add virtuals to optimize composing colorfilters

src/effects/SkColorMatrixFilter.cpp

 
 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 #include "SkColorMatrixFilter.h"
 #include "SkColorMatrix.h"
 #include "SkColorPriv.h"
@@ skipping 304 matching lines @@
     return NULL;
 }
 
 bool SkColorMatrixFilter::asColorMatrix(SkScalar matrix[20]) const {
     if (matrix) {
         memcpy(matrix, fMatrix.fMat, 20 * sizeof(SkScalar));
     }
     return true;
 }
 
+SkColorFilter* SkColorMatrixFilter::newComposed(const SkColorFilter* innerFilter) const {
+    SkScalar innerMatrix[20];
+    if (innerFilter->asColorMatrix(innerMatrix) && !SkColorMatrix::NeedsClamping(innerMatrix)) {
+        SkScalar concat[20];
+        SkColorMatrix::SetConcat(concat, fMatrix.fMat, innerMatrix);
+        return SkColorMatrixFilter::Create(concat);
+    }
+    return NULL;
+}
+
 #if SK_SUPPORT_GPU
 #include "GrFragmentProcessor.h"
 #include "GrInvariantOutput.h"
 #include "gl/GrGLProcessor.h"
 #include "gl/builders/GrGLProgramBuilder.h"
 
 class ColorMatrixEffect : public GrFragmentProcessor {
 public:
     static GrFragmentProcessor* Create(const SkColorMatrix& matrix) {
         return SkNEW_ARGS(ColorMatrixEffect, (matrix));
@@ skipping 162 matching lines @@
     str->append("matrix: (");
     for (int i = 0; i < 20; ++i) {
         str->appendScalar(fMatrix.fMat[i]);
         if (i < 19) {
             str->append(", ");
         }
     }
     str->append(")");
 }
 #endif