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 import java.util.stream.Collectors;
  30 import sun.awt.image.MultiResolutionToolkitImage;
  31 
  32 /**
  33  * This class provides default implementations of several {@code Image} methods
  34  * for classes that want to implement the {@MultiResolutionImage} interface.
  35  *
  36  * For example,
  37  * <pre> {@code
  38  * public class CustomMultiResolutionImage extends AbstractMultiResolutionImage {
  39  *
  40  *     final Image[] resolutionVariants;
  41  *
  42  *     public CustomMultiResolutionImage(Image... resolutionVariants) {
  43  *          this.resolutionVariants = resolutionVariants;
  44  *     }
  45  *
  46  *     public Image getResolutionVariant(
  47  *             double destImageWidth, double destImageHeight) {
  48  *         // return a resolution variant based on the given destination image size
  49  *     }
  50  *
  51  *     public List<Image> getResolutionVariants() {
  52  *         return Collections.unmodifiableList(Arrays.asList(resolutionVariants));
  53  *     }
  54  *
  55  *     protected Image getBaseImage() {
  56  *         return resolutionVariants[0];
  57  *     }
  58  * }
  59  * } </pre>
  60  *
  61  * @see java.awt.Image
  62  * @see java.awt.image.MultiResolutionImage
  63  *
  64  * @since 9
  65  */
  66 public abstract class AbstractMultiResolutionImage extends java.awt.Image
  67         implements MultiResolutionImage {
  68 
  69     @Override
  70     public int getWidth(ImageObserver observer) {
  71         return getBaseImage().getWidth(observer);
  72     }
  73 
  74     @Override
  75     public int getHeight(ImageObserver observer) {
  76         return getBaseImage().getHeight(observer);
  77     }
  78 
  79     @Override
  80     public ImageProducer getSource() {
  81         Image baseImage = getBaseImage();
  82         int baseWidth = baseImage.getWidth(null);
  83         int baseHeight = baseImage.getHeight(null);
  84 
  85         return new MultiResolutionToolkitImage.MultiResolutionImageProducer(
  86                 getResolutionVariants().stream()
  87                 .map(rvImage -> new ResolutionVariantItem<>(
  88                         rvImage.getSource(),
  89                         rvImage.getWidth(null) / baseWidth,
  90                         rvImage.getHeight(null) / baseHeight))
  91                 .collect(Collectors.toList()));
  92     }
  93 
  94     @Override
  95     public Graphics getGraphics() {
  96         throw new UnsupportedOperationException("getGraphics() not supported"
  97                 + " on Multi-Resolution Images");
  98     }
  99 
 100     @Override
 101     public Object getProperty(String name, ImageObserver observer) {
 102         return getBaseImage().getProperty(name, observer);
 103     }
 104 
 105     /**
 106      * Return the base image representing the best version of the image for
 107      * rendering at the default width and height.
 108      *
 109      * @return the base image of the set of multi-resolution images
 110      *
 111      * @since 9
 112      */
 113     protected abstract Image getBaseImage();
 114 }