001/* LookAndFeel.java --
002   Copyright (C) 2002, 2004, 2005, 2006,  Free Software Foundation, Inc.
003
004This file is part of GNU Classpath.
005
006GNU Classpath is free software; you can redistribute it and/or modify
007it under the terms of the GNU General Public License as published by
008the Free Software Foundation; either version 2, or (at your option)
009any later version.
010
011GNU Classpath is distributed in the hope that it will be useful, but
012WITHOUT ANY WARRANTY; without even the implied warranty of
013MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
014General Public License for more details.
015
016You should have received a copy of the GNU General Public License
017along with GNU Classpath; see the file COPYING.  If not, write to the
018Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
01902110-1301 USA.
020
021Linking this library statically or dynamically with other modules is
022making a combined work based on this library.  Thus, the terms and
023conditions of the GNU General Public License cover the whole
024combination.
025
026As a special exception, the copyright holders of this library give you
027permission to link this library with independent modules to produce an
028executable, regardless of the license terms of these independent
029modules, and to copy and distribute the resulting executable under
030terms of your choice, provided that you also meet, for each linked
031independent module, the terms and conditions of the license of that
032module.  An independent module is a module which is not derived from
033or based on this library.  If you modify this library, you may extend
034this exception to your version of the library, but you are not
035obligated to do so.  If you do not wish to do so, delete this
036exception statement from your version. */
037
038
039package javax.swing;
040
041import java.awt.Color;
042import java.awt.Component;
043import java.awt.Font;
044import java.awt.Toolkit;
045import java.net.URL;
046
047import javax.swing.border.Border;
048import javax.swing.plaf.ComponentInputMapUIResource;
049import javax.swing.plaf.IconUIResource;
050import javax.swing.plaf.InputMapUIResource;
051import javax.swing.plaf.UIResource;
052import javax.swing.plaf.metal.MetalLookAndFeel;
053import javax.swing.text.JTextComponent;
054
055/**
056 * A <i>look-and-feel</i> controls most aspects of the appearance and 
057 * operation of user interface components in <code>javax.swing</code>.  A 
058 * cross-platform look-and-feel (the {@link MetalLookAndFeel}) is provided.
059 * 
060 * @see UIManager#getInstalledLookAndFeels()
061 * @see UIManager#setLookAndFeel(LookAndFeel)
062 */
063public abstract class LookAndFeel
064{
065  /**
066   * Creates and returns a look-and-feel specific defaults table.  This method 
067   * is called once by {@link UIManager#setLookAndFeel(LookAndFeel)} and 
068   * shouldn't be called again (as it creates a large table of defaults).
069   *
070   * @return The UI defaults.
071   */
072  public UIDefaults getDefaults()
073  {
074    return null;
075  }
076
077  /**
078   * Returns a description of the look and feel.
079   * 
080   * @return A description of the look and feel.
081   */
082  public abstract String getDescription();
083
084  /**
085   * Returns the value of <code>Toolkit.getDefaultToolkit()
086   * .getDesktopProperty(systemPropertyName)</code>, or 
087   * <code>fallbackValue</code> if no such property is defined.
088   * 
089   * @param systemPropertyName  the system property name.
090   * @param fallbackValue  the fallback value.
091   * 
092   * @return The property value or <code>fallbackValue</code>.
093   */
094  public static Object getDesktopPropertyValue(String systemPropertyName, 
095      Object fallbackValue)
096  {
097    Object value = Toolkit.getDefaultToolkit().getDesktopProperty(
098        systemPropertyName);
099    return value != null ? value : fallbackValue;
100  }
101  
102  /**
103   * Returns an identifier for the look and feel.
104   * 
105   * @return An identifier for the look and feel.
106   */
107  public abstract String getID();
108
109  /**
110   * Returns the name for the look and feel.
111   * 
112   * @return The name for the look and feel.
113   */
114  public abstract String getName();
115
116  /**
117   * Returns <code>true</code> when the look-and-feel supports window 
118   * decorations, and <code>false</code> otherwise. This default implementation
119   * always returns <code>false</code> and needs to be overridden when the 
120   * derived look-and-feel supports this.
121   *
122   * @return <code>false</code>.
123   *
124   * @since 1.4
125   */
126  public boolean getSupportsWindowDecorations()
127  {
128    return false;
129  }
130  
131  /**
132   * Initializes the look-and-feel.  The 
133   * {@link UIManager#setLookAndFeel(LookAndFeel)} method calls this method 
134   * before the first call (and typically the only call) to 
135   * {@link #getDefaults()}.  This default implementation does nothing, but
136   * subclasses can override this behaviour. 
137   */
138  public void initialize()
139  {
140    // We do nothing here. This method is meant to be overridden by
141    // LookAndFeel implementations.
142  }
143
144  /**
145   * Convenience method for installing a component's default {@link Border} 
146   * object on the specified component if either the border is currently 
147   * <code>null</code> or already an instance of {@link UIResource}. 
148   * 
149   * @param c  the component (<code>null</code> not permitted).
150   * @param defaultBorderName  the border name (for lookup in the UIDefaults 
151   *     table).
