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1: /* ComponentUI.java -- 2: Copyright (C) 2002, 2003, 2004 Free Software Foundation, Inc. 3: 4: This file is part of GNU Classpath. 5: 6: GNU Classpath is free software; you can redistribute it and/or modify 7: it under the terms of the GNU General Public License as published by 8: the Free Software Foundation; either version 2, or (at your option) 9: any later version. 10: 11: GNU Classpath is distributed in the hope that it will be useful, but 12: WITHOUT ANY WARRANTY; without even the implied warranty of 13: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 14: General Public License for more details. 15: 16: You should have received a copy of the GNU General Public License 17: along with GNU Classpath; see the file COPYING. If not, write to the 18: Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 19: 02110-1301 USA. 20: 21: Linking this library statically or dynamically with other modules is 22: making a combined work based on this library. Thus, the terms and 23: conditions of the GNU General Public License cover the whole 24: combination. 25: 26: As a special exception, the copyright holders of this library give you 27: permission to link this library with independent modules to produce an 28: executable, regardless of the license terms of these independent 29: modules, and to copy and distribute the resulting executable under 30: terms of your choice, provided that you also meet, for each linked 31: independent module, the terms and conditions of the license of that 32: module. An independent module is a module which is not derived from 33: or based on this library. If you modify this library, you may extend 34: this exception to your version of the library, but you are not 35: obligated to do so. If you do not wish to do so, delete this 36: exception statement from your version. */ 37: 38: 39: package javax.swing.plaf; 40: 41: import java.awt.Dimension; 42: import java.awt.Graphics; 43: 44: import javax.accessibility.Accessible; 45: import javax.swing.JComponent; 46: 47: /** 48: * The abstract base class for all delegates that provide the 49: * pluggable look and feel for Swing components. User applications 50: * should not need to access this class; it is internal to Swing 51: * and the look-and-feel implementations. 52: * 53: * <p><img src="doc-files/ComponentUI-1.png" width="700" height="550" 54: * alt="[UML diagram illustrating the architecture for pluggable 55: * look and feels]" /></p> 56: * 57: * <p>Components such as {@link javax.swing.JSlider} do not directly 58: * implement operations related to the look and feel of the user 59: * interface, such as painting or layout. Instead, they use a delegate 60: * object for all such tasks. In the case of <code>JSlider</code>, the 61: * user interface would be provided by some concrete subclass of 62: * {@link javax.swing.plaf.SliderUI}. 63: * 64: * <p>Soon after its creation, a <code>ComponentUI</code> will be sent 65: * an {@link #installUI} message. The <code>ComponentUI</code> will 66: * react by setting properties such as the border or the background 67: * color of the <code>JComponent</code> for which it provides its 68: * services. Soon before the end of its lifecycle, the 69: * <code>ComponentUI</code> will receive an {@link #uninstallUI} 70: * message, at which time the <code>ComponentUI</code> is expected to 71: * undo any changes.</p> 72: * 73: * <p>Note that the <code>ui</code> of a <code>JComponent</code> 74: * changes whenever the user switches between look and feels. For 75: * example, the <code>ui</code> property of a <code>JSlider</code> 76: * could change from an instance of <code>MetalSliderUI</code> to an 77: * instance of <code>FooSliderUI</code>. This switch can happen at any 78: * time, but it will always be performed from inside the Swing thread.</p> 79: * 80: * @author Sascha Brawer (brawer@dandelis.ch) 81: */ 82: public abstract class ComponentUI 83: { 84: /** 85: * Constructs a new UI delegate. 86: */ 87: public ComponentUI() 88: { 89: } 90: 91: 92: /** 93: * Sets up the specified component so it conforms the the design 94: * guidelines of the implemented look and feel. When the look and 95: * feel changes, a <code>ComponentUI</code> delegate is created. 96: * The delegate object then receives an <code>installUI</code> 97: * message. 98: * 99: * <p>This method should perform the following tasks:</p> 100: * 101: * <ul> 102: * <li>Set visual properties such as borders, fonts, colors, or 103: * icons. However, no change should be performed for those 104: * properties whose values have been directly set by the client 105: * application. To allow the distinction, LookAndFeels are expected 106: * to use values that implement the {@link UIResource} marker 107: * interface, such as {@link BorderUIResource} or {@link 108: * ColorUIResource}.</li> 109: * <li>If necessary, install a {@link java.awt.LayoutManager}.</li> 110: * <li>Embed custom sub-components. For instance, the UI delegate 111: * for a {@link javax.swing.JSplitPane} might install a special 112: * component for the divider.</li> 113: * <li>Register event listeners.</li> 114: * <li>Set up properties related to keyborad navigation, such as 115: * mnemonics or focus traversal policies.</li> 116: * </ul> 117: * 118: * @param c the component for which this delegate will provide 119: * services. 120: * 121: * @see #uninstallUI 122: * @see javax.swing.JComponent#setUI 123: * @see javax.swing.JComponent#updateUI 124: */ 125: public void installUI(JComponent c) 126: { 127: // The default implementation does not change any properties. 128: } 129: 130: 131: /** 132: * Puts the specified component into the state it had before 133: * {@link #installUI} was called. 134: * 135: * @param c the component for which this delegate has provided 136: * services. 137: * 138: * @see #installUI 139: * @see javax.swing.JComponent#setUI 140: * @see javax.swing.JComponent#updateUI 141: */ 142: public void uninstallUI(JComponent c) 143: { 144: // The default implementation does not change any properties. 