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- /*
- * 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 "include/core/SkStream.h"
- #include "include/private/SkColorData.h"
- #include "src/codec/SkBmpRLECodec.h"
- #include "src/codec/SkCodecPriv.h"
- /*
- * Creates an instance of the decoder
- * Called only by NewFromStream
- */
- SkBmpRLECodec::SkBmpRLECodec(SkEncodedInfo&& info,
- std::unique_ptr<SkStream> stream,
- uint16_t bitsPerPixel, uint32_t numColors,
- uint32_t bytesPerColor, uint32_t offset,
- SkCodec::SkScanlineOrder rowOrder)
- : INHERITED(std::move(info), std::move(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,
- int* rowsDecoded) {
- if (opts.fSubset) {
- // Subsets are not supported.
- return kUnimplemented;
- }
- Result result = this->prepareToDecode(dstInfo, opts);
- 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) {
- // 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;
- }
- // 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) {
- // 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.
- 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)) {
- SkCodecPrintf("Error: could not create color table.\n");
- return SkCodec::kInvalidInput;
- }
- // 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) {
- int height = info.height();
- // Account for sampling.
- SkImageInfo dstInfo = info.makeWH(this->fillWidth(), 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, 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(dst, decodeDst, dstInfo.width());
- 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->dimensions().width();
- // This tells us the number of rows that we are meant to decode.
- const int height = dstInfo.height();
- // Set RLE flags
- constexpr uint8_t RLE_ESCAPE = 0;
- constexpr uint8_t RLE_EOL = 0;
- constexpr uint8_t RLE_EOF = 1;
- constexpr 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->dimensions().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);
- }
- int fillWidth() const override {
- return fCodec->fillWidth();
- }
- 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) {
- if (!fSampler && createIfNecessary) {
- fSampler.reset(new SkBmpRLESampler(this));
- }
- return fSampler.get();
- }
- int SkBmpRLECodec::setSampleX(int sampleX) {
- fSampleX = sampleX;
- return this->fillWidth();
- }
- int SkBmpRLECodec::fillWidth() const {
- return get_scaled_dimension(this->dimensions().width(), fSampleX);
- }
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