152   */
153  public static void installBorder(JComponent c, String defaultBorderName)
154  {
155    Border b = c.getBorder();
156    if (b == null || b instanceof UIResource)
157      c.setBorder(UIManager.getBorder(defaultBorderName));
158  }
159
160  /**
161   * Convenience method for initializing a component's foreground and
162   * background color properties with values from the current defaults table.
163   * 
164   * @param c  the component (<code>null</code> not permitted).
165   * @param defaultBgName  the key for the background color in the UIDefaults 
166   *     table.
167   * @param defaultFgName  the key for the foreground color in the UIDefaults
168   *     table.
169   */
170  public static void installColors(JComponent c, String defaultBgName,
171                                   String defaultFgName)
172  {
173    // Install background.
174    Color bg = c.getBackground();
175    if (bg == null || bg instanceof UIResource)
176      c.setBackground(UIManager.getColor(defaultBgName));
177
178    // Install foreground.
179    Color fg = c.getForeground();
180    if (fg == null || fg instanceof UIResource)
181      c.setForeground(UIManager.getColor(defaultFgName));
182  }
183
184  /**
185   * Convenience method for initializing a component's foreground, background
186   * and font properties with values from the current defaults table.
187   * 
188   * @param component  the component (<code>null</code> not permitted).
189   * @param defaultBgName  the key for the background color in the UIDefaults 
190   *     table.
191   * @param defaultFgName  the key for the foreground color in the UIDefaults
192   *     table.
193   * @param defaultFontName  the key for the font in the UIDefaults table.
194   */
195  public static void installColorsAndFont(JComponent component,
196                                          String defaultBgName,
197                                          String defaultFgName,
198                                          String defaultFontName)
199  {
200    // Install colors.
201    installColors(component, defaultBgName, defaultFgName);
202    // Install font.
203    Font f = component.getFont();
204    if (f == null || f instanceof UIResource)
205      component.setFont(UIManager.getFont(defaultFontName));
206  }
207
208  /**
209   * Returns <code>true</code> if the look-and-feel is the "native" 
210   * look-and-feel for the current platform, and <code>false</code> otherwise.
211   * A native look-and-feel emulates the appearance and behaviour of the 
212   * default windowing system on the host operating system.
213   * 
214   * @return A flag indicating whether or not this is the native look and feel
215   *         for the current platform.
216   */
217  public abstract boolean isNativeLookAndFeel();
218
219  /**
220   * Returns <code>true</code> if the look-and-feel is supported on the 
221   * current operating system, and <code>false</code> otherwise.  This 
222   * mechanism is provided so that it is possible to prevent a look-and-feel
223   * from being used on some operating systems (usually for legal, not
224   * technical, reasons).
225   * 
226   * @return A flag indicating whether or not the look-and-feel is supported
227   *         on the current platform.
228   */
229  public abstract boolean isSupportedLookAndFeel();
230
231  /**
232   * Loads the bindings in keys into retMap. Does not remove existing entries
233   * from retMap.  <code>keys</code> describes the InputMap, every even indexed
234   * item is either a KeyStroke or a String representing a KeyStroke and every
235   * odd indexed item is the Object associated with that KeyStroke in an 
236   * ActionMap.
237   * 
238   * @param retMap the InputMap into which we load bindings
239   * @param keys the Object array describing the InputMap as above
240   */
241  public static void loadKeyBindings(InputMap retMap, Object[] keys)
242  {
243    if (keys == null)
244      return;
245    for (int i = 0; i < keys.length - 1; i += 2)
246      {
247        Object key = keys[i];
248        KeyStroke keyStroke;
249        if (key instanceof KeyStroke)
250          keyStroke = (KeyStroke) key;
251        else
252          keyStroke = KeyStroke.getKeyStroke((String) key);
253        retMap.put(keyStroke, keys[i + 1]);
254      }
255  }
256
257  /**
258   * Creates a ComponentInputMap from keys.  
259   * <code>keys</code> describes the InputMap, every even indexed
260   * item is either a KeyStroke or a String representing a KeyStroke and every
261   * odd indexed item is the Object associated with that KeyStroke in an 
262   * ActionMap.
263   * 
264   * @param c the JComponent associated with the ComponentInputMap
265   * @param keys the Object array describing the InputMap as above
266   * 
267   * @return A new input map.
268   */
269  public static ComponentInputMap makeComponentInputMap(JComponent c,
270                                                        Object[] keys)
271  {
272    ComponentInputMap retMap = new ComponentInputMapUIResource(c);
273    loadKeyBindings(retMap, keys);
274    return retMap;
275  }
276
277  /**
278   * Utility method that creates a UIDefaults.LazyValue that creates an
279   * ImageIcon UIResource for the specified gifFile filename.
280   * 
281   * @param baseClass  the base class for accessing the icon resource.
282   * @param gifFile  the file name.
283   * 
284   * @return A {@link UIDefaults.LazyValue} that serves up an 
285   *     {@link IconUIResource}.
