllegalArgumentException if {@code component} is {@code null}
 442      * @see #setHonorsVisibility(Component,Boolean)
 443      */
 444     public void setHonorsVisibility(Component component,
 445             Boolean honorsVisibility) {
 446         if (component == null) {
 447             throw new IllegalArgumentException("Component must be non-null");
 448         }
 449         getComponentInfo(component).setHonorsVisibility(honorsVisibility);
 450         springsChanged = true;
 451         isValid = false;
 452         invalidateHost();
 453     }
 454 
 455     /**
 456      * Sets whether a gap between components should automatically be
 457      * created.  For example, if this is {@code true} and you add two
 458      * components to a {@code SequentialGroup} a gap between the
 459      * two components is automatically be created.  The default is
 460      * {@code false}.
 461      *
 462      * @param autoCreatePadding whether a gap between components is
 463      *        automatically created
 464      */
 465     public void setAutoCreateGaps(boolean autoCreatePadding) {
 466         if (this.autocreatePadding != autoCreatePadding) {
 467             this.autocreatePadding = autoCreatePadding;
 468             invalidateHost();
 469         }
 470     }
 471 
 472     /**
 473      * Returns {@code true} if gaps between components are automatically
 474      * created.
 475      *
 476      * @return {@code true} if gaps between components are automatically
 477      *         created
 478      */
 479     public boolean getAutoCreateGaps() {
 480         return autocreatePadding;
 481     }
 482 
 483     /**
 484      * Sets whether a gap between the container and components that
 485      * touch the border of the container should automatically be
 486      * created. The default is {@code false}.
 487      *
 488      * @param autoCreateContainerPadding whether a gap between the container and
 489      *        components that touch the border of the container should
 490      *        automatically be created
 491      */
 492     public void setAutoCreateContainerGaps(boolean autoCreateContainerPadding){
 493         if (this.autocreateContainerPadding != autoCreateContainerPadding) {
 494             this.autocreateContainerPadding = autoCreateContainerPadding;
 495             horizontalGroup = createTopLevelGroup(getHorizontalGroup());
 496             verticalGroup = createTopLevelGroup(getVerticalGroup());
 497             invalidateHost();
 498         }
 499     }
 500 
 501     /**
 502      * Returns {@code true} if gaps between the container and components that
 503      * border the container are automatically created.
 504      *
 505      * @return {@code true} if gaps between the container and components that
 506      *         border the container are automatically created
 507      */
 508     public boolean getAutoCreateContainerGaps() {
 509         return autocreateContainerPadding;
 510     }
 511 
 512     /**
 513      * Sets the {@code Group} that positions and sizes
 514      * components along the horizontal axis.
 515      *
 516      * @param group the {@code Group} that positions and sizes
 517      *        components along the horizontal axis
 518      * @throws IllegalArgumentException if group is {@code null}
 519      */
 520     public void setHorizontalGroup(Group group) {
 521         if (group == null) {
 522             throw new IllegalArgumentException("Group must be non-null");
 523         }
 524         horizontalGroup = createTopLevelGroup(group);
 525         invalidateHost();
 526     }
 527 
 528     /**
 529      * Returns the {@code Group} that positions and sizes components
 530      * along the horizontal axis.
 531      *
 532      * @return the {@code Group} responsible for positioning and
 533      *         sizing component along the horizontal axis
 534      */
 535     private Group getHorizontalGroup() {
 536         int index = 0;
 537         if (horizontalGroup.springs.size() > 1) {
 538             index = 1;
 539         }
 540         return (Group)horizontalGroup.springs.get(index);
 541     }
 542 
 543     /**
 544      * Sets the {@code Group} that positions and sizes
 545      * components along the vertical axis.
 546      *
 547      * @param group the {@code Group} that positions and sizes
 548      *        components along the vertical axis
 549      * @throws IllegalArgumentException if group is {@code null}
 550      */
 551     public void setVerticalGroup(Group group) {
 552         if (group == null) {
 553             throw new IllegalArgumentException("Group must be non-null");
 554         }
 555         verticalGroup = createTopLevelGroup(group);
 556         invalidateHost();
 557     }
 558 
 559     /**
 560      * Returns the {@code Group} that positions and sizes components
 561      * along the vertical axis.
 562      *
 563      * @return the {@code Group} responsible for positioning and
 564      *         sizing component along the vertical axis
 565      */
 566     private Group getVerticalGroup() {
 567         int index = 0;
 568         if (verticalGroup.springs.size() > 1) {
 569             index = 1;
 570         }
 571         return (Group)verticalGroup.springs.get(index);
 572     }
 573 
 574     /**
 575      * Wraps the user specified group in a sequential group.  If
 576      * container gaps should be generated the necessary springs are
 577      * added.
 578      */
 579     private Group createTopLevelGroup(Group specifiedGroup) {
 580         SequentialGroup group = createSequentialGroup();
 581         if (getAutoCreateContainerGaps()) {
 582             group.addSpring(new ContainerAutoPreferredGapSpring());
 583             group.addGroup(specifiedGroup);
 584             group.addSpring(new ContainerAutoPreferredGapSpring());
 585         } else {
 586             group.addGroup(specifiedGroup);
 587         }
 588         return group;
 589     }
 590 
 591     /**
 592      * Creates and returns a {@code SequentialGroup}.
 593      *
 594      * @return a new {@code SequentialGroup}
 595      */
 596     public SequentialGroup createSequentialGroup() {
 597         return new SequentialGroup();
 598     }
 599 
 600     /**
 601      * Creates and returns a {@code ParallelGroup} with an alignment of
 602      * {@code Alignment.LEADING}.  This is a cover method for the more
 603      * general {@code createParallelGroup(Alignment)} method.
 604      *
 605      * @return a new {@code ParallelGroup}
 606      * @see #createParallelGroup(Alignment)
 607      */
 608     public ParallelGroup createParallelGroup() {
 609         return createParallelGroup(Alignment.LEADING);
 610     }
 611 
 612     /**
 613      * Creates and returns a {@code ParallelGroup} with the specified
 614      * alignment.  This is a cover method for the more general {@code
 615      * createParallelGroup(Alignment,boolean)} method with {@code true}
 616      * supplied for the second argument.
 617      *
 618      * @param alignment the alignment for the elements of the group
 619      * @throws IllegalArgumentException if {@code alignment} is {@code null}
 620      * @return a new {@code ParallelGroup}
 621      * @see #createBaselineGroup
 622      * @see ParallelGroup
 623      */
 624     public ParallelGroup createParallelGroup(Alignment alignment) {
 625         return createParallelGroup(alignment, true);
 626     }
 627 
 628     /**
 629      * Creates and returns a {@code ParallelGroup} with the specified
 630      * alignment and resize behavior. The {@code
 631      * alignment} argument specifies how children elements are
 632      * positioned that do not fill the group. For example, if a {@code
 633      * ParallelGroup} with an alignment of {@code TRAILING} is given
 634      * 100 and a child only needs 50, the child is
 635      * positioned at the position 50 (with a component orientation of
 636      * left-to-right).
 637      * <p>
 638      * Baseline alignment is only useful when used along the vertical
 639      * axis. A {@code ParallelGroup} created with a baseline alignment
 640      * along the horizontal axis is treated as {@code LEADING}.
 641      * <p>
 642      * Refer to {@link GroupLayout.ParallelGroup ParallelGroup} for details on
 643      * the behavior of baseline groups.
 644      *
 645      * @param alignment the alignment for the elements of the group
 646      * @param resizable {@code true} if the group is resizable; if the group
 647      *        is not resizable the preferred size is used for the
 648      *        minimum and maximum size of the group
 649      * @throws IllegalArgumentException if {@code alignment} is {@code null}
 650      * @return a new {@code ParallelGroup}
 651      * @see #createBaselineGroup
 652      * @see GroupLayout.ParallelGroup
 653      */
 654     public ParallelGroup createParallelGroup(Alignment alignment,
 655             boolean resizable){
 656         if (alignment == null) {
 657             throw new IllegalArgumentException("alignment must be non null");
 658         }
 659 
 660         if (alignment == Alignment.BASELINE) {
 661             return new BaselineGroup(resizable);
 662         }
 663         return new ParallelGroup(alignment, resizable);
 664     }
 665 
 666     /**
 667      * Creates and returns a {@code ParallelGroup} that aligns it's
 668      * elements along the baseline.
 669      *
 670      * @param resizable whether the group is resizable
 671      * @param anchorBaselineToTop whether the baseline is anchored to
 672      *        the top or bottom of the group
 673      * @return the {@code ParallelGroup}
 674      * @see #createBaselineGroup
 675      * @see ParallelGroup
 676      */
 677     public ParallelGroup createBaselineGroup(boolean resizable,
 678             boolean anchorBaselineToTop) {
 679         return new BaselineGroup(resizable, anchorBaselineToTop);
 680     }
 681 
 682     /**
 683      * Forces the specified components to have the same size
 684      * regardless of their preferred, minimum or maximum sizes. Components that
 685      * are linked are given the maximum of the preferred size of each of
 686      * the linked components. For example, if you link two components with
 687      * a preferred width of 10 and 20, both components are given a width of 20.
 688      * <p>
 689      * This can be used multiple times to force any number of
 690      * components to share the same size.
 691      * <p>
 692      * Linked Components are not be resizable.
 693      *
 694      * @param components the {@code Component}s that are to have the same size
 695      * @throws IllegalArgumentException if {@code components} is
 696      *         {@code null}, or contains {@code null}
 697      * @see #linkSize(int,Component[])
 698      */
 699     public void linkSize(Component... components) {
 700         linkSize(SwingConstants.HORIZONTAL, components);
 701         linkSize(SwingConstants.VERTICAL, components);
 702     }
 703 
 704     /**
 705      * Forces the specified components to have the same size along the
 706      * specified axis regardless of their preferred, minimum or
 707      * maximum sizes. Components that are linked are given the maximum
 708      * of the preferred size of each of the linked components. For
 709      * example, if you link two components along the horizontal axis
 710      * and the preferred width is 10 and 20, both components are given
 711      * a width of 20.
 712      * <p>
 713      * This can be used multiple times to force any number of
 714      * components to share the same size.
 715      * <p>
 716      * Linked {@code Component}s are not be resizable.
 717      *
 718      * @param components the {@code Component}s that are to have the same size
 719      * @param axis the axis to link the size along; one of
 720      *             {@code SwingConstants.HORIZONTAL} or
 721      *             {@code SwingConstans.VERTICAL}
 722      * @throws IllegalArgumentException if {@code components} is
 723      *         {@code null}, or contains {@code null}; or {@code axis}
 724      *          is not {@code SwingConstants.HORIZONTAL} or
 725      *          {@code SwingConstants.VERTICAL}
 726      */
 727     public void linkSize(int axis, Component... components) {
 728         if (components == null) {
 729             throw new IllegalArgumentException("Components must be non-null");
 730         }
 731         for (int counter = components.length - 1; counter >= 0; counter--) {
 732             Component c = components[counter];
 733             if (components[counter] == null) {
 734                 throw new IllegalArgumentException(
 735                         "Components must be non-null");
 736             }
 737             // Force the component to be added
 738             getComponentInfo(c);
 739         }
 740         int glAxis;
 741         if (axis == SwingConstants.HORIZONTAL) {
 742             glAxis = HORIZONTAL;
 743         } else if (axis == SwingConstants.VERTICAL) {
 744             glAxis = VERTICAL;
 745         } else {
 746             throw new IllegalArgumentException("Axis must be one of " +
 747                     "SwingConstants.HORIZONTAL or SwingConstants.VERTICAL");
 748         }
 749         LinkInfo master = getComponentInfo(
 750                 components[components.length - 1]).getLinkInfo(glAxis);
 751         for (int counter = components.length - 2; counter >= 0; counter--) {
 752             master.add(getComponentInfo(components[counter]));
 753         }
 754         invalidateHost();
 755     }
 756 
 757     /**
 758      * Replaces an existing component with a new one.
 759      *
 760      * @param existingComponent the component that should be removed
 761      *        and replaced with {@code newComponent}
 762      * @param newComponent the component to put in
 763      *        {@code existingComponent}'s place
 764      * @throws IllegalArgumentException if either of the components are
 765      *         {@code null} or {@code existingComponent} is not being managed
 766      *         by this layout manager
 767      */
 768     public void replace(Component existingComponent, Component newComponent) {
 769         if (existingComponent == null || newComponent == null) {
 770             throw new IllegalArgumentException("Components must be non-null");
 771         }
 772         // Make sure all the components have been registered, otherwise we may
 773         // not update the correct Springs.
 774         if (springsChanged) {
 775             registerComponents(horizontalGroup, HORIZONTAL);
 776             registerComponents(verticalGroup, VERTICAL);
 777         }
 778         ComponentInfo info = componentInfos.remove(existingComponent);
 779         if (info == null) {
 780             throw new IllegalArgumentException("Component must already exist");
 781         }
 782         host.remove(existingComponent);
 783         if (newComponent.getParent() != host) {
 784             host.add(newComponent);
 785         }
 786         info.setComponent(newComponent);
 787         componentInfos.put(newComponent, info);
 788         invalidateHost();
 789     }
 790 
 791     /**
 792      * Sets the {@code LayoutStyle} used to calculate the preferred
 793      * gaps between components. A value of {@code null} indicates the
 794      * shared instance of {@code LayoutStyle} should be used.
 795      *
 796      * @param layoutStyle the {@code LayoutStyle} to use
 797      * @see LayoutStyle
 798      */
 799     public void setLayoutStyle(LayoutStyle layoutStyle) {
 800         this.layoutStyle = layoutStyle;
 801         invalidateHost();
 802     }
 803 
 804     /**
 805      * Returns the {@code LayoutStyle} used for calculating the preferred
 806      * gap between components. This returns the value specified to
 807      * {@code setLayoutStyle}, which may be {@code null}.
 808      *
 809      * @return the {@code LayoutStyle} used for calculating the preferred
 810      *         gap between components
 811      */
 812     public LayoutStyle getLayoutStyle() {
 813         return layoutStyle;
 814     }
 815 
 816     private LayoutStyle getLayoutStyle0() {
 817         LayoutStyle layoutStyle = getLayoutStyle();
 818         if (layoutStyle == null) {
 819             layoutStyle = LayoutStyle.getInstance();
 820         }
 821         return layoutStyle;
 822     }
 823 
 824     private void invalidateHost() {
 825         if (host instanceof JComponent) {
 826             ((JComponent)host).revalidate();
 827         } else {
 828             host.invalidate();
 829         }
 830         host.repaint();
 831     }
 832 
 833     //
 834     // LayoutManager
 835     //
 836     /**
 837      * Notification that a {@code Component} has been added to
 838      * the parent container.  You should not invoke this method
 839      * directly, instead you should use one of the {@code Group}
 840      * methods to add a {@code Component}.
 841      *
 842      * @param name the string to be associated with the component
 843      * @param component the {@code Component} to be added
 844      */
 845     public void addLayoutComponent(String name, Component component) {
 846     }
 847 
 848     /**
 849      * Notification that a {@code Component} has been removed from
 850      * the parent container.  You should not invoke this method
 851      * directly, instead invoke {@code remove} on the parent
 852      * {@code Container}.
