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-/* 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.
- *
- */
-
-#include "graphics/png.h"
-
-#include "graphics/pixelformat.h"
-#include "graphics/surface.h"
-
-#include "common/endian.h"
-#include "common/memstream.h"
-#include "common/stream.h"
-#include "common/types.h"
-#include "common/util.h"
-#include "common/zlib.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/
-
-/*
-LodePNG version 20101211
-
-Copyright (c) 2005-2010 Lode Vandevenne
-
-This software is provided 'as-is', without any express or implied
-warranty. In no event will the authors be held liable for any damages
-arising from the use of this software.
-
-Permission is granted to anyone to use this software for any purpose,
-including commercial applications, and to alter it and redistribute it
-freely, subject to the following restrictions:
-
- 1. The origin of this software must not be misrepresented; you must not
- claim that you wrote the original software. If you use this software
- in a product, an acknowledgment in the product documentation would be
- appreciated but is not required.
-
- 2. Altered source versions must be plainly marked as such, and must not be
- misrepresented as being the original software.
-
- 3. This notice may not be removed or altered from any source
- distribution.
-*/
-
-namespace Graphics {
-
-enum PNGChunks {
- // == Critical chunks =====================================================
- kChunkIHDR = MKTAG('I','H','D','R'), // Image header
- kChunkIDAT = MKTAG('I','D','A','T'), // Image data
- kChunkPLTE = MKTAG('P','L','T','E'), // Palette
- kChunkIEND = MKTAG('I','E','N','D'), // Image trailer
- // == Ancillary chunks ====================================================
- kChunktRNS = MKTAG('t','R','N','S') // Transparency
- // All of the other ancillary chunks are ignored. They're added here for
- // reference only.
- // cHRM - Primary chromacities and white point
- // gAMA - Image gamma
- // iCCP - Embedded ICC profile
- // sBIT - Significant bits
- // sRGB - Standard RGB color space
- // tEXT - Textual data
- // sTXt - Compressed textual data
- // iTXt - International textual data
- // bKGD - Background color
- // hIST - Image histogram
- // pHYs - Physical pixel dimensions
- // sPLT - Suggested palette
- // tIME - Image last-modification time
-};
-
-// Refer to http://www.w3.org/TR/PNG/#9Filters
-enum PNGFilters {
- kFilterNone = 0,
- kFilterSub = 1,
- kFilterUp = 2,
- kFilterAverage = 3,
- kFilterPaeth = 4
-};
-
-PNG::PNG() : _compressedBuffer(0), _compressedBufferSize(0),
- _unfilteredSurface(0), _transparentColorSpecified(false) {
-}
-
-PNG::~PNG() {
- if (_unfilteredSurface) {
- _unfilteredSurface->free();
- delete _unfilteredSurface;
- }
-}
-
-Graphics::Surface *PNG::getSurface(const PixelFormat &format) {
- Graphics::Surface *output = new Graphics::Surface();
- output->create(_unfilteredSurface->w, _unfilteredSurface->h, format);
- byte *src = (byte *)_unfilteredSurface->pixels;
- byte a = 0xFF;
- byte bpp = _unfilteredSurface->format.bytesPerPixel;
-
- if (_header.colorType != kIndexed) {
- if (_header.colorType == kTrueColor ||
- _header.colorType == kTrueColorWithAlpha) {
- if (bpp != 3 && bpp != 4)
- error("Unsupported truecolor PNG format");
- } else if (_header.colorType == kGrayScale ||
- _header.colorType == kGrayScaleWithAlpha) {
- if (bpp != 1 && bpp != 2)
- error("Unsupported grayscale PNG format");
- }
-
- for (uint16 i = 0; i < output->h; i++) {
- for (uint16 j = 0; j < output->w; j++) {
- uint32 result = 0;
-
- switch (bpp) {
- case 1: // Grayscale
- if (_transparentColorSpecified)
- a = (src[0] == _transparentColor[0]) ? 0 : 0xFF;
- result = format.ARGBToColor( a, src[0], src[0], src[0]);
- break;
- case 2: // Grayscale + alpha
- result = format.ARGBToColor(src[1], src[0], src[0], src[0]);
- break;
- case 3: // RGB
- if (_transparentColorSpecified) {
- bool isTransparentColor = (src[0] == _transparentColor[0] &&
