| /* |
| * 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 "SkScanlineDecoder.h" |
| #include "SkStream.h" |
| |
| /* |
| * Checks if the conversion between the input image and the requested output |
| * image has been implemented |
| */ |
| static bool conversion_possible(const SkImageInfo& dst, |
| const SkImageInfo& src) { |
| // Ensure that the profile type is unchanged |
| if (dst.profileType() != src.profileType()) { |
| return false; |
| } |
| |
| // Ensure the alpha type is valid |
| if (!valid_alpha(dst.alphaType(), src.alphaType())) { |
| return false; |
| } |
| |
| // Check for supported color types |
| switch (dst.colorType()) { |
| // Allow output to kN32 from any type of input |
| case kN32_SkColorType: |
| return true; |
| // Allow output to kIndex_8 from compatible inputs |
| case kIndex_8_SkColorType: |
| return kIndex_8_SkColorType == src.colorType(); |
| default: |
| return false; |
| } |
| } |
| |
| /* |
| * Creates an instance of the decoder |
| * Called only by NewFromStream |
| */ |
| SkBmpRLECodec::SkBmpRLECodec(const SkImageInfo& info, SkStream* stream, |
| uint16_t bitsPerPixel, uint32_t numColors, |
| uint32_t bytesPerColor, uint32_t offset, |
| SkBmpCodec::RowOrder rowOrder, size_t RLEBytes) |
| : INHERITED(info, stream, bitsPerPixel, rowOrder) |
| , fColorTable(NULL) |
| , fNumColors(this->computeNumColors(numColors)) |
| , fBytesPerColor(bytesPerColor) |
| , fOffset(offset) |
| , fStreamBuffer(SkNEW_ARRAY(uint8_t, RLEBytes)) |
| , fRLEBytes(RLEBytes) |
| , fCurrRLEByte(0) |
| {} |
| |
| /* |
| * Initiates the bitmap decode |
| */ |
| SkCodec::Result SkBmpRLECodec::onGetPixels(const SkImageInfo& dstInfo, |
| void* dst, size_t dstRowBytes, |
| const Options& opts, |
| SkPMColor* inputColorPtr, |
| int* inputColorCount) { |
| if (!this->rewindIfNeeded()) { |
| return kCouldNotRewind; |
| } |
| 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; |
| } |
| |
| // 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(inputColorCount)) { |
| SkCodecPrintf("Error: could not create color table.\n"); |
| return kInvalidInput; |
| } |
| |
| // Copy the color table to the client if necessary |
| copy_color_table(dstInfo, fColorTable, inputColorPtr, inputColorCount); |
| |
| // Initialize a swizzler if necessary |
| if (!this->initializeStreamBuffer()) { |
| SkCodecPrintf("Error: cannot initialize swizzler.\n"); |
| return kInvalidConversion; |
| } |
| |
| // Perform the decode |
| return decode(dstInfo, dst, dstRowBytes, opts); |
| } |
| |
| /* |
| * Process the color table for the bmp input |
| */ |
| bool SkBmpRLECodec::createColorTable(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 (NULL != 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; |
| } |
| |
| // Read the color table from the stream |
| colorBytes = fNumColors * fBytesPerColor; |
| SkAutoTDeleteArray<uint8_t> cBuffer(SkNEW_ARRAY(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 |
| uint32_t i = 0; |
| for (; i < fNumColors; 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] = SkPackARGB32NoCheck(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(SkNEW_ARGS(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() { |
| // Setup a buffer to contain the full input stream |
| size_t totalBytes = this->stream()->read(fStreamBuffer.get(), fRLEBytes); |
| if (totalBytes < fRLEBytes) { |
| fRLEBytes = totalBytes; |
| SkCodecPrintf("Warning: incomplete RLE file.\n"); |
| } |
| if (fRLEBytes == 0) { |
| SkCodecPrintf("Error: could not read RLE image data.\n"); |
| return false; |
| } |
| return true; |
| } |
| |
| /* |
| * 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) { |
| // Set the row |
| int height = dstInfo.height(); |
| int row; |
| if (SkBmpCodec::kBottomUp_RowOrder == this->rowOrder()) { |
| row = height - y - 1; |
| } else { |
| row = y; |
| } |
| |
| // Set the pixel based on destination color type |
| switch (dstInfo.colorType()) { |
| case kN32_SkColorType: { |
| SkPMColor* dstRow = SkTAddOffset<SkPMColor>((SkPMColor*) dst, |
| row * (int) dstRowBytes); |
| dstRow[x] = 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) { |
| // Set the row |
| int height = dstInfo.height(); |
| int row; |
