/*
* 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 "SkColorPriv.h"
#include "SkStream.h"
/*
* Creates an instance of the decoder
* Called only by NewFromStream
*/
SkBmpStandardCodec::SkBmpStandardCodec(const SkImageInfo& info, SkStream* stream,
uint16_t bitsPerPixel, uint32_t numColors,
uint32_t bytesPerColor, uint32_t offset,
SkCodec::SkScanlineOrder rowOrder,
bool isOpaque, bool inIco)
: INHERITED(info, stream, bitsPerPixel, rowOrder)
, fColorTable(nullptr)
, fNumColors(numColors)
, fBytesPerColor(bytesPerColor)
, fOffset(offset)
, fSwizzler(nullptr)
, fSrcBuffer(new uint8_t [this->srcRowBytes()])
, 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,
SkPMColor* inputColorPtr,
int* inputColorCount,
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;
}
if (!conversion_possible(dstInfo, this->getInfo())) {
SkCodecPrintf("Error: cannot convert input type to output type.\n");
return kInvalidConversion;
}
Result result = this->prepareToDecode(dstInfo, opts, inputColorPtr, inputColorCount);
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(SkAlphaType dstAlphaType, int* numColors) {
// 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();
if (nullptr != numColors) {
// We set the number of colors to maxColors in order to ensure
// safe memory accesses. Otherwise, an invalid pixel could
// access memory outside of our color table array.
*numColors = maxColors;
}
// 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;
SkAutoTDeleteArray<uint8_t> cBuffer(new uint8_t[colorBytes]);
if (stream()->read(cBuffer.get(), colorBytes) != colorBytes) {
SkCodecPrintf("Error: unable to read color table.\n");
return false;
}
// Choose the proper packing function
SkPMColor (*packARGB) (uint32_t, uint32_t, uint32_t, uint32_t);
if (fIsOpaque || kUnpremul_SkAlphaType == dstAlphaType) {
packARGB = &SkPackARGB32NoCheck;
} else {
packARGB = &SkPremultiplyARGBInline;
}
// 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);
}
// 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) {
// Get swizzler configuration
SkSwizzler::SrcConfig config = SkSwizzler::kUnknown;
switch (this->bitsPerPixel()) {
case 1:
config = SkSwizzler::kIndex1;
break;
case 2:
config = SkSwizzler::kIndex2;
break;
case 4:
config = SkSwizzler::kIndex4;
break;
case 8:
config = SkSwizzler::kIndex;
break;
case 24:
config = SkSwizzler::kBGR;
break;
case 32:
if (fIsOpaque) {
config = SkSwizzler::kBGRX;
} else {
config = SkSwizzler::kBGRA;
}
break;
default:
SkASSERT(false);
}
// Get a pointer to the color table if it exists
const SkPMColor* colorPtr = get_color_ptr(fColorTable.get());
// Create swizzler
fSwizzler.reset(SkSwizzler::CreateSwizzler(config, colorPtr, dstInfo, opts));
SkASSERT(fSwizzler);
}
SkCodec::Result SkBmpStandardCodec::prepareToDecode(const SkImageInfo& dstInfo,
const SkCodec::Options& options, SkPMColor inputColorPtr[], int* inputColorCount) {
// 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.alphaType(), inputColorCount)) {
SkCodecPrintf("Error: could not create color table.\n");
return SkCodec::kInvalidInput;
}
// Copy the color table to the client if necessary
copy_color_table(dstInfo, this->fColorTable, inputColorPtr, inputColorCount);
// 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(fSrcBuffer.get(), 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);
fSwizzler->swizzle(dstRow, fSrcBuffer.get());
}
if (fInIco) {
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, and this mask
// prevents us from using kIndex8. The below code depends on the output
// being an SkPMColor.
SkASSERT(dstInfo.colorType() == kN32_SkColorType);
// 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(fSrcBuffer.get(), fAndMaskRowBytes) != fAndMaskRowBytes) {
SkCodecPrintf("Warning: incomplete AND mask for bmp-in-ico.\n");
return;
}
int row = this->getDstRow(y, dstInfo.height());
SkPMColor* dstRow =
SkTAddOffset<SkPMColor>(dstPtr, row * dstRowBytes);
int srcX = srcStartX;
for (int dstX = 0; dstX < sampledWidth; dstX++) {
int quotient;
int modulus;
SkTDivMod(srcX, 8, "ient, &modulus);
uint32_t shift = 7 - modulus;
uint32_t alphaBit = (fSrcBuffer.get()[quotient] >> shift) & 0x1;
dstRow[dstX] &= alphaBit - 1;
srcX += sampleX;
}
}
}
uint32_t SkBmpStandardCodec::onGetFillValue(SkColorType colorType) const {
const SkPMColor* colorPtr = get_color_ptr(fColorTable.get());
if (colorPtr) {
return get_color_table_fill_value(colorType, colorPtr, 0);
}
return INHERITED::onGetFillValue(colorType);
}