Add a map homogenous points to SkMatrix

include/core/SkMatrix.h

Index: include/core/SkMatrix.h
diff --git a/include/core/SkMatrix.h b/include/core/SkMatrix.h
index f148e390b5cd4930f2d985f61a286cda3748b7cc..f46aa2f65fa7149ed630d122d2b846d3604f94c7 100644
--- a/include/core/SkMatrix.h
+++ b/include/core/SkMatrix.h
@@ -423,6 +423,19 @@ public:
         }
     }
 
+    /** Apply this matrix to the array of homogeneous points, specified by src,
+        where a homogeneous point is defined by 3 contiguous scalar values,
+        and write the transformed points into the array of scalars specified by dst.
+        dst[] = M * src[]
+        @param dst  Where the transformed coordinates are written. It must
+                    contain at least 3 * count entries
+        @param src  The original coordinates that are to be transformed. It
+                    must contain at least 3 * count entries
+        @param count The number of points in src to read, and then transform

[reed1, 2013/08/07 18:16:50]

Lets be very clear what 'count' is measuring. Its is the number of
homogeneous_points, not SkPoints. Maybe the dox could say the number of triples?
Perhaps a tiny argument for declaring a struct here, so that count would be
unambiguous (tho I don't know what to call it).

+                     into dst.
+    */
+    void mapHomogeneousPoints(SkScalar dst[], const SkScalar src[], int count) const;
+
     void mapXY(SkScalar x, SkScalar y, SkPoint* result) const {
         SkASSERT(result);
         this->getMapXYProc()(*this, x, y, result);
@@ -666,6 +679,8 @@ private:
                              int count);
     static void Persp_pts(const SkMatrix&, SkPoint dst[], const SkPoint[], int);
 
+    static void Homogeneous_pts(const SkMatrix&, SkScalar dst[], const SkScalar[], int);

[reed1, 2013/08/07 18:16:50]

Why is there a separate static function? Can just put its impl inside the
method.

+
     static const MapPtsProc gMapPtsProcs[];
 
     friend class SkPerspIter;