Add matrix constructing helpers to SkMatrix

gm/convexpolyeffect.cpp

 
 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 // This test only works with the GPU backend.
 
@@ skipping 173 matching lines @@
             const SkPath* path = iter.get();
             SkScalar x = 0;
 
             for (int et = 0; et < kGrProcessorEdgeTypeCnt; ++et) {
                 GrTestTarget tt;
                 context->getTestTarget(&tt);
                 if (NULL == tt.target()) {
                     SkDEBUGFAIL("Couldn't get Gr test target.");
                     return;
                 }
-                SkMatrix m;
+                const SkMatrix m = SkMatrix::MakeTrans(x, y);
                 SkPath p;
-                m.setTranslate(x, y);
                 path->transform(m, &p);
 
                 GrPrimitiveEdgeType edgeType = (GrPrimitiveEdgeType) et;
                 SkAutoTUnref<GrFragmentProcessor> fp(GrConvexPolyEffect::Create(edgeType, p));
                 if (!fp) {
                     continue;
                 }
 
                 GrPipelineBuilder pipelineBuilder;
                 pipelineBuilder.addCoverageProcessor(fp);
@@ skipping 77 matching lines @@
     SkTLList<SkPath> fPaths;
     SkTLList<SkRect> fRects;
 
     typedef GM INHERITED;
 };
 
 DEF_GM( return SkNEW(ConvexPolyEffect); )
 }
 
 #endif