- src[1] == _transparentColor[1] &&
- src[2] == _transparentColor[2]);
- a = isTransparentColor ? 0 : 0xFF;
- }
- result = format.ARGBToColor( a, src[0], src[1], src[2]);
- break;
- case 4: // RGBA
- result = format.ARGBToColor(src[3], src[0], src[1], src[2]);
- break;
- }
-
- if (format.bytesPerPixel == 2) // 2bpp
- *((uint16 *)output->getBasePtr(j, i)) = (uint16)result;
- else // 4bpp
- *((uint32 *)output->getBasePtr(j, i)) = result;
-
- src += bpp;
- }
- }
- } else {
- byte index, r, g, b;
- uint32 mask = (0xff >> (8 - _header.bitDepth)) << (8 - _header.bitDepth);
-
- // Convert the indexed surface to the target pixel format
- for (uint16 i = 0; i < output->h; i++) {
- int data = 0;
- int bitCount = 8;
- byte *src1 = src;
-
- for (uint16 j = 0; j < output->w; j++) {
- if (bitCount == 8) {
- data = *src;
- src++;
- }
-
- index = (data & mask) >> (8 - _header.bitDepth);
- data = (data << _header.bitDepth) & 0xff;
- bitCount -= _header.bitDepth;
-
- if (bitCount == 0)
- bitCount = 8;
-
- r = _palette[index * 4 + 0];
- g = _palette[index * 4 + 1];
- b = _palette[index * 4 + 2];
- a = _palette[index * 4 + 3];
-
- if (format.bytesPerPixel == 2)
- *((uint16 *)output->getBasePtr(j, i)) = format.ARGBToColor(a, r, g, b);
- else
- *((uint32 *)output->getBasePtr(j, i)) = format.ARGBToColor(a, r, g, b);
- }
- src = src1 + output->w;
- }
- }
-
- return output;
-}
-
-bool PNG::read(Common::SeekableReadStream *str) {
- uint32 chunkLength = 0, chunkType = 0;
- _stream = str;
-
- // First, check the PNG signature
- if (_stream->readUint32BE() != MKTAG(0x89, 0x50, 0x4e, 0x47)) {
- delete _stream;
- return false;
- }
- if (_stream->readUint32BE() != MKTAG(0x0d, 0x0a, 0x1a, 0x0a)) {
- delete _stream;
- return false;
- }
-
- // Start reading chunks till we reach an IEND chunk
- while (chunkType != kChunkIEND) {
- // The chunk length does not include the type or CRC bytes
- chunkLength = _stream->readUint32BE();
- chunkType = _stream->readUint32BE();
-
- switch (chunkType) {
- case kChunkIHDR:
- readHeaderChunk();
- break;
- case kChunkIDAT:
- if (_compressedBufferSize == 0) {
- _compressedBufferSize += chunkLength;
- _compressedBuffer = (byte *)malloc(_compressedBufferSize);
- _stream->read(_compressedBuffer, chunkLength);
- } else {
- // Expand the buffer
- uint32 prevSize = _compressedBufferSize;
- _compressedBufferSize += chunkLength;
- byte *tmp = new byte[prevSize];
- memcpy(tmp, _compressedBuffer, prevSize);
- free(_compressedBuffer);
- _compressedBuffer = (byte *)malloc(_compressedBufferSize);
- memcpy(_compressedBuffer, tmp, prevSize);
- delete[] tmp;
- _stream->read(_compressedBuffer + prevSize, chunkLength);
- }
- break;
- case kChunkPLTE: // only available in indexed PNGs
- if (_header.colorType != kIndexed)
- error("A palette chunk has been found in a non-indexed PNG file");
- if (chunkLength % 3 != 0)
- error("Palette chunk not divisible by 3");
- _paletteEntries = chunkLength / 3;
- readPaletteChunk();
- break;
- case kChunkIEND:
- // End of stream
- break;
- case kChunktRNS:
- readTransparencyChunk(chunkLength);
- break;
- default:
- // Skip the chunk content
- _stream->skip(chunkLength);
- break;
- }
-
- if (chunkType != kChunkIEND)
- _stream->skip(4); // skip the chunk CRC checksum
- }
-
- // We no longer need the file stream, thus close it here
- delete _stream;
- _stream = 0;
-
- // Unpack the compressed buffer
- Common::MemoryReadStream *compData = new Common::MemoryReadStream(_compressedBuffer, _compressedBufferSize, DisposeAfterUse::YES);
- _imageData = Common::wrapCompressedReadStream(compData);
-
- // Construct the final image
- constructImage();
-
- // Close the uncompressed stream, which will also delete the memory stream,
- // and thus the original compressed buffer
- delete _imageData;
-
- return true;
-}
-
-/**
- * Paeth predictor, used by PNG filter type 4
- * The parameters are of signed 16-bit integers, but should come
- * from unsigned chars. The integers are only needed to make
- * the paeth calculation correct.
