Source for javax.swing.border.AbstractBorder

   1: /* AbstractBorder.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.Component;
  42: import java.awt.Graphics;
  43: import java.awt.Insets;
  44: import java.awt.Rectangle;
  45: import java.io.Serializable;
  46: 
  47: 
  48: /**
  49:  * An invisible zero-width border, serving as a base class for
  50:  * implementing more interesting borders.
  51:  *
  52:  * @author Sascha Brawer (brawer@dandelis.ch)
  53:  * @author Ronald Veldema (rveldema@cs.vu.nl)
  54:  */
  55: public abstract class AbstractBorder
  56:   implements Border, Serializable
  57: {
  58:   static final long serialVersionUID = -545885975315191844L;
  59: 
  60: 
  61:   /**
  62:    * Constructs a new AbstractBorder.
  63:    */
  64:   public AbstractBorder ()
  65:   {
  66:   }
  67: 
  68: 
  69:   /**
  70:    * Performs nothing, because the default implementation provided by
  71:    * this class is an invisible, zero-width border. Subclasses will
  72:    * likely want to override this method, but they are not required
  73:    * for doing so.
  74:    *
  75:    * @param c the component whose border is to be painted.
  76:    * @param g the graphics for painting.
  77:    * @param x the horizontal position for painting the border.
  78:    * @param y the vertical position for painting the border.
  79:    * @param width the width of the available area for painting the border.
  80:    * @param height the height of the available area for painting the border.
  81:    */
  82:   public void paintBorder (Component c, Graphics g,
  83:                            int x, int y, int width, int height) 
  84:   {
  85:     /* A previous version of Classpath had emitted a warning when
  86:      * this method was called. The warning was removed because it is
  87:      * perfectly legal for a subclass to not override the paintBorder
  88:      * method. An example would be EmptyBorder.
  89:      */
  90:   }
  91: 
  92: 
  93:   /**
  94:    * Measures the width of this border.
  95:    *
  96:    * @param c the component whose border is to be measured.
  97:    *
  98:    * @return an Insets object whose <code>left</code>, <code>right</code>,
  99:    *         <code>top</code> and <code>bottom</code> fields indicate the
 100:    *         width of the border at the respective edge, which is zero
 101:    *         for the default implementation provided by AbstractButton.
 102:    *
 103:    * @see #getBorderInsets(java.awt.Component, java.awt.Insets)
 104:    */
 105:   public Insets getBorderInsets (Component c)
 106:   {
 107:     return new Insets (0, 0, 0, 0);
 108:   }
 109: 
 110: 
 111:   /**
 112:    * Determines the insets of this border. The implementation provided
 113:    * by AbstractButton sets the <code>left</code>, <code>right</code>,
 114:    * <code>top</code> and <code>bottom</code> fields of the passed
 115:    * <code>insets</code> parameter to zero.
 116:    *
 117:    * @param c the component whose border is to be measured.
 118:    *
 119:    * @return the same object that was passed for <code>insets</code>.
 120:    *
 121:    * @see #getBorderInsets()
 122:    */
 123:   public Insets getBorderInsets (Component c, Insets insets) 
 124:   {
 125:     insets.left = insets.right = insets.top = insets.bottom = 0;
 126:     return insets;
 127:   }
 128: 
 129: 
 130:   /**
 131:    * Determines whether or not this border is opaque. An opaque border
 132:    * fills every pixel in its area when painting. Partially
 133:    * translucent borders must return <code>false</code>, or ugly
 134:    * artifacts can appear on screen. The default implementation
 135:    * provided by AbstractBorder always returns <code>false</code>.
 136:    *
 137:    * @return <code>false</code>.
 138:    */
 139:   public boolean isBorderOpaque () 
 140:   {
 141:     return false;
 142:   }
 143: 
 144: 
 145:   /**
 146:    * Returns a rectangle that covers the specified area minus this
 147:    * border.  Components that wish to determine an area into which
 148:    * they can safely draw without intersecting with a border might
 149:    * want to use this helper method.
 150:    *
 151:    * @param c the component in the center of this border.
 152:    * @param x the horizontal position of the border.
 153:    * @param y the vertical position of the border.
 154:    * @param width the width of the available area for the border.
 155:    * @param height the height of the available area for the border.
 156:    */
 157:   public Rectangle getInteriorRectangle (Component c,
 158:                                          int x, int y, int width, int height) 
 159:   {
 160:     return getInteriorRectangle (c, this, x, y, width, height);
 161:   }
 162: 
 163:   
 164:   /**
 165:    * Returns a rectangle that covers the specified area minus a
 166:    * border.  Components that wish to determine an area into which
 167:    * they can safely draw without intersecting with a border might
 168:    * want to use this helper method.
 169:    *
 170:    * @param c the component in the center of this border.
 171:    * @param x the horizontal position of the border.
 172:    * @param y the vertical position of the border.
 173:    * @param width the width of the available area for the border.
 174:    * @param height the height of the available area for the border.
 175:    */
 176:   public static Rectangle getInteriorRectangle (Component c, Border b,
 177:                                                 int x, int y, int width, int height)
 178:   {
 179:     Insets borderInsets;
 180: 
 181:     if (b != null)
 182:     {
 183:       borderInsets = b.getBorderInsets (c);
 184:       x += borderInsets.left;
 185:       y += borderInsets.top;
 186:       width -= borderInsets.left + borderInsets.right;
 187:       height -= borderInsets.top + borderInsets.bottom;
 188:     }
 189: 
 190:     return new Rectangle (x, y, width, height);
 191:   }
 192: }