Add ability to extract YUV planes from SkImage

src/image/SkImage.cpp

Index: src/image/SkImage.cpp
diff --git a/src/image/SkImage.cpp b/src/image/SkImage.cpp
index 25370bcff15e09ad2e7276ec3a98f23e4a79cf35..21eedff8784ffe174b15efb1c6aa41389c1da81b 100644
--- a/src/image/SkImage.cpp
+++ b/src/image/SkImage.cpp
@@ -258,6 +258,25 @@ bool SkImage::readPixels(const SkPixmap& pmap, int srcX, int srcY, CachingHint c
     return this->readPixels(pmap.info(), pmap.writable_addr(), pmap.rowBytes(), srcX, srcY, chint);
 }
 
+#if SK_SUPPORT_GPU
+#include "GrTextureToYUVPlanes.h"
+#endif
+
+#include "SkRGBAToYUV.h"
+
+bool SkImage::asYUV8Planes(const SkISize sizes[3], void* const planes[3], const size_t rowBytes[3],
+                           SkYUVColorSpace colorSpace) {
+#if SK_SUPPORT_GPU
+    if (GrTexture* texture = as_IB(this)->peekTexture()) {
+        if (GrTextureToYUVPlanes(texture, sizes, planes, rowBytes, colorSpace)) {
+            return true;
+        }
+    }
+#endif
+    SkRGBAToYUV(this, sizes, planes, rowBytes, colorSpace);

[reed1, 2016/01/29 17:17:00]

Hmmm, I thought the "utility" function would take a pixmap (simple), rather than
an image (complex) as its src.

[bsalomon, 2016/01/29 17:36:42]

I originally typed it that way and then realized I needed to convert it back to
something complex in the implementation in order to draw it. 

+    return true;
+}
+
 ///////////////////////////////////////////////////////////////////////////////////////////////////
 
 SkImage* SkImage::NewFromBitmap(const SkBitmap& bm) {