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..cde3d92f0fd8e3bb550aa8d8ed4a7b4ac8596611 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;
@@ -458,6 +459,11 @@ 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);

[jvanverth1, 2016/07/15 19:16:30]

You need to hide this (and translateZ) behind a #ifdef so it's not available as
part of the standard API. You'll also need to add a variable to
gyp/common_variables.gypi so it can be turned on easily for special builds. Then
in common.gypi you set the #define if it's enabled. See the gyp variable
skia_vulkan and the #define SK_VULKAN for an example.

[vjiaoblack, 2016/07/18 13:03:23]

Done.

+
     /**
      *  Modify the current clip with the specified rectangle.
      *  @param rect The rect to combine with the current clip
@@ -1049,6 +1055,32 @@ public:
         this->drawPicture(picture.get(), matrix, paint);
     }
 
+    /**
+     *  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*,

[jvanverth1, 2016/07/15 19:16:30]

Hide these calls in an #ifdef block too.

[vjiaoblack, 2016/07/18 13:03:22]

Done.

+                             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);
+    }
+
     enum VertexMode {
         kTriangles_VertexMode,
         kTriangleStrip_VertexMode,
@@ -1271,6 +1303,11 @@ protected:
       */
     SkScalar getZ() const;
 
+    /** Returns the current set of lights the canvas uses
+      */
+    sk_sp<SkLights> getLights() const;

[jvanverth1, 2016/07/15 19:16:30]

I'm not sure I understand the point of having a protected accessor when the
member variable is also protected. Is this a pattern we do elsewhere?

[vjiaoblack, 2016/07/18 13:03:23]

Done.

+    sk_sp<SkLights> fLights;
+
     /** 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
@@ -1402,6 +1439,9 @@ protected:
     virtual void onDiscard();
 
     virtual void onDrawPicture(const SkPicture*, const SkMatrix*, const SkPaint*);
+    virtual void onDrawShadowedPicture(const SkPicture*,
+                                       const SkMatrix*,
+                                       const SkPaint*);
 
     // Returns the canvas to be used by DrawIter. Default implementation
     // returns this. Subclasses that encapsulate an indirect canvas may