 853      *
 854      * @param component the component to be removed
 855      * @see java.awt.Component#remove
 856      */
 857     public void removeLayoutComponent(Component component) {
 858         ComponentInfo info = componentInfos.remove(component);
 859         if (info != null) {
 860             info.dispose();
 861             springsChanged = true;
 862             isValid = false;
 863         }
 864     }
 865 
 866     /**
 867      * Returns the preferred size for the specified container.
 868      *
 869      * @param parent the container to return the preferred size for
 870      * @return the preferred size for {@code parent}
 871      * @throws IllegalArgumentException if {@code parent} is not
 872      *         the same {@code Container} this was created with
 873      * @throws IllegalStateException if any of the components added to
 874      *         this layout are not in both a horizontal and vertical group
 875      * @see java.awt.Container#getPreferredSize
 876      */
 877     public Dimension preferredLayoutSize(Container parent) {
 878         checkParent(parent);
 879         prepare(PREF_SIZE);
 880         return adjustSize(horizontalGroup.getPreferredSize(HORIZONTAL),
 881                 verticalGroup.getPreferredSize(VERTICAL));
 882     }
 883 
 884     /**
 885      * Returns the minimum size for the specified container.
 886      *
 887      * @param parent the container to return the size for
 888      * @return the minimum size for {@code parent}
 889      * @throws IllegalArgumentException if {@code parent} is not
 890      *         the same {@code Container} that this was created with
 891      * @throws IllegalStateException if any of the components added to
 892      *         this layout are not in both a horizontal and vertical group
 893      * @see java.awt.Container#getMinimumSize
 894      */
 895     public Dimension minimumLayoutSize(Container parent) {
 896         checkParent(parent);
 897         prepare(MIN_SIZE);
 898         return adjustSize(horizontalGroup.getMinimumSize(HORIZONTAL),
 899                 verticalGroup.getMinimumSize(VERTICAL));
 900     }
 901 
 902     /**
 903      * Lays out the specified container.
 904      *
 905      * @param parent the container to be laid out
 906      * @throws IllegalStateException if any of the components added to
 907      *         this layout are not in both a horizontal and vertical group
 908      */
 909     public void layoutContainer(Container parent) {
 910         // Step 1: Prepare for layout.
 911         prepare(SPECIFIC_SIZE);
 912         Insets insets = parent.getInsets();
 913         int width = parent.getWidth() - insets.left - insets.right;
 914         int height = parent.getHeight() - insets.top - insets.bottom;
 915         boolean ltr = isLeftToRight();
 916         if (getAutoCreateGaps() || getAutoCreateContainerGaps() ||
 917                 hasPreferredPaddingSprings) {
 918             // Step 2: Calculate autopadding springs
 919             calculateAutopadding(horizontalGroup, HORIZONTAL, SPECIFIC_SIZE, 0,
 920                     width);
 921             calculateAutopadding(verticalGroup, VERTICAL, SPECIFIC_SIZE, 0,
 922                     height);
 923         }
 924         // Step 3: set the size of the groups.
 925         horizontalGroup.setSize(HORIZONTAL, 0, width);
 926         verticalGroup.setSize(VERTICAL, 0, height);
 927         // Step 4: apply the size to the components.
 928         for (ComponentInfo info : componentInfos.values()) {
 929             info.setBounds(insets, width, ltr);
 930         }
 931     }
 932 
 933     //
 934     // LayoutManager2
 935     //
 936     /**
 937      * Notification that a {@code Component} has been added to
 938      * the parent container.  You should not invoke this method
 939      * directly, instead you should use one of the {@code Group}
 940      * methods to add a {@code Component}.
 941      *
 942      * @param component the component added
 943      * @param constraints description of where to place the component
 944      */
 945     public void addLayoutComponent(Component component, Object constraints) {
 946     }
 947 
 948     /**
 949      * Returns the maximum size for the specified container.
 950      *
 951      * @param parent the container to return the size for
 952      * @return the maximum size for {@code parent}
 953      * @throws IllegalArgumentException if {@code parent} is not
 954      *         the same {@code Container} that this was created with
 955      * @throws IllegalStateException if any of the components added to
 956      *         this layout are not in both a horizontal and vertical group
 957      * @see java.awt.Container#getMaximumSize
 958      */
 959     public Dimension maximumLayoutSize(Container parent) {
 960         checkParent(parent);
 961         prepare(MAX_SIZE);
 962         return adjustSize(horizontalGroup.getMaximumSize(HORIZONTAL),
 963                 verticalGroup.getMaximumSize(VERTICAL));
 964     }
 965 
 966     /**
 967      * Returns the alignment along the x axis.  This specifies how
 968      * the component would like to be aligned relative to other
 969      * components.  The value should be a number between 0 and 1
 970      * where 0 represents alignment along the origin, 1 is aligned
 971      * the furthest away from the origin, 0.5 is centered, etc.
 972      *
 973      * @param parent the {@code Container} hosting this {@code LayoutManager}
 974      * @throws IllegalArgumentException if {@code parent} is not
 975      *         the same {@code Container} that this was created with
 976      * @return the alignment; this implementation returns {@code .5}
 977      */
 978     public float getLayoutAlignmentX(Container parent) {
 979         checkParent(parent);
 980         return .5f;
 981     }
 982 
 983     /**
 984      * Returns the alignment along the y axis.  This specifies how
 985      * the component would like to be aligned relative to other
 986      * components.  The value should be a number between 0 and 1
 987      * where 0 represents alignment along the origin, 1 is aligned
 988      * the furthest away from the origin, 0.5 is centered, etc.
 989      *
 990      * @param parent the {@code Container} hosting this {@code LayoutManager}
 991      * @throws IllegalArgumentException if {@code parent} is not
 992      *         the same {@code Container} that this was created with
 993      * @return alignment; this implementation returns {@code .5}
 994      */
 995     public float getLayoutAlignmentY(Container parent) {
 996         checkParent(parent);
 997         return .5f;
 998     }
 999 
1000     /**
1001      * Invalidates the layout, indicating that if the layout manager
1002      * has cached information it should be discarded.
1003      *
1004      * @param parent the {@code Container} hosting this LayoutManager
1005      * @throws IllegalArgumentException if {@code parent} is not
1006      *         the same {@code Container} that this was created with
1007      */
1008     public void invalidateLayout(Container parent) {
1009         checkParent(parent);
1010         // invalidateLayout is called from Container.invalidate, which
1011         // does NOT grab the treelock.  All other methods do.  To make sure
1012         // there aren't any possible threading problems we grab the tree lock
1013         // here.
1014         synchronized(parent.getTreeLock()) {
1015             isValid = false;
1016         }
1017     }
1018 
1019     private void prepare(int sizeType) {
1020         boolean visChanged = false;
1021         // Step 1: If not-valid, clear springs and update visibility.
1022         if (!isValid) {
1023             isValid = true;
1024             horizontalGroup.setSize(HORIZONTAL, UNSET, UNSET);
1025             verticalGroup.setSize(VERTICAL, UNSET, UNSET);
1026             for (ComponentInfo ci : componentInfos.values()) {
1027                 if (ci.updateVisibility()) {
1028                     visChanged = true;
1029                 }
1030                 ci.clearCachedSize();
1031             }
1032         }
1033         // Step 2: Make sure components are bound to ComponentInfos
1034         if (springsChanged) {
1035             registerComponents(horizontalGroup, HORIZONTAL);
1036             registerComponents(verticalGroup, VERTICAL);
1037         }
1038         // Step 3: Adjust the autopadding. This removes existing
1039         // autopadding, then recalculates where it should go.
1040         if (springsChanged || visChanged) {
1041             checkComponents();
1042             horizontalGroup.removeAutopadding();
1043             verticalGroup.removeAutopadding();
1044             if (getAutoCreateGaps()) {
1045                 insertAutopadding(true);
1046             } else if (hasPreferredPaddingSprings ||
1047                     getAutoCreateContainerGaps()) {
1048                 insertAutopadding(false);
1049             }
1050             springsChanged = false;
1051         }
1052         // Step 4: (for min/pref/max size calculations only) calculate the
1053         // autopadding. This invokes for unsetting the calculated values, then
1054         // recalculating them.
1055         // If sizeType == SPECIFIC_SIZE, it indicates we're doing layout, this
1056         // step will be done later on.
1057         if (sizeType != SPECIFIC_SIZE && (getAutoCreateGaps() ||
1058                 getAutoCreateContainerGaps() || hasPreferredPaddingSprings)) {
1059             calculateAutopadding(horizontalGroup, HORIZONTAL, sizeType, 0, 0);
1060             calculateAutopadding(verticalGroup, VERTICAL, sizeType, 0, 0);
1061         }
1062     }
1063 
1064     private void calculateAutopadding(Group group, int axis, int sizeType,
1065             int origin, int size) {
1066         group.unsetAutopadding();
1067         switch(sizeType) {
1068             case MIN_SIZE:
1069                 size = group.getMinimumSize(axis);
1070                 break;
1071             case PREF_SIZE:
1072                 size = group.getPreferredSize(axis);
1073                 break;
1074             case MAX_SIZE:
1075                 size = group.getMaximumSize(axis);
1076                 break;
1077             default:
1078                 break;
1079         }
1080         group.setSize(axis, origin, size);
1081         group.calculateAutopadding(axis);
1082     }
1083 
1084     private void checkComponents() {
1085         for (ComponentInfo info : componentInfos.values()) {
1086             if (info.horizontalSpring == null) {
1087                 throw new IllegalStateException(info.component +
1088                         " is not attached to a horizontal group");
1089             }
1090             if (info.verticalSpring == null) {
1091                 throw new IllegalStateException(info.component +
1092                         " is not attached to a vertical group");
1093             }
1094         }
1095     }
1096 
1097     private void registerComponents(Group group, int axis) {
1098         List<Spring> springs = group.springs;
1099         for (int counter = springs.size() - 1; counter >= 0; counter--) {
1100             Spring spring = springs.get(counter);
1101             if (spring instanceof ComponentSpring) {
1102                 ((ComponentSpring)spring).installIfNecessary(axis);
1103             } else if (spring instanceof Group) {
1104                 registerComponents((Group)spring, axis);
1105             }
1106         }
1107     }
1108 
1109     private Dimension adjustSize(int width, int height) {
1110         Insets insets = host.getInsets();
1111         return new Dimension(width + insets.left + insets.right,
1112                 height + insets.top + insets.bottom);
1113     }
1114 
1115     private void checkParent(Container parent) {
1116         if (parent != host) {
1117             throw new IllegalArgumentException(
1118                     "GroupLayout can only be used with one Container at a time");
1119         }
1120     }
1121 
1122     /**
1123      * Returns the {@code ComponentInfo} for the specified Component,
1124      * creating one if necessary.
1125      */
1126     private ComponentInfo getComponentInfo(Component component) {
1127         ComponentInfo info = componentInfos.get(component);
1128         if (info == null) {
1129             info = new ComponentInfo(component);
1130             componentInfos.put(component, info);
1131             if (component.getParent() != host) {
1132                 host.add(component);
1133             }
1134         }
1135         return info;
1136     }
1137 
1138     /**
1139      * Adjusts the autopadding springs for the horizontal and vertical
1140      * groups.  If {@code insert} is {@code true} this will insert auto padding
1141      * springs, otherwise this will only adjust the springs that
1142      * comprise auto preferred padding springs.
1143      */
1144     private void insertAutopadding(boolean insert) {
1145         horizontalGroup.insertAutopadding(HORIZONTAL,
1146                 new ArrayList<AutoPreferredGapSpring>(1),
1147                 new ArrayList<AutoPreferredGapSpring>(1),
1148                 new ArrayList<ComponentSpring>(1),
1149                 new ArrayList<ComponentSpring>(1), insert);
1150         verticalGroup.insertAutopadding(VERTICAL,
1151                 new ArrayList<AutoPreferredGapSpring>(1),
1152                 new ArrayList<AutoPreferredGapSpring>(1),
1153                 new ArrayList<ComponentSpring>(1),
1154                 new ArrayList<ComponentSpring>(1), insert);
1155     }
1156 
1157     /**
1158      * Returns {@code true} if the two Components have a common ParallelGroup
1159      * ancestor along the particular axis.
1160      */
1161     private boolean areParallelSiblings(Component source, Component target,
1162             int axis) {
1163         ComponentInfo sourceInfo = getComponentInfo(source);
1164         ComponentInfo targetInfo = getComponentInfo(target);
1165         Spring sourceSpring;
1166         Spring targetSpring;
1167         if (axis == HORIZONTAL) {
1168             sourceSpring = sourceInfo.horizontalSpring;
1169             targetSpring = targetInfo.horizontalSpring;
1170         } else {
1171             sourceSpring = sourceInfo.verticalSpring;
1172             targetSpring = targetInfo.verticalSpring;
1173         }
1174         Set<Spring> sourcePath = tmpParallelSet;
1175         sourcePath.clear();
1176         Spring spring = sourceSpring.getParent();
1177         while (spring != null) {
1178             sourcePath.add(spring);
1179             spring = spring.getParent();
1180         }
1181         spring = targetSpring.getParent();
1182         while (spring != null) {
1183             if (sourcePath.contains(spring)) {
1184                 sourcePath.clear();
1185                 while (spring != null) {
1186                     if (spring instanceof ParallelGroup) {
1187                         return true;
1188                     }
1189                     spring = spring.getParent();
1190                 }
1191                 return false;
1192             }
1193             spring = spring.getParent();
1194         }
1195         sourcePath.clear();
1196         return false;
1197     }
1198 
1199     private boolean isLeftToRight() {
1200         return host.getComponentOrientation().isLeftToRight();
1201     }
1202 
1203     /**
1204      * Returns a string representation of this {@code GroupLayout}.
1205      * This method is intended to be used for debugging purposes,
1206      * and the content and format of the returned string may vary
1207      * between implementations.
