libjava/javax/swing/border/EtchedBorder.java

   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., 59 Temple Place, Suite 330, Boston, MA
  19 02111-1307 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
  60   extends AbstractBorder
  61 {
  62   /**
  63    * Determined using the <code>serialver</code> tool
  64    * of Apple/Sun JDK 1.3.1 on MacOS X 10.1.5.
  65    */
  66   static final long serialVersionUID = 4001244046866360638L;
  67
  68
  69   /**
  70    * Indicates that the border appears as coming out of the
  71    * background.
  72    */
  73   public static final int RAISED = 0;
  74
  75
  76   /**
  77    * Indicates that the border appears as engraved into the
  78    * background.
  79    */
  80   public static final int LOWERED = 1;
  81
  82
  83   /**
  84    * The type of this EtchedBorder, which is either {@link #RAISED}
  85    * or {@link #LOWERED}.
  86    */
  87   protected int etchType;
  88
  89
  90   /**
  91    * The highlight color, or <code>null</code> to indicate that the
  92    * color shall be derived from the background of the enclosed
  93    * component.
  94    */
  95   protected Color highlight;
  96
  97
  98   /**
  99    * The shadow color, or <code>null</code> to indicate that the
 100    * color shall be derived from the background of the enclosed
 101    * component.
 102    */
 103   protected Color shadow;
 104
 105
 106   /**
 107    * Constructs a lowered EtchedBorder. The colors will be derived
 108    * from the background color of the enclosed Component when the
 109    * border gets painted.
 110    */
 111   public EtchedBorder()
 112   {
 113     this(LOWERED);
 114   }
 115
 116
 117   /**
 118    * Constructs an EtchedBorder with the specified appearance. The
 119    * colors will be derived from the background color of the enclosed
 120    * Component when the border gets painted.
 121    *
 122    * <p><img src="doc-files/EtchedBorder-1.png" width="500" height="200"
 123    * alt="[An illustration of the two EtchedBorder variants]" />
 124    *
 125    * @param etchType the desired appearance of the border. The value
 126    *        must be either {@link #RAISED} or {@link #LOWERED}.
 127    *
 128    * @throws IllegalArgumentException if <code>etchType</code> has
 129    *         an unsupported value.
 130    */
 131   public EtchedBorder(int etchType)
 132   {
 133     if ((etchType != RAISED) && (etchType != LOWERED))
 134       throw new IllegalArgumentException();
 135
 136     this.etchType = etchType;
 137
 138     /* The highlight and shadow fields already have a null value
 139      * when the constructor gets called, so there is no need to
 140      * assign a value here.
 141      */
 142   }
 143
 144
 145   /**
 146    * Constructs a lowered EtchedBorder, explicitly selecting the
 147    * colors that will be used for highlight and shadow.
 148    *
 149    * @param highlight the color that will be used for painting
 150    *        the highlight part of the border.
 151    *
 152    * @param shadow the color that will be used for painting
 153    *        the shadow part of the border.
 154    *
 155    * @see #EtchedBorder(int, Color, Color)
 156    */
 157   public EtchedBorder(Color highlight, Color shadow)
 158   {
 159     this(LOWERED, highlight, shadow);
 160   }
 161
 162
 163   /**
 164    * Constructs an EtchedBorder with the specified appearance,
 165    * explicitly selecting the colors that will be used for
 166    * highlight and shadow.
 167    *
 168    * <p><img src="doc-files/EtchedBorder-2.png" width="500" height="200"
 169    * alt="[An illustration that shows which pixels get painted
 170    * in what color]" />
 171    *
 172    * @param etchType the desired appearance of the border. The value
 173    *        must be either {@link #RAISED} or {@link #LOWERED}.
 174    *
 175    * @param highlight the color that will be used for painting
 176    *        the highlight part of the border.
 177    *
 178    * @param shadow the color that will be used for painting
 179    *        the shadow part of the border.
 180    *
 181    * @throws IllegalArgumentException if <code>etchType</code> has
 182    *         an unsupported value.
 183    */
 184   public EtchedBorder(int etchType, Color highlight, Color shadow)
 185   {
 186     this(etchType);  // Checks the validity of the value.
 187     this.highlight = highlight;
 188     this.shadow = shadow;
 189   }
 190
 191
 192   /**
 193    * Paints the border for a given component.
 194    *
 195    * @param c the component whose border is to be painted.
 196    * @param g the graphics for painting.
 197    * @param x the horizontal position for painting the border.
 198    * @param y the vertical position for painting the border.
 199    * @param width the width of the available area for painting the border.
 200    * @param height the height of the available area for painting the border.
 201    */
 202   public void paintBorder(Component c, Graphics  g,
 203                           int x, int y, int width, int height)
 204   {
 205     switch (etchType)
 206     {
 207     case RAISED:
 208       paintEtchedBorder(g, x, y, width, height,
 209                         getHighlightColor(c), getShadowColor(c));
 210       break;
 211
 212     case LOWERED:
 213       paintEtchedBorder(g, x, y, width, height,
 214                         getShadowColor(c), getHighlightColor(c));
 215       break;
 216     }
 217   }
 218
 219
 220   /**
 221    * Measures the width of this border.
 222    *
 223    * @param c the component whose border is to be measured.
 224    *
 225    * @return an Insets object whose <code>left</code>, <code>right</code>,
 226    *         <code>top</code> and <code>bottom</code> fields indicate the
 227    *         width of the border at the respective edge.
