Refactor SkBitmapRegionDecoderInterface for Android

tools/SkBitmapRegionSampler.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 "SkBitmapRegionSampler.h"
 #include "SkCodecPriv.h"
 
 SkBitmapRegionSampler::SkBitmapRegionSampler(SkImageDecoder* decoder, int width, 
                                              int height)
     : INHERITED(width, height)
     , fDecoder(decoder)
 {}
 
-/*
- * 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* SkBitmapRegionSampler::decodeRegion(int start_x, int start_y,
-                                              int width, int height,
-                                              int sampleSize,
-                                              SkColorType prefColorType) {
-    // Match Android's default settings
+bool SkBitmapRegionSampler::decodeRegion(SkBitmap* bitmap, SkBitmap::Allocator* allocator,
+        const SkIRect& desiredSubset, int sampleSize, SkColorType colorType, bool requireUnpremul) {
     fDecoder->setDitherImage(true);
     fDecoder->setPreferQualityOverSpeed(false);
     fDecoder->setRequireUnpremultipliedColors(false);
     fDecoder->setSampleSize(sampleSize);
+    fDecoder->setAllocator(allocator);
 
     // kAlpha8 is the legacy representation of kGray8 used by SkImageDecoder
-    if (kGray_8_SkColorType == prefColorType) {
-        prefColorType = kAlpha_8_SkColorType;
+    if (kGray_8_SkColorType == colorType) {
+        colorType = kAlpha_8_SkColorType;
     }
 
-    SkIRect region;
-    region.fLeft = start_x;
-    region.fTop = start_y;
-    region.fRight = start_x + width;
-    region.fBottom = start_y + height;
-
-    SkAutoTDelete<SkBitmap> bitmap(new SkBitmap());
-    if (!fDecoder->decodeSubset(bitmap.get(), region, prefColorType)) {
-        SkCodecPrintf("Error: decodeRegion failed.\n");
-        return nullptr;
-    }
-    return bitmap.detach();
+    bool result = fDecoder->decodeSubset(bitmap, desiredSubset, colorType);
+    fDecoder->setAllocator(nullptr);
+    return result;
 }