src/codec/SkBmpStandardCodec.cpp - platform/external/skqp - Gitiles

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */

 #include "SkBmpStandardCodec.h"
 #include "SkCodecPriv.h"
 #include "SkColorData.h"
 #include "SkStream.h"

 /*
  * Creates an instance of the decoder
  * Called only by NewFromStream
  */
 SkBmpStandardCodec::SkBmpStandardCodec(int width, int height, const SkEncodedInfo& info,
                                        std::unique_ptr<SkStream> stream, uint16_t bitsPerPixel,
                                        uint32_t numColors, uint32_t bytesPerColor, uint32_t offset,
                                        SkCodec::SkScanlineOrder rowOrder,
                                        bool isOpaque, bool inIco)
     : INHERITED(width, height, info, std::move(stream), bitsPerPixel, rowOrder)
     , fColorTable(nullptr)
     , fNumColors(numColors)
     , fBytesPerColor(bytesPerColor)
     , fOffset(offset)
     , fSwizzler(nullptr)
     , fIsOpaque(isOpaque)
     , fInIco(inIco)
     , fAndMaskRowBytes(fInIco ? SkAlign4(compute_row_bytes(this->getInfo().width(), 1)) : 0)
 {}

 /*
  * Initiates the bitmap decode
  */
 SkCodec::Result SkBmpStandardCodec::onGetPixels(const SkImageInfo& dstInfo,
                                         void* dst, size_t dstRowBytes,
                                         const Options& opts,
                                         int* rowsDecoded) {
     if (opts.fSubset) {
         // Subsets are not supported.
         return kUnimplemented;
     }
     if (dstInfo.dimensions() != this->getInfo().dimensions()) {
         SkCodecPrintf("Error: scaling not supported.\n");
         return kInvalidScale;
     }

     Result result = this->prepareToDecode(dstInfo, opts);
     if (kSuccess != result) {
         return result;
     }
     int rows = this->decodeRows(dstInfo, dst, dstRowBytes, opts);
     if (rows != dstInfo.height()) {
         *rowsDecoded = rows;
         return kIncompleteInput;
     }
     return kSuccess;
 }

 /*
  * Process the color table for the bmp input
  */
  bool SkBmpStandardCodec::createColorTable(SkColorType dstColorType, SkAlphaType dstAlphaType) {
     // Allocate memory for color table
     uint32_t colorBytes = 0;
     SkPMColor colorTable[256];
     if (this->bitsPerPixel() <= 8) {
         // Inform the caller of the number of colors
         uint32_t maxColors = 1 << this->bitsPerPixel();
         // Don't bother reading more than maxColors.
         const uint32_t numColorsToRead =
             fNumColors == 0 ? maxColors : SkTMin(fNumColors, maxColors);

         // Read the color table from the stream
         colorBytes = numColorsToRead * fBytesPerColor;
         std::unique_ptr<uint8_t[]> cBuffer(new uint8_t[colorBytes]);
         if (stream()->read(cBuffer.get(), colorBytes) != colorBytes) {
             SkCodecPrintf("Error: unable to read color table.\n");
             return false;
         }

         SkColorType packColorType = dstColorType;
         SkAlphaType packAlphaType = dstAlphaType;
         if (this->colorXform()) {
             packColorType = kBGRA_8888_SkColorType;
             packAlphaType = kUnpremul_SkAlphaType;
         }

         // Choose the proper packing function
         bool isPremul = (kPremul_SkAlphaType == packAlphaType) && !fIsOpaque;
         PackColorProc packARGB = choose_pack_color_proc(isPremul, packColorType);