 228    *
 229    * @see #getBorderInsets(java.awt.Component, java.awt.Insets)
 230    */
 231   public Insets getBorderInsets(Component c)
 232   {
 233     return new Insets(2, 2, 2, 2);
 234   }
 235
 236
 237   /**
 238    * Measures the width of this border, storing the results into a
 239    * pre-existing Insets object.
 240    *
 241    * @param insets an Insets object for holding the result values.
 242    *        After invoking this method, the <code>left</code>,
 243    *        <code>right</code>, <code>top</code> and
 244    *        <code>bottom</code> fields indicate the width of the
 245    *        border at the respective edge.
 246    *
 247    * @return the same object that was passed for <code>insets</code>.
 248    *
 249    * @see #getBorderInsets()
 250    */
 251   public Insets getBorderInsets(Component c, Insets insets)
 252   {
 253     insets.left = insets.right = insets.top = insets.bottom = 2;
 254     return insets;
 255   }
 256
 257
 258   /**
 259    * Determines whether this border fills every pixel in its area
 260    * when painting.
 261    *
 262    * <p>If the border colors are derived from the background color of
 263    * the enclosed component, the result is <code>true</code> because
 264    * the derivation method always returns opaque colors. Otherwise,
 265    * the result depends on the opacity of the individual colors.
 266    *
 267    * @return <code>true</code> if the border is fully opaque, or
 268    *         <code>false</code> if some pixels of the background
 269    *         can shine through the border.
 270    */
 271   public boolean isBorderOpaque()
 272   {
 273     /* If the colors are to be drived from the enclosed Component's
 274      * background color, the border is guaranteed to be fully opaque
 275      * because Color.brighten() and Color.darken() always return an
 276      * opaque color.
 277      */
 278     return
 279       ((highlight == null) || (highlight.getAlpha() == 255))
 280       && ((shadow == null) || (shadow.getAlpha() == 255));
 281   }
 282
 283
 284   /**
 285    * Returns the appearance of this EtchedBorder, which is either
 286    * {@link #RAISED} or {@link #LOWERED}.
 287    */
 288   public int getEtchType()
 289   {
 290     return etchType;
 291   }
 292
 293
 294   /**
 295    * Determines the color that will be used for highlighted parts when
 296    * painting the border around a given component. If a highlight
 297    * color has been specified upon constructing the border, that color
 298    * is returned. Otherwise, the background color of the enclosed
 299    * component is brightened.
 300    *
 301    * @param c the component enclosed by this border.
 302    *
 303    * @see java.awt.Component#getBackground()
 304    * @see java.awt.Color#brighter()
 305    */
 306   public Color getHighlightColor(Component c)
 307   {
 308     if (highlight != null)
 309       return highlight;
 310     else
 311       return c.getBackground().brighter();
 312   }
 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   public Color getHighlightColor()
 321   {
 322     return highlight;
 323   }
 324
 325
 326   /**
 327    * Determines the color that will be used for shadowed parts when
 328    * painting the border around a given component. If a shadow color
 329    * has been specified upon constructing the border, that color is
 330    * returned. Otherwise, the background color of the enclosed
 331    * component is darkened.
 332    *
 333    * @param c the component enclosed by this border.
 334    *
 335    * @see java.awt.Component#getBackground()
 336    * @see java.awt.Color#darker()
 337    */
 338   public Color getShadowColor(Component c)
 339   {
 340     if (shadow != null)
 341       return shadow;
 342     else
 343       return c.getBackground().darker();
 344   }
 345
 346
 347   /**
 348    * Returns the color that will be used for shadowed parts when
 349    * painting the border, or <code>null</code> if that color will be
 350    * derived from the background of the enclosed Component.
 351    */
 352   public Color getShadowColor()
 353   {
 354     return shadow;
 355   }
 356
 357
 358   /**
 359    * Paints a two-pixel etching in two colors.
 360    *
 361    * <pre>
 362    * @@@@@@@@@@@.
 363    * @.........@.    @ = color a
 364    * @.        @.    . = color b
 365    * @.        @.
 366    * @@@@@@@@@@@.
 367    * ............</pre>
 368    *
 369    * @param g the graphics for painting.
 370    * @param x the horizontal position for painting the border.
 371    * @param y the vertical position for painting the border.
 372    * @param width the width of the available area for painting the border.
 373    * @param height the height of the available area for painting the border.
 374    * @param a one of the two colors.
 375    * @param b the second of the two colors.
 376    */
 377   private static void paintEtchedBorder(Graphics g,
 378                                         int x, int y, int width, int height,
 379                                         Color a, Color b)
 380   {
 381     Color oldColor;
 382
 383     oldColor = g.getColor();
 384     g.translate(x, y);
 385     width = width - 1;
 386     height = height - 1;
 387
 388     try
 389     {
 390       /* To understand this code, it might be helpful to look at the
 391        * images that are included with the JavaDoc. They are located
 392        * in the "doc-files" subdirectory. EtchedBorder-2.png might
 393        * be especially informative.
 394        */
 395       g.setColor(a);
 396       g.drawRect(0, 0, width - 1, height - 1);
 397
 398       g.setColor(b);
 399       g.drawLine(1, 1, width - 2, 1);            // top edge
 400       g.drawLine(1, 2, 1, height - 2);           // left edge
 401       g.drawLine(0, height, width, height);      // bottom edge
 402       g.drawLine(width, 0, width, height - 1);   // right edge
 403     }
 404     finally
 405     {
 406       g.translate(-x, -y);
 407       g.setColor(oldColor);
 408     }
 409   }
 410 }
 411