1 /*
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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25 package javax.swing.text;
26
27 import java.awt.*;
28 import javax.swing.SwingConstants;
29 import javax.swing.event.*;
30
31 /**
32 * <p>
33 * A very important part of the text package is the <code>View</code> class.
34 * As the name suggests it represents a view of the text model,
35 * or a piece of the text model.
36 * It is this class that is responsible for the look of the text component.
37 * The view is not intended to be some completely new thing that one must
38 * learn, but rather is much like a lightweight component.
39 * <p>
40 By default, a view is very light. It contains a reference to the parent
41 view from which it can fetch many things without holding state, and it
42 contains a reference to a portion of the model (<code>Element</code>).
43 A view does not
44 have to exactly represent an element in the model, that is simply a typical
45 and therefore convenient mapping. A view can alternatively maintain a couple
46 of Position objects to maintain its location in the model (i.e. represent
47 a fragment of an element). This is typically the result of formatting where
48 views have been broken down into pieces. The convenience of a substantial
49 relationship to the element makes it easier to build factories to produce the
50 views, and makes it easier to keep track of the view pieces as the model is
51 changed and the view must be changed to reflect the model. Simple views
52 therefore represent an Element directly and complex views do not.
53 <p>
54 A view has the following responsibilities:
55 <dl>
56
57 <dt><b>Participate in layout.</b>
58 <dd>
59 <p>The view has a <code>setSize</code> method which is like
60 <code>doLayout</code> and <code>setSize</code> in <code>Component</code> combined.
61 The view has a <code>preferenceChanged</code> method which is
62 like <code>invalidate</code> in <code>Component</code> except that one can
63 invalidate just one axis
64 and the child requesting the change is identified.
65 <p>A View expresses the size that it would like to be in terms of three
66 values, a minimum, a preferred, and a maximum span. Layout in a view is
67 can be done independently upon each axis. For a properly functioning View
68 implementation, the minimum span will be <= the preferred span which in turn
69 will be <= the maximum span.
70 </p>
71 <p style="text-align:center"><img src="doc-files/View-flexibility.jpg"
72 alt="The above text describes this graphic.">
73 <p>The minimum set of methods for layout are:
74 <ul>
75 <li>{@link #getMinimumSpan(int) getMinimumSpan}
76 <li>{@link #getPreferredSpan(int) getPreferredSpan}
77 <li>{@link #getMaximumSpan(int) getMaximumSpan}
78 <li>{@link #getAlignment(int) getAlignment}
79 <li>{@link #preferenceChanged(javax.swing.text.View, boolean, boolean) preferenceChanged}
80 <li>{@link #setSize(float, float) setSize}
81 </ul>
82
83 <p>The <code>setSize</code> method should be prepared to be called a number of times
84 (i.e. It may be called even if the size didn't change).
85 The <code>setSize</code> method
86 is generally called to make sure the View layout is complete prior to trying
87 to perform an operation on it that requires an up-to-date layout. A view's
88 size should <em>always</em> be set to a value within the minimum and maximum
89 span specified by that view. Additionally, the view must always call the
90 <code>preferenceChanged</code> method on the parent if it has changed the
91 values for the
92 layout it would like, and expects the parent to honor. The parent View is
93 not required to recognize a change until the <code>preferenceChanged</code>
94 has been sent.
95 This allows parent View implementations to cache the child requirements if
96 desired. The calling sequence looks something like the following:
97 </p>
98 <p style="text-align:center">
99 <img src="doc-files/View-layout.jpg"
100 alt="Sample calling sequence between parent view and child view:
101 setSize, getMinimum, getPreferred, getMaximum, getAlignment, setSize">
102 <p>The exact calling sequence is up to the layout functionality of
103 the parent view (if the view has any children). The view may collect
104 the preferences of the children prior to determining what it will give
105 each child, or it might iteratively update the children one at a time.
106 </p>
107
108 <dt><b>Render a portion of the model.</b>
109 <dd>
110 <p>This is done in the paint method, which is pretty much like a component
111 paint method. Views are expected to potentially populate a fairly large
112 tree. A <code>View</code> has the following semantics for rendering:
113 </p>
114 <ul>
115 <li>The view gets its allocation from the parent at paint time, so it
116 must be prepared to redo layout if the allocated area is different from
117 what it is prepared to deal with.
118 <li>The coordinate system is the same as the hosting <code>Component</code>
119 (i.e. the <code>Component</code> returned by the
120 {@link #getContainer getContainer} method).
121 This means a child view lives in the same coordinate system as the parent
122 view unless the parent has explicitly changed the coordinate system.
123 To schedule itself to be repainted a view can call repaint on the hosting
124 <code>Component</code>.
125 <li>The default is to <em>not clip</em> the children. It is more efficient
126 to allow a view to clip only if it really feels it needs clipping.
127 <li>The <code>Graphics</code> object given is not initialized in any way.
128 A view should set any settings needed.
129 <li>A <code>View</code> is inherently transparent. While a view may render into its
130 entire allocation, typically a view does not. Rendering is performed by
131 traversing down the tree of <code>View</code> implementations.
132 Each <code>View</code> is responsible
133 for rendering its children. This behavior is depended upon for thread
134 safety. While view implementations do not necessarily have to be implemented
135 with thread safety in mind, other view implementations that do make use of
136 concurrency can depend upon a tree traversal to guarantee thread safety.
137 <li>The order of views relative to the model is up to the implementation.
138 Although child views will typically be arranged in the same order that they
139 occur in the model, they may be visually arranged in an entirely different
140 order. View implementations may have Z-Order associated with them if the
141 children are overlapping.
142 </ul>
143 <p>The methods for rendering are:
144 <ul>
145 <li>{@link #paint(java.awt.Graphics, java.awt.Shape) paint}
146 </ul>
147
148 <dt><b>Translate between the model and view coordinate systems.</b>
149 <dd>
150 <p>Because the view objects are produced from a factory and therefore cannot
151 necessarily be counted upon to be in a particular pattern, one must be able
152 to perform translation to properly locate spatial representation of the model.