1208      *
1209      * @return a string representation of this {@code GroupLayout}
1210      **/
1211     public String toString() {
1212         if (springsChanged) {
1213             registerComponents(horizontalGroup, HORIZONTAL);
1214             registerComponents(verticalGroup, VERTICAL);
1215         }
1216         StringBuilder sb = new StringBuilder();
1217         sb.append("HORIZONTAL\n");
1218         createSpringDescription(sb, horizontalGroup, "  ", HORIZONTAL);
1219         sb.append("\nVERTICAL\n");
1220         createSpringDescription(sb, verticalGroup, "  ", VERTICAL);
1221         return sb.toString();
1222     }
1223 
1224     private void createSpringDescription(StringBuilder sb, Spring spring,
1225             String indent, int axis) {
1226         String origin = "";
1227         String padding = "";
1228         if (spring instanceof ComponentSpring) {
1229             ComponentSpring cSpring = (ComponentSpring)spring;
1230             origin = Integer.toString(cSpring.getOrigin()) + " ";
1231             String name = cSpring.getComponent().getName();
1232             if (name != null) {
1233                 origin = "name=" + name + ", ";
1234             }
1235         }
1236         if (spring instanceof AutoPreferredGapSpring) {
1237             AutoPreferredGapSpring paddingSpring =
1238                     (AutoPreferredGapSpring)spring;
1239             padding = ", userCreated=" + paddingSpring.getUserCreated() +
1240                     ", matches=" + paddingSpring.getMatchDescription();
1241         }
1242         sb.append(indent).append(spring.getClass().getName()).append(' ')
1243                 .append(Integer.toHexString(spring.hashCode())).append(' ')
1244                 .append(origin).append(", size=").append(spring.getSize())
1245                 .append(", alignment=").append(spring.getAlignment())
1246                 .append(" prefs=[").append(spring.getMinimumSize(axis))
1247                 .append(' ').append(spring.getPreferredSize(axis)).append(' ')
1248                 .append(spring.getMaximumSize(axis)).append(padding)
1249                 .append("]\n");

1250         if (spring instanceof Group) {
1251             List<Spring> springs = ((Group)spring).springs;
1252             indent += "  ";
1253             for (int counter = 0; counter < springs.size(); counter++) {
1254                 createSpringDescription(sb, springs.get(counter), indent,
1255                         axis);
1256             }
1257         }
1258     }
1259 
1260 
1261     /**
1262      * Spring consists of a range: min, pref and max, a value some where in
1263      * the middle of that, and a location. Spring caches the
1264      * min/max/pref.  If the min/pref/max has internally changes, or needs
1265      * to be updated you must invoke clear.
1266      */
1267     private abstract class Spring {
1268         private int size;
1269         private int min;
1270         private int max;
1271         private int pref;
1272         private Spring parent;
1273 
1274         private Alignment alignment;
1275 
1276         Spring() {
1277             min = pref = max = UNSET;
1278         }
1279 
1280         /**
1281          * Calculates and returns the minimum size.
1282          *
1283          * @param axis the axis of layout; one of HORIZONTAL or VERTICAL
1284          * @return the minimum size
1285          */
1286         abstract int calculateMinimumSize(int axis);
1287 
1288         /**
1289          * Calculates and returns the preferred size.
1290          *
1291          * @param axis the axis of layout; one of HORIZONTAL or VERTICAL
1292          * @return the preferred size
1293          */
1294         abstract int calculatePreferredSize(int axis);
1295 
1296         /**
1297          * Calculates and returns the minimum size.
1298          *
1299          * @param axis the axis of layout; one of HORIZONTAL or VERTICAL
1300          * @return the minimum size
1301          */
1302         abstract int calculateMaximumSize(int axis);
1303 
1304         /**
1305          * Sets the parent of this Spring.
1306          */
1307         void setParent(Spring parent) {
1308             this.parent = parent;
1309         }
1310 
1311         /**
1312          * Returns the parent of this spring.
1313          */
1314         Spring getParent() {
1315             return parent;
1316         }
1317 
1318         // This is here purely as a convenience for ParallelGroup to avoid
1319         // having to track alignment separately.
1320         void setAlignment(Alignment alignment) {
1321             this.alignment = alignment;
1322         }
1323 
1324         /**
1325          * Alignment for this Spring, this may be null.
1326          */
1327         Alignment getAlignment() {
1328             return alignment;
1329         }
1330 
1331         /**
1332          * Returns the minimum size.
1333          */
1334         final int getMinimumSize(int axis) {
1335             if (min == UNSET) {
1336                 min = constrain(calculateMinimumSize(axis));
1337             }
1338             return min;
1339         }
1340 
1341         /**
1342          * Returns the preferred size.
1343          */
1344         final int getPreferredSize(int axis) {
1345             if (pref == UNSET) {
1346                 pref = constrain(calculatePreferredSize(axis));
1347             }
1348             return pref;
1349         }
1350 
1351         /**
1352          * Returns the maximum size.
1353          */
1354         final int getMaximumSize(int axis) {
1355             if (max == UNSET) {
1356                 max = constrain(calculateMaximumSize(axis));
1357             }
1358             return max;
1359         }
1360 
1361         /**
1362          * Sets the value and location of the spring.  Subclasses
1363          * will want to invoke super, then do any additional sizing.
1364          *
1365          * @param axis HORIZONTAL or VERTICAL
1366          * @param origin of this Spring
1367          * @param size of the Spring.  If size is UNSET, this invokes
1368          *        clear.
1369          */
1370         void setSize(int axis, int origin, int size) {
1371             this.size = size;
1372             if (size == UNSET) {
1373                 unset();
1374             }
1375         }
1376 
1377         /**
1378          * Resets the cached min/max/pref.
1379          */
1380         void unset() {
1381             size = min = pref = max = UNSET;
1382         }
1383 
1384         /**
1385          * Returns the current size.
1386          */
1387         int getSize() {
1388             return size;
1389         }
1390 
1391         int constrain(int value) {
1392             return Math.min(value, Short.MAX_VALUE);
1393         }
1394 
1395         int getBaseline() {
1396             return -1;
1397         }
1398 
1399         BaselineResizeBehavior getBaselineResizeBehavior() {
1400             return BaselineResizeBehavior.OTHER;
1401         }
1402 
1403         final boolean isResizable(int axis) {
1404             int min = getMinimumSize(axis);
1405             int pref = getPreferredSize(axis);
1406             return (min != pref || pref != getMaximumSize(axis));
1407         }
1408 
1409         /**
1410          * Returns {@code true} if this spring will ALWAYS have a zero
1411          * size. This should NOT check the current size, rather it's
1412          * meant to quickly test if this Spring will always have a
1413          * zero size.
1414          *
1415          * @param treatAutopaddingAsZeroSized if {@code true}, auto padding
1416          *        springs should be treated as having a size of {@code 0}
1417          * @return {@code true} if this spring will have a zero size,
1418          *         {@code false} otherwise
1419          */
1420         abstract boolean willHaveZeroSize(boolean treatAutopaddingAsZeroSized);
1421     }
1422 
1423     /**
1424      * {@code Group} provides the basis for the two types of
1425      * operations supported by {@code GroupLayout}: laying out
1426      * components one after another ({@link SequentialGroup SequentialGroup})
1427      * or aligned ({@link ParallelGroup ParallelGroup}). {@code Group} and
1428      * its subclasses have no public constructor; to create one use
1429      * one of {@code createSequentialGroup} or
1430      * {@code createParallelGroup}. Additionally, taking a {@code Group}
1431      * created from one {@code GroupLayout} and using it with another
1432      * will produce undefined results.
1433      * <p>
1434      * Various methods in {@code Group} and its subclasses allow you
1435      * to explicitly specify the range. The arguments to these methods
1436      * can take two forms, either a value greater than or equal to 0,
1437      * or one of {@code DEFAULT_SIZE} or {@code PREFERRED_SIZE}. A
1438      * value greater than or equal to {@code 0} indicates a specific
1439      * size. {@code DEFAULT_SIZE} indicates the corresponding size
1440      * from the component should be used.  For example, if {@code
1441      * DEFAULT_SIZE} is passed as the minimum size argument, the
1442      * minimum size is obtained from invoking {@code getMinimumSize}
1443      * on the component. Likewise, {@code PREFERRED_SIZE} indicates
1444      * the value from {@code getPreferredSize} should be used.
1445      * The following example adds {@code myComponent} to {@code group}
1446      * with specific values for the range. That is, the minimum is
1447      * explicitly specified as 100, preferred as 200, and maximum as
1448      * 300.
1449      * <pre>
1450      *   group.addComponent(myComponent, 100, 200, 300);
1451      * </pre>
1452      * The following example adds {@code myComponent} to {@code group} using
1453      * a combination of the forms. The minimum size is forced to be the
1454      * same as the preferred size, the preferred size is determined by
1455      * using {@code myComponent.getPreferredSize} and the maximum is
1456      * determined by invoking {@code getMaximumSize} on the component.
1457      * <pre>
1458      *   group.addComponent(myComponent, GroupLayout.PREFERRED_SIZE,
1459      *             GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE);
1460      * </pre>
1461      * <p>
1462      * Unless otherwise specified all the methods of {@code Group} and
1463      * its subclasses that allow you to specify a range throw an
1464      * {@code IllegalArgumentException} if passed an invalid range. An
1465      * invalid range is one in which any of the values are &lt; 0 and
1466      * not one of {@code PREFERRED_SIZE} or {@code DEFAULT_SIZE}, or
1467      * the following is not met (for specific values): {@code min}
1468      * &lt;= {@code pref} &lt;= {@code max}.
1469      * <p>
1470      * Similarly any methods that take a {@code Component} throw a
1471      * {@code IllegalArgumentException} if passed {@code null} and any methods
1472      * that take a {@code Group} throw an {@code NullPointerException} if
1473      * passed {@code null}.
1474      *
1475      * @see #createSequentialGroup
1476      * @see #createParallelGroup
1477      * @since 1.6
1478      */
1479     public abstract class Group extends Spring {
1480         // private int origin;
1481         // private int size;
1482         List<Spring> springs;
1483 
1484         Group() {
1485             springs = new ArrayList<Spring>();
1486         }
1487 
1488         /**
1489          * Adds a {@code Group} to this {@code Group}.
1490          *
1491          * @param group the {@code Group} to add
1492          * @return this {@code Group}
1493          */
1494         public Group addGroup(Group group) {
1495             return addSpring(group);
1496         }
1497 
1498         /**
1499          * Adds a {@code Component} to this {@code Group}.
1500          *
1501          * @param component the {@code Component} to add
1502          * @return this {@code Group}
1503          */
1504         public Group addComponent(Component component) {
1505             return addComponent(component, DEFAULT_SIZE, DEFAULT_SIZE,
1506                     DEFAULT_SIZE);
1507         }
1508 
1509         /**
1510          * Adds a {@code Component} to this {@code Group}
1511          * with the specified size.
1512          *
1513          * @param component the {@code Component} to add
1514          * @param min the minimum size or one of {@code DEFAULT_SIZE} or
1515          *            {@code PREFERRED_SIZE}
1516          * @param pref the preferred size or one of {@code DEFAULT_SIZE} or
1517          *            {@code PREFERRED_SIZE}
1518          * @param max the maximum size or one of {@code DEFAULT_SIZE} or
1519          *            {@code PREFERRED_SIZE}
1520          * @return this {@code Group}
1521          */
1522         public Group addComponent(Component component, int min, int pref,
1523                 int max) {
1524             return addSpring(new ComponentSpring(component, min, pref, max));
1525         }
1526 
1527         /**
1528          * Adds a rigid gap to this {@code Group}.
1529          *
1530          * @param size the size of the gap
1531          * @return this {@code Group}
1532          * @throws IllegalArgumentException if {@code size} is less than
1533          *         {@code 0}
1534          */
1535         public Group addGap(int size) {
1536             return addGap(size, size, size);
1537         }
1538 
1539         /**
1540          * Adds a gap to this {@code Group} with the specified size.
1541          *
1542          * @param min the minimum size of the gap
1543          * @param pref the preferred size of the gap
1544          * @param max the maximum size of the gap
1545          * @throws IllegalArgumentException if any of the values are
1546          *         less than {@code 0}
1547          * @return this {@code Group}
1548          */
1549         public Group addGap(int min, int pref, int max) {
1550             return addSpring(new GapSpring(min, pref, max));
1551         }
1552 
1553         Spring getSpring(int index) {
1554             return springs.get(index);
1555         }
1556 
1557         int indexOf(Spring spring) {
1558             return springs.indexOf(spring);
1559         }
1560 
1561         /**
1562          * Adds the Spring to the list of {@code Spring}s and returns
1563          * the receiver.
1564          */
1565         Group addSpring(Spring spring) {
1566             springs.add(spring);
1567             spring.setParent(this);
1568             if (!(spring instanceof AutoPreferredGapSpring) ||
1569                     !((AutoPreferredGapSpring)spring).getUserCreated()) {
1570                 springsChanged = true;
1571             }
1572             return this;
1573         }
1574 
1575         //
1576         // Spring methods
1577         //
1578 
1579         void setSize(int axis, int origin, int size) {
1580             super.setSize(axis, origin, size);
1581             if (size == UNSET) {
1582                 for (int counter = springs.size() - 1; counter >= 0;
1583                 counter--) {
1584                     getSpring(counter).setSize(axis, origin, size);
1585                 }
1586             } else {
1587                 setValidSize(axis, origin, size);
1588             }
1589         }
1590 
1591         /**
1592          * This is invoked from {@code setSize} if passed a value
1593          * other than UNSET.
1594          */
1595         abstract void setValidSize(int axis, int origin, int size);
1596 
1597         int calculateMinimumSize(int axis) {
1598             return calculateSize(axis, MIN_SIZE);
1599         }
1600 
1601         int calculatePreferredSize(int axis) {
1602             return calculateSize(axis, PREF_SIZE);
1603         }
1604 
1605         int calculateMaximumSize(int axis) {
1606             return calculateSize(axis, MAX_SIZE);
1607         }
1608 
1609         /**
1610          * Calculates the specified size.  This is called from
1611          * one of the {@code getMinimumSize0},
1612          * {@code getPreferredSize0} or
1613          * {@code getMaximumSize0} methods.  This will invoke
1614          * to {@code operator} to combine the values.
1615          */
1616         int calculateSize(int axis, int type) {
1617             int count = springs.size();
1618             if (count == 0) {
1619                 return 0;
1620             }
1621             if (count == 1) {
1622                 return getSpringSize(getSpring(0), axis, type);
1623             }
1624             int size = constrain(operator(getSpringSize(getSpring(0), axis,
1625                     type), getSpringSize(getSpring(1), axis, type)));
1626             for (int counter = 2; counter < count; counter++) {
1627                 size = constrain(operator(size, getSpringSize(
1628                         getSpring(counter), axis, type)));
1629             }
1630             return size;
1631         }
1632 
1633         int getSpringSize(Spring spring, int axis, int type) {
1634             switch(type) {
1635                 case MIN_SIZE:
1636                     return spring.getMinimumSize(axis);
1637                 case PREF_SIZE:
1638                     return spring.getPreferredSize(axis);
1639                 case MAX_SIZE:
1640                     return spring.getMaximumSize(axis);
1641             }
1642             assert false;
1643             return 0;
1644         }
1645 
1646         /**
1647          * Used to compute how the two values representing two springs
1648          * will be combined.  For example, a group that layed things out
1649          * one after the next would return {@code a + b}.
1650          */
1651         abstract int operator(int a, int b);
1652 
1653         //
1654         // Padding
1655         //
1656 
1657         /**
1658          * Adjusts the autopadding springs in this group and its children.
1659          * If {@code insert} is true this will insert auto padding
1660          * springs, otherwise this will only adjust the springs that
1661          * comprise auto preferred padding springs.
1662          *
1663          * @param axis the axis of the springs; HORIZONTAL or VERTICAL
1664          * @param leadingPadding List of AutopaddingSprings that occur before
1665          *                       this Group
1666          * @param trailingPadding any trailing autopadding springs are added
1667          *                        to this on exit
1668          * @param leading List of ComponentSprings that occur before this Group
1669          * @param trailing any trailing ComponentSpring are added to this
1670          *                 List
1671          * @param insert Whether or not to insert AutopaddingSprings or just
1672          *               adjust any existing AutopaddingSprings.
