Image filters: force near-zero floating point parameters to zero.

src/effects/SkArithmeticMode.cpp

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkArithmeticMode.h"
 #include "SkColorPriv.h"
 #include "SkNx.h"
 #include "SkRasterPipeline.h"
 #include "SkReadBuffer.h"
 #include "SkString.h"
 #include "SkUnPreMultiply.h"
 #include "SkWriteBuffer.h"
 #if SK_SUPPORT_GPU
 #include "SkArithmeticMode_gpu.h"
 #endif
 
 class SkArithmeticMode_scalar : public SkXfermode {
 public:
     SkArithmeticMode_scalar(SkScalar k1, SkScalar k2, SkScalar k3, SkScalar k4,
                             bool enforcePMColor) {
-        fK[0] = k1;
-        fK[1] = k2;
-        fK[2] = k3;
-        fK[3] = k4;
+        fK[0] = SkScalarNormalize(k1);
+        fK[1] = SkScalarNormalize(k2);
+        fK[2] = SkScalarNormalize(k3);
+        fK[3] = SkScalarNormalize(k4);
         fEnforcePMColor = enforcePMColor;
     }
 
     void xfer32(SkPMColor[], const SkPMColor[], int count, const SkAlpha[]) const override;
 
     bool onAppendStages(SkRasterPipeline* p) const override {
         p->append(&Stage, this);
         return true;
     }
 
@@ skipping 135 matching lines @@
                                        SkScalarToFloat(fK[2]),
                                        SkScalarToFloat(fK[3]),
                                        fEnforcePMColor);
 }
 
 #endif
 
 SK_DEFINE_FLATTENABLE_REGISTRAR_GROUP_START(SkArithmeticMode)
     SK_DEFINE_FLATTENABLE_REGISTRAR_ENTRY(SkArithmeticMode_scalar)
 SK_DEFINE_FLATTENABLE_REGISTRAR_GROUP_END