Creating framework for drawShadowedPicture

include/core/SkCanvas.h

Index: include/core/SkCanvas.h
diff --git a/include/core/SkCanvas.h b/include/core/SkCanvas.h
index 35a8d1c7b92193a4d247a4766efe54a2976ce0a6..2c6a807791a955d21c7cb06eeaf84ebc7ee6d84a 100644
--- a/include/core/SkCanvas.h
+++ b/include/core/SkCanvas.h
@@ -17,6 +17,7 @@
 #include "SkRegion.h"
 #include "SkSurfaceProps.h"
 #include "SkXfermode.h"
+#include "SkLights.h"
 
 class GrContext;
 class GrDrawContext;
@@ -451,6 +452,7 @@ public:
     */
     void resetMatrix();
 
+#ifdef SK_USE_SHADOWS
     /** Add the specified translation to the current draw depth of the canvas.
         @param z    The distance to translate in Z.
                     Negative into screen, positive out of screen.
@@ -458,6 +460,16 @@ public:
     */
     void translateZ(SkScalar z);
 
+    /** Set the current set of lights in the canvas.
+        @param lights   The lights that we want the canvas to have.
+    */
+    void setLights(sk_sp<SkLights> lights);
+
+    /** Returns the current set of lights the canvas uses
+      */
+    sk_sp<SkLights> getLights() const;
+#endif
+
     /**
      *  Modify the current clip with the specified rectangle.
      *  @param rect The rect to combine with the current clip
@@ -1049,6 +1061,34 @@ public:
         this->drawPicture(picture.get(), matrix, paint);
     }
 
+#ifdef SK_USE_SHADOWS
+    /**
+     *  Draw the picture into this canvas.
+     *
+     *  We will use the canvas's lights along with the picture information (draw depths of
+     *  objects, etc) to first create a set of shadowmaps for the light-picture pairs, and
+     *  then use that set of shadowmaps to render the scene with shadows.
+     *
+     *  If matrix is non-null, apply that matrix to the CTM when drawing this picture. This is
+     *  logically equivalent to
+     *      save/concat/drawPicture/restore
+     *
+     *  If paint is non-null, draw the picture into a temporary buffer, and then apply the paint's
+     *  alpha/colorfilter/imagefilter/xfermode to that buffer as it is drawn to the canvas.
+     *  This is logically equivalent to
+     *      saveLayer(paint)/drawPicture/restore
+     *
+     */
+    void drawShadowedPicture(const SkPicture*,
+                             const SkMatrix* matrix,
+                             const SkPaint* paint);
+    void drawShadowedPicture(const sk_sp<SkPicture>& picture,
+                             const SkMatrix* matrix,
+                             const SkPaint* paint) {
+        this->drawShadowedPicture(picture.get(), matrix, paint);
+    }
+#endif
+
     enum VertexMode {
         kTriangles_VertexMode,
         kTriangleStrip_VertexMode,
@@ -1267,10 +1307,14 @@ public:
     void temporary_internal_describeTopLayer(SkMatrix* matrix, SkIRect* clip_bounds);
 
 protected:
+#ifdef SK_USE_SHADOWS
     /** Returns the current (cumulative) draw depth of the canvas.
       */
     SkScalar getZ() const;
 
+    sk_sp<SkLights> fLights;
+#endif
+
     /** After calling saveLayer(), there can be any number of devices that make
         up the top-most drawing area. LayerIter can be used to iterate through
         those devices. Note that the iterator is only valid until the next API
@@ -1336,7 +1380,10 @@ protected:
     virtual void didRestore() {}
     virtual void didConcat(const SkMatrix&) {}
     virtual void didSetMatrix(const SkMatrix&) {}
+
+#ifdef SK_USE_SHADOWS
     virtual void didTranslateZ(SkScalar) {}
+#endif
 
     virtual void onDrawAnnotation(const SkRect&, const char key[], SkData* value);
     virtual void onDrawDRRect(const SkRRect&, const SkRRect&, const SkPaint&);
@@ -1403,6 +1450,12 @@ protected:
 
     virtual void onDrawPicture(const SkPicture*, const SkMatrix*, const SkPaint*);
 
+#ifdef SK_USE_SHADOWS
+    virtual void onDrawShadowedPicture(const SkPicture*,
+                                       const SkMatrix*,
+                                       const SkPaint*);
+#endif
+
     // Returns the canvas to be used by DrawIter. Default implementation
     // returns this. Subclasses that encapsulate an indirect canvas may
     // need to overload this method. The impl must keep track of this, as it