- *
- * Taken from lodePNG, with a slight patch:
- * http://www.atalasoft.com/cs/blogs/stevehawley/archive/2010/02/23/libpng-you-re-doing-it-wrong.aspx
- */
-byte PNG::paethPredictor(int16 a, int16 b, int16 c) {
- int16 pa = ABS<int16>(b - c);
- int16 pb = ABS<int16>(a - c);
- int16 pc = ABS<int16>(a + b - c - c);
-
- if (pa <= MIN<int16>(pb, pc))
- return (byte)a;
- else if (pb <= pc)
- return (byte)b;
- else
- return (byte)c;
-}
-
-/**
- * Unfilters a filtered PNG scan line.
- * PNG filters are defined in: http://www.w3.org/TR/PNG/#9Filters
- * Note that filters are always applied to bytes
- *
- * Taken from lodePNG
- */
-void PNG::unfilterScanLine(byte *dest, const byte *scanLine, const byte *prevLine, uint16 byteWidth, byte filterType, uint16 length) {
- uint16 i;
-
- switch (filterType) {
- case kFilterNone: // no change
- for (i = 0; i < length; i++)
- dest[i] = scanLine[i];
- break;
- case kFilterSub: // add the bytes to the left
- for (i = 0; i < byteWidth; i++)
- dest[i] = scanLine[i];
- for (i = byteWidth; i < length; i++)
- dest[i] = scanLine[i] + dest[i - byteWidth];
- break;
- case kFilterUp: // add the bytes of the above scanline
- if (prevLine) {
- for (i = 0; i < length; i++)
- dest[i] = scanLine[i] + prevLine[i];
- } else {
- for (i = 0; i < length; i++)
- dest[i] = scanLine[i];
- }
- break;
- case kFilterAverage: // average value of the left and top left
- if (prevLine) {
- for (i = 0; i < byteWidth; i++)
- dest[i] = scanLine[i] + prevLine[i] / 2;
- for (i = byteWidth; i < length; i++)
- dest[i] = scanLine[i] + ((dest[i - byteWidth] + prevLine[i]) / 2);
- } else {
- for (i = 0; i < byteWidth; i++)
- dest[i] = scanLine[i];
- for (i = byteWidth; i < length; i++)
- dest[i] = scanLine[i] + dest[i - byteWidth] / 2;
- }
- break;
- case kFilterPaeth: // Paeth filter: http://www.w3.org/TR/PNG/#9Filter-type-4-Paeth
- if (prevLine) {
- for(i = 0; i < byteWidth; i++)
- dest[i] = (scanLine[i] + prevLine[i]); // paethPredictor(0, prevLine[i], 0) is always prevLine[i]
- for(i = byteWidth; i < length; i++)
- dest[i] = (scanLine[i] + paethPredictor(dest[i - byteWidth], prevLine[i], prevLine[i - byteWidth]));
- } else {
- for(i = 0; i < byteWidth; i++)
- dest[i] = scanLine[i];
- for(i = byteWidth; i < length; i++)
- dest[i] = (scanLine[i] + dest[i - byteWidth]); // paethPredictor(dest[i - byteWidth], 0, 0) is always dest[i - byteWidth]
- }
- break;
- default:
- error("Unknown line filter");
- }
-
-}
-
-void PNG::constructImage() {
- assert (_header.bitDepth != 0);
-
- byte *dest;
- byte *scanLine;
- byte *prevLine = 0;
- byte filterType;
- uint16 scanLineWidth = (_header.width * getNumColorChannels() * _header.bitDepth + 7) / 8;
-
- if (_unfilteredSurface) {
- _unfilteredSurface->free();
- delete _unfilteredSurface;
- }
- _unfilteredSurface = new Graphics::Surface();
- // TODO/FIXME: It seems we can not properly determine the format here. But maybe there is a way...
