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 123 matching lines @@
         Rec* fCurrRec;
 
         static void ApplyInfo(SkPaint* dst, const SkPaint& src, const LayerInfo&);
     };
 
     class MyRegistrar : public SkFlattenable::Registrar {
     public:
         MyRegistrar();
     };
 
+    friend class SkLayerDrawLooperBuilder;
     typedef SkDrawLooper INHERITED;
 };
 
+class SK_API SkLayerDrawLooperBuilder {
+public:
+    SkLayerDrawLooperBuilder();
+    ~SkLayerDrawLooperBuilder();
+
+    /**
+     *  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 SkLayerDrawLooper::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 SkLayerDrawLooper::LayerInfo&);
+
+    /**
+      * Pass list of layers onto newly built looper and return it. This will
+      * also reset the builder, so it can be used to build another looper.
+      */
+    SkDrawLooper* createLooper();

[reed1, 2014/02/07 18:32:22]

possibly call this detachLooper(), as in other places Skia uses the term
"detach" to signify that one object is transferring ownership to the caller.

[Dominik Grewe, 2014/02/07 18:57:02]

Done.

+
+private:
+    SkLayerDrawLooper::Rec* fRecs;
+    SkLayerDrawLooper::Rec* fTopRec;
+    int                     fCount;
+};
+
 #endif