153 The methods for doing this are:
154 <ul>
155 <li>{@link #modelToView(int, javax.swing.text.Position.Bias, int, javax.swing.text.Position.Bias, java.awt.Shape) modelToView}
156 <li>{@link #viewToModel(float, float, java.awt.Shape, javax.swing.text.Position.Bias[]) viewToModel}
157 <li>{@link #getDocument() getDocument}
158 <li>{@link #getElement() getElement}
159 <li>{@link #getStartOffset() getStartOffset}
160 <li>{@link #getEndOffset() getEndOffset}
161 </ul>
162 <p>The layout must be valid prior to attempting to make the translation.
163 The translation is not valid, and must not be attempted while changes
164 are being broadcasted from the model via a <code>DocumentEvent</code>.
165 </p>
166
167 <dt><b>Respond to changes from the model.</b>
168 <dd>
169 <p>If the overall view is represented by many pieces (which is the best situation
170 if one want to be able to change the view and write the least amount of new code),
171 it would be impractical to have a huge number of <code>DocumentListener</code>s.
172 If each
173 view listened to the model, only a few would actually be interested in the
174 changes broadcasted at any given time. Since the model has no knowledge of
175 views, it has no way to filter the broadcast of change information. The view
176 hierarchy itself is instead responsible for propagating the change information.
177 At any level in the view hierarchy, that view knows enough about its children to
178 best distribute the change information further. Changes are therefore broadcasted
179 starting from the root of the view hierarchy.
180 The methods for doing this are:
181 <ul>
182 <li>{@link #insertUpdate insertUpdate}
183 <li>{@link #removeUpdate removeUpdate}
184 <li>{@link #changedUpdate changedUpdate}
185 </ul>
186 </dl>
187 *
188 * @author Timothy Prinzing
189 */
190 public abstract class View implements SwingConstants {
191
192 /**
193 * Creates a new <code>View</code> object.
194 *
195 * @param elem the <code>Element</code> to represent
196 */
197 public View(Element elem) {
198 this.elem = elem;
199 }
200
201 /**
202 * Returns the parent of the view.
203 *
204 * @return the parent, or <code>null</code> if none exists
205 */
206 public View getParent() {
207 return parent;
208 }
209
210 /**
211 * Returns a boolean that indicates whether
212 * the view is visible or not. By default
213 * all views are visible.
214 *
215 * @return always returns true
216 */
217 public boolean isVisible() {
218 return true;
219 }
220
221
222 /**
223 * Determines the preferred span for this view along an
224 * axis.
225 *
226 * @param axis may be either <code>View.X_AXIS</code> or
227 * <code>View.Y_AXIS</code>
228 * @return the span the view would like to be rendered into.
229 * Typically the view is told to render into the span
230 * that is returned, although there is no guarantee.
231 * The parent may choose to resize or break the view
232 * @see View#getPreferredSpan
233 */
234 public abstract float getPreferredSpan(int axis);
235
236 /**
237 * Determines the minimum span for this view along an
238 * axis.
239 *
240 * @param axis may be either <code>View.X_AXIS</code> or
241 * <code>View.Y_AXIS</code>
242 * @return the minimum span the view can be rendered into
243 * @see View#getPreferredSpan
244 */
245 public float getMinimumSpan(int axis) {
246 int w = getResizeWeight(axis);
247 if (w == 0) {
248 // can't resize
249 return getPreferredSpan(axis);
250 }
251 return 0;
252 }
253
254 /**
255 * Determines the maximum span for this view along an
256 * axis.
257 *
258 * @param axis may be either <code>View.X_AXIS</code> or
259 * <code>View.Y_AXIS</code>
260 * @return the maximum span the view can be rendered into
261 * @see View#getPreferredSpan
262 */
263 public float getMaximumSpan(int axis) {
264 int w = getResizeWeight(axis);
265 if (w == 0) {
266 // can't resize
267 return getPreferredSpan(axis);
268 }
269 return Integer.MAX_VALUE;
270 }
271
272 /**
273 * Child views can call this on the parent to indicate that
274 * the preference has changed and should be reconsidered
275 * for layout. By default this just propagates upward to
276 * the next parent. The root view will call
277 * <code>revalidate</code> on the associated text component.
278 *
279 * @param child the child view
280 * @param width true if the width preference has changed
281 * @param height true if the height preference has changed
282 * @see javax.swing.JComponent#revalidate
283 */
284 public void preferenceChanged(View child, boolean width, boolean height) {
285 View parent = getParent();
286 if (parent != null) {
287 parent.preferenceChanged(this, width, height);
288 }
289 }
290
291 /**
292 * Determines the desired alignment for this view along an
293 * axis. The desired alignment is returned. This should be
294 * a value >= 0.0 and <= 1.0, where 0 indicates alignment at
295 * the origin and 1.0 indicates alignment to the full span
296 * away from the origin. An alignment of 0.5 would be the
297 * center of the view.
298 *
299 * @param axis may be either <code>View.X_AXIS</code> or
300 * <code>View.Y_AXIS</code>
301 * @return the value 0.5
302 */
303 public float getAlignment(int axis) {
304 return 0.5f;
305 }
306
307 /**
308 * Renders using the given rendering surface and area on that
309 * surface. The view may need to do layout and create child
310 * views to enable itself to render into the given allocation.
311 *
312 * @param g the rendering surface to use
313 * @param allocation the allocated region to render into
314 */
315 public abstract void paint(Graphics g, Shape allocation);
316
317 /**
318 * Establishes the parent view for this view. This is
319 * guaranteed to be called before any other methods if the
320 * parent view is functioning properly. This is also
321 * the last method called, since it is called to indicate
322 * the view has been removed from the hierarchy as
323 * well. When this method is called to set the parent to
324 * null, this method does the same for each of its children,
325 * propagating the notification that they have been
326 * disconnected from the view tree. If this is
327 * reimplemented, <code>super.setParent()</code> should
328 * be called.
