/*
* 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 "SkBmpRLECodec.h"
#include "SkCodecPriv.h"
#include "SkColorPriv.h"
#include "SkStream.h"
/*
* Creates an instance of the decoder
* Called only by NewFromStream
*/
SkBmpRLECodec::SkBmpRLECodec(int width, int height, const SkEncodedInfo& info, SkStream* stream,
uint16_t bitsPerPixel, uint32_t numColors,
uint32_t bytesPerColor, uint32_t offset,
SkCodec::SkScanlineOrder rowOrder)
: INHERITED(width, height, info, stream, bitsPerPixel, rowOrder)
, fColorTable(nullptr)
, fNumColors(numColors)
, fBytesPerColor(bytesPerColor)
, fOffset(offset)
, fBytesBuffered(0)
, fCurrRLEByte(0)
, fSampleX(1)
{}
/*
* Initiates the bitmap decode
*/
SkCodec::Result SkBmpRLECodec::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;
}
Result result = this->prepareToDecode(dstInfo, opts, inputColorPtr, inputColorCount);
if (kSuccess != result) {
return result;
}
// Perform the decode
int rows = this->decodeRows(dstInfo, dst, dstRowBytes, opts);
if (rows != dstInfo.height()) {
// We set rowsDecoded equal to the height because the background has already
// been filled. RLE encodings sometimes skip pixels, so we always start by
// filling the background.
*rowsDecoded = dstInfo.height();
return kIncompleteInput;
}
return kSuccess;
}
/*
* Process the color table for the bmp input
*/
bool SkBmpRLECodec::createColorTable(SkColorType dstColorType, 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;
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;
}
// Fill in the color table
PackColorProc packARGB = choose_pack_color_proc(false, dstColorType);
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);
colorTable[i] = packARGB(0xFF, 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));
}
// 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;
}
bool SkBmpRLECodec::initializeStreamBuffer() {
fBytesBuffered = this->stream()->read(fStreamBuffer, kBufferSize);
if (fBytesBuffered == 0) {
SkCodecPrintf("Error: could not read RLE image data.\n");
return false;
}
fCurrRLEByte = 0;
return true;
}
/*
* @return the number of bytes remaining in the stream buffer after
* attempting to read more bytes from the stream
*/
size_t SkBmpRLECodec::checkForMoreData() {
const size_t remainingBytes = fBytesBuffered - fCurrRLEByte;
uint8_t* buffer = fStreamBuffer;
// We will be reusing the same buffer, starting over from the beginning.
// Move any remaining bytes to the start of the buffer.
// We use memmove() instead of memcpy() because there is risk that the dst
// and src memory will overlap in corrupt images.
memmove(buffer, SkTAddOffset<uint8_t>(buffer, fCurrRLEByte), remainingBytes);
// Adjust the buffer ptr to the start of the unfilled data.
buffer += remainingBytes;
// Try to read additional bytes from the stream. There are fCurrRLEByte
// bytes of additional space remaining in the buffer, assuming that we
// have already copied remainingBytes to the start of the buffer.
size_t additionalBytes = this->stream()->read(buffer, fCurrRLEByte);
// Update counters and return the number of bytes we currently have
// available. We are at the start of the buffer again.
fCurrRLEByte = 0;
fBytesBuffered = remainingBytes + additionalBytes;
return fBytesBuffered;
}
/*
* Set an RLE pixel using the color table
*/
void SkBmpRLECodec::setPixel(void* dst, size_t dstRowBytes,
const SkImageInfo& dstInfo, uint32_t x, uint32_t y,
uint8_t index) {
if (dst && is_coord_necessary(x, fSampleX, dstInfo.width())) {
// Set the row
uint32_t row = this->getDstRow(y, dstInfo.height());
// Set the pixel based on destination color type
const int dstX = get_dst_coord(x, fSampleX);
switch (dstInfo.colorType()) {
case kRGBA_8888_SkColorType:
case kBGRA_8888_SkColorType: {
SkPMColor* dstRow = SkTAddOffset<SkPMColor>(dst, row * (int) dstRowBytes);
dstRow[dstX] = fColorTable->operator[](index);
break;
}
case kRGB_565_SkColorType: {
uint16_t* dstRow = SkTAddOffset<uint16_t>(dst, row * (int) dstRowBytes);
dstRow[dstX] = SkPixel32ToPixel16(fColorTable->operator[](index));
break;
}
default:
// This case should not be reached. We should catch an invalid
// color type when we check that the conversion is possible.
