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Unified Diff: src/codec/SkBmpStandardCodec.cpp

Issue 1472933002: Make SkAndroidCodec support ico (Closed) Base URL: https://skia.googlesource.com/skia.git@master
Patch Set: Response to comments Created 5 years ago
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Index: src/codec/SkBmpStandardCodec.cpp
diff --git a/src/codec/SkBmpStandardCodec.cpp b/src/codec/SkBmpStandardCodec.cpp
index fd4d6d18bc2d3df2ea6366554dc3bf56ec72700e..5bbdcd25e255cc3c237ea598a2789d2a71bc9f3f 100644
--- a/src/codec/SkBmpStandardCodec.cpp
+++ b/src/codec/SkBmpStandardCodec.cpp
@@ -27,6 +27,7 @@ SkBmpStandardCodec::SkBmpStandardCodec(const SkImageInfo& info, SkStream* stream
, fSrcRowBytes(SkAlign4(compute_row_bytes(this->getInfo().width(), this->bitsPerPixel())))
, fSrcBuffer(new uint8_t [fSrcRowBytes])
, fInIco(inIco)
+ , fAndMaskRowBytes(fInIco ? SkAlign4(compute_row_bytes(this->getInfo().width(), 1)) : 0)
{}
/*
@@ -60,9 +61,6 @@ SkCodec::Result SkBmpStandardCodec::onGetPixels(const SkImageInfo& dstInfo,
*rowsDecoded = rows;
return kIncompleteInput;
}
- if (fInIco) {
- return this->decodeIcoMask(dstInfo, dst, dstRowBytes);
- }
return kSuccess;
}
@@ -227,9 +225,8 @@ SkCodec::Result SkBmpStandardCodec::prepareToDecode(const SkImageInfo& dstInfo,
/*
* Performs the bitmap decoding for standard input format
*/
-int SkBmpStandardCodec::decodeRows(const SkImageInfo& dstInfo,
- void* dst, size_t dstRowBytes,
- const Options& opts) {
+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++) {
@@ -246,29 +243,77 @@ int SkBmpStandardCodec::decodeRows(const SkImageInfo& dstInfo,
fSwizzler->swizzle(dstRow, fSrcBuffer.get());
}
- // Finished decoding the entire image
+ 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 * fSrcRowBytes +
+ 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;
}
-// TODO (msarett): This function will need to be modified in order to perform row by row decodes
-// when the Ico scanline decoder is implemented.
-SkCodec::Result SkBmpStandardCodec::decodeIcoMask(const SkImageInfo& dstInfo,
+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);
- // The AND mask is always 1 bit per pixel
- const int width = this->getInfo().width();
- const size_t rowBytes = SkAlign4(compute_row_bytes(width, 1));
+ // 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(), rowBytes) != rowBytes) {
+ if (stream->read(fSrcBuffer.get(), fAndMaskRowBytes) != fAndMaskRowBytes) {
SkCodecPrintf("Warning: incomplete AND mask for bmp-in-ico.\n");
- return kIncompleteInput;
+ return;
}
int row = this->getDstRow(y, dstInfo.height());
@@ -276,17 +321,17 @@ SkCodec::Result SkBmpStandardCodec::decodeIcoMask(const SkImageInfo& dstInfo,
SkPMColor* dstRow =
SkTAddOffset<SkPMColor>(dstPtr, row * dstRowBytes);
- for (int x = 0; x < width; x++) {
+ int srcX = srcStartX;
+ for (int dstX = 0; dstX < sampledWidth; dstX++) {
int quotient;
int modulus;
- SkTDivMod(x, 8, &quotient, &modulus);
+ SkTDivMod(srcX, 8, &quotient, &modulus);
uint32_t shift = 7 - modulus;
- uint32_t alphaBit =
- (fSrcBuffer.get()[quotient] >> shift) & 0x1;
- dstRow[x] &= alphaBit - 1;
+ uint32_t alphaBit = (fSrcBuffer.get()[quotient] >> shift) & 0x1;
+ dstRow[dstX] &= alphaBit - 1;
+ srcX += sampleX;
}
}
- return kSuccess;
}
uint32_t SkBmpStandardCodec::onGetFillValue(SkColorType colorType, SkAlphaType alphaType) const {
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