001/* Image.java -- superclass for images 002 Copyright (C) 1999, 2002, 2004, 2005, 2006 Free Software Foundation, Inc. 003 004This file is part of GNU Classpath. 005 006GNU Classpath is free software; you can redistribute it and/or modify 007it under the terms of the GNU General Public License as published by 008the Free Software Foundation; either version 2, or (at your option) 009any later version. 010 011GNU Classpath is distributed in the hope that it will be useful, but 012WITHOUT ANY WARRANTY; without even the implied warranty of 013MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 014General Public License for more details. 015 016You should have received a copy of the GNU General Public License 017along with GNU Classpath; see the file COPYING. If not, write to the 018Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 01902110-1301 USA. 020 021Linking this library statically or dynamically with other modules is 022making a combined work based on this library. Thus, the terms and 023conditions of the GNU General Public License cover the whole 024combination. 025 026As a special exception, the copyright holders of this library give you 027permission to link this library with independent modules to produce an 028executable, regardless of the license terms of these independent 029modules, and to copy and distribute the resulting executable under 030terms of your choice, provided that you also meet, for each linked 031independent module, the terms and conditions of the license of that 032module. An independent module is a module which is not derived from 033or based on this library. If you modify this library, you may extend 034this exception to your version of the library, but you are not 035obligated to do so. If you do not wish to do so, delete this 036exception statement from your version. */ 037 038 039package java.awt; 040 041import java.awt.image.AreaAveragingScaleFilter; 042import java.awt.image.FilteredImageSource; 043import java.awt.image.ImageFilter; 044import java.awt.image.ImageObserver; 045import java.awt.image.ImageProducer; 046import java.awt.image.ReplicateScaleFilter; 047 048/** 049 * This is the abstract superclass of all image objects in Java. 050 * 051 * @author Aaron M. Renn (arenn@urbanophile.com) 052 * @since 1.0 053 * @status updated to 1.5 054 */ 055public abstract class Image 056{ 057 /** 058 * This variable is returned whenever a property that is not defined 059 * is requested. 060 */ 061 // For debug purposes, this might as well be a unique string. 062 public static final Object UndefinedProperty 063 = new String("undefined property"); 064 065 /** 066 * Constant indicating that the default scaling algorithm should be used. 067 * 068 * @since 1.1 069 */ 070 public static final int SCALE_DEFAULT = 1; 071 072 /** 073 * Constant indicating that a fast scaling algorithm should be used. 074 * 075 * @since 1.1 076 */ 077 public static final int SCALE_FAST = 2; 078 079 /** 080 * Constant indicating that a smooth scaling algorithm should be used. 081 * 082 * @since 1.1 083 */ 084 public static final int SCALE_SMOOTH = 4; 085 086 /** 087 * Constant indicating that the <code>ReplicateScaleFilter</code> class 088 * algorithm should be used for scaling. 089 * 090 * @see ReplicateScaleFilter 091 * @since 1.1 092 */ 093 public static final int SCALE_REPLICATE = 8; 094 095 /** 096 * Constant indicating that the area averaging scaling algorithm should be 097 * used. 098 * 099 * @see java.awt.image.AreaAveragingScaleFilter 100 * @since 1.1 101 */ 102 public static final int SCALE_AREA_AVERAGING = 16; 103 104 /** 105 * The acceleration priority of the image 106 * @since 1.5 107 */ 108 protected float accelerationPriority; 109 110 /** 111 * A default constructor for subclasses. 112 */ 113 public Image() 114 { 115 } 116 117 /** 118 * Returns the width of the image, or -1 if it is unknown. If the 119 * image width is unknown, the observer object will be notified when 120 * the value is known. 121 * 122 * @param observer the image observer for this object 123 * @return the width in pixels 124 * @see #getHeight(ImageObserver) 125 */ 126 public abstract int getWidth(ImageObserver observer); 127 128 /** 129 * Returns the height of the image, or -1 if it is unknown. If the 130 * image height is unknown, the observer object will be notified when 131 * the value is known. 132 * 133 * @param observer the image observer for this object 134 * @return the height in pixels 135 * @see #getWidth(ImageObserver) 136 */ 137 public abstract int getHeight(ImageObserver observer); 138 139 /** 140 * Returns the image producer object for this object. The producer is the 141 * object which generates pixels for this image. 142 * 143 * @return the image producer for this object 144 */ 145 public abstract ImageProducer getSource(); 146 147 /** 148 * Returns a graphics context object for drawing an off-screen object. 149 * This method is only valid for off-screen objects. 150 * 151 * @return a graphics context object for an off-screen object 152 */ 153 public abstract Graphics getGraphics(); 154 155 /** 156 * This method requests a named property for an object. The value of the 157 * property is returned. The value <code>UndefinedProperty</code> is 158 * returned if there is no property with the specified name. The value 159 * <code>null</code> is returned if the properties for the object are 160 * not yet known. In this case, the specified image observer is notified 161 * when the properties are known. 162 * 163 * @param name the requested property name 164 * @param observer the image observer for this object 165 * @return the named property, if available 166 * @see #UndefinedProperty 167 */ 168 public abstract Object getProperty(String name, ImageObserver observer); 169 170 /** 171 * Scales the image to the requested dimension. A new Image with asynchronous 172 * loading will be produced according to the hints of the algorithm 173 * requested. If either the width or height is non-positive, it is adjusted 174 * to preserve the original aspect ratio. 175 * If an illegal value of <code>flags</code> is passed, 176 * the default algorithm is used. 177 * 178 * @param width the width of the scaled image 179 * @param height the height of the scaled image 180 * @param flags a value indicating the algorithm to use 181 * @return the scaled <code>Image</code> object 182 * @see #SCALE_DEFAULT 183 * @see #SCALE_FAST 184 * @see #SCALE_SMOOTH 185 * @see #SCALE_REPLICATE 186 * @see #SCALE_AREA_AVERAGING 187 * @since 1.1 188 */ 189 public Image getScaledInstance(int width, int height, int flags) 190 { 191 ImageFilter filter; 192 switch (flags) 193 { 194 case SCALE_AREA_AVERAGING: 195 case SCALE_SMOOTH: 196 filter = new AreaAveragingScaleFilter(width, height); 197 break; 198 case SCALE_DEFAULT: 199 case SCALE_FAST: 200 case SCALE_REPLICATE: 201 default: 202 filter = new ReplicateScaleFilter(width, height); 203 } 204 205 ImageProducer producer = new FilteredImageSource(getSource(), filter); 206 return Toolkit.getDefaultToolkit().createImage(producer); 207 } 208 209 /** 210 * Flushes (that is, destroys) any resources used for this image. This 211 * includes the actual image data. 212 */ 213 public abstract void flush(); 214 215 /** 216 * Sets the acceleration priority of the image. 217 * This is a value from 0 (lowest) to 1 (highest), which may 218 * be used as a hint for image acceleration. 219 * E.g. higher priority images may be stored in video memory. 220 * @param priority - the priority 221 * @throws IllegalArgumentException if priority is not >= 0 and <= 1. 222 * 223 * @since 1.5 224 */ 225 public void setAccelerationPriority(float priority) 226 { 227 if( priority < 0f || priority > 1f) 228 throw new IllegalArgumentException("Invalid priority value."); 229 accelerationPriority = priority; 230 } 231 232 /** 233 * Returns the acceleration priority of the image. 234 * 235 * @see #setAccelerationPriority(float) 236 * @since 1.5 237 */ 238 public float getAccelerationPriority() 239 { 240 return accelerationPriority; 241 } 242} // class Image