4 files changed, 202 insertions, 218 deletions

diff --git a/engines/sword25/gfx/image/imgloader.cpp b/engines/sword25/gfx/image/imgloader.cpp
index 1df0fba70c..e103626416 100644
--- a/engines/sword25/gfx/image/imgloader.cpp
+++ b/engines/sword25/gfx/image/imgloader.cpp
@@ -33,18 +33,19 @@
 #include "sword25/gfx/image/image.h"
 #include "sword25/gfx/image/imgloader.h"
 #include "graphics/pixelformat.h"
-#include "graphics/png.h"
+#include "graphics/decoders/png.h"
 
 namespace Sword25 {
 
 bool ImgLoader::decodePNGImage(const byte *fileDataPtr, uint fileSize, byte *&uncompressedDataPtr, int &width, int &height, int &pitch) {
 	Common::MemoryReadStream *fileStr = new Common::MemoryReadStream(fileDataPtr, fileSize, DisposeAfterUse::NO);
-	Graphics::PNG *png = new Graphics::PNG();
-	if (!png->read(fileStr))	// the fileStr pointer, and thus pFileData will be deleted after this is done
+
+	Graphics::PNGDecoder png;
+	if (!png.loadStream(*fileStr)) // the fileStr pointer, and thus pFileData will be deleted after this is done
 		error("Error while reading PNG image");
 
-	Graphics::PixelFormat format = Graphics::PixelFormat(4, 8, 8, 8, 8, 16, 8, 0, 24);
-	Graphics::Surface *pngSurface = png->getSurface(format);
+	const Graphics::Surface *sourceSurface = png.getSurface();
+	Graphics::Surface *pngSurface = sourceSurface->convertTo(Graphics::PixelFormat(4, 8, 8, 8, 8, 16, 8, 0, 24), png.getPalette());
 
 	width = pngSurface->w;
 	height = pngSurface->h;
@@ -53,7 +54,7 @@ bool ImgLoader::decodePNGImage(const byte *fileDataPtr, uint fileSize, byte *&un
 	pngSurface->free();
 
 	delete pngSurface;
-	delete png;
+	delete fileStr;
 
 	// Signal success
 	return true;
diff --git a/graphics/png.cpp b/graphics/decoders/png.cpp
index 156c405780..b87b6fdc7a 100644
--- a/graphics/png.cpp
+++ b/graphics/decoders/png.cpp
@@ -20,7 +20,7 @@
  *
  */
 
-#include "graphics/png.h"
+#include "graphics/decoders/png.h"
 
 #include "graphics/pixelformat.h"
 #include "graphics/surface.h"
@@ -98,113 +98,27 @@ enum PNGFilters {
 	kFilterPaeth   = 4
 };
 
-PNG::PNG() : _compressedBuffer(0), _compressedBufferSize(0),
-			_unfilteredSurface(0), _transparentColorSpecified(false) {
+PNGDecoder::PNGDecoder() : _compressedBuffer(0), _compressedBufferSize(0),
+			_transparentColorSpecified(false), _outputSurface(0) {
 }
 
-PNG::~PNG() {
-	if (_unfilteredSurface) {
-		_unfilteredSurface->free();
-		delete _unfilteredSurface;
-	}
+PNGDecoder::~PNGDecoder() {
+	destroy();
 }
 
-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;
-		}
+void PNGDecoder::destroy() {
+	if (_outputSurface) {
+		_outputSurface->free();
+		delete _outputSurface;
+		_outputSurface = 0;
 	}
-
-	return output;
 }
 
-bool PNG::read(Common::SeekableReadStream *str) {
+bool PNGDecoder::loadStream(Common::SeekableReadStream &stream) {
+	destroy();
+
 	uint32 chunkLength = 0, chunkType = 0;
-	_stream = str;
+	_stream = &stream;
 
 	// First, check the PNG signature
 	if (_stream->readUint32BE() != MKTAG(0x89, 'P', 'N', 'G')) {
@@ -249,8 +163,10 @@ bool PNG::read(Common::SeekableReadStream *str) {
 				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();
+			_stream->read(_palette, _paletteEntries * 3);
+			memset(_paletteTransparency, 0xff, sizeof(_paletteTransparency));
 			break;
 		case kChunkIEND:
 			// End of stream
@@ -269,7 +185,6 @@ bool PNG::read(Common::SeekableReadStream *str) {
 	}
 
 	// We no longer need the file stream, thus close it here
-	delete _stream;
 	_stream = 0;
 
 	// Unpack the compressed buffer
@@ -295,7 +210,7 @@ bool PNG::read(Common::SeekableReadStream *str) {
  * 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) {
+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);
@@ -315,7 +230,7 @@ byte PNG::paethPredictor(int16 a, int16 b, int16 c) {
  *
  * Taken from lodePNG
  */
-void PNG::unfilterScanLine(byte *dest, const byte *scanLine, const byte *prevLine, uint16 byteWidth, byte filterType, uint16 length) {
+void PNGDecoder::unfilterScanLine(byte *dest, const byte *scanLine, const byte *prevLine, uint16 byteWidth, byte filterType, uint16 length) {
 	uint16 i;
 
 	switch (filterType) {
@@ -370,33 +285,29 @@ void PNG::unfilterScanLine(byte *dest, const byte *scanLine, const byte *prevLin
 
