// check if scaling to dstInfo size from srcInfo size using sampleSize is possible
static bool scaling_supported(const SkImageInfo& dstInfo, const SkImageInfo& srcInfo,
int* sampleX, int* sampleY) {
SkScaledCodec::ComputeSampleSize(dstInfo, srcInfo, sampleX, sampleY);
const int dstWidth = dstInfo.width();
const int dstHeight = dstInfo.height();
const int srcWidth = srcInfo.width();
const int srcHeight = srcInfo.height();
// only support down sampling, not up sampling
if (dstWidth > srcWidth || dstHeight > srcHeight) {
return false;
}
// check that srcWidth is scaled down by an integer value
if (get_scaled_dimension(srcWidth, *sampleX) != dstWidth) {
return false;
}
// check that src height is scaled down by an integer value
if (get_scaled_dimension(srcHeight, *sampleY) != dstHeight) {
return false;
}
// sampleX and sampleY should be equal unless the original sampleSize requested was larger
// than srcWidth or srcHeight. If so, the result of this is dstWidth or dstHeight = 1.
// This functionality allows for tall thin images to still be scaled down by scaling factors.
if (*sampleX != *sampleY){
if (1 != dstWidth && 1 != dstHeight) {
return false;
}
}
return true;
}
// calculates sampleSize in x and y direction
void SkScaledCodec::ComputeSampleSize(const SkImageInfo& dstInfo, const SkImageInfo& srcInfo,
int* sampleXPtr, int* sampleYPtr) {
int srcWidth = srcInfo.width();
int dstWidth = dstInfo.width();
int srcHeight = srcInfo.height();
int dstHeight = dstInfo.height();
int sampleX = srcWidth / dstWidth;
int sampleY = srcHeight / dstHeight;
// only support down sampling, not up sampling
SkASSERT(dstWidth <= srcWidth);
SkASSERT(dstHeight <= srcHeight);
// sampleX and sampleY should be equal unless the original sampleSize requested was
// larger than srcWidth or srcHeight.
// If so, the result of this is dstWidth or dstHeight = 1. This functionality
// allows for tall thin images to still be scaled down by scaling factors.
if (sampleX != sampleY){
if (1 != dstWidth && 1 != dstHeight) {
// rounding during onGetScaledDimensions can cause different sampleSizes
// Ex: srcWidth = 79, srcHeight = 20, sampleSize = 10
// dstWidth = 7, dstHeight = 2, sampleX = 79/7 = 11, sampleY = 20/2 = 10
// correct for this rounding by comparing width to sampleY and height to sampleX
if (get_scaled_dimension(srcWidth, sampleY) == dstWidth) {
sampleX = sampleY;
} else if (get_scaled_dimension(srcHeight, sampleX) == dstHeight) {
sampleY = sampleX;
}
}
}
if (sampleXPtr) {
*sampleXPtr = sampleX;
}
if (sampleYPtr) {
*sampleYPtr = sampleY;
}
}
/*
* Return a valid set of output dimensions for this decoder, given an input scale
*/
SkISize SkScaledCodec::onGetScaledDimensions(float desiredScale) const {
SkISize nativeDimensions = fScanlineDecoder->getScaledDimensions(desiredScale);
// support scaling down by integer numbers. Ex: 1/2, 1/3, 1/4 ...
SkISize scaledCodecDimensions;
if (desiredScale > 0.5f) {
// sampleSize = 1
scaledCodecDimensions = fScanlineDecoder->getInfo().dimensions();
}
// sampleSize determines the step size between samples
// Ex: sampleSize = 2, sample every second pixel in x and y directions
int sampleSize = int(1 / desiredScale);
int scaledWidth = get_scaled_dimension(this->getInfo().width(), sampleSize);
int scaledHeight = get_scaled_dimension(this->getInfo().height(), sampleSize);
// Return the calculated output dimensions for the given scale
scaledCodecDimensions = SkISize::Make(scaledWidth, scaledHeight);
return best_scaled_dimensions(this->getInfo().dimensions(), nativeDimensions,
scaledCodecDimensions, desiredScale);
}
SkISize SkAndroidCodec::getSampledSubsetDimensions(int sampleSize, const SkIRect& subset) const {
if (!is_valid_sample_size(sampleSize)) {
return SkISize::Make(0, 0);
}
// We require that the input subset is a subset that is supported by SkAndroidCodec.
