Refactor SkBitmapRegionDecoderInterface for Android

tools/SkBitmapRegionSampler.cpp

Index: tools/SkBitmapRegionSampler.cpp
diff --git a/tools/SkBitmapRegionSampler.cpp b/tools/SkBitmapRegionSampler.cpp
index 514af108593ffa6113233fe9cf807e376d8169fe..cdcee9946a42df80d663b1e9c9fc901538483805 100644
--- a/tools/SkBitmapRegionSampler.cpp
+++ b/tools/SkBitmapRegionSampler.cpp
@@ -14,38 +14,18 @@ SkBitmapRegionSampler::SkBitmapRegionSampler(SkImageDecoder* decoder, int width,
     , 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);

[scroggo, 2015/10/27 18:53:55]

I think you need to undo this - setAllocator will increase the ref count on
allocator, and hang on to a pointer to it. If it was on the stack, we cannot
hang on to that pointer (or the ref). So this should be something like:

fDecoder->setAllocator(allocator);
...
const bool success = fDecoder->decodeSubset(...);
fDecoder->setAllocator(nullptr);
return success;

[msarett, 2015/10/27 19:06:16]

Nice catch!

 
     // 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();
+    return fDecoder->decodeSubset(bitmap, desiredSubset, colorType);
 }