1: /* Image.java -- superclass for images 2: Copyright (C) 1999, 2002, 2004, 2005, 2006 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.AreaAveragingScaleFilter; 42: import java.awt.image.FilteredImageSource; 43: import java.awt.image.ImageFilter; 44: import java.awt.image.ImageObserver; 45: import java.awt.image.ImageProducer; 46: import java.awt.image.ReplicateScaleFilter; 47: 48: /** 49: * This is the abstract superclass of all image objects in Java. 50: * 51: * @author Aaron M. Renn (arenn@urbanophile.com) 52: * @since 1.0 53: * @status updated to 1.5 54: */ 55: public abstract class Image 56: { 57: /** 58: * This variable is returned whenever a property that is not defined 59: * is requested. 60: */ 61: // For debug purposes, this might as well be a unique string. 62: public static final Object UndefinedProperty 63: = new String("undefined property"); 64: 65: /** 66: * Constant indicating that the default scaling algorithm should be used. 67: * 68: * @since 1.1 69: */ 70: public static final int SCALE_DEFAULT = 1; 71: 72: /** 73: * Constant indicating that a fast scaling algorithm should be used. 74: * 75: * @since 1.1 76: */ 77: public static final int SCALE_FAST = 2; 78: 79: /** 80: * Constant indicating that a smooth scaling algorithm should be used. 81: * 82: * @since 1.1 83: */ 84: public static final int SCALE_SMOOTH = 4; 85: 86: /** 87: * Constant indicating that the <code>ReplicateScaleFilter</code> class 88: * algorithm should be used for scaling. 89: * 90: * @see ReplicateScaleFilter 91: * @since 1.1 92: */ 93: public static final int SCALE_REPLICATE = 8; 94: 95: /** 96: * Constant indicating that the area averaging scaling algorithm should be 97: * used. 98: * 99: * @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