329 *
330 * @param parent the new parent, or <code>null</code> if the view is
331 * being removed from a parent
332 */
333 public void setParent(View parent) {
334 // if the parent is null then propogate down the view tree
335 if (parent == null) {
336 for (int i = 0; i < getViewCount(); i++) {
337 if (getView(i).getParent() == this) {
338 // in FlowView.java view might be referenced
339 // from two super-views as a child. see logicalView
340 getView(i).setParent(null);
341 }
342 }
343 }
344 this.parent = parent;
345 }
346
347 /**
348 * Returns the number of views in this view. Since
349 * the default is to not be a composite view this
350 * returns 0.
351 *
352 * @return the number of views >= 0
353 * @see View#getViewCount
354 */
355 public int getViewCount() {
356 return 0;
357 }
358
359 /**
360 * Gets the <i>n</i>th child view. Since there are no
361 * children by default, this returns <code>null</code>.
362 *
363 * @param n the number of the view to get, >= 0 && < getViewCount()
364 * @return the view
365 */
366 public View getView(int n) {
367 return null;
368 }
369
370
371 /**
372 * Removes all of the children. This is a convenience
373 * call to <code>replace</code>.
374 *
375 * @since 1.3
376 */
377 public void removeAll() {
378 replace(0, getViewCount(), null);
379 }
380
381 /**
382 * Removes one of the children at the given position.
383 * This is a convenience call to <code>replace</code>.
384 * @since 1.3
385 */
386 public void remove(int i) {
387 replace(i, 1, null);
388 }
389
390 /**
391 * Inserts a single child view. This is a convenience
392 * call to <code>replace</code>.
393 *
394 * @param offs the offset of the view to insert before >= 0
395 * @param v the view
396 * @see #replace
397 * @since 1.3
398 */
399 public void insert(int offs, View v) {
400 View[] one = new View[1];
401 one[0] = v;
402 replace(offs, 0, one);
403 }
404
405 /**
406 * Appends a single child view. This is a convenience
407 * call to <code>replace</code>.
408 *
409 * @param v the view
410 * @see #replace
411 * @since 1.3
412 */
413 public void append(View v) {
414 View[] one = new View[1];
415 one[0] = v;
416 replace(getViewCount(), 0, one);
417 }
418
419 /**
420 * Replaces child views. If there are no views to remove
421 * this acts as an insert. If there are no views to
422 * add this acts as a remove. Views being removed will
423 * have the parent set to <code>null</code>, and the internal reference
424 * to them removed so that they can be garbage collected.
425 * This is implemented to do nothing, because by default
426 * a view has no children.
427 *
428 * @param offset the starting index into the child views to insert
429 * the new views. This should be a value >= 0 and <= getViewCount
430 * @param length the number of existing child views to remove
431 * This should be a value >= 0 and <= (getViewCount() - offset).
432 * @param views the child views to add. This value can be
433 * <code>null</code> to indicate no children are being added
434 * (useful to remove).
435 * @since 1.3
436 */
437 public void replace(int offset, int length, View[] views) {
438 }
439
440 /**
441 * Returns the child view index representing the given position in
442 * the model. By default a view has no children so this is implemented
443 * to return -1 to indicate there is no valid child index for any
444 * position.
445 *
446 * @param pos the position >= 0
447 * @return index of the view representing the given position, or
448 * -1 if no view represents that position
449 * @since 1.3
450 */
451 public int getViewIndex(int pos, Position.Bias b) {
452 return -1;
453 }
454
455 /**
456 * Fetches the allocation for the given child view.
457 * This enables finding out where various views
458 * are located, without assuming how the views store
459 * their location. This returns <code>null</code> since the
460 * default is to not have any child views.
461 *
462 * @param index the index of the child, >= 0 && <
463 * <code>getViewCount()</code>
464 * @param a the allocation to this view
465 * @return the allocation to the child
466 */
467 public Shape getChildAllocation(int index, Shape a) {
468 return null;
469 }
470
471 /**
472 * Provides a way to determine the next visually represented model
473 * location at which one might place a caret.
474 * Some views may not be visible,
475 * they might not be in the same order found in the model, or they just
476 * might not allow access to some of the locations in the model.
477 * This method enables specifying a position to convert
478 * within the range of >=0. If the value is -1, a position
479 * will be calculated automatically. If the value < -1,
480 * the {@code BadLocationException} will be thrown.
481 *
482 * @param pos the position to convert
483 * @param a the allocated region in which to render
484 * @param direction the direction from the current position that can
485 * be thought of as the arrow keys typically found on a keyboard.
486 * This will be one of the following values:
487 * <ul>
488 * <li>SwingConstants.WEST
489 * <li>SwingConstants.EAST
490 * <li>SwingConstants.NORTH
491 * <li>SwingConstants.SOUTH
492 * </ul>
493 * @return the location within the model that best represents the next
494 * location visual position
495 * @exception BadLocationException the given position is not a valid
496 * position within the document
497 * @exception IllegalArgumentException if <code>direction</code>
498 * doesn't have one of the legal values above
499 */
500 public int getNextVisualPositionFrom(int pos, Position.Bias b, Shape a,
501 int direction, Position.Bias[] biasRet)
502 throws BadLocationException {
503 if (pos < -1 || pos > getDocument().getLength()) {
504 // -1 is a reserved value, see the code below
505 throw new BadLocationException("Invalid position", pos);
506 }
507
508 biasRet[0] = Position.Bias.Forward;
509 switch (direction) {
510 case NORTH:
511 case SOUTH:
512 {
513 if (pos == -1) {
514 pos = (direction == NORTH) ? Math.max(0, getEndOffset() - 1) :
515 getStartOffset();
516 break;
517 }
518 JTextComponent target = (JTextComponent) getContainer();
519 Caret c = (target != null) ? target.getCaret() : null;
520 // YECK! Ideally, the x location from the magic caret position
521 // would be passed in.