// We test this by calling getSupportedSubset() and verifying that no modifications
// are made to the subset.
SkIRect copySubset = subset;
if (!this->getSupportedSubset(©Subset) || copySubset != subset) {
return SkISize::Make(0, 0);
}
// If the subset is the entire image, for consistency, use getSampledDimensions().
if (fInfo.dimensions() == subset.size()) {
return this->getSampledDimensions(sampleSize);
}
// This should perhaps call a virtual function, but currently both of our subclasses
// want the same implementation.
return SkISize::Make(get_scaled_dimension(subset.width(), sampleSize),
get_scaled_dimension(subset.height(), sampleSize));
}
SkISize SkSampledCodec::onGetSampledDimensions(int sampleSize) const {
const SkISize size = this->accountForNativeScaling(&sampleSize);
return SkISize::Make(get_scaled_dimension(size.width(), sampleSize),
get_scaled_dimension(size.height(), sampleSize));
}
SkCodec::Result SkSampledCodec::sampledDecode(const SkImageInfo& info, void* pixels,
size_t rowBytes, const AndroidOptions& options) {
// We should only call this function when sampling.
SkASSERT(options.fSampleSize > 1);
// Create options struct for the codec.
SkCodec::Options sampledOptions;
sampledOptions.fZeroInitialized = options.fZeroInitialized;
sampledOptions.fPremulBehavior = SkTransferFunctionBehavior::kIgnore;
// FIXME: This was already called by onGetAndroidPixels. Can we reduce that?
int sampleSize = options.fSampleSize;
int nativeSampleSize;
SkISize nativeSize = this->accountForNativeScaling(&sampleSize, &nativeSampleSize);
// Check if there is a subset.
SkIRect subset;
int subsetY = 0;
int subsetWidth = nativeSize.width();
int subsetHeight = nativeSize.height();
if (options.fSubset) {
// We will need to know about subsetting in the y-dimension in order to use the
// scanline decoder.
// Update the subset to account for scaling done by this->codec().
const SkIRect* subsetPtr = options.fSubset;
// Do the divide ourselves, instead of calling get_scaled_dimension. If
// X and Y are 0, they should remain 0, rather than being upgraded to 1
// due to being smaller than the sampleSize.
const int subsetX = subsetPtr->x() / nativeSampleSize;
subsetY = subsetPtr->y() / nativeSampleSize;
subsetWidth = get_scaled_dimension(subsetPtr->width(), nativeSampleSize);
subsetHeight = get_scaled_dimension(subsetPtr->height(), nativeSampleSize);
// The scanline decoder only needs to be aware of subsetting in the x-dimension.
subset.setXYWH(subsetX, 0, subsetWidth, nativeSize.height());
sampledOptions.fSubset = ⊂
}
// Since we guarantee that output dimensions are always at least one (even if the sampleSize
// is greater than a given dimension), the input sampleSize is not always the sampleSize that
// we use in practice.
const int sampleX = subsetWidth / info.width();
const int sampleY = subsetHeight / info.height();
const int samplingOffsetY = get_start_coord(sampleY);
const int startY = samplingOffsetY + subsetY;
const int dstHeight = info.height();
const SkImageInfo nativeInfo = info.makeWH(nativeSize.width(), nativeSize.height());
{
// Although startScanlineDecode expects the bottom and top to match the
// SkImageInfo, startIncrementalDecode uses them to determine which rows to
// decode.
SkCodec::Options incrementalOptions = sampledOptions;
SkIRect incrementalSubset;
if (sampledOptions.fSubset) {
incrementalSubset.fTop = subsetY;
incrementalSubset.fBottom = subsetY + subsetHeight;
incrementalSubset.fLeft = sampledOptions.fSubset->fLeft;
incrementalSubset.fRight = sampledOptions.fSubset->fRight;
incrementalOptions.fSubset = &incrementalSubset;
}
const SkCodec::Result startResult = this->codec()->startIncrementalDecode(nativeInfo,
pixels, rowBytes, &incrementalOptions);
if (SkCodec::kSuccess == startResult) {
SkSampler* sampler = this->codec()->getSampler(true);
if (!sampler) {
return SkCodec::kUnimplemented;
}
if (sampler->setSampleX(sampleX) != info.width()) {
return SkCodec::kInvalidScale;
}
if (get_scaled_dimension(subsetHeight, sampleY) != info.height()) {
return SkCodec::kInvalidScale;
}
sampler->setSampleY(sampleY);
int rowsDecoded;
const SkCodec::Result incResult = this->codec()->incrementalDecode(&rowsDecoded);
if (incResult == SkCodec::kSuccess) {
return SkCodec::kSuccess;
}
SkASSERT(incResult == SkCodec::kIncompleteInput || incResult == SkCodec::kErrorInInput);
SkASSERT(rowsDecoded <= info.height());
this->codec()->fillIncompleteImage(info, pixels, rowBytes, options.fZeroInitialized,
info.height(), rowsDecoded);
return incResult;
} else if (startResult != SkCodec::kUnimplemented) {
return startResult;
} // kUnimplemented means use the old method.
