Builder class for SkLayerRasterizer.

include/effects/SkLayerRasterizer.h

 
 /*
  * Copyright 2006 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 
 #ifndef SkLayerRasterizer_DEFINED
 #define SkLayerRasterizer_DEFINED
 
 #include "SkRasterizer.h"
 #include "SkDeque.h"
 #include "SkScalar.h"
 
 class SkPaint;
 
 class SK_API SkLayerRasterizer : public SkRasterizer {
 public:
             SkLayerRasterizer();
     virtual ~SkLayerRasterizer();
 
+    class SK_API Builder {
+    public:
+        Builder();
+        ~Builder();
+
+        void addLayer(const SkPaint& paint) {
+            this->addLayer(paint, 0, 0);
+        }
+
+        /**
+          *  Add a new layer (above any previous layers) to the rasterizer.
+          *  The layer will extract those fields that affect the mask from
+          *  the specified paint, but will not retain a reference to the paint
+          *  object itself, so it may be reused without danger of side-effects.
+          */
+        void addLayer(const SkPaint& paint, SkScalar dx, SkScalar dy);
+
+        /**
+          *  Pass queue of layers on to newly created layer rasterizer and return it. The builder
+          *  cannot be used any more after calling this function.
+          */
+        SkLayerRasterizer* detachRasterizer();
+
+    private:
+        SkDeque* fLayers;
+    };
+
     void addLayer(const SkPaint& paint) {

[reed1, 2014/02/24 13:35:40]

Consider adding a build-guard here, to remind us to eliminate callers to the
non-builder calls like this one.

#ifndef SK_SUPPORT_LEGACY_LAYERRASTERIZER_API
    void addLayer(...);
#endif

Then we can *not* define this for skia builds (since we can fix all the callers
w/ this CL), but can #define this for Chrome if needed.

[Dominik Grewe, 2014/02/24 13:54:34]

Done.

         this->addLayer(paint, 0, 0);
     }
 
     /**    Add a new layer (above any previous layers) to the rasterizer.
         The layer will extract those fields that affect the mask from
         the specified paint, but will not retain a reference to the paint
         object itself, so it may be reused without danger of side-effects.
     */
     void addLayer(const SkPaint& paint, SkScalar dx, SkScalar dy);
 
     SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkLayerRasterizer)
 
 protected:
+    SkLayerRasterizer(SkDeque* layers);
     SkLayerRasterizer(SkReadBuffer&);
     virtual void flatten(SkWriteBuffer&) const SK_OVERRIDE;
 
     // override from SkRasterizer
     virtual bool onRasterize(const SkPath& path, const SkMatrix& matrix,
                              const SkIRect* clipBounds,
                              SkMask* mask, SkMask::CreateMode mode) const;
 
 private:
-    SkDeque fLayers;
+    SkDeque* fLayers;
 
     typedef SkRasterizer INHERITED;
 };
 
 #endif