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annotate dwt/internal/image/PngInputStream.d @ 213:36f5cb12e1a2

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Update to SWT 3.4M7
author Frank Benoit <benoit@tionex.de>
date Sat, 17 May 2008 17:34:28 +0200
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1 /*******************************************************************************
2
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2 * Copyright (c) 2000, 2006 IBM Corporation and others.
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3 * All rights reserved. This program and the accompanying materials
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4 * are made available under the terms of the Eclipse Public License v1.0
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5 * which accompanies this distribution, and is available at
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6 * http://www.eclipse.org/legal/epl-v10.html
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7 *
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8 * Contributors:
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9 * IBM Corporation - initial API and implementation
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10 * Port to the D programming language:
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11 * Frank Benoit <benoit@tionex.de>
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12 *******************************************************************************/
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13 module dwt.internal.image.PngInputStream;
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14
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15 import dwt.dwthelper.InputStream;
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16 import dwt.dwthelper.System;
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17 import dwt.internal.image.PngIdatChunk;
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18 import dwt.internal.image.PngChunkReader;
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19 import dwt.internal.image.PngChunk;
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20
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21 import tango.core.Exception;
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22 import Math = tango.math.Math;
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23
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24 public class PngInputStream : InputStream {
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25
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26 alias InputStream.read read;
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27
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28 PngChunkReader reader;
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29 PngChunk chunk;
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30 int offset, length;
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31
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32 final static int DATA_OFFSET = 8;
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33
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34 public this(PngIdatChunk chunk, PngChunkReader reader) {
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35 this.chunk = chunk;
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36 this.reader = reader;
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37 length = chunk.getLength();
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38 offset = 0;
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39 }
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40
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41 private bool checkChunk() {
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42 while (offset is length) {
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43 chunk = reader.readNextChunk();
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44 if (chunk is null) throw new IOException("no data");
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45 if (chunk.getChunkType() is PngChunk.CHUNK_IEND) return false;
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46 if (chunk.getChunkType() !is PngChunk.CHUNK_IDAT) throw new IOException("");
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47 length = chunk.getLength();
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48 offset = 0;
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49 }
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50 return true;
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51 }
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52
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53 public override void close() {
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54 chunk = null;
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55 }
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56
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57 public override int read() {
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58 if (chunk is null) throw new IOException("");
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59 if (offset is length && !checkChunk()) return -1;
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60 int b = chunk.reference[DATA_OFFSET + offset] & 0xFF;
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61 offset++;
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62 return b;
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63 }
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64
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65 public override int read(byte[] b, int off, int len) {
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66 if (chunk is null) throw new IOException("");
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67 if (offset is length && !checkChunk()) return -1;
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68 len = Math.min(len, length - offset);
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69 System.arraycopy(chunk.reference, DATA_OFFSET + offset, b, off, len);
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70 offset += len;
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71 return len;
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72 }
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73 }