}
// Start the scanline decode.
SkCodec::Result result = this->codec()->startScanlineDecode(nativeInfo,
&sampledOptions);
if (SkCodec::kSuccess != result) {
return result;
}
SkSampler* sampler = this->codec()->getSampler(true);
if (!sampler) {
return SkCodec::kUnimplemented;
}
if (sampler->setSampleX(sampleX) != info.width()) {
return SkCodec::kInvalidScale;
}
if (get_scaled_dimension(subsetHeight, sampleY) != info.height()) {
return SkCodec::kInvalidScale;
}
switch(this->codec()->getScanlineOrder()) {
case SkCodec::kTopDown_SkScanlineOrder: {
if (!this->codec()->skipScanlines(startY)) {
this->codec()->fillIncompleteImage(info, pixels, rowBytes, options.fZeroInitialized,
dstHeight, 0);
return SkCodec::kIncompleteInput;
}
void* pixelPtr = pixels;
for (int y = 0; y < dstHeight; y++) {
if (1 != this->codec()->getScanlines(pixelPtr, 1, rowBytes)) {
this->codec()->fillIncompleteImage(info, pixels, rowBytes,
options.fZeroInitialized, dstHeight, y + 1);
return SkCodec::kIncompleteInput;
}
if (y < dstHeight - 1) {
if (!this->codec()->skipScanlines(sampleY - 1)) {
this->codec()->fillIncompleteImage(info, pixels, rowBytes,
options.fZeroInitialized, dstHeight, y + 1);
return SkCodec::kIncompleteInput;
}
}
pixelPtr = SkTAddOffset<void>(pixelPtr, rowBytes);
}
return SkCodec::kSuccess;
}
case SkCodec::kBottomUp_SkScanlineOrder: {
// Note that these modes do not support subsetting.
SkASSERT(0 == subsetY && nativeSize.height() == subsetHeight);
int y;
for (y = 0; y < nativeSize.height(); y++) {
int srcY = this->codec()->nextScanline();
if (is_coord_necessary(srcY, sampleY, dstHeight)) {
void* pixelPtr = SkTAddOffset<void>(pixels,
rowBytes * get_dst_coord(srcY, sampleY));
if (1 != this->codec()->getScanlines(pixelPtr, 1, rowBytes)) {
break;
}
} else {
if (!this->codec()->skipScanlines(1)) {
break;
}
}
}
if (nativeSize.height() == y) {
return SkCodec::kSuccess;
}
// We handle filling uninitialized memory here instead of using this->codec().
// this->codec() does not know that we are sampling.
const uint64_t fillValue = this->codec()->getFillValue(info);
const SkImageInfo fillInfo = info.makeWH(info.width(), 1);
for (; y < nativeSize.height(); y++) {
int srcY = this->codec()->outputScanline(y);
if (!is_coord_necessary(srcY, sampleY, dstHeight)) {
continue;
}
void* rowPtr = SkTAddOffset<void>(pixels, rowBytes * get_dst_coord(srcY, sampleY));
SkSampler::Fill(fillInfo, rowPtr, rowBytes, fillValue, options.fZeroInitialized);
}
return SkCodec::kIncompleteInput;
}
default:
SkASSERT(false);
return SkCodec::kUnimplemented;
}
}
/*
* Three differences from the Android version:
* Returns a Skia bitmap instead of an Android bitmap.
* Android version attempts to reuse a recycled bitmap.
* Removed the options object and used parameters for color type and
* sample size.
