add SkBitmap::installPixelRef()

src/core/SkBitmap.cpp

Index: src/core/SkBitmap.cpp
diff --git a/src/core/SkBitmap.cpp b/src/core/SkBitmap.cpp
index cb8ac7231b29a9728dcf0d4804c6660c40291a04..79c63d32919abbc311e9e5c35b337bfa48d7f9d5 100644
--- a/src/core/SkBitmap.cpp
+++ b/src/core/SkBitmap.cpp
@@ -333,6 +333,31 @@ bool SkBitmap::setAlphaType(SkAlphaType alphaType) {
     return true;
 }
 
+SkPixelRef* SkBitmap::installPixelRef(SkPixelRef* pr, const SkIRect* subset) {
+    if (NULL == pr) {
+        this->reset();
+        return NULL;
+    }
+
+    const SkImageInfo& info = pr->info();
+
+    fConfig = SkColorTypeToBitmapConfig(info.fColorType);
+    fAlphaType = info.fAlphaType;
+    fBytesPerPixel = info.bytesPerPixel();
+    
+    SkIRect bounds = { 0, 0, info.fWidth, info.fHeight };
+    if (subset && !bounds.intersect(*subset)) {
+        bounds.setEmpty();
+    }
+
+    fRowBytes       = 0;              // not known until we're locked
+    fPixelRefOrigin.set(bounds.left(), bounds.top());
+    fWidth          = bounds.width();
+    fHeight         = bounds.height();
+  
+    return this->setPixelRef(pr);

[scroggo, 2014/01/09 00:02:11]

This will overwrite fPixelRefOrigin. Instead, I think you should remove line 354
and change this to

return this->setPixelRef(pr, bounds.left(), bounds.top());

[reed1, 2014/01/13 16:27:26]

Done.

+}
+
 void SkBitmap::updatePixelsFromRef() const {
     if (NULL != fPixelRef) {
         if (fPixelLockCount > 0) {