         // Fill in the color table
         uint32_t i = 0;
         for (; i < numColorsToRead; i++) {
             uint8_t blue = get_byte(cBuffer.get(), i*fBytesPerColor);
             uint8_t green = get_byte(cBuffer.get(), i*fBytesPerColor + 1);
             uint8_t red = get_byte(cBuffer.get(), i*fBytesPerColor + 2);
             uint8_t alpha;
             if (fIsOpaque) {
                 alpha = 0xFF;
             } else {
                 alpha = get_byte(cBuffer.get(), i*fBytesPerColor + 3);
             }
             colorTable[i] = packARGB(alpha, red, green, blue);
         }

         // To avoid segmentation faults on bad pixel data, fill the end of the
         // color table with black.  This is the same the behavior as the
         // chromium decoder.
         for (; i < maxColors; i++) {
             colorTable[i] = SkPackARGB32NoCheck(0xFF, 0, 0, 0);
         }

         if (this->colorXform() && !this->xformOnDecode()) {
             this->applyColorXform(colorTable, colorTable, maxColors);
         }

         // Set the color table
         fColorTable.reset(new SkColorTable(colorTable, maxColors));
     }

     // Bmp-in-Ico files do not use an offset to indicate where the pixel data
     // begins.  Pixel data always begins immediately after the color table.
     if (!fInIco) {
         // Check that we have not read past the pixel array offset
         if(fOffset < colorBytes) {
             // This may occur on OS 2.1 and other old versions where the color
             // table defaults to max size, and the bmp tries to use a smaller
             // color table.  This is invalid, and our decision is to indicate
             // an error, rather than try to guess the intended size of the
             // color table.
             SkCodecPrintf("Error: pixel data offset less than color table size.\n");
             return false;
         }

         // After reading the color table, skip to the start of the pixel array
         if (stream()->skip(fOffset - colorBytes) != fOffset - colorBytes) {
             SkCodecPrintf("Error: unable to skip to image data.\n");
             return false;
         }
     }

     // Return true on success
     return true;
 }

 void SkBmpStandardCodec::initializeSwizzler(const SkImageInfo& dstInfo, const Options& opts) {
     // In the case of bmp-in-icos, we will report BGRA to the client,
     // since we may be required to apply an alpha mask after the decode.
     // However, the swizzler needs to know the actual format of the bmp.
     SkEncodedInfo encodedInfo = this->getEncodedInfo();
     if (fInIco) {
         if (this->bitsPerPixel() <= 8) {
             encodedInfo = SkEncodedInfo::Make(SkEncodedInfo::kPalette_Color,
                     encodedInfo.alpha(), this->bitsPerPixel());
         } else if (this->bitsPerPixel() == 24) {
             encodedInfo = SkEncodedInfo::Make(SkEncodedInfo::kBGR_Color,
                     SkEncodedInfo::kOpaque_Alpha, 8);
         }
     }

     // Get a pointer to the color table if it exists
     const SkPMColor* colorPtr = get_color_ptr(fColorTable.get());

     SkImageInfo swizzlerInfo = dstInfo;
     SkCodec::Options swizzlerOptions = opts;
     if (this->colorXform()) {
         swizzlerInfo = swizzlerInfo.makeColorType(kXformSrcColorType);
         if (kPremul_SkAlphaType == dstInfo.alphaType()) {
             swizzlerInfo = swizzlerInfo.makeAlphaType(kUnpremul_SkAlphaType);
         }

         swizzlerOptions.fZeroInitialized = kNo_ZeroInitialized;
     }


     fSwizzler.reset(SkSwizzler::CreateSwizzler(encodedInfo, colorPtr, swizzlerInfo,
                                                swizzlerOptions));
     SkASSERT(fSwizzler);
 }

 SkCodec::Result SkBmpStandardCodec::onPrepareToDecode(const SkImageInfo& dstInfo,
         const SkCodec::Options& options) {
     if (this->xformOnDecode()) {
         this->resetXformBuffer(dstInfo.width());
     }

     // Create the color table if necessary and prepare the stream for decode
     // Note that if it is non-NULL, inputColorCount will be modified
     if (!this->createColorTable(dstInfo.colorType(), dstInfo.alphaType())) {
         SkCodecPrintf("Error: could not create color table.\n");
         return SkCodec::kInvalidInput;
     }