*/
SkBitmap* SkBitmapRegionCanvas::decodeRegion(int inputX, int inputY,
int inputWidth, int inputHeight,
int sampleSize,
SkColorType dstColorType) {
// Reject color types not supported by this method
if (kIndex_8_SkColorType == dstColorType || kGray_8_SkColorType == dstColorType) {
SkDebugf("Error: Color type not supported.\n");
return nullptr;
}
// The client may not necessarily request a region that is fully within
// the image. We may need to do some calculation to determine what part
// of the image to decode.
// The left offset of the portion of the image we want, where zero
// indicates the left edge of the image.
int imageSubsetX;
// The size of the output bitmap is determined by the size of the
// requested region, not by the size of the intersection of the region
// and the image dimensions. If inputX is negative, we will need to
// place decoded pixels into the output bitmap starting at a left offset.
// If this is non-zero, imageSubsetX must be zero.
int outX;
// The width of the portion of the image that we will write to the output
// bitmap. If the region is not fully contained within the image, this
// will not be the same as inputWidth.
int imageSubsetWidth;
set_subset_region(inputX, inputWidth, this->width(), &imageSubsetX, &outX, &imageSubsetWidth);
// The top offset of the portion of the image we want, where zero
// indicates the top edge of the image.
int imageSubsetY;
// The size of the output bitmap is determined by the size of the
// requested region, not by the size of the intersection of the region
// and the image dimensions. If inputY is negative, we will need to
// place decoded pixels into the output bitmap starting at a top offset.
// If this is non-zero, imageSubsetY must be zero.
int outY;
// The height of the portion of the image that we will write to the output
// bitmap. If the region is not fully contained within the image, this
// will not be the same as inputHeight.
int imageSubsetHeight;
set_subset_region(inputY, inputHeight, this->height(), &imageSubsetY, &outY,
&imageSubsetHeight);
if (imageSubsetWidth <= 0 || imageSubsetHeight <= 0) {
SkDebugf("Error: Region must intersect part of the image.\n");
return nullptr;
}
// Create the image info for the decode
SkAlphaType dstAlphaType = fDecoder->getInfo().alphaType();
if (kUnpremul_SkAlphaType == dstAlphaType) {
dstAlphaType = kPremul_SkAlphaType;
}
SkImageInfo decodeInfo = SkImageInfo::Make(this->width(), this->height(),
dstColorType, dstAlphaType);
// Start the scanline decoder
SkCodec::Result r = fDecoder->startScanlineDecode(decodeInfo);
if (SkCodec::kSuccess != r) {
SkDebugf("Error: Could not start scanline decoder.\n");
return nullptr;
}
// Allocate a bitmap for the unscaled decode
SkBitmap tmp;
SkImageInfo tmpInfo = decodeInfo.makeWH(this->width(), imageSubsetHeight);
if (!tmp.tryAllocPixels(tmpInfo)) {
SkDebugf("Error: Could not allocate pixels.\n");
return nullptr;
}
// Skip the unneeded rows
if (!fDecoder->skipScanlines(imageSubsetY)) {
SkDebugf("Error: Failed to skip scanlines.\n");
return nullptr;
}
// Decode the necessary rows
fDecoder->getScanlines(tmp.getAddr(0, 0), imageSubsetHeight, tmp.rowBytes());
// Calculate the size of the output
const int outWidth = get_scaled_dimension(inputWidth, sampleSize);
const int outHeight = get_scaled_dimension(inputHeight, sampleSize);
// Initialize the destination bitmap
SkAutoTDelete<SkBitmap> bitmap(new SkBitmap());
SkImageInfo dstInfo = decodeInfo.makeWH(outWidth, outHeight);
if (!bitmap->tryAllocPixels(dstInfo)) {
SkDebugf("Error: Could not allocate pixels.\n");
return nullptr;
}
// Zero the bitmap if the region is not completely within the image.
// TODO (msarett): Can we make this faster by implementing it to only
// zero parts of the image that we won't overwrite with
// pixels?
// TODO (msarett): This could be skipped if memory is zero initialized.
// This would matter if this code is moved to Android and
// uses Android bitmaps.
if (0 != outX || 0 != outY ||
inputX + inputWidth > this->width() ||
inputY + inputHeight > this->height()) {
bitmap->eraseColor(0);
}
// Use a canvas to crop and scale to the destination bitmap
SkCanvas canvas(*bitmap);
// TODO (msarett): Maybe we can take advantage of the fact that SkRect uses floats?