522 Point mcp;
523 if (c != null) {
524 mcp = c.getMagicCaretPosition();
525 }
526 else {
527 mcp = null;
528 }
529 int x;
530 if (mcp == null) {
531 Rectangle loc = target.modelToView(pos);
532 x = (loc == null) ? 0 : loc.x;
533 }
534 else {
535 x = mcp.x;
536 }
537 if (direction == NORTH) {
538 pos = Utilities.getPositionAbove(target, pos, x);
539 }
540 else {
541 pos = Utilities.getPositionBelow(target, pos, x);
542 }
543 }
544 break;
545 case WEST:
546 if(pos == -1) {
547 pos = Math.max(0, getEndOffset() - 1);
548 }
549 else {
550 pos = Math.max(0, pos - 1);
551 }
552 break;
553 case EAST:
554 if(pos == -1) {
555 pos = getStartOffset();
556 }
557 else {
558 pos = Math.min(pos + 1, getDocument().getLength());
559 }
560 break;
561 default:
562 throw new IllegalArgumentException("Bad direction: " + direction);
563 }
564 return pos;
565 }
566
567 /**
568 * Provides a mapping, for a given character,
569 * from the document model coordinate space
570 * to the view coordinate space.
571 *
572 * @param pos the position of the desired character (>=0)
573 * @param a the area of the view, which encompasses the requested character
574 * @param b the bias toward the previous character or the
575 * next character represented by the offset, in case the
576 * position is a boundary of two views; <code>b</code> will have one
577 * of these values:
578 * <ul>
579 * <li> <code>Position.Bias.Forward</code>
580 * <li> <code>Position.Bias.Backward</code>
581 * </ul>
582 * @return the bounding box, in view coordinate space,
583 * of the character at the specified position
584 * @exception BadLocationException if the specified position does
585 * not represent a valid location in the associated document
586 * @exception IllegalArgumentException if <code>b</code> is not one of the
587 * legal <code>Position.Bias</code> values listed above
588 * @see View#viewToModel
589 */
590 public abstract Shape modelToView(int pos, Shape a, Position.Bias b) throws BadLocationException;
591
592 /**
593 * Provides a mapping, for a given region,
594 * from the document model coordinate space
595 * to the view coordinate space. The specified region is
596 * created as a union of the first and last character positions.
597 *
598 * @param p0 the position of the first character (>=0)
599 * @param b0 the bias of the first character position,
600 * toward the previous character or the
601 * next character represented by the offset, in case the
602 * position is a boundary of two views; <code>b0</code> will have one
603 * of these values:
604 * <ul style="list-style-type:none">
605 * <li> <code>Position.Bias.Forward</code>
606 * <li> <code>Position.Bias.Backward</code>
607 * </ul>
608 * @param p1 the position of the last character (>=0)
609 * @param b1 the bias for the second character position, defined
610 * one of the legal values shown above
611 * @param a the area of the view, which encompasses the requested region
612 * @return the bounding box which is a union of the region specified
613 * by the first and last character positions
614 * @exception BadLocationException if the given position does
615 * not represent a valid location in the associated document
616 * @exception IllegalArgumentException if <code>b0</code> or
617 * <code>b1</code> are not one of the
618 * legal <code>Position.Bias</code> values listed above
619 * @see View#viewToModel
620 */
621 public Shape modelToView(int p0, Position.Bias b0, int p1, Position.Bias b1, Shape a) throws BadLocationException {
622 Shape s0 = modelToView(p0, a, b0);
623 Shape s1;
624 if (p1 == getEndOffset()) {
625 try {
626 s1 = modelToView(p1, a, b1);
627 } catch (BadLocationException ble) {
628 s1 = null;
629 }
630 if (s1 == null) {
631 // Assume extends left to right.
632 Rectangle alloc = (a instanceof Rectangle) ? (Rectangle)a :
633 a.getBounds();
634 s1 = new Rectangle(alloc.x + alloc.width - 1, alloc.y,
635 1, alloc.height);
636 }
637 }
638 else {
639 s1 = modelToView(p1, a, b1);
640 }
641 Rectangle r0 = s0.getBounds();
642 Rectangle r1 = (s1 instanceof Rectangle) ? (Rectangle) s1 :
643 s1.getBounds();
644 if (r0.y != r1.y) {
645 // If it spans lines, force it to be the width of the view.
646 Rectangle alloc = (a instanceof Rectangle) ? (Rectangle)a :
647 a.getBounds();
648 r0.x = alloc.x;
649 r0.width = alloc.width;
650 }
651 r0.add(r1);
652 return r0;
653 }
654
655 /**
656 * Provides a mapping from the view coordinate space to the logical
657 * coordinate space of the model. The <code>biasReturn</code>
658 * argument will be filled in to indicate that the point given is
659 * closer to the next character in the model or the previous
660 * character in the model.
661 *
662 * @param x the X coordinate >= 0
663 * @param y the Y coordinate >= 0
664 * @param a the allocated region in which to render
665 * @return the location within the model that best represents the
666 * given point in the view >= 0. The <code>biasReturn</code>
667 * argument will be
668 * filled in to indicate that the point given is closer to the next
669 * character in the model or the previous character in the model.
670 */
671 public abstract int viewToModel(float x, float y, Shape a, Position.Bias[] biasReturn);
672
673 /**
674 * Gives notification that something was inserted into
675 * the document in a location that this view is responsible for.
676 * To reduce the burden to subclasses, this functionality is
677 * spread out into the following calls that subclasses can
678 * reimplement:
679 * <ol>
680 * <li>{@link #updateChildren updateChildren} is called
681 * if there were any changes to the element this view is
682 * responsible for. If this view has child views that are
683 * represent the child elements, then this method should do
684 * whatever is necessary to make sure the child views correctly
685 * represent the model.
686 * <li>{@link #forwardUpdate forwardUpdate} is called
687 * to forward the DocumentEvent to the appropriate child views.
688 * <li>{@link #updateLayout updateLayout} is called to
689 * give the view a chance to either repair its layout, to reschedule
690 * layout, or do nothing.
