Enable flattening/unflattening with custom unflatten procs

src/core/SkReadBuffer.h

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkReadBuffer_DEFINED
 #define SkReadBuffer_DEFINED
 
 #include "SkBitmapHeap.h"
 #include "SkColorFilter.h"
 #include "SkData.h"
 #include "SkDrawLooper.h"
 #include "SkImageFilter.h"
 #include "SkMaskFilter.h"
 #include "SkPath.h"
 #include "SkPathEffect.h"
 #include "SkPicture.h"
 #include "SkRasterizer.h"
 #include "SkReadBuffer.h"
 #include "SkReader32.h"
 #include "SkRefCnt.h"
 #include "SkShader.h"
+#include "SkTHash.h"
 #include "SkWriteBuffer.h"
 #include "SkXfermode.h"
 
 class SkBitmap;
 class SkImage;
 
 #if defined(SK_DEBUG) && defined(SK_BUILD_FOR_MAC)
     #define DEBUG_NON_DETERMINISTIC_ASSERT
 #endif
 
@@ skipping 152 matching lines @@
     /**
      *  Call this with a pre-loaded array of Factories, in the same order as
      *  were created/written by the writer. SkPicture uses this.
      */
     void setFactoryPlayback(SkFlattenable::Factory array[], int count) {
         fFactoryArray = array;
         fFactoryCount = count;
     }
 
     /**
+     *  For an input flattenable (specified by name), set a custom factory proc
+     *  to use when unflattening.  Will make a copy of |name|.
+     *
+     *  If the global registry already has a default factory for the flattenable,
+     *  this will override that factory.  If a custom factory has already been
+     *  set for the flattenable, this will override that factory.
+     *
+     *  Custom factories cannot be removed.
+     */
+    void setCustomFactory(const SkString& name, SkFlattenable::Factory factory) {

[mtklein, 2016/04/19 18:14:55]

Seems like calling setCustomFactory("...", nullptr) will actually effectively
unset the factory.

[msarett, 2016/04/19 18:55:51]

Oh yeah of course.  Will change the comment to reflect that.

+        fCustomFactory.set(name, factory);
+    }
+
+    /**
      *  Provide a function to decode an SkBitmap from encoded data. Only used if the writer
      *  encoded the SkBitmap. If the proper decoder cannot be used, a red bitmap with the
      *  appropriate size will be used.
      */
     void setBitmapDecoder(SkPicture::InstallPixelRefProc bitmapDecoder) {
         fBitmapDecoder = bitmapDecoder;
     }
 
     // Default impelementations don't check anything.
     virtual bool validate(bool isValid) { return true; }
     virtual bool isValid() const { return true; }
     virtual bool validateAvailable(size_t size) { return true; }
 
 protected:
     SkReader32 fReader;
 
+    /**
+     *  Checks if a custom factory has been set for a given flattenable.
+     *  Returns the custom factory if it exists, or nullptr otherwise.
+     */
+    SkFlattenable::Factory getCustomFactory(const SkString& name) {
+        SkFlattenable::Factory* factoryPtr = fCustomFactory.find(name);
+        return factoryPtr ? *factoryPtr : nullptr;
+    }
+
 private:
     bool readArray(void* value, size_t size, size_t elementSize);
 
     uint32_t fFlags;
     int fVersion;
 
     void* fMemoryPtr;
 
     SkBitmapHeapReader* fBitmapStorage;
     SkTypeface** fTFArray;
     int        fTFCount;
 
     SkFlattenable::Factory* fFactoryArray;
     int                     fFactoryCount;
 
+    // Only used if we do not have an fFactoryArray.
+    SkTHashMap<SkString, SkFlattenable::Factory> fCustomFactory;
+    SkTHashMap<uint32_t, SkString> fFlattenableDict;
+
     SkPicture::InstallPixelRefProc fBitmapDecoder;
 
 #ifdef DEBUG_NON_DETERMINISTIC_ASSERT
     // Debugging counter to keep track of how many bitmaps we
     // have decoded.
     int fDecodedBitmapIndex;
 #endif // DEBUG_NON_DETERMINISTIC_ASSERT
 };
 
 #endif // SkReadBuffer_DEFINED