SkBitmapRegionCodec needs to use the rowBytes on the pixel ref

tools/SkBitmapRegionCodec.cpp

Index: tools/SkBitmapRegionCodec.cpp
diff --git a/tools/SkBitmapRegionCodec.cpp b/tools/SkBitmapRegionCodec.cpp
index cac99452e0d37bcffdf762063bf9e17c7c0515c5..fe1744fc87ed468eb89dcf41bf3226509e09a9ad 100644
--- a/tools/SkBitmapRegionCodec.cpp
+++ b/tools/SkBitmapRegionCodec.cpp
@@ -9,6 +9,7 @@
 #include "SkAndroidCodec.h"
 #include "SkCodecPriv.h"
 #include "SkCodecTools.h"
+#include "SkPixelRef.h"
 
 SkBitmapRegionCodec::SkBitmapRegionCodec(SkAndroidCodec* codec)
     : INHERITED(codec->getInfo().width(), codec->getInfo().height())
@@ -119,7 +120,9 @@ bool SkBitmapRegionCodec::decodeRegion(SkBitmap* bitmap, SkBitmap::Allocator* al
     options.fColorPtr = colorPtr;
     options.fColorCount = colorCountPtr;
     void* dst = bitmap->getAddr(scaledOutX, scaledOutY);
-    size_t rowBytes = bitmap->rowBytes();
+    // It is important that we use the rowBytes on the pixelRef.
+    // skbug.com/4538
+    size_t rowBytes = bitmap->pixelRef()->rowBytes();

[scroggo, 2015/11/05 20:20:48]

Should we update the bitmap so that it matches?

That has a weird side effect - we can only update the bitmap's rowBytes by
calling setInfo, which unref's the pixel ref. In order to make this code robust,
we need to do the following:

  SkPixelRef* pr = SkRef(bitmap->pixelRef());
  size_t rowBytes = pr->rowBytes();
  bitmap->setInfo(outInfo, rowBytes);
  bitmap->setPixelRef(pr)->unref();

Probably makes sense to make that change (along with a FIXME).

[msarett, 2015/11/05 22:34:59]

Done.

Yeah we are fine without this change, but I agree it's dangerous to leave the
rowBytes mismatched.

     SkCodec::Result result = fCodec->getAndroidPixels(decodeInfo, dst, rowBytes, &options);
     if (SkCodec::kSuccess != result && SkCodec::kIncompleteInput != result) {
         SkCodecPrintf("Error: Could not get pixels.\n");