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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.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 1.4 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: * A default constructor for subclasses. 106: */ 107: public Image() 108: { 109: } 110: 111: /** 112: * Returns the width of the image, or -1 if it is unknown. If the 113: * image width is unknown, the observer object will be notified when 114: * the value is known. 115: * 116: * @param observer the image observer for this object 117: * @return the width in pixels 118: * @see #getHeight(ImageObserver) 119: */ 120: public abstract int getWidth(ImageObserver observer); 121: 122: /** 123: * Returns the height of the image, or -1 if it is unknown. If the 124: * image height is unknown, the observer object will be notified when 125: * the value is known. 126: * 127: * @param observer the image observer for this object 128: * @return the height in pixels 129: * @see #getWidth(ImageObserver) 130: */ 131: public abstract int getHeight(ImageObserver observer); 132: 133: /** 134: * Returns the image producer object for this object. The producer is the 135: * object which generates pixels for this image. 136: * 137: * @return the image producer for this object 138: */ 139: public abstract ImageProducer getSource(); 140: 141: /** 142: * Returns a graphics context object for drawing an off-screen object. 143: * This method is only valid for off-screen objects. 144: * 145: * @return a graphics context object for an off-screen object 146: */ 147: public abstract Graphics getGraphics(); 148: 149: /** 150: * This method requests a named property for an object. The value of the 151: * property is returned. The value <code>UndefinedProperty</code> is 152: * returned if there is no property with the specified name. The value 153: * <code>null</code> is returned if the properties for the object are 154: * not yet known. In this case, the specified image observer is notified 155: * when the properties are known. 156: * 157: * @param name the requested property name 158: * @param observer the image observer for this object 159: * @return the named property, if available 160: * @see #UndefinedProperty 161: */ 162: public abstract Object getProperty(String name, ImageObserver observer); 163: 164: /** 165: * Scales the image to the requested dimension. A new Image with asynchronous 166: * loading will be produced according to the hints of the algorithm 167: * requested. If either the width or height is non-positive, it is adjusted 168: * to preserve the original aspect ratio. 169: * 170: * @param width the width of the scaled image 171: * @param height the height of the scaled image 172: * @param flags a value indicating the algorithm to use 173: * @return the scaled <code>Image</code> object 174: * @see #SCALE_DEFAULT 175: * @see #SCALE_FAST 176: * @see #SCALE_SMOOTH 177: * @see #SCALE_REPLICATE 178: * @see #SCALE_AREA_AVERAGING 179: * @since 1.1 180: */ 181: public Image getScaledInstance(int width, int height, int flags) 182: { 183: ImageFilter filter; 184: switch (flags) 185: { 186: case SCALE_DEFAULT: 187: case SCALE_FAST: 188: case SCALE_REPLICATE: 189: filter = new ReplicateScaleFilter(width, height); 190: break; 191: case SCALE_AREA_AVERAGING: 192: filter = new AreaAveragingScaleFilter(width, height); 193: break; 194: case SCALE_SMOOTH: 195: throw new Error("SCALE_SMOOTH: not implemented"); 196: default: 197: throw new Error("Unknown flag or not implemented: " + flags); 198: } 199: 200: ImageProducer producer = new FilteredImageSource(getSource(), filter); 201: return Toolkit.getDefaultToolkit().createImage(producer); 202: } 203: 204: /** 205: * Flushes (that is, destroys) any resources used for this image. This 206: * includes the actual image data. 207: */ 208: public abstract void flush(); 209: } // class Image
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