diff options
Diffstat (limited to 'graphics/decoders/png.h')
| -rw-r--r-- | graphics/decoders/png.h | 135 |
1 files changed, 135 insertions, 0 deletions
diff --git a/graphics/decoders/png.h b/graphics/decoders/png.h new file mode 100644 index 0000000000..1da0bea1ab --- /dev/null +++ b/graphics/decoders/png.h @@ -0,0 +1,135 @@ +/* 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. + * + */ + +/* + * PNG decoder used in engines: + * - sword25 + * Dependencies: + * - zlib + */ + +#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" +#include "graphics/decoders/image_decoder.h" + +namespace Common { +class SeekableReadStream; +} + +namespace Graphics { + +struct Surface; +struct PixelFormat; + +class PNGDecoder : public ImageDecoder { +public: + PNGDecoder(); + ~PNGDecoder(); + + bool loadStream(Common::SeekableReadStream &stream); + void destroy(); + const Graphics::Surface *getSurface() const { return _outputSurface; } + const byte *getPalette() const { return _palette; } + +private: + 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; + }; + + void readHeaderChunk(); + byte getNumColorChannels() const; + + 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 * 3]; // RGB + byte _paletteTransparency[256]; + uint16 _paletteEntries; + uint16 _transparentColor[3]; + bool _transparentColorSpecified; + + byte *_compressedBuffer; + uint32 _compressedBufferSize; + + Graphics::Surface *_outputSurface; + Graphics::PixelFormat findPixelFormat() const; + int getBytesPerPixel() const; + void constructOutput(const byte *surface); +}; + +} // End of namespace Graphics + +#endif // GRAPHICS_PNG_H |