691 * </ol>
692 *
693 * @param e the change information from the associated document
694 * @param a the current allocation of the view
695 * @param f the factory to use to rebuild if the view has children
696 * @see View#insertUpdate
697 */
698 public void insertUpdate(DocumentEvent e, Shape a, ViewFactory f) {
699 if (getViewCount() > 0) {
700 Element elem = getElement();
701 DocumentEvent.ElementChange ec = e.getChange(elem);
702 if (ec != null) {
703 if (! updateChildren(ec, e, f)) {
704 // don't consider the element changes they
705 // are for a view further down.
706 ec = null;
707 }
708 }
709 forwardUpdate(ec, e, a, f);
710 updateLayout(ec, e, a);
711 }
712 }
713
714 /**
715 * Gives notification that something was removed from the document
716 * in a location that this view is responsible for.
717 * To reduce the burden to subclasses, this functionality is
718 * spread out into the following calls that subclasses can
719 * reimplement:
720 * <ol>
721 * <li>{@link #updateChildren updateChildren} is called
722 * if there were any changes to the element this view is
723 * responsible for. If this view has child views that are
724 * represent the child elements, then this method should do
725 * whatever is necessary to make sure the child views correctly
726 * represent the model.
727 * <li>{@link #forwardUpdate forwardUpdate} is called
728 * to forward the DocumentEvent to the appropriate child views.
729 * <li>{@link #updateLayout updateLayout} is called to
730 * give the view a chance to either repair its layout, to reschedule
731 * layout, or do nothing.
732 * </ol>
733 *
734 * @param e the change information from the associated document
735 * @param a the current allocation of the view
736 * @param f the factory to use to rebuild if the view has children
737 * @see View#removeUpdate
738 */
739 public void removeUpdate(DocumentEvent e, Shape a, ViewFactory f) {
740 if (getViewCount() > 0) {
741 Element elem = getElement();
742 DocumentEvent.ElementChange ec = e.getChange(elem);
743 if (ec != null) {
744 if (! updateChildren(ec, e, f)) {
745 // don't consider the element changes they
746 // are for a view further down.
747 ec = null;
748 }
749 }
750 forwardUpdate(ec, e, a, f);
751 updateLayout(ec, e, a);
752 }
753 }
754
755 /**
756 * Gives notification from the document that attributes were changed
757 * in a location that this view is responsible for.
758 * To reduce the burden to subclasses, this functionality is
759 * spread out into the following calls that subclasses can
760 * reimplement:
761 * <ol>
762 * <li>{@link #updateChildren updateChildren} is called
763 * if there were any changes to the element this view is
764 * responsible for. If this view has child views that are
765 * represent the child elements, then this method should do
766 * whatever is necessary to make sure the child views correctly
767 * represent the model.
768 * <li>{@link #forwardUpdate forwardUpdate} is called
769 * to forward the DocumentEvent to the appropriate child views.
770 * <li>{@link #updateLayout updateLayout} is called to
771 * give the view a chance to either repair its layout, to reschedule
772 * layout, or do nothing.
773 * </ol>
774 *
775 * @param e the change information from the associated document
776 * @param a the current allocation of the view
777 * @param f the factory to use to rebuild if the view has children
778 * @see View#changedUpdate
779 */
780 public void changedUpdate(DocumentEvent e, Shape a, ViewFactory f) {
781 if (getViewCount() > 0) {
782 Element elem = getElement();
783 DocumentEvent.ElementChange ec = e.getChange(elem);
784 if (ec != null) {
785 if (! updateChildren(ec, e, f)) {
786 // don't consider the element changes they
787 // are for a view further down.
788 ec = null;
789 }
790 }
791 forwardUpdate(ec, e, a, f);
792 updateLayout(ec, e, a);
793 }
794 }
795
796 /**
797 * Fetches the model associated with the view.
798 *
799 * @return the view model, <code>null</code> if none
800 * @see View#getDocument
801 */
802 public Document getDocument() {
803 return elem.getDocument();
804 }
805
806 /**
807 * Fetches the portion of the model for which this view is
808 * responsible.
809 *
810 * @return the starting offset into the model >= 0
811 * @see View#getStartOffset
812 */
813 public int getStartOffset() {
814 return elem.getStartOffset();
815 }
816
817 /**
818 * Fetches the portion of the model for which this view is
819 * responsible.
820 *
821 * @return the ending offset into the model >= 0
822 * @see View#getEndOffset
823 */
824 public int getEndOffset() {
825 return elem.getEndOffset();
826 }
827
828 /**
829 * Fetches the structural portion of the subject that this
830 * view is mapped to. The view may not be responsible for the
831 * entire portion of the element.
832 *
833 * @return the subject
834 * @see View#getElement
835 */
836 public Element getElement() {
837 return elem;
838 }
839
840 /**
841 * Fetch a <code>Graphics</code> for rendering.
842 * This can be used to determine
843 * font characteristics, and will be different for a print view
844 * than a component view.
845 *
846 * @return a <code>Graphics</code> object for rendering
847 * @since 1.3
848 */
849 public Graphics getGraphics() {
850 // PENDING(prinz) this is a temporary implementation
851 Component c = getContainer();
852 return c.getGraphics();
853 }
854
855 /**
856 * Fetches the attributes to use when rendering. By default
857 * this simply returns the attributes of the associated element.
858 * This method should be used rather than using the element
859 * directly to obtain access to the attributes to allow
860 * view-specific attributes to be mixed in or to allow the
861 * view to have view-specific conversion of attributes by
862 * subclasses.
863 * Each view should document what attributes it recognizes
864 * for the purpose of rendering or layout, and should always
865 * access them through the <code>AttributeSet</code> returned
866 * by this method.
867 */
868 public AttributeSet getAttributes() {
869 return elem.getAttributes();
870 }
871
872 /**
873 * Tries to break this view on the given axis. This is
874 * called by views that try to do formatting of their
875 * children. For example, a view of a paragraph will
876 * typically try to place its children into row and
877 * views representing chunks of text can sometimes be
878 * broken down into smaller pieces.
879 * <p>
880 * This is implemented to return the view itself, which
881 * represents the default behavior on not being
882 * breakable. If the view does support breaking, the
883 * starting offset of the view returned should be the
884 * given offset, and the end offset should be less than
885 * or equal to the end offset of the view being broken.