SkRect src = SkRect::MakeXYWH((SkScalar) imageSubsetX, (SkScalar) 0,
(SkScalar) imageSubsetWidth, (SkScalar) imageSubsetHeight);
SkRect dst = SkRect::MakeXYWH((SkScalar) (outX / sampleSize), (SkScalar) (outY / sampleSize),
(SkScalar) get_scaled_dimension(imageSubsetWidth, sampleSize),
(SkScalar) get_scaled_dimension(imageSubsetHeight, sampleSize));
SkPaint paint;
// Overwrite the dst with the src pixels
paint.setXfermodeMode(SkXfermode::kSrc_Mode);
// TODO (msarett): Test multiple filter qualities. kNone is the default.
canvas.drawBitmapRect(tmp, src, dst, &paint);
return bitmap.detach();
}
/*
* 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) {
// 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;
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.
// Because of the need for transparent pixels, kN32 is the only color
// type that makes sense for the destination format.
SkASSERT(kRGBA_8888_SkColorType == dstInfo.colorType() ||
kBGRA_8888_SkColorType == dstInfo.colorType());
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;
dst = SkTAddOffset<void>(dst, fLinesToSkip * dstRowBytes);
fLinesToSkip = 0;
} else {
fLinesToSkip -= height;
return height;
}
// 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) fRLEBytes - fCurrRLEByte < 2) {
SkCodecPrintf("Warning: might be incomplete RLE input.\n");
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.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 height;
case RLE_DELTA: {
// Two bytes are needed to specify delta
if ((int) fRLEBytes - fCurrRLEByte < 2) {
SkCodecPrintf("Warning: might be incomplete RLE input.\n");
if (this->checkForMoreData() < 2) {
return y;
}
}
// 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) {
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.
if ((int) fRLEBytes - fCurrRLEByte < SkAlign2(rowBytes)) {
SkCodecPrintf("Warning: might be incomplete RLE input.\n");
if (this->checkForMoreData() < SkAlign2(rowBytes)) {
return y;
}
}
// 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--;
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) fRLEBytes - fCurrRLEByte < 2) {
SkCodecPrintf("Warning: might be incomplete RLE input.\n");
if (this->checkForMoreData() < 2) {
return y;
}
}
// 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;
}
}
}
SkCodec::Result SkSampledCodec::sampledDecode(const SkImageInfo& info, void* pixels,
size_t rowBytes, const AndroidOptions& options) {
// We should only call this function when sampling.
SkASSERT(options.fSampleSize > 1);
// Create options struct for the codec.
SkCodec::Options sampledOptions;
sampledOptions.fZeroInitialized = options.fZeroInitialized;
// FIXME: This was already called by onGetAndroidPixels. Can we reduce that?
int sampleSize = options.fSampleSize;
int nativeSampleSize;
SkISize nativeSize = this->accountForNativeScaling(&sampleSize, &nativeSampleSize);
// Check if there is a subset.
SkIRect subset;
int subsetY = 0;
int subsetWidth = nativeSize.width();
int subsetHeight = nativeSize.height();
if (options.fSubset) {
// We will need to know about subsetting in the y-dimension in order to use the
// scanline decoder.
// Update the subset to account for scaling done by this->codec().
SkIRect* subsetPtr = options.fSubset;
// Do the divide ourselves, instead of calling get_scaled_dimension. If
// X and Y are 0, they should remain 0, rather than being upgraded to 1
// due to being smaller than the sampleSize.
const int subsetX = subsetPtr->x() / nativeSampleSize;
subsetY = subsetPtr->y() / nativeSampleSize;
subsetWidth = get_scaled_dimension(subsetPtr->width(), nativeSampleSize);
subsetHeight = get_scaled_dimension(subsetPtr->height(), nativeSampleSize);
// The scanline decoder only needs to be aware of subsetting in the x-dimension.
subset.setXYWH(subsetX, 0, subsetWidth, nativeSize.height());
sampledOptions.fSubset = ⊂
}
// Start the scanline decode.
