Make BitmapRegionDecoder succeed on invalid requests

src/android/SkBitmapRegionCanvas.cpp

Index: src/android/SkBitmapRegionCanvas.cpp
diff --git a/src/android/SkBitmapRegionCanvas.cpp b/src/android/SkBitmapRegionCanvas.cpp
index bac5dc1ffc7995fa57cb954f5db2987cf99a71c1..295a2462c764e77edd6397251f54825c53f1f16c 100644
--- a/src/android/SkBitmapRegionCanvas.cpp
+++ b/src/android/SkBitmapRegionCanvas.cpp
@@ -18,6 +18,15 @@ SkBitmapRegionCanvas::SkBitmapRegionCanvas(SkCodec* decoder)
 bool SkBitmapRegionCanvas::decodeRegion(SkBitmap* bitmap, SkBRDAllocator* allocator,
         const SkIRect& desiredSubset, int sampleSize, SkColorType dstColorType,
         bool requireUnpremul) {
+    // FIXME: This class works well as a performance/quality comparison for

[scroggo, 2015/12/09 20:57:31]

Maybe this should be in the header?

[msarett, 2015/12/10 15:19:26]

Done.

+    //        SkBitmapRegionCodec, but it lacks several capabilities that are
+    //        required by BitmapRegionDecoder in Android.
+    //        (1) Decodes to kGray8 and kIndex8.
+    //        (2) Decodes to kUnpremul.
+    //        (3) Correcting an invalid dstColorType.  For example, if the
+    //            client requests kRGB_565 for a non-opaque image, rather than
+    //            fail, we need to go ahead and decode to kN32.
+
     // Reject color types not supported by this method
     if (kIndex_8_SkColorType == dstColorType || kGray_8_SkColorType == dstColorType) {
         SkCodecPrintf("Error: Color type not supported.\n");
@@ -34,8 +43,6 @@ bool SkBitmapRegionCanvas::decodeRegion(SkBitmap* bitmap, SkBRDAllocator* alloca
         dstAlphaType = kPremul_SkAlphaType;
     }
 
-    // FIXME: Can we add checks and support kIndex8 or unpremultiplied alpha in special cases?
-
     // Fix the input sampleSize if necessary.
     if (sampleSize < 1) {
         sampleSize = 1;