1 /*
   2  * Copyright (c) 2015, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 package java.awt.image;
  26 
  27 import java.awt.Graphics;
  28 import java.awt.Image;
  29 
  30 /**
  31  * This class provides default implementations of several {@code Image} methods
  32  * for classes that want to implement the {@MultiResolutionImage} interface.
  33  *
  34  * For example,
  35  * <pre> {@code
  36  * public class CustomMultiResolutionImage extends AbstractMultiResolutionImage {
  37  *
  38  *     final Image[] resolutionVariants;
  39  *
  40  *     public CustomMultiResolutionImage(Image... resolutionVariants) {
  41  *          this.resolutionVariants = resolutionVariants;
  42  *     }
  43  *
  44  *     public Image getResolutionVariant(
  45  *             double destImageWidth, double destImageHeight) {
  46  *         // return a resolution variant based on the given destination image size
  47  *     }
  48  *
  49  *     public List<Image> getResolutionVariants() {
  50  *         return Collections.unmodifiableList(Arrays.asList(resolutionVariants));
  51  *     }
  52  *
  53  *     protected Image getBaseImage() {
  54  *         return resolutionVariants[0];
  55  *     }
  56  * }
  57  * } </pre>
  58  *
  59  * @see java.awt.Image
  60  * @see java.awt.image.MultiResolutionImage
  61  *
  62  * @since 9
  63  */
  64 public abstract class AbstractMultiResolutionImage extends java.awt.Image
  65         implements MultiResolutionImage {
  66 
  67     /**
  68      * This method simply delegates to the same method on the base image and
  69      * it is equivalent to: {@code getBaseImage().getWidth(observer)}.
  70      * @return returns an integer value of the image width
  71      * @see #getBaseImage()
  72      *
  73      * @since 9
  74      */
  75     @Override
  76     public int getWidth(ImageObserver observer) {
  77         return getBaseImage().getWidth(observer);
  78     }
  79 
  80     /**
  81      * This method simply delegates to the same method on the base image and
  82      * it is equivalent to: {@code getBaseImage().getHeight(observer)}.
  83      *
  84      * @return returns an integer value of the image height
  85      * @see #getBaseImage()
  86      *
  87      * @since 9
  88      */
  89     @Override
  90     public int getHeight(ImageObserver observer) {
  91         return getBaseImage().getHeight(observer);
  92     }
  93 
  94     /**
  95      * This method simply delegates to the same method on the base image and
  96      * it is equivalent to: {@code getBaseImage().getSource()}.
  97      *
  98      * @return returns an ImageProducer object reference to the source image
  99      * @see #getBaseImage()
 100      *
 101      * @since 9
 102      */
 103     @Override
 104     public ImageProducer getSource() {
 105         return getBaseImage().getSource();
 106     }
 107 
 108     /**
 109      * As per the contract of the base {@code Image#getGraphics()} method,
 110      * this implementation will always throw {@code UnsupportedOperationException}
 111      * since only off-screen images can return a {@code Graphics} object.
 112      * @return Only {@code UnsupportedOperationException} is thrown
 113      * @throws UnsupportedOperationException this method is not supported
 114      */
 115     @Override
 116     public Graphics getGraphics() {
 117         throw new UnsupportedOperationException("getGraphics() not supported"
 118                 + " on Multi-Resolution Images");
 119     }
 120 
 121     /**
 122      * This method simply delegates to the same method on the base image and
 123      * it is equivalent to: {@code getBaseImage().getProperty(name, observer)}.
 124      *
 125      * @return returns an Object corresponding to the property of base image
 126      * @see #getBaseImage()
 127      *
 128      * @since 9
 129      */
 130     @Override
 131     public Object getProperty(String name, ImageObserver observer) {
 132         return getBaseImage().getProperty(name, observer);
 133     }
 134 
 135     /**
 136      * Return the base image representing the best version of the image for
 137      * rendering at the default width and height.
 138      *
 139      * @return the base image of the set of multi-resolution images
 140      *
 141      * @since 9
 142      */
 143     protected abstract Image getBaseImage();
 144 }