 }
 
-void PNG::constructImage() {
+int PNGDecoder::getBytesPerPixel() const {
+	return (getNumColorChannels() * _header.bitDepth + 7) / 8;
+}
+
+void PNGDecoder::constructImage() {
 	assert (_header.bitDepth != 0);
 
-	byte *dest;
-	byte *scanLine;
-	byte *prevLine = 0;
-	byte filterType;
+	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;
-
-	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);
+	byte *scanLine = new byte[scanLineWidth];
+	byte *prevLine = 0;
 
 	switch(_header.interlaceType) {
 	case kNonInterlaced:
-		for (uint16 y = 0; y < _unfilteredSurface->h; y++) {
-			filterType = _imageData->readByte();
+		for (uint16 y = 0; y < _header.height; y++) {
+			byte filterType = _imageData->readByte();
 			_imageData->read(scanLine, scanLineWidth);
-			unfilterScanLine(dest, scanLine, prevLine, _unfilteredSurface->format.bytesPerPixel, filterType, scanLineWidth);
+			unfilterScanLine(dest, scanLine, prevLine, bytesPerPixel, filterType, scanLineWidth);
 			prevLine = dest;
-			dest += _unfilteredSurface->pitch;
+			dest += pitch;
 		}
 		break;
 	case kInterlaced:
@@ -409,9 +320,123 @@ void PNG::constructImage() {
 	}
 
 	delete[] scanLine;
+
+	constructOutput(unfilteredSurface);
+	delete[] unfilteredSurface;
 }
 
-void PNG::readHeaderChunk() {
+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();
@@ -431,7 +456,7 @@ void PNG::readHeaderChunk() {
 	_header.interlaceType = (PNGInterlaceType)_stream->readByte();
 }
 
-byte PNG::getNumColorChannels() {
+byte PNGDecoder::getNumColorChannels() const {
 	switch (_header.colorType) {
 	case kGrayScale:
 		return 1; // Gray
@@ -448,16 +473,7 @@ byte PNG::getNumColorChannels() {
 	}
 }
 
-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) {
+void PNGDecoder::readTransparencyChunk(uint32 chunkLength) {
 	_transparentColorSpecified = true;
 
 	switch(_header.colorType) {
@@ -472,8 +488,8 @@ void PNG::readTransparencyChunk(uint32 chunkLength) {
 		_transparentColor[2] = _stream->readUint16BE();
 		break;
 	case kIndexed:
-		for (uint32 i = 0; i < chunkLength; i++)
-			_palette[i * 4 + 3] = _stream->readByte();
+		_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:
diff --git a/graphics/png.h b/graphics/decoders/png.h
index 078c76fc6b..1da0bea1ab 100644
--- a/graphics/png.h
+++ b/graphics/decoders/png.h
@@ -53,6 +53,7 @@
 
 #include "common/scummsys.h"
 #include "common/textconsole.h"
+#include "graphics/decoders/image_decoder.h"
 
 namespace Common {
 class SeekableReadStream;
@@ -61,82 +62,44 @@ 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 {
+class PNGDecoder : public ImageDecoder {
 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;
-	}
+	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();
+	byte getNumColorChannels() const;
 
 	void readPaletteChunk();
 	void readTransparencyChunk(uint32 chunkLength);
@@ -152,7 +115,8 @@ private:
 
 	PNGHeader _header;
 
-	byte _palette[256 * 4];	// RGBA
+	byte _palette[256 * 3];	// RGB
+	byte _paletteTransparency[256];
 	uint16 _paletteEntries;
 	uint16 _transparentColor[3];
 	bool _transparentColorSpecified;
@@ -160,9 +124,12 @@ private:
 	byte *_compressedBuffer;
 	uint32 _compressedBufferSize;
 
-	Graphics::Surface *_unfilteredSurface;
+	Graphics::Surface *_outputSurface;
+	Graphics::PixelFormat findPixelFormat() const;
+	int getBytesPerPixel() const;
+	void constructOutput(const byte *surface);
 };
 
-} // End of Graphics namespace
+} // End of namespace Graphics
 
 #endif // GRAPHICS_PNG_H
diff --git a/graphics/module.mk b/graphics/module.mk
index d9f3802a68..281f904b38 100644
--- a/graphics/module.mk
+++ b/graphics/module.mk
@@ -13,7 +13,6 @@ MODULE_OBJS := \
 	fonts/winfont.o \
 	iff.o \
 	maccursor.o \
-	png.o \
 	primitives.o \
 	scaler.o \
 	scaler/thumbnail_intern.o \
@@ -26,7 +25,8 @@ MODULE_OBJS := \
 	yuv_to_rgb.o \
 	decoders/bmp.o \
 	decoders/jpeg.o \
-	decoders/pict.o
+	decoders/pict.o \
+	decoders/png.o
 
 ifdef USE_SCALERS
 MODULE_OBJS += \