Try out SkMatrix::Concat.

include/core/SkMatrix.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 SkMatrix_DEFINED
@@ skipping 572 matching lines @@
      */
     static const SkMatrix& I();
 
     /**
      *  Return a reference to a const matrix that is "invalid", one that could
      *  never be used.
      */
     static const SkMatrix& InvalidMatrix();
 
     /**
+     * Return the concatenation of two matrices, a * b.
+     */
+    static SkMatrix Concat(const SkMatrix& a, const SkMatrix& b) {
+        SkMatrix result;
+        result.setConcat(a, b);
+        return result;
+    }
+
+    /**
      * Testing routine; the matrix's type cache should never need to be
      * manually invalidated during normal use.
      */
     void dirtyMatrixTypeCache() {
         this->setTypeMask(kUnknown_Mask);
     }
 
 private:
     enum {
         /** Set if the matrix will map a rectangle to another rectangle. This
@@ skipping 91 matching lines @@
     static void RotTrans_pts(const SkMatrix&, SkPoint dst[], const SkPoint[],
                              int count);
     static void Persp_pts(const SkMatrix&, SkPoint dst[], const SkPoint[], int);
 
     static const MapPtsProc gMapPtsProcs[];
 
     friend class SkPerspIter;
 };
 
 #endif