SkASSERT(false);
break;
}
}
}
/*
* Set an RLE pixel from R, G, B values
*/
void SkBmpRLECodec::setRGBPixel(void* dst, size_t dstRowBytes,
const SkImageInfo& dstInfo, uint32_t x,
uint32_t y, uint8_t red, uint8_t green,
uint8_t blue) {
if (dst && is_coord_necessary(x, fSampleX, dstInfo.width())) {
// Set the row
uint32_t row = this->getDstRow(y, dstInfo.height());
// Set the pixel based on destination color type
const int dstX = get_dst_coord(x, fSampleX);
switch (dstInfo.colorType()) {
case kRGBA_8888_SkColorType: {
SkPMColor* dstRow = SkTAddOffset<SkPMColor>(dst, row * (int) dstRowBytes);
dstRow[dstX] = SkPackARGB_as_RGBA(0xFF, red, green, blue);
break;
}
case kBGRA_8888_SkColorType: {
SkPMColor* dstRow = SkTAddOffset<SkPMColor>(dst, row * (int) dstRowBytes);
dstRow[dstX] = SkPackARGB_as_BGRA(0xFF, red, green, blue);
break;
}
case kRGB_565_SkColorType: {
uint16_t* dstRow = SkTAddOffset<uint16_t>(dst, row * (int) dstRowBytes);
dstRow[dstX] = SkPack888ToRGB16(red, green, blue);
break;
}
default:
// This case should not be reached. We should catch an invalid
// color type when we check that the conversion is possible.
SkASSERT(false);
break;
}
}
}
SkCodec::Result SkBmpRLECodec::onPrepareToDecode(const SkImageInfo& dstInfo,
const SkCodec::Options& options, SkPMColor inputColorPtr[], int* inputColorCount) {
// FIXME: Support subsets for scanline decodes.
if (options.fSubset) {
// Subsets are not supported.
return kUnimplemented;
}
// Reset fSampleX. If it needs to be a value other than 1, it will get modified by
// the sampler.
fSampleX = 1;
fLinesToSkip = 0;
SkColorType colorTableColorType = dstInfo.colorType();
if (this->colorXform()) {
// Just set a known colorType for the colorTable. No need to actually transform
// the colors in the colorTable since we do not allow decoding RLE to kIndex8.
colorTableColorType = kBGRA_8888_SkColorType;
}
// 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(colorTableColorType, 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, fColorTable.get(), inputColorPtr, inputColorCount);
// Initialize a buffer for encoded RLE data
if (!this->initializeStreamBuffer()) {
SkCodecPrintf("Error: cannot initialize stream buffer.\n");
return SkCodec::kInvalidInput;
}
return SkCodec::kSuccess;
}
/*
* Performs the bitmap decoding for RLE input format
* RLE decoding is performed all at once, rather than a one row at a time
*/
int SkBmpRLECodec::decodeRows(const SkImageInfo& info, void* dst, size_t dstRowBytes,
const Options& opts) {
const int width = this->getInfo().width();
int height = info.height();
// Account for sampling.
SkImageInfo dstInfo = info.makeWH(get_scaled_dimension(width, fSampleX), height);
// Set the background as transparent. Then, if the RLE code skips pixels,
// the skipped pixels will be transparent.
if (dst) {
SkSampler::Fill(dstInfo, dst, dstRowBytes, SK_ColorTRANSPARENT, opts.fZeroInitialized);
}
// Adjust the height and the dst if the previous call to decodeRows() left us
// with lines that need to be skipped.