286   */
287  public static Object makeIcon(Class<?> baseClass, String gifFile)
288  {
289    final URL file = baseClass.getResource(gifFile);
290    return new UIDefaults.LazyValue() 
291      {
292        public Object createValue(UIDefaults table)
293        {
294          return new IconUIResource(new ImageIcon(file));
295        }
296      };
297  }
298
299  /**
300   * Creates a InputMap from keys. 
301   * <code>keys</code> describes the InputMap, every even indexed
302   * item is either a KeyStroke or a String representing a KeyStroke and every
303   * odd indexed item is the Object associated with that KeyStroke in an 
304   * ActionMap.
305   * 
306   * @param keys the Object array describing the InputMap as above
307   * 
308   * @return A new input map.
309   */
310  public static InputMap makeInputMap(Object[] keys)
311  {
312    InputMap retMap = new InputMapUIResource();
313    loadKeyBindings(retMap, keys);
314    return retMap;
315  }
316
317  /**
318   * Convenience method for building lists of KeyBindings.
319   * <code>keyBindingList</code> is an array of KeyStroke-Action pairs where
320   * even indexed elements are KeyStrokes or Strings representing KeyStrokes
321   * and odd indexed elements are the associated Actions.
322   * 
323   * @param keyBindingList the array of KeyStroke-Action pairs
324   * @return a JTextComponent.KeyBinding array
325   */
326  public static JTextComponent.KeyBinding[] makeKeyBindings(
327      Object[] keyBindingList)
328  {
329    JTextComponent.KeyBinding[] retBindings = 
330      new JTextComponent.KeyBinding[keyBindingList.length / 2];
331    for (int i = 0; i < keyBindingList.length - 1; i += 2)
332      {
333        KeyStroke stroke;
334        if (keyBindingList[i] instanceof KeyStroke)
335          stroke = (KeyStroke) keyBindingList[i];
336        else
337          stroke = KeyStroke.getKeyStroke((String) keyBindingList[i]);
338        retBindings[i / 2] = new JTextComponent.KeyBinding(stroke, 
339            (String) keyBindingList[i + 1]);
340      }
341    return retBindings;
342  }
343
344  /**
345   * Invoked when the user attempts an invalid operation. The default 
346   * implementation just beeps. Subclasses that wish to change this need to 
347   * override this method.
348   *
349   * @param component the component the error occured in
350   */
351  public void provideErrorFeedback(Component component)
352  {
353    Toolkit.getDefaultToolkit().beep();
354  }
355
356  /**
357   * Returns a string that displays and identifies this object's properties.
358   *
359   * @return string containing the description and class name.
360   */
361  public String toString()
362  {
363    return getDescription() + " " + getClass().getName();
364  }
365
366  /**
367   * UIManager.setLookAndFeel calls this method just before we're replaced by
368   * a new default look and feel. 
369   */
370  public void uninitialize()
371  {
372    // We do nothing here. This method is meant to be overridden by
373    // LookAndFeel implementations.
374  }
375
376  /**
377   * Convenience method for un-installing a component's default border on the
378   * specified component if the border is currently an instance of UIResource.
379   * 
380   * @param c  the component (<code>null</code> not permitted).
381   */
382  public static void uninstallBorder(JComponent c)
383  {
384    if (c.getBorder() instanceof UIResource)
385      c.setBorder(null);
386  }
387
388  /**
389   * This methods installs a UI property if it hasn't already been set by an
390   * application. This method is used by UI delegates that install a default
391   * value for a property with a primitive type but do not want to override
392   * a value that has been set by an application.
393   *
394   * The supported properties depend on the actual type of the component and
395   * are listed in the table below. The supported properties are of course
396   * inherited to subclasses.
397   *
398   * <table>
399   * <tr><th>Type</th><th>Supported properties</th></tr>
400   * <tr><td><code>JComponent</code></td>
401   *     <td><code>opaque, autoscrolls</code></td></tr>
402   * <tr><td><code>AbstractButton</code></td>
403   *     <td><code>borderPainted, rolloverEnabled, iconTextGap,
404   *      contentAreaFilled</code></td></tr>
405   * <tr><td><code>JDesktopPane</code></td>
406   *     <td><code>dragMode</code></td></tr>
407   * <tr><td><code>JSplitPane</code></td>
408   *     <td><code>dividerSize, oneTouchExpandable</code></td></tr>
409   * <tr><td><code>JTable</code></td>
410   *     <td><code>rowHeight</code></td></tr>
411   * <tr><td><code>JTree</code></td>
412   *     <td><code>rowHeight, scrollsOnExpand, showsRootHandles</code></td></tr>
413   * </table>
414   *
415   * @param c the component to install the property to
416   * @param propertyName the name of the property
417   * @param value the value of the property
418   *
419   * @throws IllegalArgumentException if the specified property cannot be set
420   *         by this method
421   * @throws ClassCastException if the property value does not match the
422   *         property type
423   * @throws NullPointerException if <code>c</code> or
424   *         <code>propertyValue</code> is <code>null</code>
425   *
426   * @since 1.5
427   */
428  public static void installProperty(JComponent c, String propertyName,
429                                     Object value)
430  {
431    c.setUIProperty(propertyName, value);
432  }
433}