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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.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: */ 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: */ 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: */ 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: */ 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: */ 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: */ 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: */ 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: */ 201: public abstract void flush(); 202: } // class Image
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