Source for javax.swing.border.EtchedBorder

   1: /* EtchedBorder.java -- 
   2:    Copyright (C) 2003 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.border;
  40: 
  41: import java.awt.Color;
  42: import java.awt.Component;
  43: import java.awt.Graphics;
  44: import java.awt.Insets;
  45: 
  46: 
  47: /**
  48:  * A border that looks like an engraving etched into the background
  49:  * surface, or (in its raised variant) coming out of the surface
  50:  * plane. Using different constructors, it is possible to either
  51:  * explicitly specify the border colors, or to let the colors derive
  52:  * from the background color of the enclosed Component.
  53:  *
  54:  * <p><img src="doc-files/EtchedBorder-1.png" width="500" height="200"
  55:  * alt="[An illustration of the two EtchedBorder variants]" />
  56:  *
  57:  * @author Sascha Brawer (brawer@dandelis.ch)
  58:  */
  59: public class EtchedBorder extends AbstractBorder
  60: {
  61:   /**
  62:    * Determined using the <code>serialver</code> tool
  63:    * of Apple/Sun JDK 1.3.1 on MacOS X 10.1.5.
  64:    */
  65:   static final long serialVersionUID = 4001244046866360638L;
  66:   
  67:   
  68:   /**
  69:    * Indicates that the border appears as coming out of the
  70:    * background.
  71:    */
  72:   public static final int RAISED = 0;
  73: 
  74: 
  75:   /**
  76:    * Indicates that the border appears as engraved into the
  77:    * background.
  78:    */
  79:   public static final int LOWERED = 1;
  80: 
  81:   
  82:   /**
  83:    * The type of this EtchedBorder, which is either {@link #RAISED}
  84:    * or {@link #LOWERED}.
  85:    */
  86:   protected int etchType;
  87:   
  88: 
  89:   /**
  90:    * The highlight color, or <code>null</code> to indicate that the
  91:    * color shall be derived from the background of the enclosed
  92:    * component.
  93:    */
  94:   protected Color highlight;
  95: 
  96: 
  97:   /**
  98:    * The shadow color, or <code>null</code> to indicate that the
  99:    * color shall be derived from the background of the enclosed
 100:    * component.
 101:    */
 102:   protected Color shadow;
 103: 
 104: 
 105:   /**
 106:    * Constructs a lowered EtchedBorder. The colors will be derived
 107:    * from the background color of the enclosed Component when the
 108:    * border gets painted.
 109:    */
 110:   public EtchedBorder()
 111:   {
 112:     this(LOWERED);
 113:   }
 114: 
 115: 
 116:   /**
 117:    * Constructs an EtchedBorder with the specified appearance. The
 118:    * colors will be derived from the background color of the enclosed
 119:    * Component when the border gets painted.
 120:    *
 121:    * <p><img src="doc-files/EtchedBorder-1.png" width="500" height="200"
 122:    * alt="[An illustration of the two EtchedBorder variants]" />
 123:    *
 124:    * @param etchType the desired appearance of the border. The value
 125:    *        must be either {@link #RAISED} or {@link #LOWERED}.
 126:    *
 127:    * @throws IllegalArgumentException if <code>etchType</code> has
 128:    *         an unsupported value.
 129:    */
 130:   public EtchedBorder(int etchType)
 131:   {
 132:     if ((etchType != RAISED) && (etchType != LOWERED))
 133:       throw new IllegalArgumentException();
 134: 
 135:     this.etchType = etchType;
 136: 
 137:     /* The highlight and shadow fields already have a null value
 138:      * when the constructor gets called, so there is no need to
 139:      * assign a value here.
 140:      */
 141:   }
 142:   
 143:   
 144:   /**
 145:    * Constructs a lowered EtchedBorder, explicitly selecting the
 146:    * colors that will be used for highlight and shadow.
 147:    *
 148:    * @param highlight the color that will be used for painting
 149:    *        the highlight part of the border.
 150:    *
 151:    * @param shadow the color that will be used for painting
 152:    *        the shadow part of the border.
 153:    *
 154:    * @see #EtchedBorder(int, Color, Color)
 155:    */
 156:   public EtchedBorder(Color highlight, Color shadow)
 157:   {
 158:     this(LOWERED, highlight, shadow);
 159:   }
 160:   
 161:   
 162:   /**
 163:    * Constructs an EtchedBorder with the specified appearance,
 164:    * explicitly selecting the colors that will be used for
 165:    * highlight and shadow.
