1 /*
2 * Copyright (c) 2000, 2014, 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 @SuppressWarnings("serial") // JDK-implementation class
43 final class LayoutComparator implements Comparator<Component>, java.io.Serializable {
44
45 private static final int ROW_TOLERANCE = 10;
46
47 private boolean horizontal = true;
48 private boolean leftToRight = true;
49
50 void setComponentOrientation(ComponentOrientation orientation) {
51 horizontal = orientation.isHorizontal();
52 leftToRight = orientation.isLeftToRight();
53 }
54
55 public int compare(Component a, Component b) {
56 if (a == b) {
57 return 0;
58 }
59
60 // Row/Column algorithm only applies to siblings. If 'a' and 'b'
61 // aren't siblings, then we need to find their most inferior
62 // ancestors which share a parent. Compute the ancestory lists for
63 // each Component and then search from the Window down until the
64 // hierarchy branches.
65 if (a.getParent() != b.getParent()) {
66 LinkedList<Component> aAncestory = new LinkedList<Component>();
67
68 for(; a != null; a = a.getParent()) {
69 aAncestory.add(a);
70 if (a instanceof Window) {
71 break;
72 }
73 }
74 if (a == null) {
75 // 'a' is not part of a Window hierarchy. Can't cope.
76 throw new ClassCastException();
77 }
78
79 LinkedList<Component> bAncestory = new LinkedList<Component>();
80
81 for(; b != null; b = b.getParent()) {
82 bAncestory.add(b);
83 if (b instanceof Window) {
84 break;
85 }
86 }
87 if (b == null) {
88 // 'b' is not part of a Window hierarchy. Can't cope.
89 throw new ClassCastException();
90 }
91
92 for (ListIterator<Component>
93 aIter = aAncestory.listIterator(aAncestory.size()),
94 bIter = bAncestory.listIterator(bAncestory.size()); ;) {
95 if (aIter.hasPrevious()) {
96 a = aIter.previous();
97 } else {
98 // a is an ancestor of b
99 return -1;
100 }
101
102 if (bIter.hasPrevious()) {
103 b = bIter.previous();
104 } else {
105 // b is an ancestor of a
106 return 1;
107 }
108
109 if (a != b) {
110 break;
111 }
112 }
113 }
114
115 int ax = a.getX(), ay = a.getY(), bx = b.getX(), by = b.getY();
116
117 int zOrder = a.getParent().getComponentZOrder(a) - b.getParent().getComponentZOrder(b);
118 if (horizontal) {
119 if (leftToRight) {
120
121 // LT - Western Europe (optional for Japanese, Chinese, Korean)
122
123 if (Math.abs(ay - by) < ROW_TOLERANCE) {
124 return (ax < bx) ? -1 : ((ax > bx) ? 1 : zOrder);
125 } else {
126 return (ay < by) ? -1 : 1;
127 }
128 } else { // !leftToRight
129
130 // RT - Middle East (Arabic, Hebrew)
131
132 if (Math.abs(ay - by) < ROW_TOLERANCE) {
133 return (ax > bx) ? -1 : ((ax < bx) ? 1 : zOrder);
134 } else {
135 return (ay < by) ? -1 : 1;
136 }
137 }
138 } else { // !horizontal
139 if (leftToRight) {
140
141 // TL - Mongolian
142
143 if (Math.abs(ax - bx) < ROW_TOLERANCE) {
144 return (ay < by) ? -1 : ((ay > by) ? 1 : zOrder);
145 } else {
146 return (ax < bx) ? -1 : 1;
147 }
148 } else { // !leftToRight
149
150 // TR - Japanese, Chinese, Korean
151
152 if (Math.abs(ax - bx) < ROW_TOLERANCE) {
153 return (ay < by) ? -1 : ((ay > by) ? 1 : zOrder);
154 } else {
155 return (ax > bx) ? -1 : 1;
156 }
157 }
158 }
159 }
160 }