145: } 146: 147: 148: /** 149: * Paints the component according to the design guidelines 150: * of the look and feel. Most subclasses will want to override 151: * this method. 152: * 153: * @param g the graphics for painting. 154: * 155: * @param c the component for which this delegate performs 156: * services. 157: */ 158: public void paint(Graphics g, JComponent c) 159: { 160: } 161: 162: 163: /** 164: * Fills the specified component with its background color 165: * (unless the <code>opaque</code> property is <code>false</code>) 166: * before calling {@link #paint}. 167: * 168: * <p>It is unlikely that a subclass needs to override this method. 169: * The actual rendering should be performed by the {@link #paint} 170: * method. 171: * 172: * @param g the graphics for painting. 173: * 174: * @param c the component for which this delegate performs 175: * services. 176: * 177: * @see #paint 178: * @see javax.swing.JComponent#paintComponent 179: */ 180: public void update(Graphics g, JComponent c) 181: { 182: if (c.isOpaque()) 183: { 184: g.setColor(c.getBackground()); 185: g.fillRect(0, 0, c.getWidth(), c.getHeight()); 186: } 187: paint(g, c); 188: } 189: 190: 191: /** 192: * Determines the preferred size of a component. The default 193: * implementation returns <code>null</code>, which means that 194: * <code>c</code>’s layout manager should be asked to 195: * calculate the preferred size. 196: * 197: * @param c the component for which this delegate performs services. 198: * 199: * @return the preferred size, or <code>null</code> to indicate that 200: * <code>c</code>’s layout manager should be asked 201: * for the preferred size. 202: */ 203: public Dimension getPreferredSize(JComponent c) 204: { 205: return null; 206: } 207: 208: 209: /** 210: * Determines the minimum size of a component. The default 211: * implementation calls {@link #getPreferredSize}, but subclasses 212: * might want to override this. 213: * 214: * @param c the component for which this delegate performs services. 215: * 216: * @return the minimum size, or <code>null</code> to indicate that 217: * <code>c</code>’s layout manager should be asked 218: * to calculate the minimum size. 219: */ 220: public Dimension getMinimumSize(JComponent c) 221: { 222: return getPreferredSize(c); 223: } 224: 225: 226: /** 227: * Determines the maximum size of a component. The default 228: * implementation calls {@link #getPreferredSize}, but subclasses 229: * might want to override this. 230: * 231: * @param c the component for which this delegate performs services. 232: * 233: * @return the maximum size, or <code>null</code> to indicate that 234: * <code>c</code>’s layout manager should be asked 235: * to calculate the maximum size. 236: */ 237: public Dimension getMaximumSize(JComponent c) 238: { 239: return getPreferredSize(c); 240: } 241: 242: 243: /** 244: * Determines whether a click into the component at a specified 245: * location is considered as having hit the component. The default 246: * implementation checks whether the point falls into the 247: * component’s bounding rectangle. Some subclasses might want 248: * to override this, for example in the case of a rounded button. 249: * 250: * @param c the component for which this delegate performs services. 251: * 252: * @param x the x coordinate of the point, relative to the local 253: * coordinate system of the component. Zero would be be 254: * component’s left edge, irrespective of the location 255: * inside its parent. 256: * 257: * @param y the y coordinate of the point, relative to the local 258: * coordinate system of the component. Zero would be be 259: * component’s top edge, irrespective of the location 260: * inside its parent. 261: */ 262: public boolean contains(JComponent c, int x, int y) 263: { 264: /* JComponent.contains calls the ui delegate for hit 265: * testing. Therefore, endless mutual recursion would result if we 266: * called c.contains(x, y) here. 267: * 268: * The previous Classpath implementation called the deprecated 269: * method java.awt.Component.inside. In the Sun implementation, it 270: * can be observed that inside, other than contains, does not call 271: * the ui delegate. But that inside() behaves different to 272: * contains() clearly is in violation of the method contract, and 273: * it is not something that a good implementation should rely upon 274: * -- even if Classpath ends up being forced to replicate this 275: * apparent bug of the Sun implementation. 276: */ 277: return (x >= 0) && (x < c.getWidth()) 278: && (y >= 0) && (y < c.getHeight()); 279: } 280: 281: 282: /** 283: * Creates a delegate object for the specified component. Users 284: * should use the <code>createUI</code> method of a suitable 285: * subclass. The implementation of <code>ComponentUI</code> 286: * always throws an error. 287: * 288: * @param c the component for which a UI delegate is requested. 289: */ 290: public static ComponentUI createUI(JComponent c) 291: { 292: throw new Error( 293: "javax.swing.plaf.ComponentUI does not implement createUI; call " 294: + "createUI on a subclass."); 295: } 296: 297: 298: /** 299: * Counts the number of accessible children in the component. The 300: * default implementation delegates the inquiry to the {@link 301: * javax.accessibility.AccessibleContext} of <code>c</code>. 302: * 303: * @param c the component whose accessible children 304: * are to be counted. 305: */ 306: public int getAccessibleChildrenCount(JComponent c) 307: { 308: return c.getAccessibleContext().getAccessibleChildrenCount(); 309: } 310: 311: 312: /** 313: * Returns the specified accessible child of the component. The 314: * default implementation delegates the inquiry to the {@link 315: * javax.accessibility.AccessibleContext} of <code>c</code>. 316: * 317: * @param i the index of the accessible child, starting at zero. 318: * 319: * @param c the component whose <code>i</code>-th accessible child 320: * is requested. 321: */ 322: public Accessible getAccessibleChild(JComponent c, int i) 323: { 324: return c.getAccessibleContext().getAccessibleChild(i); 325: } 326: }
GNU Classpath (0.17) |