1673          */
1674         abstract void insertAutopadding(int axis,
1675                 List<AutoPreferredGapSpring> leadingPadding,
1676                 List<AutoPreferredGapSpring> trailingPadding,
1677                 List<ComponentSpring> leading, List<ComponentSpring> trailing,
1678                 boolean insert);
1679 
1680         /**
1681          * Removes any AutopaddingSprings for this Group and its children.
1682          */
1683         void removeAutopadding() {
1684             unset();
1685             for (int counter = springs.size() - 1; counter >= 0; counter--) {
1686                 Spring spring = springs.get(counter);
1687                 if (spring instanceof AutoPreferredGapSpring) {
1688                     if (((AutoPreferredGapSpring)spring).getUserCreated()) {
1689                         ((AutoPreferredGapSpring)spring).reset();
1690                     } else {
1691                         springs.remove(counter);
1692                     }
1693                 } else if (spring instanceof Group) {
1694                     ((Group)spring).removeAutopadding();
1695                 }
1696             }
1697         }
1698 
1699         void unsetAutopadding() {
1700             // Clear cached pref/min/max.
1701             unset();
1702             for (int counter = springs.size() - 1; counter >= 0; counter--) {
1703                 Spring spring = springs.get(counter);
1704                 if (spring instanceof AutoPreferredGapSpring) {
1705                     spring.unset();
1706                 } else if (spring instanceof Group) {
1707                     ((Group)spring).unsetAutopadding();
1708                 }
1709             }
1710         }
1711 
1712         void calculateAutopadding(int axis) {
1713             for (int counter = springs.size() - 1; counter >= 0; counter--) {
1714                 Spring spring = springs.get(counter);
1715                 if (spring instanceof AutoPreferredGapSpring) {
1716                     // Force size to be reset.
1717                     spring.unset();
1718                     ((AutoPreferredGapSpring)spring).calculatePadding(axis);
1719                 } else if (spring instanceof Group) {
1720                     ((Group)spring).calculateAutopadding(axis);
1721                 }
1722             }
1723             // Clear cached pref/min/max.
1724             unset();
1725         }
1726 
1727         @Override
1728         boolean willHaveZeroSize(boolean treatAutopaddingAsZeroSized) {
1729             for (int i = springs.size() - 1; i >= 0; i--) {
1730                 Spring spring = springs.get(i);
1731                 if (!spring.willHaveZeroSize(treatAutopaddingAsZeroSized)) {
1732                     return false;
1733                 }
1734             }
1735             return true;
1736         }
1737     }
1738 
1739 
1740     /**
1741      * A {@code Group} that positions and sizes its elements
1742      * sequentially, one after another.  This class has no public
1743      * constructor, use the {@code createSequentialGroup} method
1744      * to create one.
1745      * <p>
1746      * In order to align a {@code SequentialGroup} along the baseline
1747      * of a baseline aligned {@code ParallelGroup} you need to specify
1748      * which of the elements of the {@code SequentialGroup} is used to
1749      * determine the baseline.  The element used to calculate the
1750      * baseline is specified using one of the {@code add} methods that
1751      * take a {@code boolean}. The last element added with a value of
1752      * {@code true} for {@code useAsBaseline} is used to calculate the
1753      * baseline.
1754      *
1755      * @see #createSequentialGroup
1756      * @since 1.6
1757      */
1758     public class SequentialGroup extends Group {
1759         private Spring baselineSpring;
1760 
1761         SequentialGroup() {
1762         }
1763 
1764         /**
1765          * {@inheritDoc}
1766          */
1767         public SequentialGroup addGroup(Group group) {
1768             return (SequentialGroup)super.addGroup(group);
1769         }
1770 
1771         /**
1772          * Adds a {@code Group} to this {@code Group}.
1773          *
1774          * @param group the {@code Group} to add
1775          * @param useAsBaseline whether the specified {@code Group} should
1776          *        be used to calculate the baseline for this {@code Group}
1777          * @return this {@code Group}
1778          */
1779         public SequentialGroup addGroup(boolean useAsBaseline, Group group) {
1780             super.addGroup(group);
1781             if (useAsBaseline) {
1782                 baselineSpring = group;
1783             }
1784             return this;
1785         }
1786 
1787         /**
1788          * {@inheritDoc}
1789          */
1790         public SequentialGroup addComponent(Component component) {
1791             return (SequentialGroup)super.addComponent(component);
1792         }
1793 
1794         /**
1795          * Adds a {@code Component} to this {@code Group}.
1796          *
1797          * @param useAsBaseline whether the specified {@code Component} should
1798          *        be used to calculate the baseline for this {@code Group}
1799          * @param component the {@code Component} to add
1800          * @return this {@code Group}
1801          */
1802         public SequentialGroup addComponent(boolean useAsBaseline,
1803                 Component component) {
1804             super.addComponent(component);
1805             if (useAsBaseline) {
1806                 baselineSpring = springs.get(springs.size() - 1);
1807             }
1808             return this;
1809         }
1810 
1811         /**
1812          * {@inheritDoc}
1813          */
1814         public SequentialGroup addComponent(Component component, int min,
1815                 int pref, int max) {
1816             return (SequentialGroup)super.addComponent(
1817                     component, min, pref, max);
1818         }
1819 
1820         /**
1821          * Adds a {@code Component} to this {@code Group}
1822          * with the specified size.
1823          *
1824          * @param useAsBaseline whether the specified {@code Component} should
1825          *        be used to calculate the baseline for this {@code Group}
1826          * @param component the {@code Component} to add
1827          * @param min the minimum size or one of {@code DEFAULT_SIZE} or
1828          *            {@code PREFERRED_SIZE}
1829          * @param pref the preferred size or one of {@code DEFAULT_SIZE} or
1830          *            {@code PREFERRED_SIZE}
1831          * @param max the maximum size or one of {@code DEFAULT_SIZE} or
1832          *            {@code PREFERRED_SIZE}
1833          * @return this {@code Group}
1834          */
1835         public SequentialGroup addComponent(boolean useAsBaseline,
1836                 Component component, int min, int pref, int max) {
1837             super.addComponent(component, min, pref, max);
1838             if (useAsBaseline) {
1839                 baselineSpring = springs.get(springs.size() - 1);
1840             }
1841             return this;
1842         }
1843 
1844         /**
1845          * {@inheritDoc}
1846          */
1847         public SequentialGroup addGap(int size) {
1848             return (SequentialGroup)super.addGap(size);
1849         }
1850 
1851         /**
1852          * {@inheritDoc}
1853          */
1854         public SequentialGroup addGap(int min, int pref, int max) {
1855             return (SequentialGroup)super.addGap(min, pref, max);
1856         }
1857 
1858         /**
1859          * Adds an element representing the preferred gap between two
1860          * components. The element created to represent the gap is not
1861          * resizable.
1862          *
1863          * @param comp1 the first component
1864          * @param comp2 the second component
1865          * @param type the type of gap; one of the constants defined by
1866          *        {@code LayoutStyle}
1867          * @return this {@code SequentialGroup}
1868          * @throws IllegalArgumentException if {@code type}, {@code comp1} or
1869          *         {@code comp2} is {@code null}
1870          * @see LayoutStyle
1871          */
1872         public SequentialGroup addPreferredGap(JComponent comp1,
1873                 JComponent comp2, ComponentPlacement type) {
1874             return addPreferredGap(comp1, comp2, type, DEFAULT_SIZE,
1875                     PREFERRED_SIZE);
1876         }
1877 
1878         /**
1879          * Adds an element representing the preferred gap between two
1880          * components.
1881          *
1882          * @param comp1 the first component
1883          * @param comp2 the second component
1884          * @param type the type of gap
1885          * @param pref the preferred size of the grap; one of
1886          *        {@code DEFAULT_SIZE} or a value &gt;= 0
1887          * @param max the maximum size of the gap; one of
1888          *        {@code DEFAULT_SIZE}, {@code PREFERRED_SIZE}
1889          *        or a value &gt;= 0
1890          * @return this {@code SequentialGroup}
1891          * @throws IllegalArgumentException if {@code type}, {@code comp1} or
1892          *         {@code comp2} is {@code null}
1893          * @see LayoutStyle
1894          */
1895         public SequentialGroup addPreferredGap(JComponent comp1,
1896                 JComponent comp2, ComponentPlacement type, int pref,
1897                 int max) {
1898             if (type == null) {
1899                 throw new IllegalArgumentException("Type must be non-null");
1900             }
1901             if (comp1 == null || comp2 == null) {
1902                 throw new IllegalArgumentException(
1903                         "Components must be non-null");
1904             }
1905             checkPreferredGapValues(pref, max);
1906             return (SequentialGroup)addSpring(new PreferredGapSpring(
1907                     comp1, comp2, type, pref, max));
1908         }
1909 
1910         /**
1911          * Adds an element representing the preferred gap between the
1912          * nearest components.  During layout, neighboring
1913          * components are found, and the size of the added gap is set
1914          * based on the preferred gap between the components.  If no
1915          * neighboring components are found the gap has a size of {@code 0}.
1916          * <p>
1917          * The element created to represent the gap is not
1918          * resizable.
1919          *
1920          * @param type the type of gap; one of
1921          *        {@code LayoutStyle.ComponentPlacement.RELATED} or
1922          *        {@code LayoutStyle.ComponentPlacement.UNRELATED}
1923          * @return this {@code SequentialGroup}
1924          * @see LayoutStyle
1925          * @throws IllegalArgumentException if {@code type} is not one of
1926          *         {@code LayoutStyle.ComponentPlacement.RELATED} or
1927          *         {@code LayoutStyle.ComponentPlacement.UNRELATED}
1928          */
1929         public SequentialGroup addPreferredGap(ComponentPlacement type) {
1930             return addPreferredGap(type, DEFAULT_SIZE, DEFAULT_SIZE);
1931         }
1932 
1933         /**
1934          * Adds an element representing the preferred gap between the
1935          * nearest components.  During layout, neighboring
1936          * components are found, and the minimum of this
1937          * gap is set based on the size of the preferred gap between the
1938          * neighboring components.  If no neighboring components are found the
1939          * minimum size is set to 0.
1940          *
1941          * @param type the type of gap; one of
1942          *        {@code LayoutStyle.ComponentPlacement.RELATED} or
1943          *        {@code LayoutStyle.ComponentPlacement.UNRELATED}
1944          * @param pref the preferred size of the grap; one of
1945          *        {@code DEFAULT_SIZE} or a value &gt;= 0
1946          * @param max the maximum size of the gap; one of
1947          *        {@code DEFAULT_SIZE}, {@code PREFERRED_SIZE}
1948          *        or a value &gt;= 0
1949          * @return this {@code SequentialGroup}
1950          * @throws IllegalArgumentException if {@code type} is not one of
1951          *         {@code LayoutStyle.ComponentPlacement.RELATED} or
1952          *         {@code LayoutStyle.ComponentPlacement.UNRELATED}
1953          * @see LayoutStyle
1954          */
1955         public SequentialGroup addPreferredGap(ComponentPlacement type,
1956                 int pref, int max) {
1957             if (type != ComponentPlacement.RELATED &&
1958                     type != ComponentPlacement.UNRELATED) {
1959                 throw new IllegalArgumentException(
1960                         "Type must be one of " +
1961                         "LayoutStyle.ComponentPlacement.RELATED or " +
1962                         "LayoutStyle.ComponentPlacement.UNRELATED");
1963             }
1964             checkPreferredGapValues(pref, max);
1965             hasPreferredPaddingSprings = true;
1966             return (SequentialGroup)addSpring(new AutoPreferredGapSpring(
1967                     type, pref, max));
1968         }
1969 
1970         /**
1971          * Adds an element representing the preferred gap between an edge
1972          * the container and components that touch the border of the
1973          * container. This has no effect if the added gap does not
1974          * touch an edge of the parent container.
1975          * <p>
1976          * The element created to represent the gap is not
1977          * resizable.
1978          *
1979          * @return this {@code SequentialGroup}
1980          */
1981         public SequentialGroup addContainerGap() {
1982             return addContainerGap(DEFAULT_SIZE, DEFAULT_SIZE);
1983         }
1984 
1985         /**
1986          * Adds an element representing the preferred gap between one
1987          * edge of the container and the next or previous {@code
1988          * Component} with the specified size. This has no
1989          * effect if the next or previous element is not a {@code
1990          * Component} and does not touch one edge of the parent
1991          * container.
1992          *
1993          * @param pref the preferred size; one of {@code DEFAULT_SIZE} or a
1994          *              value &gt;= 0
1995          * @param max the maximum size; one of {@code DEFAULT_SIZE},
1996          *        {@code PREFERRED_SIZE} or a value &gt;= 0
1997          * @return this {@code SequentialGroup}
1998          */
1999         public SequentialGroup addContainerGap(int pref, int max) {
2000             if ((pref < 0 && pref != DEFAULT_SIZE) ||
2001                     (max < 0 && max != DEFAULT_SIZE && max != PREFERRED_SIZE)||
2002                     (pref >= 0 && max >= 0 && pref > max)) {
2003                 throw new IllegalArgumentException(
2004                         "Pref and max must be either DEFAULT_VALUE " +
2005                         "or >= 0 and pref <= max");
2006             }
2007             hasPreferredPaddingSprings = true;
2008             return (SequentialGroup)addSpring(
2009                     new ContainerAutoPreferredGapSpring(pref, max));
2010         }
2011 
2012         int operator(int a, int b) {
2013             return constrain(a) + constrain(b);
2014         }
2015 
2016         void setValidSize(int axis, int origin, int size) {
2017             int pref = getPreferredSize(axis);
2018             if (size == pref) {
2019                 // Layout at preferred size
2020                 for (Spring spring : springs) {
2021                     int springPref = spring.getPreferredSize(axis);
2022                     spring.setSize(axis, origin, springPref);
2023                     origin += springPref;
2024                 }
2025             } else if (springs.size() == 1) {
2026                 Spring spring = getSpring(0);
2027                 spring.setSize(axis, origin, Math.min(
2028                         Math.max(size, spring.getMinimumSize(axis)),
2029                         spring.getMaximumSize(axis)));
2030             } else if (springs.size() > 1) {
2031                 // Adjust between min/pref
2032                 setValidSizeNotPreferred(axis, origin, size);
2033             }
2034         }
2035 
2036         private void setValidSizeNotPreferred(int axis, int origin, int size) {
2037             int delta = size - getPreferredSize(axis);
2038             assert delta != 0;
2039             boolean useMin = (delta < 0);
2040             int springCount = springs.size();
2041             if (useMin) {
2042                 delta *= -1;
2043             }
2044 
2045             // The following algorithm if used for resizing springs:
2046             // 1. Calculate the resizability of each spring (pref - min or
2047             //    max - pref) into a list.