886 *
887 * @param axis may be either <code>View.X_AXIS</code> or
888 * <code>View.Y_AXIS</code>
889 * @param offset the location in the document model
890 * that a broken fragment would occupy >= 0. This
891 * would be the starting offset of the fragment
892 * returned
893 * @param pos the position along the axis that the
894 * broken view would occupy >= 0. This may be useful for
895 * things like tab calculations
896 * @param len specifies the distance along the axis
897 * where a potential break is desired >= 0
898 * @return the fragment of the view that represents the
899 * given span, if the view can be broken. If the view
900 * doesn't support breaking behavior, the view itself is
901 * returned.
902 * @see ParagraphView
903 */
904 public View breakView(int axis, int offset, float pos, float len) {
905 return this;
906 }
907
908 /**
909 * Creates a view that represents a portion of the element.
910 * This is potentially useful during formatting operations
911 * for taking measurements of fragments of the view. If
912 * the view doesn't support fragmenting (the default), it
913 * should return itself.
914 *
915 * @param p0 the starting offset >= 0. This should be a value
916 * greater or equal to the element starting offset and
917 * less than the element ending offset.
918 * @param p1 the ending offset > p0. This should be a value
919 * less than or equal to the elements end offset and
920 * greater than the elements starting offset.
921 * @return the view fragment, or itself if the view doesn't
922 * support breaking into fragments
923 * @see LabelView
924 */
925 public View createFragment(int p0, int p1) {
926 return this;
927 }
928
929 /**
930 * Determines how attractive a break opportunity in
931 * this view is. This can be used for determining which
932 * view is the most attractive to call <code>breakView</code>
933 * on in the process of formatting. A view that represents
934 * text that has whitespace in it might be more attractive
935 * than a view that has no whitespace, for example. The
936 * higher the weight, the more attractive the break. A
937 * value equal to or lower than <code>BadBreakWeight</code>
938 * should not be considered for a break. A value greater
939 * than or equal to <code>ForcedBreakWeight</code> should
940 * be broken.
941 * <p>
942 * This is implemented to provide the default behavior
943 * of returning <code>BadBreakWeight</code> unless the length
944 * is greater than the length of the view in which case the
945 * entire view represents the fragment. Unless a view has
946 * been written to support breaking behavior, it is not
947 * attractive to try and break the view. An example of
948 * a view that does support breaking is <code>LabelView</code>.
949 * An example of a view that uses break weight is
950 * <code>ParagraphView</code>.
951 *
952 * @param axis may be either <code>View.X_AXIS</code> or
953 * <code>View.Y_AXIS</code>
954 * @param pos the potential location of the start of the
955 * broken view >= 0. This may be useful for calculating tab
956 * positions
957 * @param len specifies the relative length from <em>pos</em>
958 * where a potential break is desired >= 0
959 * @return the weight, which should be a value between
960 * ForcedBreakWeight and BadBreakWeight
961 * @see LabelView
962 * @see ParagraphView
963 * @see #BadBreakWeight
964 * @see #GoodBreakWeight
965 * @see #ExcellentBreakWeight
966 * @see #ForcedBreakWeight
967 */
968 public int getBreakWeight(int axis, float pos, float len) {
969 if (len > getPreferredSpan(axis)) {
970 return GoodBreakWeight;
971 }
972 return BadBreakWeight;
973 }
974
975 /**
976 * Determines the resizability of the view along the
977 * given axis. A value of 0 or less is not resizable.
978 *
979 * @param axis may be either <code>View.X_AXIS</code> or
980 * <code>View.Y_AXIS</code>
981 * @return the weight
982 */
983 public int getResizeWeight(int axis) {
984 return 0;
985 }
986
987 /**
988 * Sets the size of the view. This should cause
989 * layout of the view along the given axis, if it
990 * has any layout duties.
991 *
992 * @param width the width >= 0
993 * @param height the height >= 0
994 */
995 public void setSize(float width, float height) {
996 }
997
998 /**
999 * Fetches the container hosting the view. This is useful for
1000 * things like scheduling a repaint, finding out the host
1001 * components font, etc. The default implementation
1002 * of this is to forward the query to the parent view.
1003 *
1004 * @return the container, <code>null</code> if none
1005 */
1006 public Container getContainer() {
1007 View v = getParent();
1008 return (v != null) ? v.getContainer() : null;
1009 }
1010
1011 /**
1012 * Fetches the <code>ViewFactory</code> implementation that is feeding
1013 * the view hierarchy. Normally the views are given this
1014 * as an argument to updates from the model when they
1015 * are most likely to need the factory, but this
1016 * method serves to provide it at other times.
1017 *
1018 * @return the factory, <code>null</code> if none
1019 */
1020 public ViewFactory getViewFactory() {
1021 View v = getParent();
1022 return (v != null) ? v.getViewFactory() : null;
1023 }
1024
1025 /**
1026 * Returns the tooltip text at the specified location. The default
1027 * implementation returns the value from the child View identified by
1028 * the passed in location.
1029 *
1030 * @since 1.4
1031 * @see JTextComponent#getToolTipText
1032 */
1033 public String getToolTipText(float x, float y, Shape allocation) {
1034 int viewIndex = getViewIndex(x, y, allocation);
1035 if (viewIndex >= 0) {
1036 allocation = getChildAllocation(viewIndex, allocation);
1037 Rectangle rect = (allocation instanceof Rectangle) ?
1038 (Rectangle)allocation : allocation.getBounds();
1039 if (rect.contains(x, y)) {
1040 return getView(viewIndex).getToolTipText(x, y, allocation);
1041 }
1042 }
1043 return null;
1044 }
1045
1046 /**
1047 * Returns the child view index representing the given position in
1048 * the view. This iterates over all the children returning the
1049 * first with a bounds that contains <code>x</code>, <code>y</code>.
1050 *
1051 * @param x the x coordinate
1052 * @param y the y coordinate
1053 * @param allocation current allocation of the View.
