1 /*
2 * Copyright (c) 1998, 2017, 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 javax.swing;
27
28 import javax.swing.*;
29 import javax.swing.event.*;
30 import javax.swing.border.*;
31
32 import java.awt.Component;
33 import java.awt.Color;
34 import java.awt.Rectangle;
35
36 import java.io.Serializable;
37 import sun.swing.DefaultLookup;
38
39
40 /**
41 * Renders an item in a list.
42 * <p>
43 * <strong><a id="override">Implementation Note:</a></strong>
44 * This class overrides
45 * <code>invalidate</code>,
46 * <code>validate</code>,
47 * <code>revalidate</code>,
48 * <code>repaint</code>,
49 * <code>isOpaque</code>,
50 * and
51 * <code>firePropertyChange</code>
52 * solely to improve performance.
53 * If not overridden, these frequently called methods would execute code paths
54 * that are unnecessary for the default list cell renderer.
55 * If you write your own renderer,
56 * take care to weigh the benefits and
57 * drawbacks of overriding these methods.
58 *
59 * <p>
60 *
61 * <strong>Warning:</strong>
62 * Serialized objects of this class will not be compatible with
63 * future Swing releases. The current serialization support is
64 * appropriate for short term storage or RMI between applications running
65 * the same version of Swing. As of 1.4, support for long term storage
66 * of all JavaBeans™
67 * has been added to the <code>java.beans</code> package.
68 * Please see {@link java.beans.XMLEncoder}.
69 *
70 * @author Philip Milne
71 * @author Hans Muller
72 * @since 1.2
73 */
74 @SuppressWarnings("serial") // Same-version serialization only
75 public class DefaultListCellRenderer extends JLabel
76 implements ListCellRenderer<Object>, Serializable
77 {
78
79 /**
80 * An empty <code>Border</code>. This field might not be used. To change the
81 * <code>Border</code> used by this renderer override the
82 * <code>getListCellRendererComponent</code> method and set the border
83 * of the returned component directly.
84 */
85 private static final Border SAFE_NO_FOCUS_BORDER = new EmptyBorder(1, 1, 1, 1);
86 private static final Border DEFAULT_NO_FOCUS_BORDER = new EmptyBorder(1, 1, 1, 1);
87 /**
88 * No focus border
89 */
90 protected static Border noFocusBorder = DEFAULT_NO_FOCUS_BORDER;
91
92 /**
93 * Constructs a default renderer object for an item
94 * in a list.
95 */
96 public DefaultListCellRenderer() {
97 super();
98 setOpaque(true);
99 setBorder(getNoFocusBorder());
100 setName("List.cellRenderer");
101 }
102
103 private Border getNoFocusBorder() {
104 Border border = DefaultLookup.getBorder(this, ui, "List.cellNoFocusBorder");
105 if (System.getSecurityManager() != null) {
106 if (border != null) return border;
107 return SAFE_NO_FOCUS_BORDER;
108 } else {
109 if (border != null &&
110 (noFocusBorder == null ||
111 noFocusBorder == DEFAULT_NO_FOCUS_BORDER)) {
112 return border;
113 }
114 return noFocusBorder;
115 }
116 }
117
118 public Component getListCellRendererComponent(
119 JList<?> list,
120 Object value,
121 int index,
122 boolean isSelected,
123 boolean cellHasFocus)
124 {
125 setComponentOrientation(list.getComponentOrientation());
126
127 Color bg = null;
128 Color fg = null;
129
130 JList.DropLocation dropLocation = list.getDropLocation();
131 if (dropLocation != null
132 && !dropLocation.isInsert()
133 && dropLocation.getIndex() == index) {
134
135 bg = DefaultLookup.getColor(this, ui, "List.dropCellBackground");
136 fg = DefaultLookup.getColor(this, ui, "List.dropCellForeground");
137
138 isSelected = true;
139 }
140
141 if (isSelected) {
142 setBackground(bg == null ? list.getSelectionBackground() : bg);
143 setForeground(fg == null ? list.getSelectionForeground() : fg);
144 }
145 else {
146 setBackground(list.getBackground());
147 setForeground(list.getForeground());
148 }
149
150 if (value instanceof Icon) {
151 setIcon((Icon)value);
152 setText("");
153 }
154 else {
155 setIcon(null);
156 setText((value == null) ? "" : value.toString());
157 }
158
159 setEnabled(list.isEnabled());
160 setFont(list.getFont());
161
162 Border border = null;
163 if (cellHasFocus) {
164 if (isSelected) {
165 border = DefaultLookup.getBorder(this, ui, "List.focusSelectedCellHighlightBorder");
166 }
167 if (border == null) {
168 border = DefaultLookup.getBorder(this, ui, "List.focusCellHighlightBorder");
169 }
170 } else {
171 border = getNoFocusBorder();
172 }
173 setBorder(border);
174
175 return this;
176 }
177
178 /**
179 * Overridden for performance reasons.
180 * See the <a href="#override">Implementation Note</a>
181 * for more information.
