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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/decoders/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
+};
+
+PNGDecoder::PNGDecoder() : _compressedBuffer(0), _compressedBufferSize(0),
+ _transparentColorSpecified(false), _outputSurface(0) {
+}
+
+PNGDecoder::~PNGDecoder() {
+ destroy();
+}
+
+void PNGDecoder::destroy() {
+ if (_outputSurface) {
+ _outputSurface->free();
+ delete _outputSurface;
+ _outputSurface = 0;
+ }
+}
+
+bool PNGDecoder::loadStream(Common::SeekableReadStream &stream) {
+ destroy();
+
+ uint32 chunkLength = 0, chunkType = 0;
+ _stream = &stream;
+
+ // First, check the PNG signature
+ if (_stream->readUint32BE() != MKTAG(0x89, 'P', 'N', 'G')) {
+ 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;
+ _stream->read(_palette, _paletteEntries * 3);
+ memset(_paletteTransparency, 0xff, sizeof(_paletteTransparency));
+ 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
+ _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 PNGDecoder::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 PNGDecoder::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");
+ }
+
+}
+
+int PNGDecoder::getBytesPerPixel() const {
+ return (getNumColorChannels() * _header.bitDepth + 7) / 8;
+}
+
+void PNGDecoder::constructImage() {
+ assert (_header.bitDepth != 0);
+
+ int bytesPerPixel = getBytesPerPixel();
+ int pitch = bytesPerPixel * _header.width;
+ byte *unfilteredSurface = new byte[pitch * _header.height];
+ byte *dest = unfilteredSurface;
+ uint16 scanLineWidth = (_header.width * getNumColorChannels() * _header.bitDepth + 7) / 8;
+ byte *scanLine = new byte[scanLineWidth];
+ byte *prevLine = 0;
+
+ switch(_header.interlaceType) {
+ case kNonInterlaced:
+ for (uint16 y = 0; y < _header.height; y++) {
+ byte filterType = _imageData->readByte();
+ _imageData->read(scanLine, scanLineWidth);
+ unfilterScanLine(dest, scanLine, prevLine, bytesPerPixel, filterType, scanLineWidth);
+ prevLine = dest;
+ dest += 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;
+
+ constructOutput(unfilteredSurface);
+ delete[] unfilteredSurface;
+}
+
+Graphics::PixelFormat PNGDecoder::findPixelFormat() const {
+ // Try to find the best pixel format based on what we have here
+ // Which is basically 8bpp for paletted non-transparent
+ // and 32bpp for everything else
+
+ switch (_header.colorType) {
+ case kIndexed:
+ if (!_transparentColorSpecified)
+ return Graphics::PixelFormat::createFormatCLUT8();
+ // fall through
+ case kGrayScale:
+ case kTrueColor:
+ case kGrayScaleWithAlpha:
+ case kTrueColorWithAlpha:
+ // We'll go with standard RGBA 32-bit
+ return Graphics::PixelFormat(4, 8, 8, 8, 8, 24, 16, 8, 0);
+ }
+
+ error("Unknown PNG color type");
+ return Graphics::PixelFormat();
+}
+
+void PNGDecoder::constructOutput(const byte *surface) {
+ _outputSurface = new Graphics::Surface();
+ _outputSurface->create(_header.width, _header.height, findPixelFormat());
+
+ const byte *src = surface;
+ byte a = 0xFF;
+ int bytesPerPixel = getBytesPerPixel();
+
+ if (_header.colorType != kIndexed) {
+ if (_header.colorType == kTrueColor ||
+ _header.colorType == kTrueColorWithAlpha) {
+ if (bytesPerPixel != 3 && bytesPerPixel != 4)
+ error("Unsupported truecolor PNG format");
+ } else if (_header.colorType == kGrayScale ||
+ _header.colorType == kGrayScaleWithAlpha) {
+ if (bytesPerPixel != 1 && bytesPerPixel != 2)
+ error("Unsupported grayscale PNG format");
+ }
+
+ for (uint16 i = 0; i < _outputSurface->h; i++) {
+ for (uint16 j = 0; j < _outputSurface->w; j++) {
+ uint32 result = 0;
+
+ switch (bytesPerPixel) {
+ case 1: // Grayscale
+ if (_transparentColorSpecified)
+ a = (src[0] == _transparentColor[0]) ? 0 : 0xFF;
+ result = _outputSurface->format.ARGBToColor(a, src[0], src[0], src[0]);
+ break;
+ case 2: // Grayscale + alpha
+ result = _outputSurface->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 = _outputSurface->format.ARGBToColor(a, src[0], src[1], src[2]);
+ break;
+ case 4: // RGBA
+ result = _outputSurface->format.ARGBToColor(src[3], src[0], src[1], src[2]);
+ break;
+ }
+
+ *((uint32 *)_outputSurface->getBasePtr(j, i)) = result;
+ src += bytesPerPixel;
+ }
+ }
+ } else {
+ uint32 mask = (0xff >> (8 - _header.bitDepth)) << (8 - _header.bitDepth);
+
+ // Convert the indexed surface to the target pixel format
+ for (uint16 i = 0; i < _outputSurface->h; i++) {
+ int data = 0;
+ int bitCount = 8;
+ const byte *src1 = src;
+
+ for (uint16 j = 0; j < _outputSurface->w; j++) {
+ if (bitCount == 8) {
+ data = *src;
+ src++;
+ }
+
+ byte index = (data & mask) >> (8 - _header.bitDepth);
+ data = (data << _header.bitDepth) & 0xff;
+ bitCount -= _header.bitDepth;
+
+ if (bitCount == 0)
+ bitCount = 8;
+
+ if (_transparentColorSpecified) {
+ byte r = _palette[index * 3 + 0];
+ byte g = _palette[index * 3 + 1];
+ byte b = _palette[index * 3 + 2];
+ a = _paletteTransparency[index];
+ *((uint32 *)_outputSurface->getBasePtr(j, i)) = _outputSurface->format.ARGBToColor(a, r, g, b);
+ } else {
+ *((byte *)_outputSurface->getBasePtr(j, i)) = index;
+ }
+ }
+
+ src = src1 + _outputSurface->w;
+ }
+ }
+}
+
+void PNGDecoder::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 PNGDecoder::getNumColorChannels() const {
+ 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 PNGDecoder::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:
+ _stream->read(_paletteTransparency, chunkLength);
+
+ // 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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