     // Initialize a swizzler
     this->initializeSwizzler(dstInfo, options);
     return SkCodec::kSuccess;
 }

 /*
  * Performs the bitmap decoding for standard input format
  */
 int SkBmpStandardCodec::decodeRows(const SkImageInfo& dstInfo, void* dst, size_t dstRowBytes,
         const Options& opts) {
     // Iterate over rows of the image
     const int height = dstInfo.height();
     for (int y = 0; y < height; y++) {
         // Read a row of the input
         if (this->stream()->read(this->srcBuffer(), this->srcRowBytes()) != this->srcRowBytes()) {
             SkCodecPrintf("Warning: incomplete input stream.\n");
             return y;
         }

         // Decode the row in destination format
         uint32_t row = this->getDstRow(y, dstInfo.height());

         void* dstRow = SkTAddOffset<void>(dst, row * dstRowBytes);

         if (this->xformOnDecode()) {
             SkASSERT(this->colorXform());
             fSwizzler->swizzle(this->xformBuffer(), this->srcBuffer());
             this->applyColorXform(dstRow, this->xformBuffer(), fSwizzler->swizzleWidth());
         } else {
             fSwizzler->swizzle(dstRow, this->srcBuffer());
         }
     }

     if (fInIco && fIsOpaque) {
         const int startScanline = this->currScanline();
         if (startScanline < 0) {
             // We are not performing a scanline decode.
             // Just decode the entire ICO mask and return.
             decodeIcoMask(this->stream(), dstInfo, dst, dstRowBytes);
             return height;
         }

         // In order to perform a scanline ICO decode, we must be able
         // to skip ahead in the stream in order to apply the AND mask
         // to the requested scanlines.
         // We will do this by taking advantage of the fact that
         // SkIcoCodec always uses a SkMemoryStream as its underlying
         // representation of the stream.
         const void* memoryBase = this->stream()->getMemoryBase();
         SkASSERT(nullptr != memoryBase);
         SkASSERT(this->stream()->hasLength());
         SkASSERT(this->stream()->hasPosition());

         const size_t length = this->stream()->getLength();
         const size_t currPosition = this->stream()->getPosition();

         // Calculate how many bytes we must skip to reach the AND mask.
         const int remainingScanlines = this->getInfo().height() - startScanline - height;
         const size_t bytesToSkip = remainingScanlines * this->srcRowBytes() +
                 startScanline * fAndMaskRowBytes;
         const size_t subStreamStartPosition = currPosition + bytesToSkip;
         if (subStreamStartPosition >= length) {
             // FIXME: How can we indicate that this decode was actually incomplete?
             return height;
         }

         // Create a subStream to pass to decodeIcoMask().  It is useful to encapsulate
         // the memory base into a stream in order to safely handle incomplete images
         // without reading out of bounds memory.
         const void* subStreamMemoryBase = SkTAddOffset<const void>(memoryBase,
                 subStreamStartPosition);
         const size_t subStreamLength = length - subStreamStartPosition;
         // This call does not transfer ownership of the subStreamMemoryBase.
         SkMemoryStream subStream(subStreamMemoryBase, subStreamLength, false);

         // FIXME: If decodeIcoMask does not succeed, is there a way that we can
         //        indicate the decode was incomplete?
         decodeIcoMask(&subStream, dstInfo, dst, dstRowBytes);
     }

     return height;
 }

 void SkBmpStandardCodec::decodeIcoMask(SkStream* stream, const SkImageInfo& dstInfo,
         void* dst, size_t dstRowBytes) {
     // BMP in ICO have transparency, so this cannot be 565. The below code depends
     // on the output being an SkPMColor.
     SkASSERT(kRGBA_8888_SkColorType == dstInfo.colorType() ||
              kBGRA_8888_SkColorType == dstInfo.colorType() ||
              kRGBA_F16_SkColorType == dstInfo.colorType());

