Purge cached resources on SkImage destruction.

src/core/SkImageCacherator.h

Index: src/core/SkImageCacherator.h
diff --git a/src/core/SkImageCacherator.h b/src/core/SkImageCacherator.h
index dc6b0f2c1a0cfcadc867124a7253e8e5510f29af..6812c72fccb092b1b0172d6f251f37cbc0bb0d19 100644
--- a/src/core/SkImageCacherator.h
+++ b/src/core/SkImageCacherator.h
@@ -14,6 +14,7 @@
 
 class GrContext;
 class SkBitmap;
+class SkImage;
 
 /*
  *  Internal class to manage caching the output of an ImageGenerator.
@@ -29,16 +30,22 @@ public:
     /**
      *  On success (true), bitmap will point to the pixels for this generator. If this returns
      *  false, the bitmap will be reset to empty.
+     *
+     *  If not NULL, the client will be notified (->notifyAddedToCache()) when resources are
+     *  added to the cache on its behalf.
      */
-    bool lockAsBitmap(SkBitmap*);
+    bool lockAsBitmap(SkBitmap*, const SkImage* client);

[mtklein, 2015/09/18 14:32:36]

I think I'm having trouble catching up on our new toys.  We have an
SkImageGenerator, which presumably generates bitmaps and/or textures, and an
SkImageCacherator that wraps an SkImageGenerator to make lockAsFoo() faster
after the first call.  Is that roughly right?

If so, how does this client SkImage fit into this?  Is it a source that the
bitmap / texture are derived from?  (Is it somehow also pointed to by the
SkImageGenerator?)

[f(malita), 2015/09/18 15:00:40]

Sounds about right to me.
We have a SkImage_Generator specialization, which is backed by a
cacherator+generator.  The genID is shared by the whole gang.

 
     /**
      *  Returns a ref() on the texture produced by this generator. The caller must call unref()
      *  when it is done. Will return nullptr on failure.
      *
+     *  If not NULL, the client will be notified (->notifyAddedToCache()) when resources are
+     *  added to the cache on its behalf.
+     *
      *  The caller is responsible for calling texture->unref() when they are done.
      */
-    GrTexture* lockAsTexture(GrContext*, SkImageUsageType);
+    GrTexture* lockAsTexture(GrContext*, SkImageUsageType, const SkImage* client);
 
     /**
      *  If the underlying src naturally is represented by an encoded blob (in SkData), this returns
@@ -50,7 +57,7 @@ private:
     SkImageCacherator(SkImageGenerator*, const SkImageInfo&, const SkIPoint&, uint32_t uniqueID);
 
     bool generateBitmap(SkBitmap*);
-    bool tryLockAsBitmap(SkBitmap*);
+    bool tryLockAsBitmap(SkBitmap*, const SkImage*);
 
     class ScopedGenerator {
         SkImageCacherator* fCacher;