1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
|
/* ScummVM - Graphic Adventure Engine
*
* ScummVM is the legal property of its developers, whose names
* are too numerous to list here. Please refer to the COPYRIGHT
* file distributed with this source distribution.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*
* $URL$
* $Id$
*
*/
/*
* PNG decoder used in engines:
* - sword25
*/
#ifndef GRAPHICS_PNG_H
#define GRAPHICS_PNG_H
// PNG decoder, based on the W3C specs:
// http://www.w3.org/TR/PNG/
// Parts of the code have been adapted from LodePNG, by Lode Vandevenne:
// http://members.gamedev.net/lode/projects/LodePNG/
// All the numbers are BE: http://www.w3.org/TR/PNG/#7Integers-and-byte-order
// Note: At the moment, this decoder only supports non-interlaced images, and
// does not support truecolor/grayscale images with 16bit depth.
//
// Theoretically, interlaced images shouldn't be needed for games, as
// interlacing is only useful for images in websites.
//
// PNG images with 16bit depth (i.e. 48bit images) are quite rare, and can
// theoretically contain more than 16.7 millions of colors (the so-called "deep
// color" representation). In essence, each of the R, G, B and A components in
// them is specified with 2 bytes, instead of 1. However, the PNG specification
// always refers to color components with 1 byte each, so this part of the spec
// is a bit unclear. For now, these won't be supported, until a suitable sample
// is found.
#include "common/scummsys.h"
#include "common/textconsole.h"
namespace Common {
class SeekableReadStream;
}
namespace Graphics {
struct Surface;
enum PNGColorType {
kGrayScale = 0, // bit depths: 1, 2, 4, 8, 16
kTrueColor = 2, // bit depths: 8, 16
kIndexed = 3, // bit depths: 1, 2, 4, 8
kGrayScaleWithAlpha = 4, // bit depths: 8, 16
kTrueColorWithAlpha = 6 // bit depths: 8, 16
};
enum PNGInterlaceType {
kNonInterlaced = 0,
kInterlaced = 1
};
struct PNGHeader {
uint32 width;
uint32 height;
byte bitDepth;
PNGColorType colorType;
byte compressionMethod;
byte filterMethod;
PNGInterlaceType interlaceType;
};
struct PixelFormat;
class PNG {
public:
PNG();
~PNG();
/**
* Reads a PNG image from the specified stream
*/
bool read(Common::SeekableReadStream *str);
/**
* Returns the information obtained from the PNG header.
*/
PNGHeader getHeader() const { return _header; }
/**
* Returns the PNG image, formatted for the specified pixel format.
*/
Graphics::Surface *getSurface(const PixelFormat &format);
/**
* Returns the indexed PNG8 image. Used for PNGs with an indexed 256 color
* palette, when they're shown on an 8-bit color screen, as no translation
* is taking place.
*/
Graphics::Surface *getIndexedSurface() {
if (_header.colorType != kIndexed)
error("Indexed surface requested for a non-indexed PNG");
return _unfilteredSurface;
}
/**
* Returns the palette of the specified PNG8 image, given a pointer to
* an RGBA palette array (4 x 256).
*/
void getPalette(byte *palette, uint16 &entries) {
if (_header.colorType != kIndexed)
error("Palette requested for a non-indexed PNG");
for (int i = 0; i < 256; i++) {
palette[0 + i * 4] = _palette[0 + i * 4]; // R
palette[1 + i * 4] = _palette[1 + i * 4]; // G
palette[2 + i * 4] = _palette[2 + i * 4]; // B
palette[3 + i * 4] = _palette[3 + i * 4]; // A
}
entries = _paletteEntries;
}
private:
void readHeaderChunk();
byte getNumColorChannels();
void readPaletteChunk();
void readTransparencyChunk(uint32 chunkLength);
void constructImage();
void unfilterScanLine(byte *dest, const byte *scanLine, const byte *prevLine, uint16 byteWidth, byte filterType, uint16 length);
byte paethPredictor(int16 a, int16 b, int16 c);
// The original file stream
Common::SeekableReadStream *_stream;
// The unzipped image data stream
Common::SeekableReadStream *_imageData;
PNGHeader _header;
byte _palette[256 * 4]; // RGBA
uint16 _paletteEntries;
uint16 _transparentColor[3];
bool _transparentColorSpecified;
byte *_compressedBuffer;
uint32 _compressedBufferSize;
Graphics::Surface *_unfilteredSurface;
};
} // End of Graphics namespace
#endif // GRAPHICS_PNG_H
|