- _unfilteredSurface->create(_header.width, _header.height, PixelFormat((getNumColorChannels() * _header.bitDepth + 7) / 8, 0, 0, 0, 0, 0, 0, 0, 0));
- scanLine = new byte[_unfilteredSurface->pitch];
- dest = (byte *)_unfilteredSurface->getBasePtr(0, 0);
-
- switch(_header.interlaceType) {
- case kNonInterlaced:
- for (uint16 y = 0; y < _unfilteredSurface->h; y++) {
- filterType = _imageData->readByte();
- _imageData->read(scanLine, scanLineWidth);
- unfilterScanLine(dest, scanLine, prevLine, _unfilteredSurface->format.bytesPerPixel, filterType, scanLineWidth);
- prevLine = dest;
- dest += _unfilteredSurface->pitch;
- }
- break;
- case kInterlaced:
- // Theoretically, this shouldn't be needed, as interlacing is only
- // useful for web images. Interlaced PNG images require more complex
- // handling, so unless having support for such images is needed, there
- // is no reason to add support for them.
- error("TODO: Support for interlaced PNG images");
- break;
- }
-
- delete[] scanLine;
-}
-
-void PNG::readHeaderChunk() {
- _header.width = _stream->readUint32BE();
- _header.height = _stream->readUint32BE();
- _header.bitDepth = _stream->readByte();
- if (_header.bitDepth > 8)
- error("Only PNGs with a bit depth of 1-8 bits are supported (i.e. PNG24)");
- _header.colorType = (PNGColorType)_stream->readByte();
- _header.compressionMethod = _stream->readByte();
- // Compression methods: http://www.w3.org/TR/PNG/#10Compression
- // Only compression method 0 (deflate) is documented and supported
- if (_header.compressionMethod != 0)
- error("Unknown PNG compression method: %d", _header.compressionMethod);
- _header.filterMethod = _stream->readByte();
- // Filter methods: http://www.w3.org/TR/PNG/#9Filters
- // Only filter method 0 is documented and supported
- if (_header.filterMethod != 0)
- error("Unknown PNG filter method: %d", _header.filterMethod);
- _header.interlaceType = (PNGInterlaceType)_stream->readByte();
-}
-
-byte PNG::getNumColorChannels() {
- switch (_header.colorType) {
- case kGrayScale:
- return 1; // Gray
- case kTrueColor:
- return 3; // RGB
- case kIndexed:
- return 1; // Indexed
- case kGrayScaleWithAlpha:
- return 2; // Gray + Alpha
- case kTrueColorWithAlpha:
- return 4; // RGBA
- default:
- error("Unknown color type");
- }
-}
-
-void PNG::readPaletteChunk() {
- for (uint16 i = 0; i < _paletteEntries; i++) {
- _palette[i * 4 + 0] = _stream->readByte(); // R
- _palette[i * 4 + 1] = _stream->readByte(); // G
- _palette[i * 4 + 2] = _stream->readByte(); // B
- _palette[i * 4 + 3] = 0xFF; // Alpha, set in the tRNS chunk
- }
-}
-
-void PNG::readTransparencyChunk(uint32 chunkLength) {
- _transparentColorSpecified = true;
-
- switch(_header.colorType) {
- case kGrayScale:
- _transparentColor[0] = _stream->readUint16BE();
- _transparentColor[1] = _transparentColor[0];
- _transparentColor[2] = _transparentColor[0];
- break;
- case kTrueColor:
- _transparentColor[0] = _stream->readUint16BE();
- _transparentColor[1] = _stream->readUint16BE();
- _transparentColor[2] = _stream->readUint16BE();
- break;
- case kIndexed:
- for (uint32 i = 0; i < chunkLength; i++)
- _palette[i * 4 + 3] = _stream->readByte();
- // A transparency chunk may have less entries
- // than the palette entries. The remaining ones
- // are unmodified (set to 255). Check here:
- // http://www.w3.org/TR/PNG/#11tRNS
- break;
- default:
- error("Transparency chunk found in a PNG that has a separate transparency channel");
- }
-}
-
-} // End of Graphics namespace
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