     // If we are sampling, make sure that we only mask the sampled pixels.
     // We do not need to worry about sampling in the y-dimension because that
     // should be handled by SkSampledCodec.
     const int sampleX = fSwizzler->sampleX();
     const int sampledWidth = get_scaled_dimension(this->getInfo().width(), sampleX);
     const int srcStartX = get_start_coord(sampleX);


     SkPMColor* dstPtr = (SkPMColor*) dst;
     for (int y = 0; y < dstInfo.height(); y++) {
         // The srcBuffer will at least be large enough
         if (stream->read(this->srcBuffer(), fAndMaskRowBytes) != fAndMaskRowBytes) {
             SkCodecPrintf("Warning: incomplete AND mask for bmp-in-ico.\n");
             return;
         }

         auto applyMask = [dstInfo](void* dstRow, int x, uint64_t bit) {
             if (kRGBA_F16_SkColorType == dstInfo.colorType()) {
                 uint64_t* dst64 = (uint64_t*) dstRow;
                 dst64[x] &= bit - 1;
             } else {
                 uint32_t* dst32 = (uint32_t*) dstRow;
                 dst32[x] &= bit - 1;
             }
         };

         int row = this->getDstRow(y, dstInfo.height());

         void* dstRow = SkTAddOffset<SkPMColor>(dstPtr, row * dstRowBytes);

         int srcX = srcStartX;
         for (int dstX = 0; dstX < sampledWidth; dstX++) {
             int quotient;
             int modulus;
             SkTDivMod(srcX, 8, &quotient, &modulus);
             uint32_t shift = 7 - modulus;
             uint64_t alphaBit = (this->srcBuffer()[quotient] >> shift) & 0x1;
             applyMask(dstRow, dstX, alphaBit);
             srcX += sampleX;
         }
     }
 }
	/*
	* Copyright 2015 Google Inc.
	*
	* Use of this source code is governed by a BSD-style license that can be
	* found in the LICENSE file.
	*/

	#include "SkBmpStandardCodec.h"
	#include "SkCodecPriv.h"
	#include "SkColorData.h"
	#include "SkStream.h"

	/*
	* Creates an instance of the decoder
	* Called only by NewFromStream
	*/
	SkBmpStandardCodec::SkBmpStandardCodec(int width, int height, const SkEncodedInfo& info,
	std::unique_ptr<SkStream> stream, uint16_t bitsPerPixel,
	uint32_t numColors, uint32_t bytesPerColor, uint32_t offset,
	SkCodec::SkScanlineOrder rowOrder,
	bool isOpaque, bool inIco)
	: INHERITED(width, height, info, std::move(stream), bitsPerPixel, rowOrder)
	, fColorTable(nullptr)
	, fNumColors(numColors)
	, fBytesPerColor(bytesPerColor)
	, fOffset(offset)
	, fSwizzler(nullptr)
	, fIsOpaque(isOpaque)
	, fInIco(inIco)
	, fAndMaskRowBytes(fInIco ? SkAlign4(compute_row_bytes(this->getInfo().width(), 1)) : 0)
	{}

	/*
	* Initiates the bitmap decode
	*/
	SkCodec::Result SkBmpStandardCodec::onGetPixels(const SkImageInfo& dstInfo,
	void* dst, size_t dstRowBytes,
	const Options& opts,
	int* rowsDecoded) {
	if (opts.fSubset) {
	// Subsets are not supported.
	return kUnimplemented;
	}
	if (dstInfo.dimensions() != this->getInfo().dimensions()) {
	SkCodecPrintf("Error: scaling not supported.\n");
	return kInvalidScale;
	}