if (height > fLinesToSkip) {
height -= fLinesToSkip;
if (dst) {
dst = SkTAddOffset<void>(dst, fLinesToSkip * dstRowBytes);
}
fLinesToSkip = 0;
dstInfo = dstInfo.makeWH(dstInfo.width(), height);
} else {
fLinesToSkip -= height;
return height;
}
void* decodeDst = dst;
size_t decodeRowBytes = dstRowBytes;
SkImageInfo decodeInfo = dstInfo;
if (decodeDst) {
if (this->colorXform()) {
decodeInfo = decodeInfo.makeColorType(kXformSrcColorType);
if (kRGBA_F16_SkColorType == dstInfo.colorType()) {
int count = height * dstInfo.width();
this->resetXformBuffer(count);
sk_bzero(this->xformBuffer(), count * sizeof(uint32_t));
decodeDst = this->xformBuffer();
decodeRowBytes = dstInfo.width() * sizeof(uint32_t);
}
}
}
int decodedHeight = this->decodeRLE(decodeInfo, decodeDst, decodeRowBytes);
if (this->colorXform() && decodeDst) {
for (int y = 0; y < decodedHeight; y++) {
this->applyColorXform(dstInfo, dst, decodeDst);
decodeDst = SkTAddOffset<void>(decodeDst, decodeRowBytes);
dst = SkTAddOffset<void>(dst, dstRowBytes);
}
}
return decodedHeight;
}
int SkBmpRLECodec::decodeRLE(const SkImageInfo& dstInfo, void* dst, size_t dstRowBytes) {
// Use the original width to count the number of pixels in each row.
const int width = this->getInfo().width();
// This tells us the number of rows that we are meant to decode.
const int height = dstInfo.height();
// Set RLE flags
static const uint8_t RLE_ESCAPE = 0;
static const uint8_t RLE_EOL = 0;
static const uint8_t RLE_EOF = 1;
static const uint8_t RLE_DELTA = 2;
// Destination parameters
int x = 0;
int y = 0;
while (true) {
// If we have reached a row that is beyond the requested height, we have
// succeeded.
if (y >= height) {
// It would be better to check for the EOF marker before indicating
// success, but we may be performing a scanline decode, which
// would require us to stop before decoding the full height.
return height;
}
// Every entry takes at least two bytes
if ((int) fBytesBuffered - fCurrRLEByte < 2) {
if (this->checkForMoreData() < 2) {
return y;
}
}
// Read the next two bytes. These bytes have different meanings
// depending on their values. In the first interpretation, the first
// byte is an escape flag and the second byte indicates what special
// task to perform.
const uint8_t flag = fStreamBuffer[fCurrRLEByte++];
const uint8_t task = fStreamBuffer[fCurrRLEByte++];
// Perform decoding
if (RLE_ESCAPE == flag) {
switch (task) {
case RLE_EOL:
x = 0;
y++;
break;
case RLE_EOF:
return height;
case RLE_DELTA: {
// Two bytes are needed to specify delta
if ((int) fBytesBuffered - fCurrRLEByte < 2) {
if (this->checkForMoreData() < 2) {
return y;
}
}
// Modify x and y
const uint8_t dx = fStreamBuffer[fCurrRLEByte++];
const uint8_t dy = fStreamBuffer[fCurrRLEByte++];
x += dx;
y += dy;
if (x > width) {
SkCodecPrintf("Warning: invalid RLE input.\n");
return y - dy;
} else if (y > height) {
fLinesToSkip = y - height;
return height;
}
break;
}
default: {
// If task does not match any of the above signals, it
// indicates that we have a sequence of non-RLE pixels.
// Furthermore, the value of task is equal to the number
// of pixels to interpret.
uint8_t numPixels = task;
const size_t rowBytes = compute_row_bytes(numPixels,
this->bitsPerPixel());
// Abort if setting numPixels moves us off the edge of the
// image.
if (x + numPixels > width) {
SkCodecPrintf("Warning: invalid RLE input.\n");
return y;
}
// Also abort if there are not enough bytes
// remaining in the stream to set numPixels.
// At most, alignedRowBytes can be 255 (max uint8_t) *
// 3 (max bytes per pixel) + 1 (aligned) = 766. If
// fStreamBuffer was smaller than this,
// checkForMoreData would never succeed for some bmps.