SkCodec::Result result = this->codec()->startScanlineDecode(
info.makeWH(nativeSize.width(), nativeSize.height()), &sampledOptions,
options.fColorPtr, options.fColorCount);
if (SkCodec::kSuccess != result) {
return result;
}
SkSampler* sampler = this->codec()->getSampler(true);
if (!sampler) {
return SkCodec::kUnimplemented;
}
// Since we guarantee that output dimensions are always at least one (even if the sampleSize
// is greater than a given dimension), the input sampleSize is not always the sampleSize that
// we use in practice.
const int sampleX = subsetWidth / info.width();
const int sampleY = subsetHeight / info.height();
if (sampler->setSampleX(sampleX) != info.width()) {
return SkCodec::kInvalidScale;
}
if (get_scaled_dimension(subsetHeight, sampleY) != info.height()) {
return SkCodec::kInvalidScale;
}
const int samplingOffsetY = get_start_coord(sampleY);
const int startY = samplingOffsetY + subsetY;
int dstHeight = info.height();
switch(this->codec()->getScanlineOrder()) {
case SkCodec::kTopDown_SkScanlineOrder: {
if (!this->codec()->skipScanlines(startY)) {
this->codec()->fillIncompleteImage(info, pixels, rowBytes, options.fZeroInitialized,
dstHeight, 0);
return SkCodec::kIncompleteInput;
}
void* pixelPtr = pixels;
for (int y = 0; y < dstHeight; y++) {
if (1 != this->codec()->getScanlines(pixelPtr, 1, rowBytes)) {
this->codec()->fillIncompleteImage(info, pixels, rowBytes,
options.fZeroInitialized, dstHeight, y + 1);
return SkCodec::kIncompleteInput;
}
if (y < dstHeight - 1) {
if (!this->codec()->skipScanlines(sampleY - 1)) {
this->codec()->fillIncompleteImage(info, pixels, rowBytes,
options.fZeroInitialized, dstHeight, y + 1);
return SkCodec::kIncompleteInput;
}
}
pixelPtr = SkTAddOffset<void>(pixelPtr, rowBytes);
}
return SkCodec::kSuccess;
}
case SkCodec::kOutOfOrder_SkScanlineOrder:
case SkCodec::kBottomUp_SkScanlineOrder: {
// Note that these modes do not support subsetting.
SkASSERT(0 == subsetY && nativeSize.height() == subsetHeight);
int y;
for (y = 0; y < nativeSize.height(); y++) {
int srcY = this->codec()->nextScanline();
if (is_coord_necessary(srcY, sampleY, dstHeight)) {
void* pixelPtr = SkTAddOffset<void>(pixels,
rowBytes * get_dst_coord(srcY, sampleY));
if (1 != this->codec()->getScanlines(pixelPtr, 1, rowBytes)) {
break;
}
} else {
if (!this->codec()->skipScanlines(1)) {
break;
}
}
}
if (nativeSize.height() == y) {
return SkCodec::kSuccess;
}
// We handle filling uninitialized memory here instead of using this->codec().
// this->codec() does not know that we are sampling.
const uint32_t fillValue = this->codec()->getFillValue(info.colorType());
const SkImageInfo fillInfo = info.makeWH(info.width(), 1);
for (; y < nativeSize.height(); y++) {
int srcY = this->codec()->outputScanline(y);
if (!is_coord_necessary(srcY, sampleY, dstHeight)) {
continue;
}
void* rowPtr = SkTAddOffset<void>(pixels, rowBytes * get_dst_coord(srcY, sampleY));
SkSampler::Fill(fillInfo, rowPtr, rowBytes, fillValue, options.fZeroInitialized);
}
return SkCodec::kIncompleteInput;
}
case SkCodec::kNone_SkScanlineOrder: {
const int linesNeeded = subsetHeight - samplingOffsetY;
SkAutoTMalloc<uint8_t> storage(linesNeeded * rowBytes);
uint8_t* storagePtr = storage.get();
if (!this->codec()->skipScanlines(startY)) {
this->codec()->fillIncompleteImage(info, pixels, rowBytes, options.fZeroInitialized,
dstHeight, 0);
return SkCodec::kIncompleteInput;
}
int scanlines = this->codec()->getScanlines(storagePtr, linesNeeded, rowBytes);
for (int y = 0; y < dstHeight; y++) {
memcpy(pixels, storagePtr, info.minRowBytes());
storagePtr += sampleY * rowBytes;
pixels = SkTAddOffset<void>(pixels, rowBytes);
}
if (scanlines < dstHeight) {
// this->codec() has already handled filling uninitialized memory.
return SkCodec::kIncompleteInput;
}
return SkCodec::kSuccess;
}
default:
SkASSERT(false);
return SkCodec::kUnimplemented;
}
}