SkImage method for detecting lazy decoding

include/core/SkPixelRef.h

 /*
  * Copyright 2008 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkPixelRef_DEFINED
 #define SkPixelRef_DEFINED
 
@@ skipping 247 matching lines @@
     void addGenIDChangeListener(GenIDChangeListener* listener);
 
     // Call when this pixelref is part of the key to a resourcecache entry. This allows the cache
     // to know automatically those entries can be purged when this pixelref is changed or deleted.
     void notifyAddedToCache() {
         fAddedToCache.store(true);
     }
 
     virtual SkDiscardableMemory* diagnostic_only_getDiscardable() const { return NULL; }
 
+    /**
+     *  Returns true if the pixels are generated on-the-fly (when required).
+     */
+    bool isLazyGenerated() const { return this->onIsLazyGenerated(); }
+
 protected:
     /**
      *  On success, returns true and fills out the LockRec for the pixels. On
      *  failure returns false and ignores the LockRec parameter.
      *
      *  The caller will have already acquired a mutex for thread safety, so this
      *  method need not do that.
      */
     virtual bool onNewLockPixels(LockRec*) = 0;
 
@@ skipping 33 matching lines @@
      *  This should be implemented in all serializable SkPixelRef derived classes.
      *  SkBitmap::fPixelRefOffset + SkBitmap::getSafeSize() should never overflow this value,
      *  otherwise the rendering code may attempt to read memory out of bounds.
      *
      *  @return default impl returns 0.
      */
     virtual size_t getAllocatedSizeInBytes() const;
 
     virtual bool onRequestLock(const LockRequest&, LockResult*);
 
+    virtual bool onIsLazyGenerated() const { return false; }
+
     /** Return the mutex associated with this pixelref. This value is assigned
         in the constructor, and cannot change during the lifetime of the object.
     */
     SkBaseMutex* mutex() const { return &fMutex; }
 
     // only call from constructor. Flags this to always be locked, removing
     // the need to grab the mutex and call onLockPixels/onUnlockPixels.
     // Performance tweak to avoid those calls (esp. in multi-thread use case).
     void setPreLocked(void*, size_t rowBytes, SkColorTable*);
 
@@ skipping 60 matching lines @@
     /**
      *  Allocate a new pixelref matching the specified ImageInfo, allocating
      *  the memory for the pixels. If the ImageInfo requires a ColorTable,
      *  the pixelref will ref() the colortable.
      *  On failure return NULL.
      */
     virtual SkPixelRef* create(const SkImageInfo&, size_t rowBytes, SkColorTable*) = 0;
 };
 
 #endif