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
 
@@ skipping 176 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

[reed1, 2016/04/11 15:07:48]

Dox comments:

1. Does the name get copied, or must the caller keep the ptr alive for the life
of this readbuffer (or longer)?
2. Is there a way to remove a factory?
3. What happens if I specify the same name twice? (but possibly w/ different
factories)

nit: const char name[]

[msarett, 2016/04/19 18:03:50]

Done.
I said no.  I don't think this would be hard to support, I just don't see a
reason to yet.
Done.
Changed to const SkString&.

+     *  to use when unflattening.
+     */
+    void setCustomFactory(const char* name, SkFlattenable::Factory factory) {
+        NameFactoryEntry entry;
+        entry.fName = name;
+        entry.fFactory = factory;
+        fCustomFactory.push_back(entry);
+    }
+
+    /**
      *  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 char* name) {
+        for (int i = 0; i < fCustomFactory.count(); i++) {
+            if (!strcmp(fCustomFactory[i].fName, name)) {
+                return fCustomFactory[i].fFactory;
+            }
+        }
+
+        return 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;
 
+    // Maps the flattenable name to a custom factory that should be used to
+    // create the flattenable.
+    struct NameFactoryEntry {
+        const char*            fName;
+        SkFlattenable::Factory fFactory;
+    };
+    SkTArray<NameFactoryEntry> fCustomFactory;
+
     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