Builder class for SkLayerDrawLooper.

include/effects/SkLayerDrawLooper.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 SkLayerDrawLooper_DEFINED
 #define SkLayerDrawLooper_DEFINED
 
@@ skipping 89 matching lines @@
     void addLayer() { this->addLayer(0, 0); }
 
     /// Similar to addLayer, but adds a layer to the top.
     SkPaint* addLayerOnTop(const LayerInfo&);
 
     // overrides from SkDrawLooper
     virtual void init(SkCanvas*);
     virtual bool next(SkCanvas*, SkPaint* paint);
 
     SK_DEVELOPER_TO_STRING()
-    SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkLayerDrawLooper)
+
+    /// Implements Flattenable.
+    virtual Factory getFactory() const SK_OVERRIDE { return CreateProc; }
+    static SkFlattenable* CreateProc(SkReadBuffer& buffer);
 
 protected:
-    SkLayerDrawLooper(SkReadBuffer&);
     virtual void flatten(SkWriteBuffer&) const SK_OVERRIDE;
 
 private:
     struct Rec {
         Rec*    fNext;
         SkPaint fPaint;
         LayerInfo fInfo;
     };
     Rec*    fRecs;
     Rec*    fTopRec;
     int     fCount;
 
     // state-machine during the init/next cycle
     Rec* fCurrRec;
 
     static void ApplyInfo(SkPaint* dst, const SkPaint& src, const LayerInfo&);
 
     class MyRegistrar : public SkFlattenable::Registrar {
     public:
         MyRegistrar();
     };
 
     typedef SkDrawLooper INHERITED;
+
+public:
+    class SK_API Builder {
+    public:
+        Builder();
+        ~Builder();
+
+        /**
+         *  Call for each layer you want to add (from top to bottom).
+         *  This returns a paint you can modify, but that ptr is only valid until
+         *  the next call made to addLayer().
+         */
+        SkPaint* addLayer(const LayerInfo&);
+
+        /**
+         *  This layer will draw with the original paint, at the specified offset
+         */
+        void addLayer(SkScalar dx, SkScalar dy);
+
+        /**
+         *  This layer will with the original paint and no offset.
+         */
+        void addLayer() { this->addLayer(0, 0); }
+
+        /// Similar to addLayer, but adds a layer to the top.
+        SkPaint* addLayerOnTop(const LayerInfo&);
+
+        /**
+          * Pass list of layers on to newly built looper and return it. This will
+          * also reset the builder, so it can be used to build another looper.
+          */
+        SkLayerDrawLooper* detachLooper();
+
+    private:
+        Rec* fRecs;
+        Rec* fTopRec;
+        int  fCount;
+    };
 };
 
 #endif