182 *
183 * @since 1.5
184 * @return <code>true</code> if the background is completely opaque
185 * and differs from the JList's background;
186 * <code>false</code> otherwise
187 */
188 @Override
189 public boolean isOpaque() {
190 Color back = getBackground();
191 Component p = getParent();
192 if (p != null) {
193 p = p.getParent();
194 }
195 // p should now be the JList.
196 boolean colorMatch = (back != null) && (p != null) &&
197 back.equals(p.getBackground()) &&
198 p.isOpaque();
199 return !colorMatch && super.isOpaque();
200 }
201
202 /**
203 * Overridden for performance reasons.
204 * See the <a href="#override">Implementation Note</a>
205 * for more information.
206 */
207 @Override
208 public void validate() {}
209
210 /**
211 * Overridden for performance reasons.
212 * See the <a href="#override">Implementation Note</a>
213 * for more information.
214 *
215 * @since 1.5
216 */
217 @Override
218 public void invalidate() {}
219
220 /**
221 * Overridden for performance reasons.
222 * See the <a href="#override">Implementation Note</a>
223 * for more information.
224 *
225 * @since 1.5
226 */
227 @Override
228 public void repaint() {}
229
230 /**
231 * Overridden for performance reasons.
232 * See the <a href="#override">Implementation Note</a>
233 * for more information.
234 */
235 @Override
236 public void revalidate() {}
237 /**
238 * Overridden for performance reasons.
239 * See the <a href="#override">Implementation Note</a>
240 * for more information.
241 */
242 @Override
243 public void repaint(long tm, int x, int y, int width, int height) {}
244
245 /**
246 * Overridden for performance reasons.
247 * See the <a href="#override">Implementation Note</a>
248 * for more information.
249 */
250 @Override
251 public void repaint(Rectangle r) {}
252
253 /**
254 * Overridden for performance reasons.
255 * See the <a href="#override">Implementation Note</a>
256 * for more information.
257 */
258 @Override
259 protected void firePropertyChange(String propertyName, Object oldValue, Object newValue) {
260 // Strings get interned...
261 if (propertyName == "text"
262 || ((propertyName == "font" || propertyName == "foreground")
263 && oldValue != newValue
264 && getClientProperty(javax.swing.plaf.basic.BasicHTML.propertyKey) != null)) {
265
266 super.firePropertyChange(propertyName, oldValue, newValue);
267 }
268 }
269
270 /**
271 * Overridden for performance reasons.
272 * See the <a href="#override">Implementation Note</a>
273 * for more information.
274 */
275 @Override
276 public void firePropertyChange(String propertyName, byte oldValue, byte newValue) {}
277
278 /**
279 * Overridden for performance reasons.
280 * See the <a href="#override">Implementation Note</a>
281 * for more information.
282 */
283 @Override
284 public void firePropertyChange(String propertyName, char oldValue, char newValue) {}
285
286 /**
287 * Overridden for performance reasons.
288 * See the <a href="#override">Implementation Note</a>
289 * for more information.
290 */
291 @Override
292 public void firePropertyChange(String propertyName, short oldValue, short newValue) {}
293
294 /**
295 * Overridden for performance reasons.
296 * See the <a href="#override">Implementation Note</a>
297 * for more information.
298 */
299 @Override
300 public void firePropertyChange(String propertyName, int oldValue, int newValue) {}
301
302 /**
303 * Overridden for performance reasons.
304 * See the <a href="#override">Implementation Note</a>
305 * for more information.
306 */
307 @Override
308 public void firePropertyChange(String propertyName, long oldValue, long newValue) {}
309
310 /**
311 * Overridden for performance reasons.
312 * See the <a href="#override">Implementation Note</a>
313 * for more information.
314 */
315 @Override
316 public void firePropertyChange(String propertyName, float oldValue, float newValue) {}
317
318 /**
319 * Overridden for performance reasons.
320 * See the <a href="#override">Implementation Note</a>
321 * for more information.
322 */
323 @Override
324 public void firePropertyChange(String propertyName, double oldValue, double newValue) {}
325
326 /**
327 * Overridden for performance reasons.
328 * See the <a href="#override">Implementation Note</a>
329 * for more information.
330 */
331 @Override
332 public void firePropertyChange(String propertyName, boolean oldValue, boolean newValue) {}
333
334 /**
335 * A subclass of DefaultListCellRenderer that implements UIResource.
336 * DefaultListCellRenderer doesn't implement UIResource
337 * directly so that applications can safely override the
338 * cellRenderer property with DefaultListCellRenderer subclasses.
339 * <p>
340 * <strong>Warning:</strong>
341 * Serialized objects of this class will not be compatible with
342 * future Swing releases. The current serialization support is
343 * appropriate for short term storage or RMI between applications running
344 * the same version of Swing. As of 1.4, support for long term storage
345 * of all JavaBeans™
346 * has been added to the <code>java.beans</code> package.
347 * Please see {@link java.beans.XMLEncoder}.
348 */
349 @SuppressWarnings("serial") // Same-version serialization only
350 public static class UIResource extends DefaultListCellRenderer
351 implements javax.swing.plaf.UIResource
352 {
353 }
354 }