001    /* LookAndFeel.java --
002       Copyright (C) 2002, 2004, 2005, 2006,  Free Software Foundation, Inc.
003    
004    This file is part of GNU Classpath.
005    
006    GNU Classpath is free software; you can redistribute it and/or modify
007    it under the terms of the GNU General Public License as published by
008    the Free Software Foundation; either version 2, or (at your option)
009    any later version.
010    
011    GNU Classpath is distributed in the hope that it will be useful, but
012    WITHOUT ANY WARRANTY; without even the implied warranty of
013    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
014    General Public License for more details.
015    
016    You should have received a copy of the GNU General Public License
017    along with GNU Classpath; see the file COPYING.  If not, write to the
018    Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
019    02110-1301 USA.
020    
021    Linking this library statically or dynamically with other modules is
022    making a combined work based on this library.  Thus, the terms and
023    conditions of the GNU General Public License cover the whole
024    combination.
025    
026    As a special exception, the copyright holders of this library give you
027    permission to link this library with independent modules to produce an
028    executable, regardless of the license terms of these independent
029    modules, and to copy and distribute the resulting executable under
030    terms of your choice, provided that you also meet, for each linked
031    independent module, the terms and conditions of the license of that
032    module.  An independent module is a module which is not derived from
033    or based on this library.  If you modify this library, you may extend
034    this exception to your version of the library, but you are not
035    obligated to do so.  If you do not wish to do so, delete this
036    exception statement from your version. */
037    
038    
039    package javax.swing;
040    
041    import java.awt.Color;
042    import java.awt.Component;
043    import java.awt.Font;
044    import java.awt.Toolkit;
045    import java.net.URL;
046    
047    import javax.swing.border.Border;
048    import javax.swing.plaf.ComponentInputMapUIResource;
049    import javax.swing.plaf.IconUIResource;
050    import javax.swing.plaf.InputMapUIResource;
051    import javax.swing.plaf.UIResource;
052    import javax.swing.plaf.metal.MetalLookAndFeel;
053    import 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     */
063    public 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    }