[Scummvm-cvs-logs] scummvm master -> 05eb6eecfce5a049a100872ba4a4fb414cf913a5
lordhoto
lordhoto at gmail.com
Tue Aug 21 02:13:17 CEST 2012
This automated email contains information about 2 new commits which have been
pushed to the 'scummvm' repo located at https://github.com/scummvm/scummvm .
Summary:
af05b1b80e GRAPHICS: Reimplement the PNG-decoder using libpng
05eb6eecfc Merge pull request #262 from somaen/pngwithlibpng
Commit: af05b1b80edfc8674845d6e42c9872fea9eeb381
https://github.com/scummvm/scummvm/commit/af05b1b80edfc8674845d6e42c9872fea9eeb381
Author: Einar Johan Trøan Sømåen (einarjohants at gmail.com)
Date: 2012-08-20T12:14:59-07:00
Commit Message:
GRAPHICS: Reimplement the PNG-decoder using libpng
Changed paths:
configure
graphics/decoders/png.cpp
graphics/decoders/png.h
diff --git a/configure b/configure
index 06492ff..f98c1c9 100755
--- a/configure
+++ b/configure
@@ -97,7 +97,7 @@ _sndio=auto
_timidity=auto
_zlib=auto
_sparkle=auto
-_png=no
+_png=auto
_theoradec=auto
_faad=auto
_fluidsynth=auto
diff --git a/graphics/decoders/png.cpp b/graphics/decoders/png.cpp
index 492c697..f047189 100644
--- a/graphics/decoders/png.cpp
+++ b/graphics/decoders/png.cpp
@@ -19,87 +19,23 @@
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*
*/
+#define FORBIDDEN_SYMBOL_ALLOW_ALL
+#include "common/scummsys.h"
+
+#ifdef USE_PNG
+#include <png.h>
+#endif
#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), _paletteEntries(0) {
+PNGDecoder::PNGDecoder() : _outputSurface(0), _palette(0), _paletteColorCount(0) {
}
PNGDecoder::~PNGDecoder() {
@@ -112,16 +48,43 @@ void PNGDecoder::destroy() {
delete _outputSurface;
_outputSurface = 0;
}
+ delete[] _palette;
+ _palette = NULL;
+}
+
+#ifdef USE_PNG
+// libpng-error-handling:
+void pngError(png_structp pngptr, png_const_charp errorMsg) {
+ error("%s", errorMsg);
+}
- _paletteEntries = 0;
+void pngWarning(png_structp pngptr, png_const_charp warningMsg) {
+ warning("%s", warningMsg);
}
+// libpng-I/O-helper:
+void pngReadFromStream(png_structp pngPtr, png_bytep data, png_size_t length) {
+ void *readIOptr = png_get_io_ptr(pngPtr);
+ Common::SeekableReadStream *stream = (Common::SeekableReadStream *)readIOptr;
+ stream->read(data, length);
+}
+#endif
+
+/*
+ * This code is based on Broken Sword 2.5 engine
+ *
+ * Copyright (c) Malte Thiesen, Daniel Queteschiner and Michael Elsdoerfer
+ *
+ * Licensed under GNU GPL v2
+ *
+ */
+
bool PNGDecoder::loadStream(Common::SeekableReadStream &stream) {
+#ifdef USE_PNG
destroy();
- uint32 chunkLength = 0, chunkType = 0;
_stream = &stream;
-
+
// First, check the PNG signature
if (_stream->readUint32BE() != MKTAG(0x89, 'P', 'N', 'G')) {
delete _stream;
@@ -132,374 +95,143 @@ bool PNGDecoder::loadStream(Common::SeekableReadStream &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
+ // The following is based on the guide provided in:
+ //http://www.libpng.org/pub/png/libpng-1.2.5-manual.html#section-3
+ //http://www.libpng.org/pub/png/libpng-1.4.0-manual.pdf
+ // along with the png-loading code used in the sword25-engine.
+ png_structp pngPtr = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
+ if (!pngPtr) {
+ delete _stream;
+ return false;
}
-
- // 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");
+ png_infop infoPtr = png_create_info_struct(pngPtr);
+ if (!infoPtr) {
+ png_destroy_read_struct(&pngPtr, NULL, NULL);
+ delete _stream;
+ return false;
}
-
-}
-
-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;
+ png_infop endInfo = png_create_info_struct(pngPtr);
+ if (!endInfo) {
+ png_destroy_read_struct(&pngPtr, &infoPtr, NULL);
+ delete _stream;
+ return false;
}
- delete[] scanLine;
+ png_set_error_fn(pngPtr, NULL, pngError, pngWarning);
+ // TODO: The manual says errors should be handled via setjmp
- constructOutput(unfilteredSurface);
- delete[] unfilteredSurface;
-}
+ png_set_read_fn(pngPtr, _stream, pngReadFromStream);
+ png_set_crc_action(pngPtr, PNG_CRC_DEFAULT, PNG_CRC_WARN_USE);
+ // We already verified the PNG-header
+ png_set_sig_bytes(pngPtr, 8);
-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
+ // Read PNG header
+ png_read_info(pngPtr, infoPtr);
- 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();
-}
+ // No handling for unknown chunks yet.
+ int bitDepth, colorType, width, height, interlaceType;
+ png_uint_32 w, h;
+ png_get_IHDR(pngPtr, infoPtr, &w, &h, &bitDepth, &colorType, &interlaceType, NULL, NULL);
+ width = w;
+ height = h;
-void PNGDecoder::constructOutput(const byte *surface) {
+ // Allocate memory for the final image data.
+ // To keep memory framentation low this happens before allocating memory for temporary image data.
