libjava/javax/swing/plaf/basic/BasicViewportUI.java

   1 /* BasicViewportUI.java
   2    Copyright (C) 2002, 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., 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.plaf.basic;
  40
  41 import java.awt.Component;
  42 import java.awt.Dimension;
  43 import java.awt.Graphics;
  44 import java.awt.Image;
  45 import java.awt.Point;
  46 import java.awt.Rectangle;
  47 import java.awt.image.ImageObserver;
  48 import javax.swing.JComponent;
  49 import javax.swing.JViewport;
  50 import javax.swing.ViewportLayout;
  51 import javax.swing.event.ChangeEvent;
  52 import javax.swing.event.ChangeListener;
  53 import javax.swing.plaf.ComponentUI;
  54 import javax.swing.plaf.ViewportUI;
  55
  56 public class BasicViewportUI extends ViewportUI
  57 {
  58
  59   ChangeListener changeListener;
  60   Image backingStoreImage;
  61   int backingStoreWidth = -1;
  62   int backingStoreHeight = -1;
  63
  64   class ChangeHandler implements ChangeListener
  65   {
  66     public void stateChanged(ChangeEvent event)
  67     {
  68       JViewport v = (JViewport) event.getSource();
  69       v.repaint();
  70     }
  71   }
  72
  73   void installDefaults(JComponent c)
  74   {
  75     c.setOpaque(true);
  76   }
  77
  78   void uninstallDefaults(JComponent c)
  79   {
  80   }
  81
  82   void installListeners(JComponent c)
  83   {
  84     ((JViewport)c).addChangeListener(changeListener);
  85   }
  86
  87   void uninstallListeners(JComponent c)
  88   {
  89     ((JViewport)c).removeChangeListener(changeListener);
  90   }
  91
  92   public BasicViewportUI()
  93   {
  94     changeListener = new ChangeHandler();
  95   }
  96
  97   public static ComponentUI createUI(JComponent c)
  98   {
  99     return new BasicViewportUI();
 100   }
 101
 102   public void installUI(JComponent c)
 103   {
 104     super.installUI(c);
 105     c.setLayout(new ViewportLayout());
 106     installListeners(c);
 107   }
 108
 109   public void uninstallUI(JComponent c)
 110   {
 111     uninstallListeners(c);
 112   }
 113
 114
 115   public Dimension getPreferredSize(JComponent c)
 116   {
 117     // let the ViewportLayout decide
 118     return null;
 119   }
 120
 121   public void paint(Graphics g, JComponent c)
 122   {
 123
 124     JViewport v = (JViewport)c;
 125     Component view = v.getView();
 126
 127     if (view == null)
 128       return;
 129
 130     Point pos = v.getViewPosition();
 131     Rectangle viewBounds = view.getBounds();
 132     Rectangle portBounds = v.getBounds();
 133
 134     if (viewBounds.width == 0
 135         || viewBounds.height == 0
 136         || portBounds.width == 0
 137         || portBounds.height == 0)
 138       return;
 139
 140     if (backingStoreImage == null
 141         || backingStoreWidth != viewBounds.width
 142         || backingStoreHeight != viewBounds.height)
 143       {
 144         backingStoreImage = v.createImage(viewBounds.width, viewBounds.height);
 145         backingStoreWidth = viewBounds.width;
 146         backingStoreHeight = viewBounds.height;
 147       }
 148
 149     Graphics g2 = backingStoreImage.getGraphics();
 150
 151
 152     if (c.getBackground() != null)
 153       {
 154         // fill the backing store background
 155         java.awt.Color save = g2.getColor();
 156         g2.setColor(c.getBackground());
 157         g2.fillRect (0, 0, backingStoreWidth, backingStoreHeight);
 158         g2.setColor(save);
 159
 160         // fill the viewport background
 161         save = g.getColor();
 162         g.setColor(c.getBackground());
 163         g.fillRect (0, 0, portBounds.width, portBounds.height);
 164         g.setColor(save);
 165
 166       }
 167     else
 168       {
 169         // clear the backing store background
 170         g2.clearRect(0, 0, backingStoreWidth, backingStoreHeight);
 171
 172         // clear the viewport background
 173         g.clearRect(0, 0, portBounds.width, portBounds.height);
 174       }
 175
 176     view.paint(g2);
 177     g2 = null;
 178     g.drawImage(backingStoreImage,
 179                 -pos.x, -pos.y,
 180                 (ImageObserver)null);
 181   }
 182 }