Add subsetting to SkScanlineDecoder

src/codec/SkBmpMaskCodec.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 "SkBmpMaskCodec.h"
 #include "SkCodecPriv.h"
 #include "SkColorPriv.h"
@@ skipping 40 matching lines @@
     }
 
     uint32_t rows = this->decodeRows(dstInfo, dst, dstRowBytes, opts);
     if (rows != dstInfo.height()) {
         *rowsDecoded = rows;
         return kIncompleteInput;
     }
     return kSuccess;
 }
 
-bool SkBmpMaskCodec::initializeSwizzler(const SkImageInfo& dstInfo) {
+bool SkBmpMaskCodec::initializeSwizzler(const SkImageInfo& dstInfo, const Options& options) {
     // Create the swizzler
-    fMaskSwizzler.reset(SkMaskSwizzler::CreateMaskSwizzler(
-            dstInfo, this->getInfo(), fMasks, this->bitsPerPixel()));
+    fMaskSwizzler.reset(SkMaskSwizzler::CreateMaskSwizzler(dstInfo, this->getInfo(), fMasks,
+            this->bitsPerPixel(), options));
 
     if (nullptr == fMaskSwizzler.get()) {
         return false;
     }
 
     return true;
 }
 
 SkCodec::Result SkBmpMaskCodec::prepareToDecode(const SkImageInfo& dstInfo,
         const SkCodec::Options& options, SkPMColor inputColorPtr[], int* inputColorCount) {
     // Initialize a the mask swizzler
-    if (!this->initializeSwizzler(dstInfo)) {
+    if (!this->initializeSwizzler(dstInfo, options)) {
         SkCodecPrintf("Error: cannot initialize swizzler.\n");
         return SkCodec::kInvalidConversion;
     }
 
     return SkCodec::kSuccess;
 }
 
 /*
  * Performs the decoding
  */
@@ skipping 12 matching lines @@
 
         // Decode the row in destination format
         uint32_t row = this->getDstRow(y, height);
         void* dstRow = SkTAddOffset<void>(dst, row * dstRowBytes);
         fMaskSwizzler->swizzle(dstRow, srcRow);
     }
 
     // Finished decoding the entire image
     return height;
 }