1054 * @return index of the view representing the given location, or
1055 * -1 if no view represents that position
1056 * @since 1.4
1057 */
1058 public int getViewIndex(float x, float y, Shape allocation) {
1059 for (int counter = getViewCount() - 1; counter >= 0; counter--) {
1060 Shape childAllocation = getChildAllocation(counter, allocation);
1061
1062 if (childAllocation != null) {
1063 Rectangle rect = (childAllocation instanceof Rectangle) ?
1064 (Rectangle)childAllocation : childAllocation.getBounds();
1065
1066 if (rect.contains(x, y)) {
1067 return counter;
1068 }
1069 }
1070 }
1071 return -1;
1072 }
1073
1074 /**
1075 * Updates the child views in response to receiving notification
1076 * that the model changed, and there is change record for the
1077 * element this view is responsible for. This is implemented
1078 * to assume the child views are directly responsible for the
1079 * child elements of the element this view represents. The
1080 * <code>ViewFactory</code> is used to create child views for each element
1081 * specified as added in the <code>ElementChange</code>, starting at the
1082 * index specified in the given <code>ElementChange</code>. The number of
1083 * child views representing the removed elements specified are
1084 * removed.
1085 *
1086 * @param ec the change information for the element this view
1087 * is responsible for. This should not be <code>null</code> if
1088 * this method gets called
1089 * @param e the change information from the associated document
1090 * @param f the factory to use to build child views
1091 * @return whether or not the child views represent the
1092 * child elements of the element this view is responsible
1093 * for. Some views create children that represent a portion
1094 * of the element they are responsible for, and should return
1095 * false. This information is used to determine if views
1096 * in the range of the added elements should be forwarded to
1097 * or not
1098 * @see #insertUpdate
1099 * @see #removeUpdate
1100 * @see #changedUpdate
1101 * @since 1.3
1102 */
1103 protected boolean updateChildren(DocumentEvent.ElementChange ec,
1104 DocumentEvent e, ViewFactory f) {
1105 Element[] removedElems = ec.getChildrenRemoved();
1106 Element[] addedElems = ec.getChildrenAdded();
1107 View[] added = null;
1108 if (addedElems != null) {
1109 added = new View[addedElems.length];
1110 for (int i = 0; i < addedElems.length; i++) {
1111 added[i] = f.create(addedElems[i]);
1112 }
1113 }
1114 int nremoved = 0;
1115 int index = ec.getIndex();
1116 if (removedElems != null) {
1117 nremoved = removedElems.length;
1118 }
1119 replace(index, nremoved, added);
1120 return true;
1121 }
1122
1123 /**
1124 * Forwards the given <code>DocumentEvent</code> to the child views
1125 * that need to be notified of the change to the model.
1126 * If there were changes to the element this view is
1127 * responsible for, that should be considered when
1128 * forwarding (i.e. new child views should not get
1129 * notified).
1130 *
1131 * @param ec changes to the element this view is responsible
1132 * for (may be <code>null</code> if there were no changes).
1133 * @param e the change information from the associated document
1134 * @param a the current allocation of the view
1135 * @param f the factory to use to rebuild if the view has children
1136 * @see #insertUpdate
1137 * @see #removeUpdate
1138 * @see #changedUpdate
1139 * @since 1.3
1140 */
1141 protected void forwardUpdate(DocumentEvent.ElementChange ec,
1142 DocumentEvent e, Shape a, ViewFactory f) {
1143 calculateUpdateIndexes(e);
1144
1145 int hole0 = lastUpdateIndex + 1;
1146 int hole1 = hole0;
1147 Element[] addedElems = (ec != null) ? ec.getChildrenAdded() : null;
1148 if ((addedElems != null) && (addedElems.length > 0)) {
1149 hole0 = ec.getIndex();
1150 hole1 = hole0 + addedElems.length - 1;
1151 }
1152
1153 // forward to any view not in the forwarding hole
1154 // formed by added elements (i.e. they will be updated
1155 // by initialization.
1156 for (int i = firstUpdateIndex; i <= lastUpdateIndex; i++) {
1157 if (! ((i >= hole0) && (i <= hole1))) {
1158 View v = getView(i);
1159 if (v != null) {
1160 Shape childAlloc = getChildAllocation(i, a);
1161 forwardUpdateToView(v, e, childAlloc, f);
1162 }
1163 }
1164 }
1165 }
1166
1167 /**
1168 * Calculates the first and the last indexes of the child views
1169 * that need to be notified of the change to the model.
1170 * @param e the change information from the associated document
1171 */
1172 void calculateUpdateIndexes(DocumentEvent e) {
1173 int pos = e.getOffset();
1174 firstUpdateIndex = getViewIndex(pos, Position.Bias.Forward);
1175 if (firstUpdateIndex == -1 && e.getType() == DocumentEvent.EventType.REMOVE &&
1176 pos >= getEndOffset()) {
1177 // Event beyond our offsets. We may have represented this, that is
1178 // the remove may have removed one of our child Elements that
1179 // represented this, so, we should forward to last element.
1180 firstUpdateIndex = getViewCount() - 1;
1181 }
1182 lastUpdateIndex = firstUpdateIndex;
1183 View v = (firstUpdateIndex >= 0) ? getView(firstUpdateIndex) : null;
1184 if (v != null) {
1185 if ((v.getStartOffset() == pos) && (pos > 0)) {
1186 // If v is at a boundary, forward the event to the previous
1187 // view too.
1188 firstUpdateIndex = Math.max(firstUpdateIndex - 1, 0);
1189 }
1190 }
1191 if (e.getType() != DocumentEvent.EventType.REMOVE) {
1192 lastUpdateIndex = getViewIndex(pos + e.getLength(), Position.Bias.Forward);
1193 if (lastUpdateIndex < 0) {
1194 lastUpdateIndex = getViewCount() - 1;
1195 }
1196 }
1197 firstUpdateIndex = Math.max(firstUpdateIndex, 0);
1198 }
1199
1200 /**
1201 * Updates the view to reflect the changes.