2048             // 2. Sort the list in ascending order
2049             // 3. Iterate through each of the resizable Springs, attempting
2050             //    to give them (pref - size) / resizeCount
2051             // 4. For any Springs that can not accommodate that much space
2052             //    add the remainder back to the amount to distribute and
2053             //    recalculate how must space the remaining springs will get.
2054             // 5. Set the size of the springs.
2055 
2056             // First pass, sort the resizable springs into the List resizable
2057             List<SpringDelta> resizable = buildResizableList(axis, useMin);
2058             int resizableCount = resizable.size();
2059 
2060             if (resizableCount > 0) {
2061                 // How much we would like to give each Spring.
2062                 int sDelta = delta / resizableCount;
2063                 // Remaining space.
2064                 int slop = delta - sDelta * resizableCount;
2065                 int[] sizes = new int[springCount];
2066                 int sign = useMin ? -1 : 1;
2067                 // Second pass, accumulate the resulting deltas (relative to
2068                 // preferred) into sizes.
2069                 for (int counter = 0; counter < resizableCount; counter++) {
2070                     SpringDelta springDelta = resizable.get(counter);
2071                     if ((counter + 1) == resizableCount) {
2072                         sDelta += slop;
2073                     }
2074                     springDelta.delta = Math.min(sDelta, springDelta.delta);
2075                     delta -= springDelta.delta;
2076                     if (springDelta.delta != sDelta && counter + 1 <
2077                             resizableCount) {
2078                         // Spring didn't take all the space, reset how much
2079                         // each spring will get.
2080                         sDelta = delta / (resizableCount - counter - 1);
2081                         slop = delta - sDelta * (resizableCount - counter - 1);
2082                     }
2083                     sizes[springDelta.index] = sign * springDelta.delta;
2084                 }
2085 
2086                 // And finally set the size of each spring
2087                 for (int counter = 0; counter < springCount; counter++) {
2088                     Spring spring = getSpring(counter);
2089                     int sSize = spring.getPreferredSize(axis) + sizes[counter];
2090                     spring.setSize(axis, origin, sSize);
2091                     origin += sSize;
2092                 }
2093             } else {
2094                 // Nothing resizable, use the min or max of each of the
2095                 // springs.
2096                 for (int counter = 0; counter < springCount; counter++) {
2097                     Spring spring = getSpring(counter);
2098                     int sSize;
2099                     if (useMin) {
2100                         sSize = spring.getMinimumSize(axis);
2101                     } else {
2102                         sSize = spring.getMaximumSize(axis);
2103                     }
2104                     spring.setSize(axis, origin, sSize);
2105                     origin += sSize;
2106                 }
2107             }
2108         }
2109 
2110         /**
2111          * Returns the sorted list of SpringDelta's for the current set of
2112          * Springs. The list is ordered based on the amount of flexibility of
2113          * the springs.
2114          */
2115         private List<SpringDelta> buildResizableList(int axis,
2116                 boolean useMin) {
2117             // First pass, figure out what is resizable
2118             int size = springs.size();
2119             List<SpringDelta> sorted = new ArrayList<SpringDelta>(size);
2120             for (int counter = 0; counter < size; counter++) {
2121                 Spring spring = getSpring(counter);
2122                 int sDelta;
2123                 if (useMin) {
2124                     sDelta = spring.getPreferredSize(axis) -
2125                             spring.getMinimumSize(axis);
2126                 } else {
2127                     sDelta = spring.getMaximumSize(axis) -
2128                             spring.getPreferredSize(axis);
2129                 }
2130                 if (sDelta > 0) {
2131                     sorted.add(new SpringDelta(counter, sDelta));
2132                 }
2133             }
2134             Collections.sort(sorted);
2135             return sorted;
2136         }
2137 
2138         private int indexOfNextNonZeroSpring(
2139                 int index, boolean treatAutopaddingAsZeroSized) {
2140             while (index < springs.size()) {
2141                 Spring spring = springs.get(index);
2142                 if (!spring.willHaveZeroSize(treatAutopaddingAsZeroSized)) {
2143                     return index;
2144                 }
2145                 index++;
2146             }
2147             return index;
2148         }
2149 
2150         @Override
2151         void insertAutopadding(int axis,
2152                 List<AutoPreferredGapSpring> leadingPadding,
2153                 List<AutoPreferredGapSpring> trailingPadding,
2154                 List<ComponentSpring> leading, List<ComponentSpring> trailing,
2155                 boolean insert) {
2156             List<AutoPreferredGapSpring> newLeadingPadding =
2157                     new ArrayList<AutoPreferredGapSpring>(leadingPadding);
2158             List<AutoPreferredGapSpring> newTrailingPadding =
2159                     new ArrayList<AutoPreferredGapSpring>(1);
2160             List<ComponentSpring> newLeading =
2161                     new ArrayList<ComponentSpring>(leading);
2162             List<ComponentSpring> newTrailing = null;
2163             int counter = 0;
2164             // Warning, this must use springs.size, as it may change during the
2165             // loop.
2166             while (counter < springs.size()) {
2167                 Spring spring = getSpring(counter);
2168                 if (spring instanceof AutoPreferredGapSpring) {
2169                     if (newLeadingPadding.size() == 0) {
2170                         // Autopadding spring. Set the sources of the
2171                         // autopadding spring based on newLeading.
2172                         AutoPreferredGapSpring padding =
2173                             (AutoPreferredGapSpring)spring;
2174                         padding.setSources(newLeading);
2175                         newLeading.clear();
2176                         counter = indexOfNextNonZeroSpring(counter + 1, true);
2177                         if (counter == springs.size()) {
2178                             // Last spring in the list, add it to
2179                             // trailingPadding.
2180                             if (!(padding instanceof
2181                                   ContainerAutoPreferredGapSpring)) {
2182                                 trailingPadding.add(padding);
2183                             }
2184                         } else {
2185                             newLeadingPadding.clear();
2186                             newLeadingPadding.add(padding);
2187                         }
2188                     } else {
2189                         counter = indexOfNextNonZeroSpring(counter + 1, true);
2190                     }
2191                 } else {
2192                     // Not a padding spring
2193                     if (newLeading.size() > 0 && insert) {
2194                         // There's leading ComponentSprings, create an
2195                         // autopadding spring.
2196                         AutoPreferredGapSpring padding =
2197                                 new AutoPreferredGapSpring();
2198                         // Force the newly created spring to be considered
2199                         // by NOT incrementing counter
2200                         springs.add(counter, padding);
2201                         continue;
2202                     }
2203                     if (spring instanceof ComponentSpring) {
2204                         // Spring is a Component, make it the target of any
2205                         // leading AutopaddingSpring.
2206                         ComponentSpring cSpring = (ComponentSpring)spring;
2207                         if (!cSpring.isVisible()) {
2208                             counter++;
2209                             continue;
2210                         }
2211                         for (AutoPreferredGapSpring gapSpring : newLeadingPadding) {
2212                             gapSpring.addTarget(cSpring, axis);
2213                         }
2214                         newLeading.clear();
2215                         newLeadingPadding.clear();
2216                         counter = indexOfNextNonZeroSpring(counter + 1, false);
2217                         if (counter == springs.size()) {
2218                             // Last Spring, add it to trailing
2219                             trailing.add(cSpring);
2220                         } else {
2221                             // Not that last Spring, add it to leading
2222                             newLeading.add(cSpring);
2223                         }
2224                     } else if (spring instanceof Group) {
2225                         // Forward call to child Group
2226                         if (newTrailing == null) {
2227                             newTrailing = new ArrayList<ComponentSpring>(1);
2228                         } else {
2229                             newTrailing.clear();
2230                         }
2231                         newTrailingPadding.clear();
2232                         ((Group)spring).insertAutopadding(axis,
2233                                 newLeadingPadding, newTrailingPadding,
2234                                 newLeading, newTrailing, insert);
2235                         newLeading.clear();
2236                         newLeadingPadding.clear();
2237                         counter = indexOfNextNonZeroSpring(
2238                                     counter + 1, (newTrailing.size() == 0));
2239                         if (counter == springs.size()) {
2240                             trailing.addAll(newTrailing);
2241                             trailingPadding.addAll(newTrailingPadding);
2242                         } else {
2243                             newLeading.addAll(newTrailing);
2244                             newLeadingPadding.addAll(newTrailingPadding);
2245                         }
2246                     } else {
2247                         // Gap
2248                         newLeadingPadding.clear();
2249                         newLeading.clear();
2250                         counter++;
2251                     }
2252                 }
2253             }
2254         }
2255 
2256         int getBaseline() {
2257             if (baselineSpring != null) {
2258                 int baseline = baselineSpring.getBaseline();
2259                 if (baseline >= 0) {
2260                     int size = 0;
2261                     for (Spring spring : springs) {
2262                         if (spring == baselineSpring) {
2263                             return size + baseline;
2264                         } else {
2265                             size += spring.getPreferredSize(VERTICAL);
2266                         }
2267                     }
2268                 }
2269             }
2270             return -1;
2271         }
2272 
2273         BaselineResizeBehavior getBaselineResizeBehavior() {
2274             if (isResizable(VERTICAL)) {
2275                 if (!baselineSpring.isResizable(VERTICAL)) {
2276                     // Spring to use for baseline isn't resizable. In this case
2277                     // baseline resize behavior can be determined based on how
2278                     // preceding springs resize.
2279                     boolean leadingResizable = false;
2280                     for (Spring spring : springs) {
2281                         if (spring == baselineSpring) {
2282                             break;
2283                         } else if (spring.isResizable(VERTICAL)) {
2284                             leadingResizable = true;
2285                             break;
2286                         }
2287                     }
2288                     boolean trailingResizable = false;
2289                     for (int i = springs.size() - 1; i >= 0; i--) {
2290                         Spring spring = springs.get(i);
2291                         if (spring == baselineSpring) {
2292                             break;
2293                         }
2294                         if (spring.isResizable(VERTICAL)) {
2295                             trailingResizable = true;
2296                             break;
2297                         }
2298                     }
2299                     if (leadingResizable && !trailingResizable) {
2300                         return BaselineResizeBehavior.CONSTANT_DESCENT;
2301                     } else if (!leadingResizable && trailingResizable) {
2302                         return BaselineResizeBehavior.CONSTANT_ASCENT;
2303                     }
2304                     // If we get here, both leading and trailing springs are
2305                     // resizable. Fall through to OTHER.
2306                 } else {
2307                     BaselineResizeBehavior brb = baselineSpring.getBaselineResizeBehavior();
2308                     if (brb == BaselineResizeBehavior.CONSTANT_ASCENT) {
2309                         for (Spring spring : springs) {
2310                             if (spring == baselineSpring) {
2311                                 return BaselineResizeBehavior.CONSTANT_ASCENT;
2312                             }
2313                             if (spring.isResizable(VERTICAL)) {
2314                                 return BaselineResizeBehavior.OTHER;
2315                             }
2316                         }
2317                     } else if (brb == BaselineResizeBehavior.CONSTANT_DESCENT) {
2318                         for (int i = springs.size() - 1; i >= 0; i--) {
2319                             Spring spring = springs.get(i);
2320                             if (spring == baselineSpring) {
2321                                 return BaselineResizeBehavior.CONSTANT_DESCENT;
2322                             }
2323                             if (spring.isResizable(VERTICAL)) {
2324                                 return BaselineResizeBehavior.OTHER;
2325                             }
2326                         }
2327                     }
2328                 }
2329                 return BaselineResizeBehavior.OTHER;
2330             }
2331             // Not resizable, treat as constant_ascent
2332             return BaselineResizeBehavior.CONSTANT_ASCENT;
2333         }
2334 
2335         private void checkPreferredGapValues(int pref, int max) {
2336             if ((pref < 0 && pref != DEFAULT_SIZE && pref != PREFERRED_SIZE) ||
2337                     (max < 0 && max != DEFAULT_SIZE && max != PREFERRED_SIZE)||
2338                     (pref >= 0 && max >= 0 && pref > max)) {
2339                 throw new IllegalArgumentException(
2340                         "Pref and max must be either DEFAULT_SIZE, " +
2341                         "PREFERRED_SIZE, or >= 0 and pref <= max");
2342             }
2343         }
2344     }
2345 
2346 
2347     /**
2348      * Used by SequentialGroup in calculating resizability of springs.
2349      */
2350     private static final class SpringDelta implements Comparable<SpringDelta> {
2351         // Original index.
2352         public final int index;
2353         // Delta, one of pref - min or max - pref.
2354         public int delta;
2355 
2356         public SpringDelta(int index, int delta) {
2357             this.index = index;
2358             this.delta = delta;
2359         }
2360 
2361         public int compareTo(SpringDelta o) {
2362             return delta - o.delta;
2363         }
2364 
2365         public String toString() {
2366             return super.toString() + "[index=" + index + ", delta=" +
2367                     delta + "]";
2368         }
2369     }
2370 
2371 
2372     /**
2373      * A {@code Group} that aligns and sizes it's children.
2374      * {@code ParallelGroup} aligns it's children in
2375      * four possible ways: along the baseline, centered, anchored to the
2376      * leading edge, or anchored to the trailing edge.
2377      * <h3>Baseline</h3>
2378      * A {@code ParallelGroup} that aligns it's children along the
2379      * baseline must first decide where the baseline is
2380      * anchored. The baseline can either be anchored to the top, or
2381      * anchored to the bottom of the group. That is, the distance between the
2382      * baseline and the beginning of the group can be a constant
2383      * distance, or the distance between the end of the group and the
2384      * baseline can be a constant distance. The possible choices
2385      * correspond to the {@code BaselineResizeBehavior} constants
2386      * {@link
2387      * java.awt.Component.BaselineResizeBehavior#CONSTANT_ASCENT CONSTANT_ASCENT} and
2388      * {@link
2389      * java.awt.Component.BaselineResizeBehavior#CONSTANT_DESCENT CONSTANT_DESCENT}.
2390      * <p>
2391      * The baseline anchor may be explicitly specified by the
2392      * {@code createBaselineGroup} method, or determined based on the elements.
2393      * If not explicitly specified, the baseline will be anchored to
2394      * the bottom if all the elements with a baseline, and that are
2395      * aligned to the baseline, have a baseline resize behavior of
2396      * {@code CONSTANT_DESCENT}; otherwise the baseline is anchored to the top
2397      * of the group.
2398      * <p>
2399      * Elements aligned to the baseline are resizable if they have have
2400      * a baseline resize behavior of {@code CONSTANT_ASCENT} or
2401      * {@code CONSTANT_DESCENT}. Elements with a baseline resize
2402      * behavior of {@code OTHER} or {@code CENTER_OFFSET} are not resizable.
2403      * <p>
2404      * The baseline is calculated based on the preferred height of each
2405      * of the elements that have a baseline. The baseline is
2406      * calculated using the following algorithm:
2407      * {@code max(maxNonBaselineHeight, maxAscent + maxDescent)}, where the
2408      * {@code maxNonBaselineHeight} is the maximum height of all elements
2409      * that do not have a baseline, or are not aligned along the baseline.
2410      * {@code maxAscent} is the maximum ascent (baseline) of all elements that
2411      * have a baseline and are aligned along the baseline.