 166:    *
 167:    * <p><img src="doc-files/EtchedBorder-2.png" width="500" height="200"
 168:    * alt="[An illustration that shows which pixels get painted
 169:    * in what color]" />
 170:    *
 171:    * @param etchType the desired appearance of the border. The value
 172:    *        must be either {@link #RAISED} or {@link #LOWERED}.
 173:    *
 174:    * @param highlight the color that will be used for painting
 175:    *        the highlight part of the border.
 176:    *
 177:    * @param shadow the color that will be used for painting
 178:    *        the shadow part of the border.
 179:    *
 180:    * @throws IllegalArgumentException if <code>etchType</code> has
 181:    *         an unsupported value.
 182:    */
 183:   public EtchedBorder(int etchType, Color highlight, Color shadow)
 184:   {
 185:     this(etchType);  // Checks the validity of the value.
 186:     this.highlight = highlight;
 187:     this.shadow = shadow;
 188:   }
 189:   
 190:   
 191:   /**
 192:    * Paints the border for a given component.
 193:    *
 194:    * @param c the component whose border is to be painted.
 195:    * @param g the graphics for painting.
 196:    * @param x the horizontal position for painting the border.
 197:    * @param y the vertical position for painting the border.
 198:    * @param width the width of the available area for painting the border.
 199:    * @param height the height of the available area for painting the border.
 200:    */
 201:   public void paintBorder(Component c, Graphics  g, int x, int y, int width,
 202:                           int height)
 203:   {
 204:     switch (etchType)
 205:     {
 206:     case RAISED:
 207:       paintEtchedBorder(g, x, y, width, height,
 208:                         getHighlightColor(c), getShadowColor(c));
 209:       break;
 210: 
 211:     case LOWERED:
 212:       paintEtchedBorder(g, x, y, width, height,
 213:                         getShadowColor(c), getHighlightColor(c));
 214:       break;
 215:     }
 216:   }
 217:   
 218:   
 219:   /**
 220:    * Measures the width of this border.
 221:    *
 222:    * @param c the component whose border is to be measured.
 223:    *
 224:    * @return an Insets object whose <code>left</code>, <code>right</code>,
 225:    *         <code>top</code> and <code>bottom</code> fields indicate the
 226:    *         width of the border at the respective edge.
 227:    *
 228:    * @see #getBorderInsets(java.awt.Component, java.awt.Insets)
 229:    */
 230:   public Insets getBorderInsets(Component c)
 231:   {
 232:     return new Insets(2, 2, 2, 2);
 233:   }
 234: 
 235: 
 236:   /**
 237:    * Measures the width of this border, storing the results into a
 238:    * pre-existing Insets object.
 239:    *
 240:    * @param insets an Insets object for holding the result values.
 241:    *        After invoking this method, the <code>left</code>,
 242:    *        <code>right</code>, <code>top</code> and
 243:    *        <code>bottom</code> fields indicate the width of the
 244:    *        border at the respective edge.
 245:    *
 246:    * @return the same object that was passed for <code>insets</code>.
 247:    *
 248:    * @see #getBorderInsets(Component)
 249:    */
 250:   public Insets getBorderInsets(Component c, Insets insets)
 251:   {
 252:     insets.left = insets.right = insets.top = insets.bottom = 2;
 253:     return insets;
 254:   }
 255: 
 256: 
 257:   /**
 258:    * Determines whether this border fills every pixel in its area
 259:    * when painting.
 260:    *
 261:    * <p>If the border colors are derived from the background color of
 262:    * the enclosed component, the result is <code>true</code> because
 263:    * the derivation method always returns opaque colors. Otherwise,
 264:    * the result depends on the opacity of the individual colors.
 265:    *
 266:    * @return <code>true</code> if the border is fully opaque, or
 267:    *         <code>false</code> if some pixels of the background
 268:    *         can shine through the border.
 269:    */
 270:   public boolean isBorderOpaque()
 271:   {
 272:     // If the colors are to be derived from the enclosed Component's
 273:     // background color, the border is guaranteed to be fully opaque
 274:     // because Color.brighten() and Color.darken() always return an
 275:     // opaque color.
 276:     return
 277:       ((highlight == null) || (highlight.getAlpha() == 255))
 278:       && ((shadow == null) || (shadow.getAlpha() == 255));
 279:   }
 280:   
 281:   /**
 282:    * Returns the appearance of this EtchedBorder, which is either
 283:    * {@link #RAISED} or {@link #LOWERED}.
