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Unified Diff: src/codec/SkScaledCodec.cpp

Issue 1285173003: Revert of SkScaledCodec class (Closed) Base URL: https://skia.googlesource.com/skia.git@master
Patch Set: Created 5 years, 4 months ago
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Index: src/codec/SkScaledCodec.cpp
diff --git a/src/codec/SkScaledCodec.cpp b/src/codec/SkScaledCodec.cpp
deleted file mode 100644
index e0158b6b4ef005d035ac6ef54576debdb28b7b98..0000000000000000000000000000000000000000
--- a/src/codec/SkScaledCodec.cpp
+++ /dev/null
@@ -1,261 +0,0 @@
-/*
- * 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 "SkCodecPriv.h"
-#include "SkScaledCodec.h"
-#include "SkStream.h"
-#include "SkWebpCodec.h"
-
-
-SkCodec* SkScaledCodec::NewFromStream(SkStream* stream) {
- bool isWebp = SkWebpCodec::IsWebp(stream);
- if (!stream->rewind()) {
- return NULL;
- }
- if (isWebp) {
- // Webp codec supports scaling and subsetting natively
- return SkWebpCodec::NewFromStream(stream);
- }
-
- SkAutoTDelete<SkScanlineDecoder> scanlineDecoder(SkScanlineDecoder::NewFromStream(stream));
- if (NULL == scanlineDecoder) {
- return NULL;
- }
-
- // wrap in new SkScaledCodec
- return SkNEW_ARGS(SkScaledCodec, (scanlineDecoder.detach()));
-}
-
-SkCodec* SkScaledCodec::NewFromData(SkData* data) {
- if (!data) {
- return NULL;
- }
- return NewFromStream(SkNEW_ARGS(SkMemoryStream, (data)));
-}
-
-SkScaledCodec::SkScaledCodec(SkScanlineDecoder* scanlineDecoder)
- : INHERITED(scanlineDecoder->getInfo(), NULL)
- , fScanlineDecoder(scanlineDecoder)
-{}
-
-SkScaledCodec::~SkScaledCodec() {}
-
-// returns a scaled dimension based on the original dimension and the sampleSize
-// NOTE: we round down here for scaled dimension to match the behavior of SkImageDecoder
-static int get_scaled_dimension(int srcDimension, int sampleSize) {
- if (sampleSize > srcDimension) {
- return 1;
- }
- return srcDimension / sampleSize;
-}
-
-static SkISize best_scaled_dimensions(const SkISize& origDims, const SkISize& nativeDims,
- const SkISize& scaledCodecDims, float desiredScale) {
- if (nativeDims == scaledCodecDims) {
- // does not matter which to return if equal. Return here to skip below calculations
- return nativeDims;
- }
- float idealWidth = origDims.width() * desiredScale;
- float idealHeight = origDims.height() * desiredScale;
-
- // calculate difference between native dimensions and ideal dimensions
- float nativeWDiff = SkTAbs(idealWidth - nativeDims.width());
- float nativeHDiff = SkTAbs(idealHeight - nativeDims.height());
- float nativeDiff = (nativeWDiff + nativeHDiff) / 2;
-
- // calculate difference between scaledCodec dimensions and ideal dimensions
- float scaledCodecWDiff = SkTAbs(idealWidth - scaledCodecDims.width());
- float scaledCodecHDiff = SkTAbs(idealHeight - scaledCodecDims.height());
- float scaledCodecDiff = (scaledCodecWDiff + scaledCodecHDiff) / 2;
-
- // return dimensions closest to ideal dimensions.
- // If the differences are equal, return nativeDims, as native scaling is more efficient.
- return nativeDiff > scaledCodecDiff ? scaledCodecDims : nativeDims;
-
-}
-/*
- * 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);
-}
-
-// 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;
- }
-}
-
-// TODO: Implement subsetting in onGetPixels which works when and when not sampling
-
-SkCodec::Result SkScaledCodec::onGetPixels(const SkImageInfo& requestedInfo, void* dst,
- size_t rowBytes, const Options& options,
- SkPMColor ctable[], int* ctableCount) {
-
- if (options.fSubset) {
- // Subsets are not supported.
- return kUnimplemented;
- }
-
- Result result = fScanlineDecoder->start(requestedInfo, &options, ctable, ctableCount);
- if (kSuccess == result) {
- // native decode supported
- return fScanlineDecoder->getScanlines(dst, requestedInfo.height(), rowBytes);
-
- }
-
- if (kInvalidScale != result) {
- // no scaling requested
- return result;
- }
-
- // scaling requested
- int sampleX;
- int sampleY;
- if (!scaling_supported(requestedInfo, fScanlineDecoder->getInfo(), &sampleX, &sampleY)) {
- return kInvalidScale;
- }
- // set first sample pixel in y direction
- int Y0 = sampleY >> 1;
-
- int dstHeight = requestedInfo.height();
- int srcHeight = fScanlineDecoder->getInfo().height();
-
- SkImageInfo info = requestedInfo;
- // use original height as scanlineDecoder does not support y sampling natively
- info = info.makeWH(requestedInfo.width(), srcHeight);
-
- // update scanlineDecoder with new info
- result = fScanlineDecoder->start(info, &options, ctable, ctableCount);
- if (kSuccess != result) {
- return result;
- }
-
- const bool requiresPostYSampling = fScanlineDecoder->requiresPostYSampling();
-
- if (requiresPostYSampling) {
- SkAutoMalloc storage(srcHeight * rowBytes);
- uint8_t* storagePtr = static_cast<uint8_t*>(storage.get());
- result = fScanlineDecoder->getScanlines(storagePtr, srcHeight, rowBytes);
- if (kSuccess != result) {
- return result;
- }
- storagePtr += Y0 * rowBytes;
- for (int y = 0; y < dstHeight; y++) {
- memcpy(dst, storagePtr, rowBytes);
- storagePtr += sampleY * rowBytes;
- dst = SkTAddOffset<void>(dst, rowBytes);
- }
- } else {
- // does not require post y sampling
- result = fScanlineDecoder->skipScanlines(Y0);
- if (kSuccess != result) {
- return result;
- }
- for (int y = 0; y < dstHeight; y++) {
- result = fScanlineDecoder->getScanlines(dst, 1, rowBytes);
- if (kSuccess != result) {
- return result;
- }
- if (y < dstHeight - 1) {
- result = fScanlineDecoder->skipScanlines(sampleY - 1);
- if (kSuccess != result) {
- return result;
- }
- }
- dst = SkTAddOffset<void>(dst, rowBytes);
- }
- }
- return kSuccess;
-}
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