2412      * {@code maxDescent} is the maximum descent (preferred height - baseline)
2413      * of all elements that have a baseline and are aligned along the baseline.
2414      * <p>
2415      * A {@code ParallelGroup} that aligns it's elements along the baseline
2416      * is only useful along the vertical axis. If you create a
2417      * baseline group and use it along the horizontal axis an
2418      * {@code IllegalStateException} is thrown when you ask
2419      * {@code GroupLayout} for the minimum, preferred or maximum size or
2420      * attempt to layout the components.
2421      * <p>
2422      * Elements that are not aligned to the baseline and smaller than the size
2423      * of the {@code ParallelGroup} are positioned in one of three
2424      * ways: centered, anchored to the leading edge, or anchored to the
2425      * trailing edge.
2426      *
2427      * <h3>Non-baseline {@code ParallelGroup}</h3>
2428      * {@code ParallelGroup}s created with an alignment other than
2429      * {@code BASELINE} align elements that are smaller than the size
2430      * of the group in one of three ways: centered, anchored to the
2431      * leading edge, or anchored to the trailing edge.
2432      * <p>
2433      * The leading edge is based on the axis and {@code
2434      * ComponentOrientation}.  For the vertical axis the top edge is
2435      * always the leading edge, and the bottom edge is always the
2436      * trailing edge. When the {@code ComponentOrientation} is {@code
2437      * LEFT_TO_RIGHT}, the leading edge is the left edge and the
2438      * trailing edge the right edge. A {@code ComponentOrientation} of
2439      * {@code RIGHT_TO_LEFT} flips the left and right edges. Child
2440      * elements are aligned based on the specified alignment the
2441      * element was added with. If you do not specify an alignment, the
2442      * alignment specified for the {@code ParallelGroup} is used.
2443      * <p>
2444      * To align elements along the baseline you {@code createBaselineGroup},
2445      * or {@code createParallelGroup} with an alignment of {@code BASELINE}.
2446      * If the group was not created with a baseline alignment, and you attempt
2447      * to add an element specifying a baseline alignment, an
2448      * {@code IllegalArgumentException} is thrown.
2449      *
2450      * @see #createParallelGroup()
2451      * @see #createBaselineGroup(boolean,boolean)
2452      * @since 1.6
2453      */
2454     public class ParallelGroup extends Group {
2455         // How children are layed out.
2456         private final Alignment childAlignment;
2457         // Whether or not we're resizable.
2458         private final boolean resizable;
2459 
2460         ParallelGroup(Alignment childAlignment, boolean resizable) {
2461             this.childAlignment = childAlignment;
2462             this.resizable = resizable;
2463         }
2464 
2465         /**
2466          * {@inheritDoc}
2467          */
2468         public ParallelGroup addGroup(Group group) {
2469             return (ParallelGroup)super.addGroup(group);
2470         }
2471 
2472         /**
2473          * {@inheritDoc}
2474          */
2475         public ParallelGroup addComponent(Component component) {
2476             return (ParallelGroup)super.addComponent(component);
2477         }
2478 
2479         /**
2480          * {@inheritDoc}
2481          */
2482         public ParallelGroup addComponent(Component component, int min, int pref,
2483                 int max) {
2484             return (ParallelGroup)super.addComponent(component, min, pref, max);
2485         }
2486 
2487         /**
2488          * {@inheritDoc}
2489          */
2490         public ParallelGroup addGap(int pref) {
2491             return (ParallelGroup)super.addGap(pref);
2492         }
2493 
2494         /**
2495          * {@inheritDoc}
2496          */
2497         public ParallelGroup addGap(int min, int pref, int max) {
2498             return (ParallelGroup)super.addGap(min, pref, max);
2499         }
2500 
2501         /**
2502          * Adds a {@code Group} to this {@code ParallelGroup} with the
2503          * specified alignment. If the child is smaller than the
2504          * {@code Group} it is aligned based on the specified
2505          * alignment.
2506          *
2507          * @param alignment the alignment
2508          * @param group the {@code Group} to add
2509          * @return this {@code ParallelGroup}
2510          * @throws IllegalArgumentException if {@code alignment} is
2511          *         {@code null}
2512          */
2513         public ParallelGroup addGroup(Alignment alignment, Group group) {
2514             checkChildAlignment(alignment);
2515             group.setAlignment(alignment);
2516             return (ParallelGroup)addSpring(group);
2517         }
2518 
2519         /**
2520          * Adds a {@code Component} to this {@code ParallelGroup} with
2521          * the specified alignment.
2522          *
2523          * @param alignment the alignment
2524          * @param component the {@code Component} to add
2525          * @return this {@code Group}
2526          * @throws IllegalArgumentException if {@code alignment} is
2527          *         {@code null}
2528          */
2529         public ParallelGroup addComponent(Component component,
2530                 Alignment alignment) {
2531             return addComponent(component, alignment, DEFAULT_SIZE, DEFAULT_SIZE,
2532                     DEFAULT_SIZE);
2533         }
2534 
2535         /**
2536          * Adds a {@code Component} to this {@code ParallelGroup} with the
2537          * specified alignment and size.
2538          *
2539          * @param alignment the alignment
2540          * @param component the {@code Component} to add
2541          * @param min the minimum size
2542          * @param pref the preferred size
2543          * @param max the maximum size
2544          * @throws IllegalArgumentException if {@code alignment} is
2545          *         {@code null}
2546          * @return this {@code Group}
2547          */
2548         public ParallelGroup addComponent(Component component,
2549                 Alignment alignment, int min, int pref, int max) {
2550             checkChildAlignment(alignment);
2551             ComponentSpring spring = new ComponentSpring(component,
2552                     min, pref, max);
2553             spring.setAlignment(alignment);
2554             return (ParallelGroup)addSpring(spring);
2555         }
2556 
2557         boolean isResizable() {
2558             return resizable;
2559         }
2560 
2561         int operator(int a, int b) {
2562             return Math.max(a, b);
2563         }
2564 
2565         int calculateMinimumSize(int axis) {
2566             if (!isResizable()) {
2567                 return getPreferredSize(axis);
2568             }
2569             return super.calculateMinimumSize(axis);
2570         }
2571 
2572         int calculateMaximumSize(int axis) {
2573             if (!isResizable()) {
2574                 return getPreferredSize(axis);
2575             }
2576             return super.calculateMaximumSize(axis);
2577         }
2578 
2579         void setValidSize(int axis, int origin, int size) {
2580             for (Spring spring : springs) {
2581                 setChildSize(spring, axis, origin, size);
2582             }
2583         }
2584 
2585         void setChildSize(Spring spring, int axis, int origin, int size) {
2586             Alignment alignment = spring.getAlignment();
2587             int springSize = Math.min(
2588                     Math.max(spring.getMinimumSize(axis), size),
2589                     spring.getMaximumSize(axis));
2590             if (alignment == null) {
2591                 alignment = childAlignment;
2592             }
2593             switch (alignment) {
2594                 case TRAILING:
2595                     spring.setSize(axis, origin + size - springSize,
2596                             springSize);
2597                     break;
2598                 case CENTER:
2599                     spring.setSize(axis, origin +
2600                             (size - springSize) / 2,springSize);
2601                     break;
2602                 default: // LEADING, or BASELINE
2603                     spring.setSize(axis, origin, springSize);
2604                     break;
2605             }
2606         }
2607 
2608         @Override
2609         void insertAutopadding(int axis,
2610                 List<AutoPreferredGapSpring> leadingPadding,
2611                 List<AutoPreferredGapSpring> trailingPadding,
2612                 List<ComponentSpring> leading, List<ComponentSpring> trailing,
2613                 boolean insert) {
2614             for (Spring spring : springs) {
2615                 if (spring instanceof ComponentSpring) {
2616                     if (((ComponentSpring)spring).isVisible()) {
2617                         for (AutoPreferredGapSpring gapSpring :
2618                                  leadingPadding) {
2619                             gapSpring.addTarget((ComponentSpring)spring, axis);
2620                         }
2621                         trailing.add((ComponentSpring)spring);
2622                     }
2623                 } else if (spring instanceof Group) {
2624                     ((Group)spring).insertAutopadding(axis, leadingPadding,
2625                             trailingPadding, leading, trailing, insert);
2626                 } else if (spring instanceof AutoPreferredGapSpring) {
2627                     ((AutoPreferredGapSpring)spring).setSources(leading);
2628                     trailingPadding.add((AutoPreferredGapSpring)spring);
2629                 }
2630             }
2631         }
2632 
2633         private void checkChildAlignment(Alignment alignment) {
2634             checkChildAlignment(alignment, (this instanceof BaselineGroup));
2635         }
2636 
2637         private void checkChildAlignment(Alignment alignment,
2638                 boolean allowsBaseline) {
2639             if (alignment == null) {
2640                 throw new IllegalArgumentException("Alignment must be non-null");
2641             }
2642             if (!allowsBaseline && alignment == Alignment.BASELINE) {
2643                 throw new IllegalArgumentException("Alignment must be one of:" +
2644                         "LEADING, TRAILING or CENTER");
2645             }
2646         }
2647     }
2648 
2649 
2650     /**
2651      * An extension of {@code ParallelGroup} that aligns its
2652      * constituent {@code Spring}s along the baseline.
2653      */
2654     private class BaselineGroup extends ParallelGroup {
2655         // Whether or not all child springs have a baseline
2656         private boolean allSpringsHaveBaseline;
2657 
2658         // max(spring.getBaseline()) of all springs aligned along the baseline
2659         // that have a baseline
2660         private int prefAscent;
2661 
2662         // max(spring.getPreferredSize().height - spring.getBaseline()) of all
2663         // springs aligned along the baseline that have a baseline
2664         private int prefDescent;
2665 
2666         // Whether baselineAnchoredToTop was explicitly set
2667         private boolean baselineAnchorSet;
2668 
2669         // Whether the baseline is anchored to the top or the bottom.
2670         // If anchored to the top the baseline is always at prefAscent,
2671         // otherwise the baseline is at (height - prefDescent)
2672         private boolean baselineAnchoredToTop;
2673 
2674         // Whether or not the baseline has been calculated.
2675         private boolean calcedBaseline;
2676 
2677         BaselineGroup(boolean resizable) {
2678             super(Alignment.LEADING, resizable);
2679             prefAscent = prefDescent = -1;
2680             calcedBaseline = false;
2681         }
2682 
2683         BaselineGroup(boolean resizable, boolean baselineAnchoredToTop) {
2684             this(resizable);
2685             this.baselineAnchoredToTop = baselineAnchoredToTop;
2686             baselineAnchorSet = true;
2687         }
2688 
2689         void unset() {
2690             super.unset();
2691             prefAscent = prefDescent = -1;
2692             calcedBaseline = false;
2693         }
2694 
2695         void setValidSize(int axis, int origin, int size) {
2696             checkAxis(axis);
2697             if (prefAscent == -1) {
2698                 super.setValidSize(axis, origin, size);
2699             } else {
2700                 // do baseline layout
2701                 baselineLayout(origin, size);
2702             }
2703         }
2704 
2705         int calculateSize(int axis, int type) {
2706             checkAxis(axis);
2707             if (!calcedBaseline) {
2708                 calculateBaselineAndResizeBehavior();
2709             }
2710             if (type == MIN_SIZE) {
2711                 return calculateMinSize();
2712             }
2713             if (type == MAX_SIZE) {
2714                 return calculateMaxSize();
2715             }
2716             if (allSpringsHaveBaseline) {
2717                 return prefAscent + prefDescent;
2718             }
2719             return Math.max(prefAscent + prefDescent,
2720                     super.calculateSize(axis, type));
2721         }
2722 
2723         private void calculateBaselineAndResizeBehavior() {
2724             // calculate baseline
2725             prefAscent = 0;
2726             prefDescent = 0;
2727             int baselineSpringCount = 0;
2728             BaselineResizeBehavior resizeBehavior = null;
2729             for (Spring spring : springs) {
2730                 if (spring.getAlignment() == null ||
2731                         spring.getAlignment() == Alignment.BASELINE) {
2732                     int baseline = spring.getBaseline();
2733                     if (baseline >= 0) {
2734                         if (spring.isResizable(VERTICAL)) {
2735                             BaselineResizeBehavior brb = spring.
2736                                     getBaselineResizeBehavior();
2737                             if (resizeBehavior == null) {
2738                                 resizeBehavior = brb;
2739                             } else if (brb != resizeBehavior) {
2740                                 resizeBehavior = BaselineResizeBehavior.
2741                                         CONSTANT_ASCENT;
2742                             }
2743                         }
2744                         prefAscent = Math.max(prefAscent, baseline);
2745                         prefDescent = Math.max(prefDescent, spring.
2746                                 getPreferredSize(VERTICAL) - baseline);
2747                         baselineSpringCount++;
2748                     }
2749                 }
2750             }
2751             if (!baselineAnchorSet) {
2752                 if (resizeBehavior == BaselineResizeBehavior.CONSTANT_DESCENT){
2753                     this.baselineAnchoredToTop = false;
2754                 } else {
2755                     this.baselineAnchoredToTop = true;
2756                 }
2757             }
2758             allSpringsHaveBaseline = (baselineSpringCount == springs.size());
2759             calcedBaseline = true;
2760         }
2761 
2762         private int calculateMaxSize() {
2763             int maxAscent = prefAscent;
2764             int maxDescent = prefDescent;
2765             int nonBaselineMax = 0;
2766             for (Spring spring : springs) {
2767                 int baseline;
2768                 int springMax = spring.getMaximumSize(VERTICAL);
2769                 if ((spring.getAlignment() == null ||
2770                         spring.getAlignment() == Alignment.BASELINE) &&
2771                         (baseline = spring.getBaseline()) >= 0) {
2772                     int springPref = spring.getPreferredSize(VERTICAL);
2773                     if (springPref != springMax) {
2774                         switch (spring.getBaselineResizeBehavior()) {
2775                             case CONSTANT_ASCENT:
2776                                 if (baselineAnchoredToTop) {
2777                                     maxDescent = Math.max(maxDescent,
2778                                             springMax - baseline);
2779                                 }
2780                                 break;
2781                             case CONSTANT_DESCENT:
2782                                 if (!baselineAnchoredToTop) {
2783                                     maxAscent = Math.max(maxAscent,
2784                                             springMax - springPref + baseline);
2785                                 }
2786                                 break;
2787                             default: // CENTER_OFFSET and OTHER, not resizable
2788                                 break;
2789                         }
2790                     }
2791                 } else {
2792                     // Not aligned along the baseline, or no baseline.
