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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).
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25  
26  package javax.imageio.event;
27  
28  import java.util.EventListener;
29  import javax.imageio.ImageReader;
30  
31  /**
32   * An interface used by <code>ImageReader</code> implementations to
33   * notify callers of their image and thumbnail reading methods of
34   * progress.
35   *
36   * <p> This interface receives general indications of decoding
37   * progress (via the <code>imageProgress</code> and
38   * <code>thumbnailProgress</code> methods), and events indicating when
39   * an entire image has been updated (via the
40   * <code>imageStarted</code>, <code>imageComplete</code>,
41   * <code>thumbnailStarted</code> and <code>thumbnailComplete</code>
42   * methods).  Applications that wish to be informed of pixel updates
43   * as they happen (for example, during progressive decoding), should
44   * provide an <code>IIOReadUpdateListener</code>.
45   *
46   * @see IIOReadUpdateListener
47   * @see javax.imageio.ImageReader#addIIOReadProgressListener
48   * @see javax.imageio.ImageReader#removeIIOReadProgressListener
49   *
50   */
51  public interface IIOReadProgressListener extends EventListener {
52  
53      /**
54       * Reports that a sequence of read operations is beginning.
55       * <code>ImageReader</code> implementations are required to call
56       * this method exactly once from their
57       * <code>readAll(Iterator)</code> method.
58       *
59       * @param source the <code>ImageReader</code> object calling this method.
60       * @param minIndex the index of the first image to be read.
61       */
62      void sequenceStarted(ImageReader source, int minIndex);
63  
64      /**
65       * Reports that a sequence of read operations has completed.
66       * <code>ImageReader</code> implementations are required to call
67       * this method exactly once from their
68       * <code>readAll(Iterator)</code> method.
69       *
70       * @param source the <code>ImageReader</code> object calling this method.
71       */
72      void sequenceComplete(ImageReader source);
73  
74      /**
75       * Reports that an image read operation is beginning.  All
76       * <code>ImageReader</code> implementations are required to call
77       * this method exactly once when beginning an image read
78       * operation.
79       *
80       * @param source the <code>ImageReader</code> object calling this method.
81       * @param imageIndex the index of the image being read within its
82       * containing input file or stream.
83       */
84      void imageStarted(ImageReader source, int imageIndex);
85  
86      /**
87       * Reports the approximate degree of completion of the current
88       * <code>read</code> call of the associated
89       * <code>ImageReader</code>.
90       *
91       * <p> The degree of completion is expressed as a percentage
92       * varying from <code>0.0F</code> to <code>100.0F</code>.  The
93       * percentage should ideally be calculated in terms of the
94       * remaining time to completion, but it is usually more practical
95       * to use a more well-defined metric such as pixels decoded or
96       * portion of input stream consumed.  In any case, a sequence of
97       * calls to this method during a given read operation should
98       * supply a monotonically increasing sequence of percentage
99       * values.  It is not necessary to supply the exact values
100      * <code>0</code> and <code>100</code>, as these may be inferred
101      * by the callee from other methods.
102      *
103      * <p> Each particular <code>ImageReader</code> implementation may
104      * call this method at whatever frequency it desires.  A rule of
105      * thumb is to call it around each 5 percent mark.
106      *
107      * @param source the <code>ImageReader</code> object calling this method.
108      * @param percentageDone the approximate percentage of decoding that
109      * has been completed.
110      */
111     void imageProgress(ImageReader source, float percentageDone);
112 
113     /**
114      * Reports that the current image read operation has completed.
115      * All <code>ImageReader</code> implementations are required to
116      * call this method exactly once upon completion of each image
117      * read operation.
118      *
119      * @param source the <code>ImageReader</code> object calling this
120      * method.
121      */
122     void imageComplete(ImageReader source);
123 
124     /**
125      * Reports that a thumbnail read operation is beginning.  All
126      * <code>ImageReader</code> implementations are required to call
127      * this method exactly once when beginning a thumbnail read
128      * operation.
129      *
130      * @param source the <code>ImageReader</code> object calling this method.
131      * @param imageIndex the index of the image being read within its
132      * containing input file or stream.
133      * @param thumbnailIndex the index of the thumbnail being read.
134      */
135     void thumbnailStarted(ImageReader source,
136                           int imageIndex, int thumbnailIndex);
137 
138     /**
139      * Reports the approximate degree of completion of the current
140      * <code>getThumbnail</code> call within the associated
141      * <code>ImageReader</code>.  The semantics are identical to those
142      * of <code>imageProgress</code>.
143      *
144      * @param source the <code>ImageReader</code> object calling this method.
145      * @param percentageDone the approximate percentage of decoding that
146      * has been completed.
147      */
148     void thumbnailProgress(ImageReader source, float percentageDone);
149 
150     /**
151      * Reports that a thumbnail read operation has completed.  All
152      * <code>ImageReader</code> implementations are required to call
153      * this method exactly once upon completion of each thumbnail read
154      * operation.
155      *
156      * @param source the <code>ImageReader</code> object calling this
157      * method.
158      */
159     void thumbnailComplete(ImageReader source);
160 
161     /**
162      * Reports that a read has been aborted via the reader's
163      * <code>abort</code> method.  No further notifications will be
164      * given.
165      *
166      * @param source the <code>ImageReader</code> object calling this
167      * method.
168      */
169     void readAborted(ImageReader source);
170 }