_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");
+ // Images of all color formats except PNG_COLOR_TYPE_PALETTE
+ // will be transformed into ARGB images
+ if (colorType == PNG_COLOR_TYPE_PALETTE && !png_get_valid(pngPtr, infoPtr, PNG_INFO_tRNS)) {
+ int numPalette = 0;
+ png_colorp palette = NULL;
+ uint32 success = png_get_PLTE(pngPtr, infoPtr, &palette, &numPalette);
+ if (success != PNG_INFO_PLTE) {
+ png_destroy_read_struct(&pngPtr, &infoPtr, NULL);
+ return false;
}
-
- 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;
- }
+ _paletteColorCount = numPalette;
+ _palette = new byte[_paletteColorCount * 3];
+ for (int i = 0; i < _paletteColorCount; i++) {
+ _palette[(i * 3)] = palette[i].red;
+ _palette[(i * 3) + 1] = palette[i].green;
+ _palette[(i * 3) + 2] = palette[i].blue;
+
}
+ _outputSurface->create(width, height, Graphics::PixelFormat::createFormatCLUT8());
+ png_set_packing(pngPtr);
} 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;
+ _outputSurface->create(width, height, Graphics::PixelFormat(4, 8, 8, 8, 8, 24, 16, 8, 0));
+ if (!_outputSurface->pixels) {
+ error("Could not allocate memory for output image.");
}
- }
-}
+ if (bitDepth == 16)
+ png_set_strip_16(pngPtr);
+ if (bitDepth < 8)
+ png_set_expand(pngPtr);
+ if (png_get_valid(pngPtr, infoPtr, PNG_INFO_tRNS))
+ png_set_expand(pngPtr);
+ if (colorType == PNG_COLOR_TYPE_GRAY ||
+ colorType == PNG_COLOR_TYPE_GRAY_ALPHA)
+ png_set_gray_to_rgb(pngPtr);
+
+ // PNGs are Big-Endian:
+#ifdef SCUMM_LITTLE_ENDIAN
+ png_set_bgr(pngPtr);
+ png_set_swap_alpha(pngPtr);
+ if (colorType != PNG_COLOR_TYPE_RGB_ALPHA)
+ png_set_filler(pngPtr, 0xff, PNG_FILLER_BEFORE);
+#else
+ if (colorType != PNG_COLOR_TYPE_RGB_ALPHA)
+ png_set_filler(pngPtr, 0xff, PNG_FILLER_AFTER);
+#endif
-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");
}
-}
+
+ // After the transformations have been registered, the image data is read again.
+ png_read_update_info(pngPtr, infoPtr);
+ png_get_IHDR(pngPtr, infoPtr, &w, &h, &bitDepth, &colorType, NULL, NULL, NULL);
+ width = w;
+ height = h;
+
+ if (interlaceType == PNG_INTERLACE_NONE) {
+ // PNGs without interlacing can simply be read row by row.
+ for (int i = 0; i < height; i++) {
+ png_read_row(pngPtr, (png_bytep)_outputSurface->getBasePtr(0, i), NULL);
+ }
+ } else {
+ // PNGs with interlacing require us to allocate an auxillary
+ // buffer with pointers to all row starts.
+
+ // Allocate row pointer buffer
+ png_bytep *rowPtr = new png_bytep[height];
+ if (!rowPtr) {
+ error("Could not allocate memory for row pointers.");
+ }
+
+ // Initialize row pointers
+ for (int i = 0; i < height; i++)
+ rowPtr[i] = (png_bytep)_outputSurface->getBasePtr(0, i);
+
+ // Read image data
+ png_read_image(pngPtr, rowPtr);
+
+ // Free row pointer buffer
+ delete[] rowPtr;
+ }
+
+ // Read additional data at the end.
+ png_read_end(pngPtr, NULL);
-void PNGDecoder::readTransparencyChunk(uint32 chunkLength) {
- _transparentColorSpecified = true;
+ // Destroy libpng structures
+ png_destroy_read_struct(&pngPtr, &infoPtr, NULL);
- 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);
+ // We no longer need the file stream, thus close it here
+ _stream = 0;
- // 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");
- }
+ return true;
+#else
+ return false;
+#endif
}
} // End of Graphics namespace
diff --git a/graphics/decoders/png.h b/graphics/decoders/png.h
index ca204f6..e52ddab 100644
--- a/graphics/decoders/png.h
+++ b/graphics/decoders/png.h
@@ -24,33 +24,12 @@
* PNG decoder used in engines:
* - sword25
* Dependencies:
- * - zlib
+ * - libpng
*/
#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"
@@ -73,62 +52,13 @@ public:
void destroy();
const Graphics::Surface *getSurface() const { return _outputSurface; }
const byte *getPalette() const { return _palette; }
- uint16 getPaletteColorCount() const { return _paletteEntries; }
-
+ uint16 getPaletteColorCount() const { return _paletteColorCount; }
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;
+ byte *_palette;
+ uint16 _paletteColorCount;
Graphics::Surface *_outputSurface;
- Graphics::PixelFormat findPixelFormat() const;
- int getBytesPerPixel() const;
- void constructOutput(const byte *surface);
};
} // End of namespace Graphics
Commit: 05eb6eecfce5a049a100872ba4a4fb414cf913a5
https://github.com/scummvm/scummvm/commit/05eb6eecfce5a049a100872ba4a4fb414cf913a5
Author: Johannes Schickel (lordhoto at gmail.com)
Date: 2012-08-20T17:12:52-07:00
Commit Message:
Merge pull request #262 from somaen/pngwithlibpng
GRAPHICS: Reimplement the PNG-decoder using libpng
Changed paths:
configure
graphics/decoders/png.cpp
graphics/decoders/png.h
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