1 /* Image.java -- superclass for images 2 Copyright (C) 1999, 2002, 2004, 2005 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 java.awt; 40 41 import java.awt.image.FilteredImageSource; 42 import java.awt.image.ImageObserver; 43 import java.awt.image.ImageProducer; 44 import java.awt.image.ReplicateScaleFilter; 45 46 /** 47 * This is the abstract superclass of all image objects in Java. 48 * 49 * @author Aaron M. Renn (arenn@urbanophile.com) 50 * @since 1.0 51 * @status updated to 1.4 52 */ 53 public abstract class Image 54 { 55 /** 56 * This variable is returned whenever a property that is not defined 57 * is requested. 58 */ 59 // For debug purposes, this might as well be a unique string. 60 public static final Object UndefinedProperty 61 = new String("undefined property"); 62 63 /** 64 * Constant indicating that the default scaling algorithm should be used. 65 * 66 * @since 1.1 67 */ 68 public static final int SCALE_DEFAULT = 1; 69 70 /** 71 * Constant indicating that a fast scaling algorithm should be used. 72 * 73 * @since 1.1 74 */ 75 public static final int SCALE_FAST = 2; 76 77 /** 78 * Constant indicating that a smooth scaling algorithm should be used. 79 * 80 * @since 1.1 81 */ 82 public static final int SCALE_SMOOTH = 4; 83 84 /** 85 * Constant indicating that the <code>ReplicateScaleFilter</code> class 86 * algorithm should be used for scaling. 87 * 88 * @see ReplicateScaleFilter 89 * @since 1.1 90 */ 91 public static final int SCALE_REPLICATE = 8; 92 93 /** 94 * Constant indicating that the area averaging scaling algorithm should be 95 * used. 96 * 97 * @see java.awt.image.AreaAveragingScaleFilter 98 * @since 1.1 99 */ 100 public static final int SCALE_AREA_AVERAGING = 16; 101 102 /** 103 * A default constructor for subclasses. 104 */ Image()105 public Image() 106 { 107 } 108 109 /** 110 * Returns the width of the image, or -1 if it is unknown. If the 111 * image width is unknown, the observer object will be notified when 112 * the value is known. 113 * 114 * @param observer the image observer for this object 115 * @return the width in pixels 116 * @see #getHeight(ImageObserver) 117 */ getWidth(ImageObserver observer)118 public abstract int getWidth(ImageObserver observer); 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 * @return the height in pixels 127 * @see #getWidth(ImageObserver) 128 */ getHeight(ImageObserver observer)129 public abstract int getHeight(ImageObserver observer); 130 131 /** 132 * Returns the image producer object for this object. The producer is the 133 * object which generates pixels for this image. 134 * 135 * @return the image producer for this object 136 */ getSource()137 public abstract ImageProducer getSource(); 138 139 /** 140 * Returns a graphics context object for drawing an off-screen object. 141 * This method is only valid for off-screen objects. 142 * 143 * @return a graphics context object for an off-screen object 144 */ getGraphics()145 public abstract Graphics getGraphics(); 146 147 /** 148 * This method requests a named property for an object. The value of the 149 * property is returned. The value <code>UndefinedProperty</code> is 150 * returned if there is no property with the specified name. The value 151 * <code>null</code> is returned if the properties for the object are 152 * not yet known. In this case, the specified image observer is notified 153 * when the properties are known. 154 * 155 * @param name the requested property name 156 * @param observer the image observer for this object 157 * @return the named property, if available 158 * @see #UndefinedProperty 159 */ getProperty(String name, ImageObserver observer)160 public abstract Object getProperty(String name, ImageObserver observer); 161 162 /** 163 * Scales the image to the requested dimension. A new Image with asynchronous 164 * loading will be produced according to the hints of the algorithm 165 * requested. If either the width or height is non-positive, it is adjusted 166 * to preserve the original aspect ratio. 167 * 168 * @param width the width of the scaled image 169 * @param height the height of the scaled image 170 * @param flags a value indicating the algorithm to use 171 * @return the scaled <code>Image</code> object 172 * @see #SCALE_DEFAULT 173 * @see #SCALE_FAST 174 * @see #SCALE_SMOOTH 175 * @see #SCALE_REPLICATE 176 * @see #SCALE_AREA_AVERAGING 177 * @since 1.1 178 */ getScaledInstance(int width, int height, int flags)179 public Image getScaledInstance(int width, int height, int flags) 180 { 181 switch (flags) 182 { 183 case SCALE_DEFAULT: 184 case SCALE_FAST: 185 case SCALE_REPLICATE: 186 ImageProducer producer = 187 new FilteredImageSource(this.getSource(), 188 new ReplicateScaleFilter(width, height)); 189 return Toolkit.getDefaultToolkit().createImage(producer); 190 case SCALE_SMOOTH: 191 case SCALE_AREA_AVERAGING: 192 default: 193 throw new Error("not implemented"); 194 } 195 } 196 197 /** 198 * Flushes (that is, destroys) any resources used for this image. This 199 * includes the actual image data. 200 */ flush()201 public abstract void flush(); 202 } // class Image 203