static_assert(255 * 3 + 1 < kBufferSize,
"kBufferSize needs to be larger!");
const size_t alignedRowBytes = SkAlign2(rowBytes);
if ((int) fBytesBuffered - fCurrRLEByte < alignedRowBytes) {
SkASSERT(alignedRowBytes < kBufferSize);
if (this->checkForMoreData() < alignedRowBytes) {
return y;
}
}
// Set numPixels number of pixels
while (numPixels > 0) {
switch(this->bitsPerPixel()) {
case 4: {
SkASSERT(fCurrRLEByte < fBytesBuffered);
uint8_t val = fStreamBuffer[fCurrRLEByte++];
setPixel(dst, dstRowBytes, dstInfo, x++,
y, val >> 4);
numPixels--;
if (numPixels != 0) {
setPixel(dst, dstRowBytes, dstInfo,
x++, y, val & 0xF);
numPixels--;
}
break;
}
case 8:
SkASSERT(fCurrRLEByte < fBytesBuffered);
setPixel(dst, dstRowBytes, dstInfo, x++,
y, fStreamBuffer[fCurrRLEByte++]);
numPixels--;
break;
case 24: {
SkASSERT(fCurrRLEByte + 2 < fBytesBuffered);
uint8_t blue = fStreamBuffer[fCurrRLEByte++];
uint8_t green = fStreamBuffer[fCurrRLEByte++];
uint8_t red = fStreamBuffer[fCurrRLEByte++];
setRGBPixel(dst, dstRowBytes, dstInfo,
x++, y, red, green, blue);
numPixels--;
break;
}
default:
SkASSERT(false);
return y;
}
}
// Skip a byte if necessary to maintain alignment
if (!SkIsAlign2(rowBytes)) {
fCurrRLEByte++;
}
break;
}
}
} else {
// If the first byte read is not a flag, it indicates the number of
// pixels to set in RLE mode.
const uint8_t numPixels = flag;
const int endX = SkTMin<int>(x + numPixels, width);
if (24 == this->bitsPerPixel()) {
// In RLE24, the second byte read is part of the pixel color.
// There are two more required bytes to finish encoding the
// color.
if ((int) fBytesBuffered - fCurrRLEByte < 2) {
if (this->checkForMoreData() < 2) {
return y;
}
}
// Fill the pixels up to endX with the specified color
uint8_t blue = task;
uint8_t green = fStreamBuffer[fCurrRLEByte++];
uint8_t red = fStreamBuffer[fCurrRLEByte++];
while (x < endX) {
setRGBPixel(dst, dstRowBytes, dstInfo, x++, y, red, green, blue);
}
} else {
// In RLE8 or RLE4, the second byte read gives the index in the
// color table to look up the pixel color.
// RLE8 has one color index that gets repeated
// RLE4 has two color indexes in the upper and lower 4 bits of
// the bytes, which are alternated
uint8_t indices[2] = { task, task };
if (4 == this->bitsPerPixel()) {
indices[0] >>= 4;
indices[1] &= 0xf;
}
// Set the indicated number of pixels
for (int which = 0; x < endX; x++) {
setPixel(dst, dstRowBytes, dstInfo, x, y, indices[which]);
which = !which;
}
}
}
}
}
bool SkBmpRLECodec::skipRows(int count) {
const SkImageInfo rowInfo = SkImageInfo::Make(this->getInfo().width(), count, kN32_SkColorType,
kUnpremul_SkAlphaType);
return count == this->decodeRows(rowInfo, nullptr, 0, this->options());
}
// FIXME: Make SkBmpRLECodec have no knowledge of sampling.
// Or it should do all sampling natively.
// It currently is a hybrid that needs to know what SkScaledCodec is doing.
class SkBmpRLESampler : public SkSampler {
public:
SkBmpRLESampler(SkBmpRLECodec* codec)
: fCodec(codec)
{
SkASSERT(fCodec);
}
private:
int onSetSampleX(int sampleX) override {
return fCodec->setSampleX(sampleX);
}
// Unowned pointer. fCodec will delete this class in its destructor.
SkBmpRLECodec* fCodec;
};
SkSampler* SkBmpRLECodec::getSampler(bool /*createIfNecessary*/) {
// We will always create an SkBmpRLESampler if one is requested.
// This allows clients to always use the SkBmpRLESampler's
// version of fill(), which does nothing since RLE decodes have
// already filled pixel memory. This seems fine, since creating
// an SkBmpRLESampler is pretty inexpensive.
if (!fSampler) {
fSampler.reset(new SkBmpRLESampler(this));
}
return fSampler.get();
}
int SkBmpRLECodec::setSampleX(int sampleX){
fSampleX = sampleX;
return get_scaled_dimension(this->getInfo().width(), sampleX);
}