cache private readback for gpu-images

src/core/SkPixelRef.cpp

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkBitmapCache.h"
 #include "SkMutex.h"
 #include "SkPixelRef.h"
@@ skipping 338 matching lines @@
     this->onNotifyPixelsChanged();
 }
 
 void SkPixelRef::changeAlphaType(SkAlphaType at) {
     *const_cast<SkImageInfo*>(&fInfo) = fInfo.makeAlphaType(at);
 }
 
 void SkPixelRef::setImmutable() {
     fMutability = kImmutable;
 }
+
+void SkPixelRef::setImmutableWithID(uint32_t genID) {
+    /*
+     *  We are forcing the genID to match an external value. The caller must ensure that this
+     *  value does not conflict with other content.
+     *
+     *  One use is to force this pixelref's id to match an SkImage's id
+     */
+    fMutability = kImmutable;
+    fTaggedGenID.store(genID);
+}
+
 void SkPixelRef::setTemporarilyImmutable() {
     SkASSERT(fMutability != kImmutable);
     fMutability = kTemporarilyImmutable;
 }
 
 void SkPixelRef::restoreMutability() {
     SkASSERT(fMutability != kImmutable);
     fMutability = kMutable;
 }
 
@@ skipping 34 matching lines @@
     }
 
     result->fUnlockProc = unlock_legacy_result;
     result->fUnlockContext = SkRef(this);   // this is balanced in our fUnlockProc
     result->fCTable = fRec.fColorTable;
     result->fPixels = fRec.fPixels;
     result->fRowBytes = fRec.fRowBytes;
     result->fSize.set(fInfo.width(), fInfo.height());
     return true;
 }