1 /*
2 * Copyright (c) 2000, 2008, 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.util.Comparator;
28 import java.util.LinkedList;
29 import java.util.ListIterator;
30 import java.awt.Component;
31 import java.awt.ComponentOrientation;
32 import java.awt.Window;
33
34
35 /**
36 * Comparator which attempts to sort Components based on their size and
37 * position. Code adapted from original javax.swing.DefaultFocusManager
38 * implementation.
39 *
40 * @author David Mendenhall
41 */
42 final class LayoutComparator implements Comparator<Component>, java.io.Serializable {
43
44 private static final int ROW_TOLERANCE = 10;
45
46 private boolean horizontal = true;
47 private boolean leftToRight = true;
48
49 void setComponentOrientation(ComponentOrientation orientation) {
50 horizontal = orientation.isHorizontal();
51 leftToRight = orientation.isLeftToRight();
52 }
53
54 public int compare(Component a, Component b) {
55 if (a == b) {
56 return 0;
57 }
58
59 // Row/Column algorithm only applies to siblings. If 'a' and 'b'
60 // aren't siblings, then we need to find their most inferior
61 // ancestors which share a parent. Compute the ancestory lists for
62 // each Component and then search from the Window down until the
63 // hierarchy branches.
64 if (a.getParent() != b.getParent()) {
65 LinkedList<Component> aAncestory = new LinkedList<Component>();
66
67 for(; a != null; a = a.getParent()) {
68 aAncestory.add(a);
69 if (a instanceof Window) {
70 break;
71 }
72 }
73 if (a == null) {
74 // 'a' is not part of a Window hierarchy. Can't cope.
75 throw new ClassCastException();
76 }
77
78 LinkedList<Component> bAncestory = new LinkedList<Component>();
79
80 for(; b != null; b = b.getParent()) {
81 bAncestory.add(b);
82 if (b instanceof Window) {
83 break;
84 }
85 }
86 if (b == null) {
87 // 'b' is not part of a Window hierarchy. Can't cope.
88 throw new ClassCastException();
89 }
90
91 for (ListIterator<Component>
92 aIter = aAncestory.listIterator(aAncestory.size()),
93 bIter = bAncestory.listIterator(bAncestory.size()); ;) {
94 if (aIter.hasPrevious()) {
95 a = aIter.previous();
96 } else {
97 // a is an ancestor of b
98 return -1;
99 }
100
101 if (bIter.hasPrevious()) {
102 b = bIter.previous();
103 } else {
104 // b is an ancestor of a
105 return 1;
106 }
107
108 if (a != b) {
109 break;
110 }
111 }
112 }
113
114 int ax = a.getX(), ay = a.getY(), bx = b.getX(), by = b.getY();
115
116 int zOrder = a.getParent().getComponentZOrder(a) - b.getParent().getComponentZOrder(b);
117 if (horizontal) {
118 if (leftToRight) {
119
120 // LT - Western Europe (optional for Japanese, Chinese, Korean)
121
122 if (Math.abs(ay - by) < ROW_TOLERANCE) {
123 return (ax < bx) ? -1 : ((ax > bx) ? 1 : zOrder);
124 } else {
125 return (ay < by) ? -1 : 1;
126 }
127 } else { // !leftToRight
128
129 // RT - Middle East (Arabic, Hebrew)
130
131 if (Math.abs(ay - by) < ROW_TOLERANCE) {
132 return (ax > bx) ? -1 : ((ax < bx) ? 1 : zOrder);
133 } else {
134 return (ay < by) ? -1 : 1;
135 }
136 }
137 } else { // !horizontal
138 if (leftToRight) {
139
140 // TL - Mongolian
141
142 if (Math.abs(ax - bx) < ROW_TOLERANCE) {
143 return (ay < by) ? -1 : ((ay > by) ? 1 : zOrder);
144 } else {
145 return (ax < bx) ? -1 : 1;
146 }
147 } else { // !leftToRight
148
149 // TR - Japanese, Chinese, Korean
150
151 if (Math.abs(ax - bx) < ROW_TOLERANCE) {
152 return (ay < by) ? -1 : ((ay > by) ? 1 : zOrder);
153 } else {
154 return (ax > bx) ? -1 : 1;
155 }
156 }
157 }
158 }
159 }