Prototype code that turns any/every flattenable into JSON

include/core/SkWriteBuffer.h

Index: include/core/SkWriteBuffer.h
diff --git a/include/core/SkWriteBuffer.h b/include/core/SkWriteBuffer.h
index b69a75ab12ae32570fbc36deed75327cf1a9b194..87ac8bf21494aa3ea8ec2aec7823a03bf74a0bea 100644
--- a/include/core/SkWriteBuffer.h
+++ b/include/core/SkWriteBuffer.h
@@ -25,15 +25,57 @@ class SkRefCntSet;
 
 class SkWriteBuffer {
 public:
+    SkWriteBuffer() {}
+    virtual ~SkWriteBuffer() {}
+
+    virtual bool isCrossProcess() const = 0;

[mtklein, 2016/05/04 15:35:09]

Just a thought: another way to reduce the burden on SkWriteBuffer subclasses
without having to maintain state here is to default this to

    virtual bool isCrossProcess() const { return false; }

That way only the buffer that cares need care.

+
+    virtual void writeByteArray(const void* data, size_t size) = 0;
+    void writeDataAsByteArray(SkData* data) {
+        this->writeByteArray(data->data(), data->size());
+    }
+    virtual void writeBool(bool value) = 0;
+    virtual void writeScalar(SkScalar value) = 0;
+    virtual void writeScalarArray(const SkScalar* value, uint32_t count) = 0;
+    virtual void writeInt(int32_t value) = 0;
+    virtual void writeIntArray(const int32_t* value, uint32_t count) = 0;
+    virtual void writeUInt(uint32_t value) = 0;
+    void write32(int32_t value) {
+        this->writeInt(value);
+    }
+    virtual void writeString(const char* value) = 0;
+
+    virtual void writeFlattenable(const SkFlattenable* flattenable) = 0;
+    virtual void writeColor(SkColor color) = 0;
+    virtual void writeColorArray(const SkColor* color, uint32_t count) = 0;
+    virtual void writePoint(const SkPoint& point) = 0;
+    virtual void writePointArray(const SkPoint* point, uint32_t count) = 0;
+    virtual void writeMatrix(const SkMatrix& matrix) = 0;
+    virtual void writeIRect(const SkIRect& rect) = 0;
+    virtual void writeRect(const SkRect& rect) = 0;
+    virtual void writeRegion(const SkRegion& region) = 0;
+    virtual void writePath(const SkPath& path) = 0;
+    virtual size_t writeStream(SkStream* stream, size_t length) = 0;
+    virtual void writeBitmap(const SkBitmap& bitmap) = 0;
+    virtual void writeImage(const SkImage*) = 0;
+    virtual void writeTypeface(SkTypeface* typeface) = 0;
+    virtual void writePaint(const SkPaint& paint) = 0;
+};
+
+/**
+ * Concrete implementation that serializes to a flat binary blob.
+ */
+class SkBinaryWriteBuffer final : public SkWriteBuffer {
+public:
     enum Flags {
-        kCrossProcess_Flag  = 1 << 0,
+        kCrossProcess_Flag = 1 << 0,
     };
 
-    SkWriteBuffer(uint32_t flags = 0);
-    SkWriteBuffer(void* initialStorage, size_t storageSize, uint32_t flags = 0);
-    ~SkWriteBuffer();
+    SkBinaryWriteBuffer(uint32_t flags = 0);
+    SkBinaryWriteBuffer(void* initialStorage, size_t storageSize, uint32_t flags = 0);
+    ~SkBinaryWriteBuffer();
 
-    bool isCrossProcess() const {
+    bool isCrossProcess() const override {
         return SkToBool(fFlags & kCrossProcess_Flag);
     }
 
@@ -43,39 +85,35 @@ public:
 
     size_t bytesWritten() const { return fWriter.bytesWritten(); }
 
-    void writeByteArray(const void* data, size_t size);
-    void writeDataAsByteArray(SkData* data) { this->writeByteArray(data->data(), data->size()); }
-    void writeBool(bool value);
-    void writeScalar(SkScalar value);
-    void writeScalarArray(const SkScalar* value, uint32_t count);
-    void writeInt(int32_t value);
-    void writeIntArray(const int32_t* value, uint32_t count);
-    void writeUInt(uint32_t value);
-    void write32(int32_t value);
-    void writeString(const char* value);
-
-    void writeFlattenable(const SkFlattenable* flattenable);
-    void writeColor(const SkColor& color);
-    void writeColorArray(const SkColor* color, uint32_t count);
-    void writePoint(const SkPoint& point);
-    void writePointArray(const SkPoint* point, uint32_t count);
-    void writeMatrix(const SkMatrix& matrix);
-    void writeIRect(const SkIRect& rect);
-    void writeRect(const SkRect& rect);
-    void writeRegion(const SkRegion& region);
-    void writePath(const SkPath& path);
-    size_t writeStream(SkStream* stream, size_t length);
-    void writeBitmap(const SkBitmap& bitmap);
-    void writeImage(const SkImage*);
-    void writeTypeface(SkTypeface* typeface);
-    void writePaint(const SkPaint& paint) { paint.flatten(*this); }
+    void writeByteArray(const void* data, size_t size) override;
+    void writeBool(bool value) override;
+    void writeScalar(SkScalar value) override;
+    void writeScalarArray(const SkScalar* value, uint32_t count) override;
+    void writeInt(int32_t value) override;
+    void writeIntArray(const int32_t* value, uint32_t count) override;
+    void writeUInt(uint32_t value) override;
+    void writeString(const char* value) override;
+
+    void writeFlattenable(const SkFlattenable* flattenable) override;
+    void writeColor(SkColor color) override;
+    void writeColorArray(const SkColor* color, uint32_t count) override;
+    void writePoint(const SkPoint& point) override;
+    void writePointArray(const SkPoint* point, uint32_t count) override;
+    void writeMatrix(const SkMatrix& matrix) override;
+    void writeIRect(const SkIRect& rect) override;
+    void writeRect(const SkRect& rect) override;
+    void writeRegion(const SkRegion& region) override;
+    void writePath(const SkPath& path) override;
+    size_t writeStream(SkStream* stream, size_t length) override;
+    void writeBitmap(const SkBitmap& bitmap) override;
+    void writeImage(const SkImage*) override;
+    void writeTypeface(SkTypeface* typeface) override;
+    void writePaint(const SkPaint& paint) override;
 
     bool writeToStream(SkWStream*);
     void writeToMemory(void* dst) { fWriter.flatten(dst); }
 
     SkFactorySet* setFactoryRecorder(SkFactorySet*);
-
-    SkRefCntSet* getTypefaceRecorder() const { return fTFSet; }
     SkRefCntSet* setTypefaceRecorder(SkRefCntSet*);
 
     /**