Allow client to force an SkImage snapshot to be unique (and uniquely own its backing store).

src/image/SkSurface_Raster.cpp

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkSurface_Base.h"
 #include "SkImagePriv.h"
 #include "SkCanvas.h"
 #include "SkDevice.h"
 #include "SkMallocPixelRef.h"
 
 static const size_t kIgnoreRowBytesValue = (size_t)~0;
 
 class SkSurface_Raster : public SkSurface_Base {
 public:
     static bool Valid(const SkImageInfo&, size_t rb = kIgnoreRowBytesValue);
 
     SkSurface_Raster(const SkImageInfo&, void*, size_t rb,
                      void (*releaseProc)(void* pixels, void* context), void* context,
                      const SkSurfaceProps*);
     SkSurface_Raster(SkPixelRef*, const SkSurfaceProps*);
 
     SkCanvas* onNewCanvas() override;
     SkSurface* onNewSurface(const SkImageInfo&) override;
-    SkImage* onNewImageSnapshot(Budgeted) override;
+    SkImage* onNewImageSnapshot(Budgeted, ForceCopyMode) override;
     void onDraw(SkCanvas*, SkScalar x, SkScalar y, const SkPaint*) override;
     void onCopyOnWrite(ContentChangeMode) override;
     void onRestoreBackingMutability() override;
 
 private:
     SkBitmap    fBitmap;
     size_t      fRowBytes;
     bool        fWeOwnThePixels;
 
     typedef SkSurface_Base INHERITED;
@@ skipping 70 matching lines @@
 
 SkSurface* SkSurface_Raster::onNewSurface(const SkImageInfo& info) {
     return SkSurface::NewRaster(info, &this->props());
 }
 
 void SkSurface_Raster::onDraw(SkCanvas* canvas, SkScalar x, SkScalar y,
                               const SkPaint* paint) {
     canvas->drawBitmap(fBitmap, x, y, paint);
 }
 
-SkImage* SkSurface_Raster::onNewImageSnapshot(Budgeted) {
+SkImage* SkSurface_Raster::onNewImageSnapshot(Budgeted, ForceCopyMode forceCopyMode) {
     if (fWeOwnThePixels) {
         // SkImage_raster requires these pixels are immutable for its full lifetime.
         // We'll undo this via onRestoreBackingMutability() if we can avoid the COW.
         if (SkPixelRef* pr = fBitmap.pixelRef()) {
             pr->setTemporarilyImmutable();
         }
+    } else {
+        forceCopyMode = kYes_ForceCopyMode;
     }
+
     // Our pixels are in memory, so read access on the snapshot SkImage could be cheap.
     // Lock the shared pixel ref to ensure peekPixels() is usable.
-    return SkNewImageFromRasterBitmap(fBitmap,
-                                      fWeOwnThePixels ? kNo_ForceCopyMode : kYes_ForceCopyMode);
+    return SkNewImageFromRasterBitmap(fBitmap, forceCopyMode);
 }
 
 void SkSurface_Raster::onRestoreBackingMutability() {
     SkASSERT(!this->hasCachedImage());  // Shouldn't be any snapshots out there.
     if (SkPixelRef* pr = fBitmap.pixelRef()) {
         pr->restoreMutability();
     }
 }
 
 void SkSurface_Raster::onCopyOnWrite(ContentChangeMode mode) {
     // are we sharing pixelrefs with the image?
-    SkASSERT(this->getCachedImage(kNo_Budgeted));
-    if (SkBitmapImageGetPixelRef(this->getCachedImage(kNo_Budgeted)) == fBitmap.pixelRef()) {
+    SkAutoTUnref<SkImage> cached(this->refCachedImage(kNo_Budgeted, kNo_ForceUnique));
+    SkASSERT(cached);
+    if (SkBitmapImageGetPixelRef(cached) == fBitmap.pixelRef()) {
         SkASSERT(fWeOwnThePixels);
         if (kDiscard_ContentChangeMode == mode) {
             fBitmap.allocPixels();
         } else {
             SkBitmap prev(fBitmap);
             fBitmap.allocPixels();
             prev.lockPixels();
             SkASSERT(prev.info() == fBitmap.info());
             SkASSERT(prev.rowBytes() == fBitmap.rowBytes());
             memcpy(fBitmap.getPixels(), prev.getPixels(), fBitmap.getSafeSize());
@@ skipping 43 matching lines @@
     }
     if (rowBytes) {
         SkASSERT(pr->rowBytes() == rowBytes);
     }
     return new SkSurface_Raster(pr, props);
 }
 
 SkSurface* SkSurface::NewRaster(const SkImageInfo& info, const SkSurfaceProps* props) {
     return NewRaster(info, 0, props);
 }