	Result result = this->prepareToDecode(dstInfo, opts);
	if (kSuccess != result) {
	return result;
	}
	int rows = this->decodeRows(dstInfo, dst, dstRowBytes, opts);
	if (rows != dstInfo.height()) {
	*rowsDecoded = rows;
	return kIncompleteInput;
	}
	return kSuccess;
	}

	/*
	* Process the color table for the bmp input
	*/
	bool SkBmpStandardCodec::createColorTable(SkColorType dstColorType, SkAlphaType dstAlphaType) {
	// Allocate memory for color table
	uint32_t colorBytes = 0;
	SkPMColor colorTable[256];
	if (this->bitsPerPixel() <= 8) {
	// Inform the caller of the number of colors
	uint32_t maxColors = 1 << this->bitsPerPixel();
	// Don't bother reading more than maxColors.
	const uint32_t numColorsToRead =
	fNumColors == 0 ? maxColors : SkTMin(fNumColors, maxColors);

	// Read the color table from the stream
	colorBytes = numColorsToRead * fBytesPerColor;
	std::unique_ptr<uint8_t[]> cBuffer(new uint8_t[colorBytes]);
	if (stream()->read(cBuffer.get(), colorBytes) != colorBytes) {
	SkCodecPrintf("Error: unable to read color table.\n");
	return false;
	}

	SkColorType packColorType = dstColorType;
	SkAlphaType packAlphaType = dstAlphaType;
	if (this->colorXform()) {
	packColorType = kBGRA_8888_SkColorType;
	packAlphaType = kUnpremul_SkAlphaType;
	}

	// Choose the proper packing function
	bool isPremul = (kPremul_SkAlphaType == packAlphaType) && !fIsOpaque;
	PackColorProc packARGB = choose_pack_color_proc(isPremul, packColorType);

	// Fill in the color table
	uint32_t i = 0;
	for (; i < numColorsToRead; i++) {
	uint8_t blue = get_byte(cBuffer.get(), i*fBytesPerColor);
	uint8_t green = get_byte(cBuffer.get(), i*fBytesPerColor + 1);
	uint8_t red = get_byte(cBuffer.get(), i*fBytesPerColor + 2);
	uint8_t alpha;
	if (fIsOpaque) {
	alpha = 0xFF;
	} else {
	alpha = get_byte(cBuffer.get(), i*fBytesPerColor + 3);
	}
	colorTable[i] = packARGB(alpha, red, green, blue);
	}

	// To avoid segmentation faults on bad pixel data, fill the end of the
	// color table with black. This is the same the behavior as the
	// chromium decoder.
	for (; i < maxColors; i++) {
	colorTable[i] = SkPackARGB32NoCheck(0xFF, 0, 0, 0);
	}

	if (this->colorXform() && !this->xformOnDecode()) {
	this->applyColorXform(colorTable, colorTable, maxColors);
	}

	// Set the color table
	fColorTable.reset(new SkColorTable(colorTable, maxColors));
	}

	// Bmp-in-Ico files do not use an offset to indicate where the pixel data
	// begins. Pixel data always begins immediately after the color table.
	if (!fInIco) {
	// Check that we have not read past the pixel array offset
	if(fOffset < colorBytes) {
	// This may occur on OS 2.1 and other old versions where the color
	// table defaults to max size, and the bmp tries to use a smaller
	// color table. This is invalid, and our decision is to indicate
	// an error, rather than try to guess the intended size of the
	// color table.
	SkCodecPrintf("Error: pixel data offset less than color table size.\n");
	return false;
	}

	// After reading the color table, skip to the start of the pixel array
	if (stream()->skip(fOffset - colorBytes) != fOffset - colorBytes) {
	SkCodecPrintf("Error: unable to skip to image data.\n");
	return false;
	}
	}

