libjava/java/awt/Canvas.java

   1 /* Copyright (C) 1999, 2000, 2002  Free Software Foundation
   2
   3 This file is part of GNU Classpath.
   4
   5 GNU Classpath is free software; you can redistribute it and/or modify
   6 it under the terms of the GNU General Public License as published by
   7 the Free Software Foundation; either version 2, or (at your option)
   8 any later version.
   9
  10 GNU Classpath is distributed in the hope that it will be useful, but
  11 WITHOUT ANY WARRANTY; without even the implied warranty of
  12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13 General Public License for more details.
  14
  15 You should have received a copy of the GNU General Public License
  16 along with GNU Classpath; see the file COPYING.  If not, write to the
  17 Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18 02111-1307 USA.
  19
  20 Linking this library statically or dynamically with other modules is
  21 making a combined work based on this library.  Thus, the terms and
  22 conditions of the GNU General Public License cover the whole
  23 combination.
  24
  25 As a special exception, the copyright holders of this library give you
  26 permission to link this library with independent modules to produce an
  27 executable, regardless of the license terms of these independent
  28 modules, and to copy and distribute the resulting executable under
  29 terms of your choice, provided that you also meet, for each linked
  30 independent module, the terms and conditions of the license of that
  31 module.  An independent module is a module which is not derived from
  32 or based on this library.  If you modify this library, you may extend
  33 this exception to your version of the library, but you are not
  34 obligated to do so.  If you do not wish to do so, delete this
  35 exception statement from your version. */
  36
  37
  38 package java.awt;
  39
  40 import java.awt.peer.ComponentPeer;
  41
  42 public class Canvas extends Component implements java.io.Serializable
  43 {
  44   transient GraphicsConfiguration graphicsConfiguration;
  45
  46   /**
  47    * Initializes a new instance of <code>Canvas</code>.
  48    */
  49   public Canvas() { }
  50
  51   public Canvas(GraphicsConfiguration graphicsConfiguration)
  52   {
  53     this.graphicsConfiguration = graphicsConfiguration;
  54   }
  55
  56   GraphicsConfiguration getGraphicsConfigurationImpl()
  57   {
  58     if (graphicsConfiguration != null)
  59       return graphicsConfiguration;
  60     return super.getGraphicsConfigurationImpl();
  61   }
  62
  63   /**
  64    * Creates the native peer for this object.
  65    */
  66   public void addNotify()
  67   {
  68     if (peer == null)
  69       peer = (ComponentPeer) getToolkit().createCanvas(this);
  70     super.addNotify();
  71   }
  72
  73   /**
  74    * Repaints the canvas window.  This method should be overriden by
  75    * a subclass to do something useful, as this method simply paints
  76    * the window with the background color.
  77    */
  78   public void paint(Graphics gfx)
  79   {
  80     /* This implementation doesn't make much sense since the filling
  81       of background color is guaranteed for heavyweight components
  82       such as this.  But there's no need to worry, since paint() is
  83       usually overridden anyway.  */
  84     gfx.setColor(getBackground());
  85     Dimension size = getSize();
  86     gfx.fillRect(0, 0, size.width, size.height);
  87   }
  88
  89   // Serialization constant
  90   private static final long serialVersionUID = -2284879212465893870L;
  91 }