2793                     nonBaselineMax = Math.max(nonBaselineMax, springMax);
2794                 }
2795             }
2796             return Math.max(nonBaselineMax, maxAscent + maxDescent);
2797         }
2798 
2799         private int calculateMinSize() {
2800             int minAscent = 0;
2801             int minDescent = 0;
2802             int nonBaselineMin = 0;
2803             if (baselineAnchoredToTop) {
2804                 minAscent = prefAscent;
2805             } else {
2806                 minDescent = prefDescent;
2807             }
2808             for (Spring spring : springs) {
2809                 int springMin = spring.getMinimumSize(VERTICAL);
2810                 int baseline;
2811                 if ((spring.getAlignment() == null ||
2812                         spring.getAlignment() == Alignment.BASELINE) &&
2813                         (baseline = spring.getBaseline()) >= 0) {
2814                     int springPref = spring.getPreferredSize(VERTICAL);
2815                     BaselineResizeBehavior brb = spring.
2816                             getBaselineResizeBehavior();
2817                     switch (brb) {
2818                         case CONSTANT_ASCENT:
2819                             if (baselineAnchoredToTop) {
2820                                 minDescent = Math.max(springMin - baseline,
2821                                         minDescent);
2822                             } else {
2823                                 minAscent = Math.max(baseline, minAscent);
2824                             }
2825                             break;
2826                         case CONSTANT_DESCENT:
2827                             if (!baselineAnchoredToTop) {
2828                                 minAscent = Math.max(
2829                                         baseline - (springPref - springMin),
2830                                         minAscent);
2831                             } else {
2832                                 minDescent = Math.max(springPref - baseline,
2833                                         minDescent);
2834                             }
2835                             break;
2836                         default:
2837                             // CENTER_OFFSET and OTHER are !resizable, use
2838                             // the preferred size.
2839                             minAscent = Math.max(baseline, minAscent);
2840                             minDescent = Math.max(springPref - baseline,
2841                                     minDescent);
2842                             break;
2843                     }
2844                 } else {
2845                     // Not aligned along the baseline, or no baseline.
2846                     nonBaselineMin = Math.max(nonBaselineMin, springMin);
2847                 }
2848             }
2849             return Math.max(nonBaselineMin, minAscent + minDescent);
2850         }
2851 
2852         /**
2853          * Lays out springs that have a baseline along the baseline.  All
2854          * others are centered.
2855          */
2856         private void baselineLayout(int origin, int size) {
2857             int ascent;
2858             int descent;
2859             if (baselineAnchoredToTop) {
2860                 ascent = prefAscent;
2861                 descent = size - ascent;
2862             } else {
2863                 ascent = size - prefDescent;
2864                 descent = prefDescent;
2865             }
2866             for (Spring spring : springs) {
2867                 Alignment alignment = spring.getAlignment();
2868                 if (alignment == null || alignment == Alignment.BASELINE) {
2869                     int baseline = spring.getBaseline();
2870                     if (baseline >= 0) {
2871                         int springMax = spring.getMaximumSize(VERTICAL);
2872                         int springPref = spring.getPreferredSize(VERTICAL);
2873                         int height = springPref;
2874                         int y;
2875                         switch(spring.getBaselineResizeBehavior()) {
2876                             case CONSTANT_ASCENT:
2877                                 y = origin + ascent - baseline;
2878                                 height = Math.min(descent, springMax -
2879                                         baseline) + baseline;
2880                                 break;
2881                             case CONSTANT_DESCENT:
2882                                 height = Math.min(ascent, springMax -
2883                                         springPref + baseline) +
2884                                         (springPref - baseline);
2885                                 y = origin + ascent +
2886                                         (springPref - baseline) - height;
2887                                 break;
2888                             default: // CENTER_OFFSET & OTHER, not resizable
2889                                 y = origin + ascent - baseline;
2890                                 break;
2891                         }
2892                         spring.setSize(VERTICAL, y, height);
2893                     } else {
2894                         setChildSize(spring, VERTICAL, origin, size);
2895                     }
2896                 } else {
2897                     setChildSize(spring, VERTICAL, origin, size);
2898                 }
2899             }
2900         }
2901 
2902         int getBaseline() {
2903             if (springs.size() > 1) {
2904                 // Force the baseline to be calculated
2905                 getPreferredSize(VERTICAL);
2906                 return prefAscent;
2907             } else if (springs.size() == 1) {
2908                 return springs.get(0).getBaseline();
2909             }
2910             return -1;
2911         }
2912 
2913         BaselineResizeBehavior getBaselineResizeBehavior() {
2914             if (springs.size() == 1) {
2915                 return springs.get(0).getBaselineResizeBehavior();
2916             }
2917             if (baselineAnchoredToTop) {
2918                 return BaselineResizeBehavior.CONSTANT_ASCENT;
2919             }
2920             return BaselineResizeBehavior.CONSTANT_DESCENT;
2921         }
2922 
2923         // If the axis is VERTICAL, throws an IllegalStateException
2924         private void checkAxis(int axis) {
2925             if (axis == HORIZONTAL) {
2926                 throw new IllegalStateException(
2927                         "Baseline must be used along vertical axis");
2928             }
2929         }
2930     }
2931 
2932 
2933     private final class ComponentSpring extends Spring {
2934         private Component component;
2935         private int origin;
2936 
2937         // min/pref/max are either a value >= 0 or one of
2938         // DEFAULT_SIZE or PREFERRED_SIZE
2939         private final int min;
2940         private final int pref;
2941         private final int max;
2942 
2943         // Baseline for the component, computed as necessary.
2944         private int baseline = -1;
2945 
2946         // Whether or not the size has been requested yet.
2947         private boolean installed;
2948 
2949         private ComponentSpring(Component component, int min, int pref,
2950                 int max) {
2951             this.component = component;
2952             if (component == null) {
2953                 throw new IllegalArgumentException(
2954                         "Component must be non-null");
2955             }
2956 
2957             checkSize(min, pref, max, true);
2958 
2959             this.min = min;
2960             this.max = max;
2961             this.pref = pref;
2962 
2963             // getComponentInfo makes sure component is a child of the
2964             // Container GroupLayout is the LayoutManager for.
2965             getComponentInfo(component);
2966         }
2967 
2968         int calculateMinimumSize(int axis) {
2969             if (isLinked(axis)) {
2970                 return getLinkSize(axis, MIN_SIZE);
2971             }
2972             return calculateNonlinkedMinimumSize(axis);
2973         }
2974 
2975         int calculatePreferredSize(int axis) {
2976             if (isLinked(axis)) {
2977                 return getLinkSize(axis, PREF_SIZE);
2978             }
2979             int min = getMinimumSize(axis);
2980             int pref = calculateNonlinkedPreferredSize(axis);
2981             int max = getMaximumSize(axis);
2982             return Math.min(max, Math.max(min, pref));
2983         }
2984 
2985         int calculateMaximumSize(int axis) {
2986             if (isLinked(axis)) {
2987                 return getLinkSize(axis, MAX_SIZE);
2988             }
2989             return Math.max(getMinimumSize(axis),
2990                     calculateNonlinkedMaximumSize(axis));
2991         }
2992 
2993         boolean isVisible() {
2994             return getComponentInfo(getComponent()).isVisible();
2995         }
2996 
2997         int calculateNonlinkedMinimumSize(int axis) {
2998             if (!isVisible()) {
2999                 return 0;
3000             }
3001             if (min >= 0) {
3002                 return min;
3003             }
3004             if (min == PREFERRED_SIZE) {
3005                 return calculateNonlinkedPreferredSize(axis);
3006             }
3007             assert (min == DEFAULT_SIZE);
3008             return getSizeAlongAxis(axis, component.getMinimumSize());
3009         }
3010 
3011         int calculateNonlinkedPreferredSize(int axis) {
3012             if (!isVisible()) {
3013                 return 0;
3014             }
3015             if (pref >= 0) {
3016                 return pref;
3017             }
3018             assert (pref == DEFAULT_SIZE || pref == PREFERRED_SIZE);
3019             return getSizeAlongAxis(axis, component.getPreferredSize());
3020         }
3021 
3022         int calculateNonlinkedMaximumSize(int axis) {
3023             if (!isVisible()) {
3024                 return 0;
3025             }
3026             if (max >= 0) {
3027                 return max;
3028             }
3029             if (max == PREFERRED_SIZE) {
3030                 return calculateNonlinkedPreferredSize(axis);
3031             }
3032             assert (max == DEFAULT_SIZE);
3033             return getSizeAlongAxis(axis, component.getMaximumSize());
3034         }
3035 
3036         private int getSizeAlongAxis(int axis, Dimension size) {
3037             return (axis == HORIZONTAL) ? size.width : size.height;
3038         }
3039 
3040         private int getLinkSize(int axis, int type) {
3041             if (!isVisible()) {
3042                 return 0;
3043             }
3044             ComponentInfo ci = getComponentInfo(component);
3045             return ci.getLinkSize(axis, type);
3046         }
3047 
3048         void setSize(int axis, int origin, int size) {
3049             super.setSize(axis, origin, size);
3050             this.origin = origin;
3051             if (size == UNSET) {
3052                 baseline = -1;
3053             }
3054         }
3055 
3056         int getOrigin() {
3057             return origin;
3058         }
3059 
3060         void setComponent(Component component) {
3061             this.component = component;
3062         }
3063 
3064         Component getComponent() {
3065             return component;
3066         }
3067 
3068         int getBaseline() {
3069             if (baseline == -1) {
3070                 Spring horizontalSpring = getComponentInfo(component).
3071                         horizontalSpring;
3072                 int width = horizontalSpring.getPreferredSize(HORIZONTAL);
3073                 int height = getPreferredSize(VERTICAL);
3074                 if (width > 0 && height > 0) {
3075                     baseline = component.getBaseline(width, height);
3076                 }
3077             }
3078             return baseline;
3079         }
3080 
3081         BaselineResizeBehavior getBaselineResizeBehavior() {
3082             return getComponent().getBaselineResizeBehavior();
3083         }
3084 
3085         private boolean isLinked(int axis) {
3086             return getComponentInfo(component).isLinked(axis);
3087         }
3088 
3089         void installIfNecessary(int axis) {
3090             if (!installed) {
3091                 installed = true;
3092                 if (axis == HORIZONTAL) {
3093                     getComponentInfo(component).horizontalSpring = this;
3094                 } else {
3095                     getComponentInfo(component).verticalSpring = this;
3096                 }
3097             }
3098         }
3099 
3100         @Override
3101         boolean willHaveZeroSize(boolean treatAutopaddingAsZeroSized) {
3102             return !isVisible();
3103         }
3104     }
3105 
3106 
3107     /**
3108      * Spring representing the preferred distance between two components.
3109      */
3110     private class PreferredGapSpring extends Spring {
3111         private final JComponent source;
3112         private final JComponent target;
3113         private final ComponentPlacement type;
3114         private final int pref;
3115         private final int max;
3116 
3117         PreferredGapSpring(JComponent source, JComponent target,
3118                 ComponentPlacement type, int pref, int max) {
3119             this.source = source;
3120             this.target = target;
3121             this.type = type;
3122             this.pref = pref;
3123             this.max = max;
3124         }
3125 
3126         int calculateMinimumSize(int axis) {
3127             return getPadding(axis);
3128         }
3129 
3130         int calculatePreferredSize(int axis) {
3131             if (pref == DEFAULT_SIZE || pref == PREFERRED_SIZE) {
3132                 return getMinimumSize(axis);
3133             }
3134             int min = getMinimumSize(axis);
3135             int max = getMaximumSize(axis);
3136             return Math.min(max, Math.max(min, pref));
3137         }
3138 
3139         int calculateMaximumSize(int axis) {
3140             if (max == PREFERRED_SIZE || max == DEFAULT_SIZE) {
3141                 return getPadding(axis);
3142             }
3143             return Math.max(getMinimumSize(axis), max);
3144         }
3145 
3146         private int getPadding(int axis) {
3147             int position;
3148             if (axis == HORIZONTAL) {
3149                 position = SwingConstants.EAST;
3150             } else {
3151                 position = SwingConstants.SOUTH;
3152             }
3153             return getLayoutStyle0().getPreferredGap(source,
3154                     target, type, position, host);
3155         }
3156 
3157         @Override
3158         boolean willHaveZeroSize(boolean treatAutopaddingAsZeroSized) {
3159             return false;
3160         }
3161     }
3162 
3163 
3164     /**
3165      * Spring represented a certain amount of space.
3166      */
3167     private class GapSpring extends Spring {
3168         private final int min;
3169         private final int pref;
3170         private final int max;
3171 
3172         GapSpring(int min, int pref, int max) {
3173             checkSize(min, pref, max, false);
3174             this.min = min;
3175             this.pref = pref;
3176             this.max = max;
3177         }
3178 
3179         int calculateMinimumSize(int axis) {
3180             if (min == PREFERRED_SIZE) {
3181                 return getPreferredSize(axis);
3182             }
3183             return min;
3184         }
3185 
3186         int calculatePreferredSize(int axis) {
3187             return pref;
3188         }
3189 
3190         int calculateMaximumSize(int axis) {
3191             if (max == PREFERRED_SIZE) {
3192                 return getPreferredSize(axis);
3193             }
3194             return max;
3195         }
3196 
3197         @Override
3198         boolean willHaveZeroSize(boolean treatAutopaddingAsZeroSized) {
3199             return false;
3200         }
3201     }
3202 
3203 
3204     /**
3205      * Spring reprensenting the distance between any number of sources and
3206      * targets.  The targets and sources are computed during layout.  An
3207      * instance of this can either be dynamically created when
3208      * autocreatePadding is true, or explicitly created by the developer.
