Add subsetting to SkScanlineDecoder

src/codec/SkCodec_libgif.cpp

 /*
  * 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 "SkCodec_libgif.h"
 #include "SkCodecPriv.h"
 #include "SkColorPriv.h"
@@ skipping 417 matching lines @@
         colorPtr[i] = colorPtr[fFillIndex];
     }
 
     fColorTable.reset(new SkColorTable(colorPtr, maxColors));
     copy_color_table(dstInfo, this->fColorTable, inputColorPtr, inputColorCount);
 }
 
 SkCodec::Result SkGifCodec::prepareToDecode(const SkImageInfo& dstInfo, SkPMColor* inputColorPtr,
         int* inputColorCount, const Options& opts) {
     // Check for valid input parameters
-    if (opts.fSubset) {
-        // Subsets are not supported.
-        return kUnimplemented;
-    }
     if (!conversion_possible(dstInfo, this->getInfo())) {
         return gif_error("Cannot convert input type to output type.\n",
                 kInvalidConversion);
     }
 
     // Initialize color table and copy to the client if necessary
     this->initializeColorTable(dstInfo, inputColorPtr, inputColorCount);
     return kSuccess;
 }
 
-SkCodec::Result SkGifCodec::initializeSwizzler(const SkImageInfo& dstInfo,
-        ZeroInitialized zeroInit) {
+SkCodec::Result SkGifCodec::initializeSwizzler(const SkImageInfo& dstInfo, const Options& opts) {
     const SkPMColor* colorPtr = get_color_ptr(fColorTable.get());
-    fSwizzler.reset(SkSwizzler::CreateSwizzler(SkSwizzler::kIndex,
-            colorPtr, dstInfo, zeroInit));
+    fSwizzler.reset(SkSwizzler::CreateSwizzler(SkSwizzler::kIndex, colorPtr, dstInfo, opts));
     if (nullptr != fSwizzler.get()) {
         return kSuccess;
     }
     return kUnimplemented;
 }
 
 bool SkGifCodec::readRow() {
     return GIF_ERROR != DGifGetLine(fGif, fSrcBuffer.get(), fFrameRect.width());
 }
 
@@ skipping 11 matching lines @@
         return result;
     }
 
     if (dstInfo.dimensions() != this->getInfo().dimensions()) {
         return gif_error("Scaling not supported.\n", kInvalidScale);
     }
 
     // Initialize the swizzler
     if (fFrameIsSubset) {
         const SkImageInfo subsetDstInfo = dstInfo.makeWH(fFrameRect.width(), fFrameRect.height());
-        if (kSuccess != this->initializeSwizzler(subsetDstInfo, opts.fZeroInitialized)) {
+        if (kSuccess != this->initializeSwizzler(subsetDstInfo, opts)) {
             return gif_error("Could not initialize swizzler.\n", kUnimplemented);
         }
 
         // Fill the background
         SkSampler::Fill(dstInfo, dst, dstRowBytes,
                 this->getFillValue(dstInfo.colorType(), dstInfo.alphaType()),
                 opts.fZeroInitialized);
 
         // Modify the dst pointer
         const int32_t dstBytesPerPixel = SkColorTypeBytesPerPixel(dstInfo.colorType());
         dst = SkTAddOffset<void*>(dst, dstRowBytes * fFrameRect.top() +
                 dstBytesPerPixel * fFrameRect.left());
     } else {
-        if (kSuccess != this->initializeSwizzler(dstInfo, opts.fZeroInitialized)) {
+        if (kSuccess != this->initializeSwizzler(dstInfo, opts)) {
             return gif_error("Could not initialize swizzler.\n", kUnimplemented);
         }
     }
 
     // Iterate over rows of the input
     uint32_t height = fFrameRect.height();
     for (uint32_t y = 0; y < height; y++) {
         if (!this->readRow()) {
             *rowsDecoded = y;
             return gif_error("Could not decode line.\n", kIncompleteInput);
@@ skipping 15 matching lines @@
         const SkCodec::Options& opts, SkPMColor inputColorPtr[], int* inputColorCount) {
 
     Result result = this->prepareToDecode(dstInfo, inputColorPtr, inputColorCount, this->options());
     if (kSuccess != result) {
         return result;
     }
 
     // Initialize the swizzler
     if (fFrameIsSubset) {
         const SkImageInfo subsetDstInfo = dstInfo.makeWH(fFrameRect.width(), fFrameRect.height());
-        if (kSuccess != this->initializeSwizzler(subsetDstInfo, opts.fZeroInitialized)) {
+        if (kSuccess != this->initializeSwizzler(subsetDstInfo, opts)) {
             return gif_error("Could not initialize swizzler.\n", kUnimplemented);
         }
     } else {
-        if (kSuccess != this->initializeSwizzler(dstInfo, opts.fZeroInitialized)) {
+        if (kSuccess != this->initializeSwizzler(dstInfo, opts)) {
             return gif_error("Could not initialize swizzler.\n", kUnimplemented);
         }
     }
 
     return kSuccess;
 }
 
 int SkGifCodec::onGetScanlines(void* dst, int count, size_t rowBytes) {
     int rowsBeforeFrame = 0;
     int rowsAfterFrame = 0;
@@ skipping 40 matching lines @@
 
 int SkGifCodec::onOutputScanline(int inputScanline) const {
     if (fGif->Image.Interlace) {
         if (inputScanline < fFrameRect.top() || inputScanline >= fFrameRect.bottom()) {
             return inputScanline;
         }
         return get_output_row_interlaced(inputScanline - fFrameRect.top(), fFrameRect.height());
     }
     return inputScanline;
 }