make cacherator thread-safe

src/core/SkImageCacherator.h

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkImageCacherator_DEFINED
 #define SkImageCacherator_DEFINED
 
 #include "SkImageGenerator.h"
+#include "SkMutex.h"
+#include "SkTemplates.h"
 
 class GrContext;
 class SkBitmap;
 
 /*
  *  Internal class to manage caching the output of an ImageGenerator.
  */
 class SkImageCacherator {
 public:
     // Takes ownership of the generator
     static SkImageCacherator* NewFromGenerator(SkImageGenerator*, const SkIRect* subset = nullptr);
 
-    ~SkImageCacherator();
-
     const SkImageInfo& info() const { return fInfo; }
     uint32_t uniqueID() const { return fUniqueID; }
 
     /**
      *  On success (true), bitmap will point to the pixels for this generator. If this returns
      *  false, the bitmap will be reset to empty.
      */
     bool lockAsBitmap(SkBitmap*);
 
     /**
      *  Returns a ref() on the texture produced by this generator. The caller must call unref()
      *  when it is done. Will return NULL on failure.
      *
      *  The caller is responsible for calling texture->unref() when they are done.
      */
     GrTexture* lockAsTexture(GrContext*, SkImageUsageType);
 
+    /**
+     *  If the underlying src naturally is represented by an encoded blob (in SkData), this returns
+     *  a ref to that data. If not, it returns null.
+     */
+    SkData* refEncoded();
+
 private:
     SkImageCacherator(SkImageGenerator*, const SkImageInfo&, const SkIPoint&, uint32_t uniqueID);
 
+    bool generateBitmap(SkBitmap*);
     bool tryLockAsBitmap(SkBitmap*);
-    GrTexture* tryLockAsTexture(GrContext*, SkImageUsageType);
 
-    SkImageGenerator*   fGenerator;
+    class ScopedGenerator {
+        SkImageCacherator* fCacher;
+    public:
+        ScopedGenerator(SkImageCacherator* cacher) : fCacher(cacher) {
+            fCacher->fMutexForGenerator.acquire();
+        }
+        ~ScopedGenerator() {
+            fCacher->fMutexForGenerator.release();
+        }
+        SkImageGenerator* operator->() const { return fCacher->fNotThreadSafeGenerator; }
+        operator SkImageGenerator*() const { return fCacher->fNotThreadSafeGenerator; }
+    };
+
+    SkMutex                         fMutexForGenerator;
+    SkAutoTDelete<SkImageGenerator> fNotThreadSafeGenerator;
+
     const SkImageInfo   fInfo;
     const SkIPoint      fOrigin;
     const uint32_t      fUniqueID;
 };
 
 #endif