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1
11 package org.eclipse.swt.internal.image;
12
13 import java.io.*;
14
15 public class PngInputStream extends InputStream {
16 PngChunkReader reader;
17 PngChunk chunk;
18 int offset, length;
19
20 final static int DATA_OFFSET = 8;
21
22 public PngInputStream(PngIdatChunk chunk, PngChunkReader reader) {
23 this.chunk = chunk;
24 this.reader = reader;
25 length = chunk.getLength();
26 offset = 0;
27 }
28
29 private boolean checkChunk() throws IOException {
30 while (offset == length) {
31 chunk = reader.readNextChunk();
32 if (chunk == null) throw new IOException();
33 if (chunk.getChunkType() == PngChunk.CHUNK_IEND) return false;
34 if (chunk.getChunkType() != PngChunk.CHUNK_IDAT) throw new IOException();
35 length = chunk.getLength();
36 offset = 0;
37 }
38 return true;
39 }
40
41 public void close() throws IOException {
42 chunk = null;
43 }
44
45 public int read() throws IOException {
46 if (chunk == null) throw new IOException();
47 if (offset == length && !checkChunk()) return -1;
48 int b = chunk.reference[DATA_OFFSET + offset] & 0xFF;
49 offset++;
50 return b;
51 }
52
53 public int read(byte[] b, int off, int len) throws IOException {
54 if (chunk == null) throw new IOException();
55 if (offset == length && !checkChunk()) return -1;
56 len = Math.min(len, length - offset);
57 System.arraycopy(chunk.reference, DATA_OFFSET + offset, b, off, len);
58 offset += len;
59 return len;
60 }
61 }
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