| if (SkBmpCodec::kBottomUp_RowOrder == this->rowOrder()) { |
| row = height - y - 1; |
| } else { |
| row = y; |
| } |
| |
| // Set the pixel based on destination color type |
| switch (dstInfo.colorType()) { |
| case kN32_SkColorType: { |
| SkPMColor* dstRow = SkTAddOffset<SkPMColor>((SkPMColor*) dst, |
| row * (int) dstRowBytes); |
| dstRow[x] = SkPackARGB32NoCheck(0xFF, 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; |
| } |
| } |
| |
| /* |
| * Performs the bitmap decoding for RLE input format |
| * RLE decoding is performed all at once, rather than a one row at a time |
| */ |
| SkCodec::Result SkBmpRLECodec::decode(const SkImageInfo& dstInfo, |
| void* dst, size_t dstRowBytes, |
| const Options& opts) { |
| // 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; |
| |
| // Set constant values |
| const int width = dstInfo.width(); |
| const int height = dstInfo.height(); |
| |
| // Destination parameters |
| int x = 0; |
| int y = 0; |
| |
| // Set the background as transparent. Then, if the RLE code skips pixels, |
| // the skipped pixels will be transparent. |
| // Because of the need for transparent pixels, kN32 is the only color |
| // type that makes sense for the destination format. |
| SkASSERT(kN32_SkColorType == dstInfo.colorType()); |
| if (kNo_ZeroInitialized == opts.fZeroInitialized) { |
| SkSwizzler::Fill(dst, dstInfo, dstRowBytes, height, SK_ColorTRANSPARENT, NULL); |
| } |
| |
| 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 returning |
| // success, but we may be performing a scanline decode, which |
| // may require us to stop before decoding the full height. |
| return kSuccess; |
| } |
| |
| // Every entry takes at least two bytes |
| if ((int) fRLEBytes - fCurrRLEByte < 2) { |
| SkCodecPrintf("Warning: incomplete RLE input.\n"); |
| return kIncompleteInput; |
| } |
| |
| // 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.get()[fCurrRLEByte++]; |
| const uint8_t task = fStreamBuffer.get()[fCurrRLEByte++]; |
| |
| // Perform decoding |
| if (RLE_ESCAPE == flag) { |
| switch (task) { |
| case RLE_EOL: |
| x = 0; |
| y++; |
| break; |
| case RLE_EOF: |
| return kSuccess; |
| case RLE_DELTA: { |
| // Two bytes are needed to specify delta |
| if ((int) fRLEBytes - fCurrRLEByte < 2) { |
| SkCodecPrintf("Warning: incomplete RLE input\n"); |
| return kIncompleteInput; |
| } |
| // Modify x and y |
| const uint8_t dx = fStreamBuffer.get()[fCurrRLEByte++]; |
| const uint8_t dy = fStreamBuffer.get()[fCurrRLEByte++]; |
| x += dx; |
| y += dy; |
| if (x > width || y > height) { |
| SkCodecPrintf("Warning: invalid RLE input 1.\n"); |
| return kIncompleteInput; |
| } |
| 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. Also abort if there are not enough bytes |
| // remaining in the stream to set numPixels. |
| if (x + numPixels > width || |
| (int) fRLEBytes - fCurrRLEByte < SkAlign2(rowBytes)) { |
| SkCodecPrintf("Warning: invalid RLE input 2.\n"); |
| return kIncompleteInput; |
| } |
| // Set numPixels number of pixels |
| while (numPixels > 0) { |
| switch(this->bitsPerPixel()) { |
| case 4: { |
| SkASSERT(fCurrRLEByte < fRLEBytes); |
| uint8_t val = fStreamBuffer.get()[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 < fRLEBytes); |
| setPixel(dst, dstRowBytes, dstInfo, x++, |
| y, fStreamBuffer.get()[fCurrRLEByte++]); |
| numPixels--; |
| break; |
| case 24: { |
| SkASSERT(fCurrRLEByte + 2 < fRLEBytes); |
| uint8_t blue = fStreamBuffer.get()[fCurrRLEByte++]; |
| uint8_t green = fStreamBuffer.get()[fCurrRLEByte++]; |
| uint8_t red = fStreamBuffer.get()[fCurrRLEByte++]; |
| setRGBPixel(dst, dstRowBytes, dstInfo, |
| x++, y, red, green, blue); |
| numPixels--; |
| } |
| default: |
| SkASSERT(false); |
| return kInvalidInput; |
| } |
| } |
| // 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) fRLEBytes - fCurrRLEByte < 2) { |
| SkCodecPrintf("Warning: incomplete RLE input\n"); |
| return kIncompleteInput; |
| } |
| |
| // Fill the pixels up to endX with the specified color |
| uint8_t blue = task; |
| uint8_t green = fStreamBuffer.get()[fCurrRLEByte++]; |
| uint8_t red = fStreamBuffer.get()[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; |
| } |
| } |
| } |
| } |
| } |