	// Return true on success
	return true;
	}

	void SkBmpStandardCodec::initializeSwizzler(const SkImageInfo& dstInfo, const Options& opts) {
	// In the case of bmp-in-icos, we will report BGRA to the client,
	// since we may be required to apply an alpha mask after the decode.
	// However, the swizzler needs to know the actual format of the bmp.
	SkEncodedInfo encodedInfo = this->getEncodedInfo();
	if (fInIco) {
	if (this->bitsPerPixel() <= 8) {
	encodedInfo = SkEncodedInfo::Make(SkEncodedInfo::kPalette_Color,
	encodedInfo.alpha(), this->bitsPerPixel());
	} else if (this->bitsPerPixel() == 24) {
	encodedInfo = SkEncodedInfo::Make(SkEncodedInfo::kBGR_Color,
	SkEncodedInfo::kOpaque_Alpha, 8);
	}
	}

	// Get a pointer to the color table if it exists
	const SkPMColor* colorPtr = get_color_ptr(fColorTable.get());

	SkImageInfo swizzlerInfo = dstInfo;
	SkCodec::Options swizzlerOptions = opts;
	if (this->colorXform()) {
	swizzlerInfo = swizzlerInfo.makeColorType(kXformSrcColorType);
	if (kPremul_SkAlphaType == dstInfo.alphaType()) {
	swizzlerInfo = swizzlerInfo.makeAlphaType(kUnpremul_SkAlphaType);
	}

	swizzlerOptions.fZeroInitialized = kNo_ZeroInitialized;
	}


	fSwizzler.reset(SkSwizzler::CreateSwizzler(encodedInfo, colorPtr, swizzlerInfo,
	swizzlerOptions));
	SkASSERT(fSwizzler);
	}

	SkCodec::Result SkBmpStandardCodec::onPrepareToDecode(const SkImageInfo& dstInfo,
	const SkCodec::Options& options) {
	if (this->xformOnDecode()) {
	this->resetXformBuffer(dstInfo.width());
	}

	// Create the color table if necessary and prepare the stream for decode
	// Note that if it is non-NULL, inputColorCount will be modified
	if (!this->createColorTable(dstInfo.colorType(), dstInfo.alphaType())) {
	SkCodecPrintf("Error: could not create color table.\n");
	return SkCodec::kInvalidInput;
	}

	// Initialize a swizzler
	this->initializeSwizzler(dstInfo, options);
	return SkCodec::kSuccess;
	}

	/*
	* Performs the bitmap decoding for standard input format
	*/
	int SkBmpStandardCodec::decodeRows(const SkImageInfo& dstInfo, void* dst, size_t dstRowBytes,
	const Options& opts) {
	// Iterate over rows of the image
	const int height = dstInfo.height();
	for (int y = 0; y < height; y++) {
	// Read a row of the input
	if (this->stream()->read(this->srcBuffer(), this->srcRowBytes()) != this->srcRowBytes()) {
	SkCodecPrintf("Warning: incomplete input stream.\n");
	return y;
	}

	// Decode the row in destination format
	uint32_t row = this->getDstRow(y, dstInfo.height());

	void* dstRow = SkTAddOffset<void>(dst, row * dstRowBytes);

	if (this->xformOnDecode()) {
	SkASSERT(this->colorXform());
	fSwizzler->swizzle(this->xformBuffer(), this->srcBuffer());
	this->applyColorXform(dstRow, this->xformBuffer(), fSwizzler->swizzleWidth());
	} else {
	fSwizzler->swizzle(dstRow, this->srcBuffer());
	}
	}

	if (fInIco && fIsOpaque) {
	const int startScanline = this->currScanline();
	if (startScanline < 0) {
	// We are not performing a scanline decode.
	// Just decode the entire ICO mask and return.
	decodeIcoMask(this->stream(), dstInfo, dst, dstRowBytes);
	return height;
	}

