Create helper functions to use in computeInvariantOutput calls

src/effects/SkDisplacementMapEffect.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 "SkDisplacementMapEffect.h"
 #include "SkReadBuffer.h"
 #include "SkWriteBuffer.h"
@@ skipping 479 matching lines @@
 const GrBackendFragmentProcessorFactory& GrDisplacementMapEffect::getFactory() const {
     return GrTBackendFragmentProcessorFactory<GrDisplacementMapEffect>::getInstance();
 }
 
 void GrDisplacementMapEffect::onComputeInvariantOutput(InvariantOutput* inout) const {
     // Any displacement offset bringing a pixel out of bounds will output a color of (0,0,0,0),
     // so the only way we'd get a constant alpha is if the input color image has a constant alpha
     // and no displacement offset push any texture coordinates out of bounds OR if the constant
     // alpha is 0. Since this isn't trivial to compute at this point, let's assume the output is
     // not of constant color when a displacement effect is applied.
-    inout->fValidFlags = 0;
-    inout->fIsSingleComponent = false;
+    inout->setToUnknown();
 }
 
 ///////////////////////////////////////////////////////////////////////////////
 
 GR_DEFINE_FRAGMENT_PROCESSOR_TEST(GrDisplacementMapEffect);
 
 GrFragmentProcessor* GrDisplacementMapEffect::TestCreate(SkRandom* random,
                                               GrContext*,
                                               const GrDrawTargetCaps&,
                                               GrTexture* textures[]) {
@@ skipping 120 matching lines @@
 void GrGLDisplacementMapEffect::GenKey(const GrProcessor& proc,
                                        const GrGLCaps&, GrProcessorKeyBuilder* b) {
     const GrDisplacementMapEffect& displacementMap = proc.cast<GrDisplacementMapEffect>();
 
     uint32_t xKey = displacementMap.xChannelSelector();
     uint32_t yKey = displacementMap.yChannelSelector() << kChannelSelectorKeyBits;
 
     b->add32(xKey | yKey);
 }
 #endif