1 /*
2 * Copyright (c) 2011, 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
26 package javafx.scene.layout;
27
28 import javafx.beans.DefaultProperty;
29 import javafx.collections.ObservableList;
30 import javafx.scene.Node;
31
32 /**
33 * Base class for layout panes which need to expose the children list as public
34 * so that users of the subclass can freely add/remove children.
35 * <p>
36 * This class may be used directly in cases where absolute positioning of children
37 * is required since it does not perform layout beyond resizing resizable children
38 * to their preferred sizes. It is the application's responsibility to position the
39 * children since the pane leaves the positions alone during layout.
40 * For example:
41 * <pre><code>
42 * Pane canvas = new Pane();
43 * canvas.setStyle("-fx-background-color: black;");
44 * canvas.setPrefSize(200,200);
45 * Circle circle = new Circle(50,Color.BLUE);
46 * circle.relocate(20, 20);
47 * Rectangle rectangle = new Rectangle(100,100,Color.RED);
48 * rectangle.relocate(70,70);
49 * canvas.getChildren().addAll(circle,rectangle);
50 * </code></pre>
51 * <p>
52 * Note: if an application needs children to be kept aligned within a parent (centered,
53 * positioned at top-left, etc), it should use a {@link javafx.scene.layout.StackPane StackPane}
54 * instead.</p>
55 *
56 * <p>
57 * Pane resizes each managed child regardless of the child's visible property value;
58 * unmanaged children are ignored for all layout calculations.</p>
59 *
60 * <h4>Resizable Range</h4>
61 *
62 * A pane's parent will resize the pane within the pane's resizable range
63 * during layout. By default the pane computes this range based on its content
64 * as outlined in the tables below:
65 *
66 * <table border="1">
67 * <tr><td></td><th>width</th><th>height</th></tr>
68 * <tr><th>minimum</th>
69 * <td>left plus right insets.</td>
70 * <td>top plus bottom insets.</td></tr>
71 * <tr><th>preferred</th>
72 * <td>width required to encompass each child at its current x location and preferred width.</td>
73 * <td>height required to encompass each child at its current y location and preferred height.</td></tr>
74 * <tr><th>maximum</th>
75 * <td>Double.MAX_VALUE</td><td>Double.MAX_VALUE</td></tr>
76 * </table>
77 * <p>
78 * A pane's unbounded maximum width and height are an indication to the parent that
79 * it may be resized beyond its preferred size to fill whatever space is assigned to it.
80 * <p>
81 * Pane provides properties for setting the size range directly. These
82 * properties default to the sentinel value Region.USE_COMPUTED_SIZE, however the
83 * application may set them to other values as needed:
84 * <pre><code>
85 * <b>pane.setPrefSize(500,400);</b>
86 * </code></pre>
87 * Applications may restore the computed values by setting these properties back
88 * to Region.USE_COMPUTED_SIZE.
89 * <p>
90 * Pane does not clip its content by default, so it is possible that childrens'
91 * bounds may extend outside its own bounds, either if children are positioned
92 * at negative coordinates or the pane is resized smaller than its preferred size.</p>
93 *
94 * @since JavaFX 2.0
95 */
96 @DefaultProperty("children")
97 public class Pane extends Region {
98
99 static void setConstraint(Node node, Object key, Object value) {
100 if (value == null) {
101 node.getProperties().remove(key);
102 } else {
103 node.getProperties().put(key, value);
104 }
105 if (node.getParent() != null) {
106 node.getParent().requestLayout();
107 }
108 }
109
110 static Object getConstraint(Node node, Object key) {
111 if (node.hasProperties()) {
112 Object value = node.getProperties().get(key);
113 if (value != null) {
114 return value;
115 }
116 }
117 return null;
118 }
119
120 /**
121 * Creates a Pane layout.
122 */
123 public Pane() {
124 super();
125 }
126
127 /**
128 * Creates a Pane layout.
129 * @param children The initial set of children for this pane.
130 * @since JavaFX 8.0
131 */
132 public Pane(Node... children) {
133 super();
134 getChildren().addAll(children);
135 }
136
137 /**
138 *
139 * @return modifiable list of children.
140 */
141 @Override public ObservableList<Node> getChildren() {
142 return super.getChildren();
143 }
144
145 }