	// In order to perform a scanline ICO decode, we must be able
	// to skip ahead in the stream in order to apply the AND mask
	// to the requested scanlines.
	// We will do this by taking advantage of the fact that
	// SkIcoCodec always uses a SkMemoryStream as its underlying
	// representation of the stream.
	const void* memoryBase = this->stream()->getMemoryBase();
	SkASSERT(nullptr != memoryBase);
	SkASSERT(this->stream()->hasLength());
	SkASSERT(this->stream()->hasPosition());

	const size_t length = this->stream()->getLength();
	const size_t currPosition = this->stream()->getPosition();

	// Calculate how many bytes we must skip to reach the AND mask.
	const int remainingScanlines = this->getInfo().height() - startScanline - height;
	const size_t bytesToSkip = remainingScanlines * this->srcRowBytes() +
	startScanline * fAndMaskRowBytes;
	const size_t subStreamStartPosition = currPosition + bytesToSkip;
	if (subStreamStartPosition >= length) {
	// FIXME: How can we indicate that this decode was actually incomplete?
	return height;
	}

	// Create a subStream to pass to decodeIcoMask(). It is useful to encapsulate
	// the memory base into a stream in order to safely handle incomplete images
	// without reading out of bounds memory.
	const void* subStreamMemoryBase = SkTAddOffset<const void>(memoryBase,
	subStreamStartPosition);
	const size_t subStreamLength = length - subStreamStartPosition;
	// This call does not transfer ownership of the subStreamMemoryBase.
	SkMemoryStream subStream(subStreamMemoryBase, subStreamLength, false);

	// FIXME: If decodeIcoMask does not succeed, is there a way that we can
	// indicate the decode was incomplete?
	decodeIcoMask(&subStream, dstInfo, dst, dstRowBytes);
	}

	return height;
	}

	void SkBmpStandardCodec::decodeIcoMask(SkStream* stream, const SkImageInfo& dstInfo,
	void* dst, size_t dstRowBytes) {
	// BMP in ICO have transparency, so this cannot be 565. The below code depends
	// on the output being an SkPMColor.
	SkASSERT(kRGBA_8888_SkColorType == dstInfo.colorType() \|\|
	kBGRA_8888_SkColorType == dstInfo.colorType() \|\|
	kRGBA_F16_SkColorType == dstInfo.colorType());

	// If we are sampling, make sure that we only mask the sampled pixels.
	// We do not need to worry about sampling in the y-dimension because that
	// should be handled by SkSampledCodec.
	const int sampleX = fSwizzler->sampleX();
	const int sampledWidth = get_scaled_dimension(this->getInfo().width(), sampleX);
	const int srcStartX = get_start_coord(sampleX);


	SkPMColor* dstPtr = (SkPMColor*) dst;
	for (int y = 0; y < dstInfo.height(); y++) {
	// The srcBuffer will at least be large enough
	if (stream->read(this->srcBuffer(), fAndMaskRowBytes) != fAndMaskRowBytes) {
	SkCodecPrintf("Warning: incomplete AND mask for bmp-in-ico.\n");
	return;
	}

	auto applyMask = [dstInfo](void* dstRow, int x, uint64_t bit) {
	if (kRGBA_F16_SkColorType == dstInfo.colorType()) {
	uint64_t* dst64 = (uint64_t*) dstRow;
	dst64[x] &= bit - 1;
	} else {
	uint32_t* dst32 = (uint32_t*) dstRow;
	dst32[x] &= bit - 1;
	}
	};

	int row = this->getDstRow(y, dstInfo.height());

	void* dstRow = SkTAddOffset<SkPMColor>(dstPtr, row * dstRowBytes);

	int srcX = srcStartX;
	for (int dstX = 0; dstX < sampledWidth; dstX++) {
	int quotient;
	int modulus;
	SkTDivMod(srcX, 8, &quotient, &modulus);
	uint32_t shift = 7 - modulus;
	uint64_t alphaBit = (this->srcBuffer()[quotient] >> shift) & 0x1;
	applyMask(dstRow, dstX, alphaBit);
	srcX += sampleX;
	}
	}
	}