 284:    * 
 285:    * @return The type ({@link #RAISED} or {@link #LOWERED}).
 286:    */
 287:   public int getEtchType()
 288:   {
 289:     return etchType;
 290:   }
 291: 
 292: 
 293:   /**
 294:    * Determines the color that will be used for highlighted parts when
 295:    * painting the border around a given component. If a highlight
 296:    * color has been specified upon constructing the border, that color
 297:    * is returned. Otherwise, the background color of the enclosed
 298:    * component is brightened.
 299:    *
 300:    * @param c the component enclosed by this border.
 301:    *
 302:    * @return The color.
 303:    * 
 304:    * @see java.awt.Component#getBackground()
 305:    * @see java.awt.Color#brighter()
 306:    */
 307:   public Color getHighlightColor(Component c)
 308:   {
 309:     if (highlight != null)
 310:       return highlight;
 311:     else
 312:       return c.getBackground().brighter();
 313:   }
 314: 
 315:   /**
 316:    * Returns the color that will be used for highlighted parts when
 317:    * painting the border, or <code>null</code> if that color will be
 318:    * derived from the background of the enclosed Component.
 319:    * 
 320:    * @return The highlight color (possibly <code>null</code>).
 321:    */
 322:   public Color getHighlightColor()
 323:   {
 324:     return highlight;
 325:   }
 326: 
 327: 
 328:   /**
 329:    * Determines the color that will be used for shadowed parts when
 330:    * painting the border around a given component. If a shadow color
 331:    * has been specified upon constructing the border, that color is
 332:    * returned. Otherwise, the background color of the enclosed
 333:    * component is darkened.
 334:    *
 335:    * @param c the component enclosed by this border.
 336:    *
 337:    * @return The shadow color.
 338:    * 
 339:    * @see java.awt.Component#getBackground()
 340:    * @see java.awt.Color#darker()
 341:    */
 342:   public Color getShadowColor(Component c)
 343:   {
 344:     if (shadow != null)
 345:       return shadow;
 346:     else
 347:       return c.getBackground().darker();
 348:   }
 349:   
 350:   
 351:   /**
 352:    * Returns the color that will be used for shadowed parts when
 353:    * painting the border, or <code>null</code> if that color will be
 354:    * derived from the background of the enclosed Component.
 355:    * 
 356:    * @return The shadow color (possibly <code>null</code>).
 357:    */
 358:   public Color getShadowColor()
 359:   {
 360:     return shadow;
 361:   }
 362: 
 363: 
 364:   /**
 365:    * Paints a two-pixel etching in two colors.
 366:    *
 367:    * <pre>
 368:    * +++++++++++.
 369:    * +.........+.    + = color a
 370:    * +.        +.    . = color b
 371:    * +.        +.
 372:    * +++++++++++.
 373:    * ............</pre>
 374:    *
 375:    * @param g the graphics for painting.
 376:    * @param x the horizontal position for painting the border.
 377:    * @param y the vertical position for painting the border.
 378:    * @param width the width of the available area for painting the border.
 379:    * @param height the height of the available area for painting the border.
 380:    * @param a one of the two colors.
 381:    * @param b the second of the two colors.
 382:    */
 383:   private static void paintEtchedBorder(Graphics g, int x, int y, int width,
 384:                                         int height, Color a, Color b)
 385:   {
 386:     Color oldColor;
 387: 
 388:     oldColor = g.getColor();
 389:     g.translate(x, y);
 390:     width = width - 1;
 391:     height = height - 1;
 392: 
 393:     try
 394:     {
 395:       // To understand this code, it might be helpful to look at the
 396:       // images that are included with the JavaDoc. They are located
 397:       // in the "doc-files" subdirectory. EtchedBorder-2.png might
 398:       // be especially informative.
 399:       g.setColor(a);
 400:       g.drawRect(0, 0, width - 1, height - 1);
 401: 
 402:       g.setColor(b);
 403:       g.drawLine(1, 1, width - 2, 1);            // top edge
 404:       g.drawLine(1, 2, 1, height - 2);           // left edge
 405:       g.drawLine(0, height, width, height);      // bottom edge
 406:       g.drawLine(width, 0, width, height - 1);   // right edge
 407:     }
 408:     finally
 409:     {
 410:       g.translate(-x, -y);
 411:       g.setColor(oldColor);
 412:     }
 413:   }
 414: }