3209      */
3210     private class AutoPreferredGapSpring extends Spring {
3211         List<ComponentSpring> sources;
3212         ComponentSpring source;
3213         private List<AutoPreferredGapMatch> matches;
3214         int size;
3215         int lastSize;
3216         private final int pref;
3217         private final int max;
3218         // Type of gap
3219         private ComponentPlacement type;
3220         private boolean userCreated;
3221 
3222         private AutoPreferredGapSpring() {
3223             this.pref = PREFERRED_SIZE;
3224             this.max = PREFERRED_SIZE;
3225             this.type = ComponentPlacement.RELATED;
3226         }
3227 
3228         AutoPreferredGapSpring(int pref, int max) {
3229             this.pref = pref;
3230             this.max = max;
3231         }
3232 
3233         AutoPreferredGapSpring(ComponentPlacement type, int pref, int max) {
3234             this.type = type;
3235             this.pref = pref;
3236             this.max = max;
3237             this.userCreated = true;
3238         }
3239 
3240         public void setSource(ComponentSpring source) {
3241             this.source = source;
3242         }
3243 
3244         public void setSources(List<ComponentSpring> sources) {
3245             this.sources = new ArrayList<ComponentSpring>(sources);
3246         }
3247 
3248         public void setUserCreated(boolean userCreated) {
3249             this.userCreated = userCreated;
3250         }
3251 
3252         public boolean getUserCreated() {
3253             return userCreated;
3254         }
3255 
3256         void unset() {
3257             lastSize = getSize();
3258             super.unset();
3259             size = 0;
3260         }
3261 
3262         public void reset() {
3263             size = 0;
3264             sources = null;
3265             source = null;
3266             matches = null;
3267         }
3268 
3269         public void calculatePadding(int axis) {
3270             size = UNSET;
3271             int maxPadding = UNSET;
3272             if (matches != null) {
3273                 LayoutStyle p = getLayoutStyle0();
3274                 int position;
3275                 if (axis == HORIZONTAL) {
3276                     if (isLeftToRight()) {
3277                         position = SwingConstants.EAST;
3278                     } else {
3279                         position = SwingConstants.WEST;
3280                     }
3281                 } else {
3282                     position = SwingConstants.SOUTH;
3283                 }
3284                 for (int i = matches.size() - 1; i >= 0; i--) {
3285                     AutoPreferredGapMatch match = matches.get(i);
3286                     maxPadding = Math.max(maxPadding,
3287                             calculatePadding(p, position, match.source,
3288                             match.target));
3289                 }
3290             }
3291             if (size == UNSET) {
3292                 size = 0;
3293             }
3294             if (maxPadding == UNSET) {
3295                 maxPadding = 0;
3296             }
3297             if (lastSize != UNSET) {
3298                 size += Math.min(maxPadding, lastSize);
3299             }
3300         }
3301 
3302         private int calculatePadding(LayoutStyle p, int position,
3303                 ComponentSpring source,
3304                 ComponentSpring target) {
3305             int delta = target.getOrigin() - (source.getOrigin() +
3306                     source.getSize());
3307             if (delta >= 0) {
3308                 int padding;
3309                 if ((source.getComponent() instanceof JComponent) &&
3310                         (target.getComponent() instanceof JComponent)) {
3311                     padding = p.getPreferredGap(
3312                             (JComponent)source.getComponent(),
3313                             (JComponent)target.getComponent(), type, position,
3314                             host);
3315                 } else {
3316                     padding = 10;
3317                 }
3318                 if (padding > delta) {
3319                     size = Math.max(size, padding - delta);
3320                 }
3321                 return padding;
3322             }
3323             return 0;
3324         }
3325 
3326         public void addTarget(ComponentSpring spring, int axis) {
3327             int oAxis = (axis == HORIZONTAL) ? VERTICAL : HORIZONTAL;
3328             if (source != null) {
3329                 if (areParallelSiblings(source.getComponent(),
3330                         spring.getComponent(), oAxis)) {
3331                     addValidTarget(source, spring);
3332                 }
3333             } else {
3334                 Component component = spring.getComponent();
3335                 for (int counter = sources.size() - 1; counter >= 0;
3336                          counter--){
3337                     ComponentSpring source = sources.get(counter);
3338                     if (areParallelSiblings(source.getComponent(),
3339                             component, oAxis)) {
3340                         addValidTarget(source, spring);
3341                     }
3342                 }
3343             }
3344         }
3345 
3346         private void addValidTarget(ComponentSpring source,
3347                 ComponentSpring target) {
3348             if (matches == null) {
3349                 matches = new ArrayList<AutoPreferredGapMatch>(1);
3350             }
3351             matches.add(new AutoPreferredGapMatch(source, target));
3352         }
3353 
3354         int calculateMinimumSize(int axis) {
3355             return size;
3356         }
3357 
3358         int calculatePreferredSize(int axis) {
3359             if (pref == PREFERRED_SIZE || pref == DEFAULT_SIZE) {
3360                 return size;
3361             }
3362             return Math.max(size, pref);
3363         }
3364 
3365         int calculateMaximumSize(int axis) {
3366             if (max >= 0) {
3367                 return Math.max(getPreferredSize(axis), max);
3368             }
3369             return size;
3370         }
3371 
3372         String getMatchDescription() {
3373             return (matches == null) ? "" : matches.toString();
3374         }
3375 
3376         public String toString() {
3377             return super.toString() + getMatchDescription();
3378         }
3379 
3380         @Override
3381         boolean willHaveZeroSize(boolean treatAutopaddingAsZeroSized) {
3382             return treatAutopaddingAsZeroSized;
3383         }
3384     }
3385 
3386 
3387     /**
3388      * Represents two springs that should have autopadding inserted between
3389      * them.
3390      */
3391     private final static class AutoPreferredGapMatch {
3392         public final ComponentSpring source;
3393         public final ComponentSpring target;
3394 
3395         AutoPreferredGapMatch(ComponentSpring source, ComponentSpring target) {
3396             this.source = source;
3397             this.target = target;
3398         }
3399 
3400         private String toString(ComponentSpring spring) {
3401             return spring.getComponent().getName();
3402         }
3403 
3404         public String toString() {
3405             return "[" + toString(source) + "-" + toString(target) + "]";
3406         }
3407     }
3408 
3409 
3410     /**
3411      * An extension of AutopaddingSpring used for container level padding.
3412      */
3413     private class ContainerAutoPreferredGapSpring extends
3414             AutoPreferredGapSpring {
3415         private List<ComponentSpring> targets;
3416 
3417         ContainerAutoPreferredGapSpring() {
3418             super();
3419             setUserCreated(true);
3420         }
3421 
3422         ContainerAutoPreferredGapSpring(int pref, int max) {
3423             super(pref, max);
3424             setUserCreated(true);
3425         }
3426 
3427         public void addTarget(ComponentSpring spring, int axis) {
3428             if (targets == null) {
3429                 targets = new ArrayList<ComponentSpring>(1);
3430             }
3431             targets.add(spring);
3432         }
3433 
3434         public void calculatePadding(int axis) {
3435             LayoutStyle p = getLayoutStyle0();
3436             int maxPadding = 0;
3437             int position;
3438             size = 0;
3439             if (targets != null) {
3440                 // Leading
3441                 if (axis == HORIZONTAL) {
3442                     if (isLeftToRight()) {
3443                         position = SwingConstants.WEST;
3444                     } else {
3445                         position = SwingConstants.EAST;
3446                     }
3447                 } else {
3448                     position = SwingConstants.SOUTH;
3449                 }
3450                 for (int i = targets.size() - 1; i >= 0; i--) {
3451                     ComponentSpring targetSpring = targets.get(i);
3452                     int padding = 10;
3453                     if (targetSpring.getComponent() instanceof JComponent) {
3454                         padding = p.getContainerGap(
3455                                 (JComponent)targetSpring.getComponent(),
3456                                 position, host);
3457                         maxPadding = Math.max(padding, maxPadding);
3458                         padding -= targetSpring.getOrigin();
3459                     } else {
3460                         maxPadding = Math.max(padding, maxPadding);
3461                     }
3462                     size = Math.max(size, padding);
3463                 }
3464             } else {
3465                 // Trailing
3466                 if (axis == HORIZONTAL) {
3467                     if (isLeftToRight()) {
3468                         position = SwingConstants.EAST;
3469                     } else {
3470                         position = SwingConstants.WEST;
3471                     }
3472                 } else {
3473                     position = SwingConstants.SOUTH;
3474                 }
3475                 if (sources != null) {
3476                     for (int i = sources.size() - 1; i >= 0; i--) {
3477                         ComponentSpring sourceSpring = sources.get(i);
3478                         maxPadding = Math.max(maxPadding,
3479                                 updateSize(p, sourceSpring, position));
3480                     }
3481                 } else if (source != null) {
3482                     maxPadding = updateSize(p, source, position);
3483                 }
3484             }
3485             if (lastSize != UNSET) {
3486                 size += Math.min(maxPadding, lastSize);
3487             }
3488         }
3489 
3490         private int updateSize(LayoutStyle p, ComponentSpring sourceSpring,
3491                 int position) {
3492             int padding = 10;
3493             if (sourceSpring.getComponent() instanceof JComponent) {
3494                 padding = p.getContainerGap(
3495                         (JComponent)sourceSpring.getComponent(), position,
3496                         host);
3497             }
3498             int delta = Math.max(0, getParent().getSize() -
3499                     sourceSpring.getSize() - sourceSpring.getOrigin());
3500             size = Math.max(size, padding - delta);
3501             return padding;
3502         }
3503 
3504         String getMatchDescription() {
3505             if (targets != null) {
3506                 return "leading: " + targets.toString();
3507             }
3508             if (sources != null) {
3509                 return "trailing: " + sources.toString();
3510             }
3511             return "--";
3512         }
3513     }
3514 
3515 
3516     // LinkInfo contains the set of ComponentInfosthat are linked along a
3517     // particular axis.
3518     private static class LinkInfo {
3519         private final int axis;
3520         private final List<ComponentInfo> linked;
3521         private int size;
3522 
3523         LinkInfo(int axis) {
3524             linked = new ArrayList<ComponentInfo>();
3525             size = UNSET;
3526             this.axis = axis;
3527         }
3528 
3529         public void add(ComponentInfo child) {
3530             LinkInfo childMaster = child.getLinkInfo(axis, false);
3531             if (childMaster == null) {
3532                 linked.add(child);
3533                 child.setLinkInfo(axis, this);
3534             } else if (childMaster != this) {
3535                 linked.addAll(childMaster.linked);
3536                 for (ComponentInfo childInfo : childMaster.linked) {
3537                     childInfo.setLinkInfo(axis, this);
3538                 }
3539             }
3540             clearCachedSize();
3541         }
3542 
3543         public void remove(ComponentInfo info) {
3544             linked.remove(info);
3545             info.setLinkInfo(axis, null);
3546             if (linked.size() == 1) {
3547                 linked.get(0).setLinkInfo(axis, null);
3548             }
3549             clearCachedSize();
3550         }
3551 
3552         public void clearCachedSize() {
3553             size = UNSET;
3554         }
3555 
3556         public int getSize(int axis) {
3557             if (size == UNSET) {
3558                 size = calculateLinkedSize(axis);
3559             }
3560             return size;
3561         }
3562 
3563         private int calculateLinkedSize(int axis) {
3564             int size = 0;
3565             for (ComponentInfo info : linked) {
3566                 ComponentSpring spring;
3567                 if (axis == HORIZONTAL) {
3568                     spring = info.horizontalSpring;
3569                 } else {
3570                     assert (axis == VERTICAL);
3571                     spring = info.verticalSpring;
3572                 }
3573                 size = Math.max(size,
3574                         spring.calculateNonlinkedPreferredSize(axis));
3575             }
3576             return size;
3577         }
3578     }
3579 
3580     /**
3581      * Tracks the horizontal/vertical Springs for a Component.
3582      * This class is also used to handle Springs that have their sizes
3583      * linked.
3584      */
3585     private class ComponentInfo {
3586         // Component being layed out
3587         private Component component;
3588 
3589         ComponentSpring horizontalSpring;
3590         ComponentSpring verticalSpring;
3591 
3592         // If the component's size is linked to other components, the
3593         // horizontalMaster and/or verticalMaster reference the group of
3594         // linked components.
3595         private LinkInfo horizontalMaster;
3596         private LinkInfo verticalMaster;
3597 
3598         private boolean visible;
3599         private Boolean honorsVisibility;
3600 
3601         ComponentInfo(Component component) {
3602             this.component = component;
3603             updateVisibility();
3604         }
3605 
3606         public void dispose() {
3607             // Remove horizontal/vertical springs
3608             removeSpring(horizontalSpring);
3609             horizontalSpring = null;
3610             removeSpring(verticalSpring);
3611             verticalSpring = null;
3612             // Clean up links
3613             if (horizontalMaster != null) {
3614                 horizontalMaster.remove(this);
3615             }
3616             if (verticalMaster != null) {
3617                 verticalMaster.remove(this);
3618             }
3619         }
3620 
3621         void setHonorsVisibility(Boolean honorsVisibility) {
3622             this.honorsVisibility = honorsVisibility;
3623         }
3624 
3625         private void removeSpring(Spring spring) {
3626             if (spring != null) {
3627                 ((Group)spring.getParent()).springs.remove(spring);
3628             }
3629         }
3630 
3631         public boolean isVisible() {
3632             return visible;
3633         }
3634 
3635         /**
3636          * Updates the cached visibility.
3637          *
3638          * @return true if the visibility changed
3639          */
3640         boolean updateVisibility() {
3641             boolean honorsVisibility;
3642             if (this.honorsVisibility == null) {
3643                 honorsVisibility = GroupLayout.this.getHonorsVisibility();
3644             } else {
3645                 honorsVisibility = this.honorsVisibility;
3646             }
3647             boolean newVisible = (honorsVisibility) ?
3648                 component.isVisible() : true;
3649             if (visible != newVisible) {
3650                 visible = newVisible;
3651                 return true;
3652             }
3653             return false;
3654         }
3655 
3656         public void setBounds(Insets insets, int parentWidth, boolean ltr) {
3657             int x = horizontalSpring.getOrigin();
3658             int w = horizontalSpring.getSize();
3659             int y = verticalSpring.getOrigin();
3660             int h = verticalSpring.getSize();
3661 
3662             if (!ltr) {
3663                 x = parentWidth - x - w;
3664             }
3665             component.setBounds(x + insets.left, y + insets.top, w, h);
3666         }
3667 
3668         public void setComponent(Component component) {
3669             this.component = component;
3670             if (horizontalSpring != null) {
3671                 horizontalSpring.setComponent(component);
3672             }
3673             if (verticalSpring != null) {
3674                 verticalSpring.setComponent(component);
3675             }
3676         }
3677 
3678         public Component getComponent() {
3679             return component;
3680         }
3681 
3682         /**
3683          * Returns true if this component has its size linked to
3684          * other components.
3685          */
3686         public boolean isLinked(int axis) {
3687             if (axis == HORIZONTAL) {
3688                 return horizontalMaster != null;
3689             }
3690             assert (axis == VERTICAL);
3691             return (verticalMaster != null);
3692         }
3693 
3694         private void setLinkInfo(int axis, LinkInfo linkInfo) {
3695             if (axis == HORIZONTAL) {
3696                 horizontalMaster = linkInfo;
3697             } else {
3698                 assert (axis == VERTICAL);
3699                 verticalMaster = linkInfo;
3700             }
3701         }
3702 
3703         public LinkInfo getLinkInfo(int axis) {
3704             return getLinkInfo(axis, true);
3705         }
3706 
3707         private LinkInfo getLinkInfo(int axis, boolean create) {
3708             if (axis == HORIZONTAL) {
3709                 if (horizontalMaster == null && create) {
3710                     // horizontalMaster field is directly set by adding
3711                     // us to the LinkInfo.
3712                     new LinkInfo(HORIZONTAL).add(this);
3713                 }
3714                 return horizontalMaster;
3715             } else {
3716                 assert (axis == VERTICAL);
3717                 if (verticalMaster == null && create) {
3718                     // verticalMaster field is directly set by adding
3719                     // us to the LinkInfo.
3720                     new LinkInfo(VERTICAL).add(this);
3721                 }
3722                 return verticalMaster;
3723             }
3724         }
3725 
3726         public void clearCachedSize() {
3727             if (horizontalMaster != null) {
3728                 horizontalMaster.clearCachedSize();
3729             }
3730             if (verticalMaster != null) {
3731                 verticalMaster.clearCachedSize();
3732             }
3733         }
3734 
3735         int getLinkSize(int axis, int type) {
3736             if (axis == HORIZONTAL) {
3737                 return horizontalMaster.getSize(axis);
3738             } else {
3739                 assert (axis == VERTICAL);
3740                 return verticalMaster.getSize(axis);
3741             }
3742         }
3743 
3744     }
3745 }
--- EOF ---