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 {@code MultiResolutionImage}

    33  * interface.

    34  *

    35  * For example,

    36  * <pre> {@code

    37  * public class CustomMultiResolutionImage extends AbstractMultiResolutionImage {

    38  *

    39  *     final Image[] resolutionVariants;

    40  *

    41  *     public CustomMultiResolutionImage(Image... resolutionVariants) {

    42  *          this.resolutionVariants = resolutionVariants;

    43  *     }

    44  *

    45  *     public Image getResolutionVariant(

    46  *             double destImageWidth, double destImageHeight) {

    47  *         // return a resolution variant based on the given destination image size

    48  *     }

    49  *

    50  *     public List<Image> getResolutionVariants() {

    51  *         return Collections.unmodifiableList(Arrays.asList(resolutionVariants));

    52  *     }

    53  *

    54  *     protected Image getBaseImage() {

    55  *         return resolutionVariants[0];

    56  *     }

    57  * }

    58  * } </pre>

    59  *

    60  * @see java.awt.Image

    61  * @see java.awt.image.MultiResolutionImage

    62  *

    63  * @since 9

    64  */

    65 public abstract class AbstractMultiResolutionImage extends java.awt.Image

    66         implements MultiResolutionImage {

    67 

    68     /**

    69      * This method simply delegates to the same method on the base image and

    70      * it is equivalent to: {@code getBaseImage().getWidth(observer)}.

    71      *

    72      * @return the width of the base image, or -1 if the width is not yet known

    73      * @see #getBaseImage()

    74      *

    75      * @since 9

    76      */

    77     @Override

    78     public int getWidth(ImageObserver observer) {

    79         return getBaseImage().getWidth(observer);

    80     }

    81 

    82     /**

    83      * This method simply delegates to the same method on the base image and

    84      * it is equivalent to: {@code getBaseImage().getHeight(observer)}.

    85      *

    86      * @return the height of the base image, or -1 if the height is not yet known

    87      * @see #getBaseImage()

    88      *

    89      * @since 9

    90      */

    91     @Override

    92     public int getHeight(ImageObserver observer) {

    93         return getBaseImage().getHeight(observer);

    94     }

    95 

    96     /**

    97      * This method simply delegates to the same method on the base image and

    98      * it is equivalent to: {@code getBaseImage().getSource()}.

    99      *

   100      * @return the image producer that produces the pixels for the base image

   101      * @see #getBaseImage()

   102      *

   103      * @since 9

   104      */

   105     @Override

   106     public ImageProducer getSource() {

   107         return getBaseImage().getSource();

   108     }

   109 

   110     /**

   111      * As per the contract of the base {@code Image#getGraphics()} method,

   112      * this implementation will always throw {@code UnsupportedOperationException}

   113      * since only off-screen images can return a {@code Graphics} object.

   114      *

   115      * @return throws {@code UnsupportedOperationException}

   116      * @throws UnsupportedOperationException this method is not supported

   117      */

   118     @Override

   119     public Graphics getGraphics() {

   120         throw new UnsupportedOperationException("getGraphics() not supported"

   121                 + " on Multi-Resolution Images");

   122     }

   123 

   124     /**

   125      * This method simply delegates to the same method on the base image and

   126      * it is equivalent to: {@code getBaseImage().getProperty(name, observer)}.

   127      *

   128      * @return the value of the named property in the base image

   129      * @see #getBaseImage()

   130      *

   131      * @since 9

   132      */

   133     @Override

   134     public Object getProperty(String name, ImageObserver observer) {

   135         return getBaseImage().getProperty(name, observer);

   136     }

   137 

   138     /**

   139      * Return the base image representing the best version of the image for

   140      * rendering at the default width and height.

   141      *

   142      * @return the base image of the set of multi-resolution images

   143      *

   144      * @since 9

   145      */

   146     protected abstract Image getBaseImage();

   147 }