View Javadoc
1   /*
2    * Copyright (c) 1995, 2013, 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  
26  package java.awt.image;
27  
28  /**
29   * The interface for objects which can produce the image data for Images.
30   * Each image contains an ImageProducer which is used to reconstruct
31   * the image whenever it is needed, for example, when a new size of the
32   * Image is scaled, or when the width or height of the Image is being
33   * requested.
34   *
35   * @see ImageConsumer
36   *
37   * @author      Jim Graham
38   */
39  public interface ImageProducer {
40      /**
41       * Registers an <code>ImageConsumer</code> with the
42       * <code>ImageProducer</code> for access to the image data
43       * during a later reconstruction of the <code>Image</code>.
44       * The <code>ImageProducer</code> may, at its discretion,
45       * start delivering the image data to the consumer
46       * using the <code>ImageConsumer</code> interface immediately,
47       * or when the next available image reconstruction is triggered
48       * by a call to the <code>startProduction</code> method.
49       * @param ic the specified <code>ImageConsumer</code>
50       * @see #startProduction
51       */
52      public void addConsumer(ImageConsumer ic);
53  
54      /**
55       * Determines if a specified <code>ImageConsumer</code>
56       * object is currently registered with this
57       * <code>ImageProducer</code> as one of its consumers.
58       * @param ic the specified <code>ImageConsumer</code>
59       * @return <code>true</code> if the specified
60       *         <code>ImageConsumer</code> is registered with
61       *         this <code>ImageProducer</code>;
62       *         <code>false</code> otherwise.
63       */
64      public boolean isConsumer(ImageConsumer ic);
65  
66      /**
67       * Removes the specified <code>ImageConsumer</code> object
68       * from the list of consumers currently registered to
69       * receive image data.  It is not considered an error
70       * to remove a consumer that is not currently registered.
71       * The <code>ImageProducer</code> should stop sending data
72       * to this consumer as soon as is feasible.
73       * @param ic the specified <code>ImageConsumer</code>
74       */
75      public void removeConsumer(ImageConsumer ic);
76  
77      /**
78       * Registers the specified <code>ImageConsumer</code> object
79       * as a consumer and starts an immediate reconstruction of
80       * the image data which will then be delivered to this
81       * consumer and any other consumer which might have already
82       * been registered with the producer.  This method differs
83       * from the addConsumer method in that a reproduction of
84       * the image data should be triggered as soon as possible.
85       * @param ic the specified <code>ImageConsumer</code>
86       * @see #addConsumer
87       */
88      public void startProduction(ImageConsumer ic);
89  
90      /**
91       * Requests, on behalf of the <code>ImageConsumer</code>,
92       * that the <code>ImageProducer</code> attempt to resend
93       * the image data one more time in TOPDOWNLEFTRIGHT order
94       * so that higher quality conversion algorithms which
95       * depend on receiving pixels in order can be used to
96       * produce a better output version of the image.  The
97       * <code>ImageProducer</code> is free to
98       * ignore this call if it cannot resend the data in that
99       * order.  If the data can be resent, the
100      * <code>ImageProducer</code> should respond by executing
101      * the following minimum set of <code>ImageConsumer</code>
102      * method calls:
103      * <pre>{@code
104      *  ic.setHints(TOPDOWNLEFTRIGHT | < otherhints >);
105      *  ic.setPixels(...);      // As many times as needed
106      *  ic.imageComplete();
107      * }</pre>
108      * @param ic the specified <code>ImageConsumer</code>
109      * @see ImageConsumer#setHints
110      */
111     public void requestTopDownLeftRightResend(ImageConsumer ic);
112 }