libjava/java/awt/Image.java

   1 /* Image.java -- Java class for images
   2    Copyright (C) 1999 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 java.awt;
  40
  41 import java.awt.image.*;
  42
  43 /**
  44   * This is the abstract superclass of all image objects in Java.
  45   *
  46   * @author Aaron M. Renn (arenn@urbanophile.com)
  47   */
  48 public abstract class Image
  49 {
  50
  51 /*
  52  * Static Variables
  53  */
  54
  55 /**
  56   * Constant indicating that the default scaling algorithm should be used.
  57   */
  58 public static final int SCALE_DEFAULT = 1;
  59
  60 /**
  61   * Constant indicating that a fast scaling algorithm should be used.
  62   */
  63 public static final int SCALE_FAST = 2;
  64
  65 /**
  66   * Constant indicating that a smooth scaling algorithm should be used.
  67   */
  68 public static final int SCALE_SMOOTH = 4;
  69
  70 /**
  71   * Constant indicating that the <code>ReplicateScaleFilter</code> class
  72   * algorithm should be used for scaling.
  73   */
  74 public static final int SCALE_REPLICATE = 8;
  75
  76 /**
  77   * Constant indicating that the area averaging scaling algorithm should be
  78   * used.
  79   */
  80 public static final int SCALE_AREA_AVERAGING = 16;
  81
  82 /**
  83   * This variable is returned whenever a property that is not defined
  84   * is requested.
  85   */
  86 public static final Object UndefinedProperty = Image.class;
  87
  88 /*************************************************************************/
  89
  90 /*
  91  * Constructors
  92  */
  93
  94 /**
  95   * A default constructor for subclasses.
  96   */
  97 public
  98 Image()
  99 {
 100 }
 101
 102 /*************************************************************************/
 103
 104 /*
 105  * Instance Methods
 106  */
 107
 108 /**
 109   * Returns the width of the image, or -1 if it is unknown.  If the
 110   * image width is unknown, the observer object will be notified when
 111   * the value is known.
 112   *
 113   * @param observer The image observer for this object.
 114   */
 115 public abstract int
 116 getWidth(ImageObserver observer);
 117
 118 /*************************************************************************/
 119
 120 /**
 121   * Returns the height of the image, or -1 if it is unknown.  If the
 122   * image height is unknown, the observer object will be notified when
 123   * the value is known.
 124   *
 125   * @param observer The image observer for this object.
 126   */
 127 public abstract int
 128 getHeight(ImageObserver observer);
 129
 130 /*************************************************************************/
 131
 132 /**
 133   * Returns the image producer object for this object.
 134   *
 135   * @return The image producer for this object.
 136   */
 137 public abstract ImageProducer
 138 getSource();
 139
 140 /*************************************************************************/
 141
 142 /**
 143   * Returns a graphics context object for drawing an off-screen object.
 144   * This method is only valid for off-screen objects.
 145   *
 146   * @return A graphics context object for an off-screen object.
 147   */
 148 public abstract Graphics
 149 getGraphics();
 150
 151 /*************************************************************************/
 152
 153 /**
 154   * This method requests a named property for an object.  The value of the
 155   * property is returned. The value <code>UndefinedProperty</code> is
 156   * returned if there is no property with the specified name.  The value
 157   * <code>null</code> is returned if the properties for the object are
 158   * not yet known.  In this case, the specified image observer is notified
 159   * when the properties are known.
 160   *
 161   * @param name The requested property name.
 162   * @param observer The image observer for this object.
 163   */
 164 public abstract Object
 165 getProperty(String name, ImageObserver observer);
 166
 167 /*************************************************************************/
 168
 169 /**
 170   * Scales the image to the requested dimension.
 171   *
 172   * XXX: FIXME
 173   *
 174   * @param width The width of the scaled image.
 175   * @param height The height of the scaled image.
 176   * @param flags A value indicating the algorithm to use, which will be
 177   * set from contants defined in this class.
 178   *
 179   * @return The scaled <code>Image</code> object.
 180   */
 181 public Image
 182 getScaledInstance(int width, int height, int flags)
 183   {
 184     return null;
 185   }
 186
 187 /*************************************************************************/
 188
 189 /**
 190   * Flushes (that is, destroys) any resources used for this image.  This
 191   * includes the actual image data.
 192   */
 193 public abstract void
 194 flush();
 195
 196 } // class Image
 197