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comparison org.eclipse.swt.win32.win32.x86/src/org/eclipse/swt/internal/image/PngDecodingDataStream.d @ 0:6dd524f61e62

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add dwt win and basic java stuff
author Frank Benoit <benoit@tionex.de>
date Mon, 02 Mar 2009 14:44:16 +0100
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children d46287db17ed
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-1:000000000000 0:6dd524f61e62
1 /*******************************************************************************
2 * Copyright (c) 2000, 2006 IBM Corporation and others.
3 * All rights reserved. This program and the accompanying materials
4 * are made available under the terms of the Eclipse Public License v1.0
5 * which accompanies this distribution, and is available at
6 * http://www.eclipse.org/legal/epl-v10.html
7 *
8 * Contributors:
9 * IBM Corporation - initial API and implementation
10 * Port to the D programming language:
11 * Frank Benoit <benoit@tionex.de>
12 *******************************************************************************/
13 module org.eclipse.swt.internal.image.PngDecodingDataStream;
14
15
16 import java.io.InputStream;
17
18 import org.eclipse.swt.SWT;
19 import org.eclipse.swt.internal.image.PngLzBlockReader;
20
21 public class PngDecodingDataStream : InputStream {
22
23 alias InputStream.read read;
24
25 InputStream stream;
26 byte currentByte;
27 int nextBitIndex;
28
29 PngLzBlockReader lzBlockReader;
30 int adlerValue;
31
32 static final int PRIME = 65521;
33 static final int MAX_BIT = 7;
34
35 this(InputStream stream) {
36 super();
37 this.stream = stream;
38 nextBitIndex = MAX_BIT + 1;
39 adlerValue = 1;
40 lzBlockReader = new PngLzBlockReader(this);
41 readCompressedDataHeader();
42 lzBlockReader.readNextBlockHeader();
43 }
44
45 /**
46 * This method should be called when the image decoder thinks
47 * that all of the compressed image data has been read. This
48 * method will ensure that the next data value is an end of
49 * block marker. If there are more blocks after this one,
50 * the method will read them and ensure that they are empty.
51 */
52 void assertImageDataAtEnd() {
53 lzBlockReader.assertCompressedDataAtEnd();
54 }
55
56 public override void close() {
57 assertImageDataAtEnd();
58 checkAdler();
59 }
60
61 int getNextIdatBits(int length) {
62 int value = 0;
63 for (int i = 0; i < length; i++) {
64 value |= (getNextIdatBit() << i);
65 }
66 return value;
67 }
68
69 int getNextIdatBit() {
70 if (nextBitIndex > MAX_BIT) {
71 currentByte = getNextIdatByte();
72 nextBitIndex = 0;
73 }
74 return (currentByte & (1 << nextBitIndex)) >> nextBitIndex++;
75 }
76
77 byte getNextIdatByte() {
78 byte nextByte = cast(byte)stream.read();
79 nextBitIndex = MAX_BIT + 1;
80 return nextByte;
81 }
82
83 void updateAdler(byte value) {
84 int low = adlerValue & 0xFFFF;
85 int high = (adlerValue >> 16) & 0xFFFF;
86 int valueInt = value & 0xFF;
87 low = (low + valueInt) % PRIME;
88 high = (low + high) % PRIME;
89 adlerValue = (high << 16) | low;
90 }
91
92 public override int read() {
93 byte nextDecodedByte = lzBlockReader.getNextByte();
94 updateAdler(nextDecodedByte);
95 return nextDecodedByte & 0xFF;
96 }
97
98 public override int read(byte[] buffer, int off, int len) {
99 for (int i = 0; i < len; i++) {
100 int b = read();
101 if (b is -1) return i;
102 buffer[off + i] = cast(byte)b;
103 }
104 return len;
105 }
106
107 void error() {
108 SWT.error(SWT.ERROR_INVALID_IMAGE);
109 }
110
111 private void readCompressedDataHeader() {
112 byte headerByte1 = getNextIdatByte();
113 byte headerByte2 = getNextIdatByte();
114
115 int number = ((headerByte1 & 0xFF) << 8) | (headerByte2 & 0xFF);
116 if (number % 31 !is 0) error();
117
118 int compressionMethod = headerByte1 & 0x0F;
119 if (compressionMethod !is 8) error();
120
121 int windowSizeHint = (headerByte1 & 0xF0) >> 4;
122 if (windowSizeHint > 7) error();
123 int windowSize = (1 << (windowSizeHint + 8));
124 lzBlockReader.setWindowSize(windowSize);
125
126 int dictionary = (headerByte2 & (1 << 5));
127 if (dictionary !is 0) error();
128
129 // int compressionLevel = (headerByte2 & 0xC0) >> 6;
130 }
131
132 void checkAdler() {
133 int storedAdler = 0;
134 storedAdler |= ((getNextIdatByte() & 0xFF) << 24);
135 storedAdler |= ((getNextIdatByte() & 0xFF) << 16);
136 storedAdler |= ((getNextIdatByte() & 0xFF) << 8);
137 storedAdler |= (getNextIdatByte() & 0xFF);
138 if (storedAdler !is adlerValue) error();
139 }
140
141 }