1202 */
1203 void updateAfterChange() {
1204 // Do nothing by default. Should be overridden in subclasses, if any.
1205 }
1206
1207 /**
1208 * Forwards the <code>DocumentEvent</code> to the give child view. This
1209 * simply messages the view with a call to <code>insertUpdate</code>,
1210 * <code>removeUpdate</code>, or <code>changedUpdate</code> depending
1211 * upon the type of the event. This is called by
1212 * {@link #forwardUpdate forwardUpdate} to forward
1213 * the event to children that need it.
1214 *
1215 * @param v the child view to forward the event to
1216 * @param e the change information from the associated document
1217 * @param a the current allocation of the view
1218 * @param f the factory to use to rebuild if the view has children
1219 * @see #forwardUpdate
1220 * @since 1.3
1221 */
1222 protected void forwardUpdateToView(View v, DocumentEvent e,
1223 Shape a, ViewFactory f) {
1224 DocumentEvent.EventType type = e.getType();
1225 if (type == DocumentEvent.EventType.INSERT) {
1226 v.insertUpdate(e, a, f);
1227 } else if (type == DocumentEvent.EventType.REMOVE) {
1228 v.removeUpdate(e, a, f);
1229 } else {
1230 v.changedUpdate(e, a, f);
1231 }
1232 }
1233
1234 /**
1235 * Updates the layout in response to receiving notification of
1236 * change from the model. This is implemented to call
1237 * <code>preferenceChanged</code> to reschedule a new layout
1238 * if the <code>ElementChange</code> record is not <code>null</code>.
1239 *
1240 * @param ec changes to the element this view is responsible
1241 * for (may be <code>null</code> if there were no changes)
1242 * @param e the change information from the associated document
1243 * @param a the current allocation of the view
1244 * @see #insertUpdate
1245 * @see #removeUpdate
1246 * @see #changedUpdate
1247 * @since 1.3
1248 */
1249 protected void updateLayout(DocumentEvent.ElementChange ec,
1250 DocumentEvent e, Shape a) {
1251 if ((ec != null) && (a != null)) {
1252 // should damage more intelligently
1253 preferenceChanged(null, true, true);
1254 Container host = getContainer();
1255 if (host != null) {
1256 host.repaint();
1257 }
1258 }
1259 }
1260
1261 /**
1262 * The weight to indicate a view is a bad break
1263 * opportunity for the purpose of formatting. This
1264 * value indicates that no attempt should be made to
1265 * break the view into fragments as the view has
1266 * not been written to support fragmenting.
1267 *
1268 * @see #getBreakWeight
1269 * @see #GoodBreakWeight
1270 * @see #ExcellentBreakWeight
1271 * @see #ForcedBreakWeight
1272 */
1273 public static final int BadBreakWeight = 0;
1274
1275 /**
1276 * The weight to indicate a view supports breaking,
1277 * but better opportunities probably exist.
1278 *
1279 * @see #getBreakWeight
1280 * @see #BadBreakWeight
1281 * @see #ExcellentBreakWeight
1282 * @see #ForcedBreakWeight
1283 */
1284 public static final int GoodBreakWeight = 1000;
1285
1286 /**
1287 * The weight to indicate a view supports breaking,
1288 * and this represents a very attractive place to
1289 * break.
1290 *
1291 * @see #getBreakWeight
1292 * @see #BadBreakWeight
1293 * @see #GoodBreakWeight
1294 * @see #ForcedBreakWeight
1295 */
1296 public static final int ExcellentBreakWeight = 2000;
1297
1298 /**
1299 * The weight to indicate a view supports breaking,
1300 * and must be broken to be represented properly
1301 * when placed in a view that formats its children
1302 * by breaking them.
1303 *
1304 * @see #getBreakWeight
1305 * @see #BadBreakWeight
1306 * @see #GoodBreakWeight
1307 * @see #ExcellentBreakWeight
1308 */
1309 public static final int ForcedBreakWeight = 3000;
1310
1311 /**
1312 * Axis for format/break operations.
1313 */
1314 public static final int X_AXIS = HORIZONTAL;
1315
1316 /**
1317 * Axis for format/break operations.
1318 */
1319 public static final int Y_AXIS = VERTICAL;
1320
1321 /**
1322 * Provides a mapping from the document model coordinate space
1323 * to the coordinate space of the view mapped to it. This is
1324 * implemented to default the bias to <code>Position.Bias.Forward</code>
1325 * which was previously implied.
1326 *
1327 * @param pos the position to convert >= 0
1328 * @param a the allocated region in which to render
1329 * @return the bounding box of the given position is returned
1330 * @exception BadLocationException if the given position does
1331 * not represent a valid location in the associated document
1332 * @see View#modelToView
1333 * @deprecated
1334 */
1335 @Deprecated
1336 public Shape modelToView(int pos, Shape a) throws BadLocationException {
1337 return modelToView(pos, a, Position.Bias.Forward);
1338 }
1339
1340
1341 /**
1342 * Provides a mapping from the view coordinate space to the logical
1343 * coordinate space of the model.
1344 *
1345 * @param x the X coordinate >= 0
1346 * @param y the Y coordinate >= 0
1347 * @param a the allocated region in which to render
1348 * @return the location within the model that best represents the
1349 * given point in the view >= 0
1350 * @see View#viewToModel
1351 * @deprecated
1352 */
1353 @Deprecated
1354 public int viewToModel(float x, float y, Shape a) {
1355 sharedBiasReturn[0] = Position.Bias.Forward;
1356 return viewToModel(x, y, a, sharedBiasReturn);
1357 }
1358
1359 // static argument available for viewToModel calls since only
1360 // one thread at a time may call this method.
1361 static final Position.Bias[] sharedBiasReturn = new Position.Bias[1];
1362
1363 private View parent;
1364 private Element elem;
1365
1366 /**
1367 * The index of the first child view to be notified.
1368 */
1369 int firstUpdateIndex;
1370
1371 /**
1372 * The index of the last child view to be notified.
1373 */
1374 int lastUpdateIndex;
1375
1376 };