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comparison dwt/internal/image/PngPlteChunk.d @ 0:380af2bdd8e5

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author Jacob Carlborg <doob@me.com> <jacob.carlborg@gmail.com>
date Sat, 09 Aug 2008 17:00:02 +0200
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children 1a8b3cb347e0
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-1:000000000000 0:380af2bdd8e5
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 *******************************************************************************/
11 module dwt.internal.image;
12
13
14 import dwt.DWT;
15 import dwt.graphics.PaletteData;
16 import dwt.graphics.RGB;
17
18 class PngPlteChunk : PngChunk {
19
20 int paletteSize;
21
22 PngPlteChunk(PaletteData palette) {
23 super(palette.getRGBs().length * 3);
24 paletteSize = length / 3;
25 setType(TYPE_PLTE);
26 setPaletteData(palette);
27 setCRC(computeCRC());
28 }
29
30 PngPlteChunk(byte[] reference){
31 super(reference);
32 paletteSize = length / 3;
33 }
34
35 int getChunkType() {
36 return CHUNK_PLTE;
37 }
38
39 /**
40 * Get the number of colors in this palette.
41 */
42 int getPaletteSize() {
43 return paletteSize;
44 }
45
46 /**
47 * Get a PaletteData object representing the colors
48 * stored in this PLTE chunk.
49 * The result should be cached as the PLTE chunk
50 * does not store the palette data created.
51 */
52 PaletteData getPaletteData() {
53 RGB[] rgbs = new RGB[paletteSize];
54 // int start = DATA_OFFSET;
55 // int end = DATA_OFFSET + length;
56 for (int i = 0; i < rgbs.length; i++) {
57 int offset = DATA_OFFSET + (i * 3);
58 int red = reference[offset] & 0xFF;
59 int green = reference[offset + 1] & 0xFF;
60 int blue = reference[offset + 2] & 0xFF;
61 rgbs[i] = new RGB(red, green, blue);
62 }
63 return new PaletteData(rgbs);
64 }
65
66 /**
67 * Set the data of a PLTE chunk to the colors
68 * stored in the specified PaletteData object.
69 */
70 void setPaletteData(PaletteData palette) {
71 RGB[] rgbs = palette.getRGBs();
72 for (int i = 0; i < rgbs.length; i++) {
73 int offset = DATA_OFFSET + (i * 3);
74 reference[offset] = (byte) rgbs[i].red;
75 reference[offset + 1] = (byte) rgbs[i].green;
76 reference[offset + 2] = (byte) rgbs[i].blue;
77 }
78 }
79
80 /**
81 * Answer whether the chunk is a valid PLTE chunk.
82 */
83 void validate(PngFileReadState readState, PngIhdrChunk headerChunk) {
84 // A PLTE chunk is invalid if no IHDR has been read or if any PLTE,
85 // IDAT, or IEND chunk has been read.
86 if (!readState.readIHDR
87 || readState.readPLTE
88 || readState.readTRNS
89 || readState.readIDAT
90 || readState.readIEND)
91 {
92 DWT.error(DWT.ERROR_INVALID_IMAGE);
93 } else {
94 readState.readPLTE = true;
95 }
96
97 super.validate(readState, headerChunk);
98
99 // Palettes cannot be included in grayscale images.
100 //
101 // Note: just ignore the palette.
102 // if (!headerChunk.getCanHavePalette()) DWT.error(DWT.ERROR_INVALID_IMAGE);
103
104 // Palette chunks' data fields must be event multiples
105 // of 3. Each 3-byte group represents an RGB value.
106 if (getLength() % 3 !is 0) DWT.error(DWT.ERROR_INVALID_IMAGE);
107
108 // Palettes cannot have more entries than 2^bitDepth
109 // where bitDepth is the bit depth of the image given
110 // in the IHDR chunk.
111 if (1 << headerChunk.getBitDepth() < paletteSize) {
112 DWT.error(DWT.ERROR_INVALID_IMAGE);
113 }
114
115 // Palettes cannot have more than 256 entries.
116 if (256 < paletteSize) DWT.error(DWT.ERROR_INVALID_IMAGE);
117 }
118
119 void contributeToString(StringBuffer buffer) {
120 buffer.append("\n\tPalette size:");
121 buffer.append(paletteSize);
122 }
123
124 }