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* Copyright 2012 Google Inc.
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
#ifndef GrGaussianConvolutionFragmentProcessor_DEFINED
#define GrGaussianConvolutionFragmentProcessor_DEFINED
#include "src/gpu/GrCoordTransform.h"
#include "src/gpu/GrFragmentProcessor.h"
#include "src/gpu/effects/GrTextureDomain.h"
* A 1D Gaussian convolution effect. The kernel is computed as an array of 2 * half-width weights.
* Each texel is multiplied by it's weight and summed to determine the filtered color. The output
* color is set to a modulation of the filtered and input colors.
class GrGaussianConvolutionFragmentProcessor : public GrFragmentProcessor {
enum class Direction { kX, kY };
/// Convolve with a Gaussian kernel
static std::unique_ptr<GrFragmentProcessor> Make(sk_sp<GrTextureProxy> proxy,
Direction dir,
int halfWidth,
float gaussianSigma,
GrTextureDomain::Mode mode,
int* bounds) {
return std::unique_ptr<GrFragmentProcessor>(new GrGaussianConvolutionFragmentProcessor(
std::move(proxy), dir, halfWidth, gaussianSigma, mode, bounds));
const float* kernel() const { return fKernel; }
const int* bounds() const { return fBounds; }
bool useBounds() const { return fMode != GrTextureDomain::kIgnore_Mode; }
int radius() const { return fRadius; }
int width() const { return 2 * fRadius + 1; }
Direction direction() const { return fDirection; }
GrTextureDomain::Mode mode() const { return fMode; }
const char* name() const override { return "GaussianConvolution"; }
#ifdef SK_DEBUG
SkString dumpInfo() const override {
SkString str;
str.appendf("dir: %s radius: %d bounds: [%d %d]",
Direction::kX == fDirection ? "X" : "Y",
fBounds[0], fBounds[1]);
return str;
std::unique_ptr<GrFragmentProcessor> clone() const override {
return std::unique_ptr<GrFragmentProcessor>(
new GrGaussianConvolutionFragmentProcessor(*this));
// This was decided based on the min allowed value for the max texture
// samples per fragment program run in DX9SM2 (32). A sigma param of 4.0
// on a blur filter gives a kernel width of 25 while a sigma of 5.0
// would exceed a 32 wide kernel.
static const int kMaxKernelRadius = 12;
// With a C++11 we could have a constexpr version of WidthFromRadius()
// and not have to duplicate this calculation.
static const int kMaxKernelWidth = 2 * kMaxKernelRadius + 1;
/// Convolve with a Gaussian kernel
GrGaussianConvolutionFragmentProcessor(sk_sp<GrTextureProxy>, Direction,
int halfWidth, float gaussianSigma,
GrTextureDomain::Mode mode, int bounds[2]);
explicit GrGaussianConvolutionFragmentProcessor(const GrGaussianConvolutionFragmentProcessor&);
GrGLSLFragmentProcessor* onCreateGLSLInstance() const override;
void onGetGLSLProcessorKey(const GrShaderCaps&, GrProcessorKeyBuilder*) const override;
bool onIsEqual(const GrFragmentProcessor&) const override;
const TextureSampler& onTextureSampler(int) const override { return fTextureSampler; }
GrCoordTransform fCoordTransform;
TextureSampler fTextureSampler;
// TODO: Inline the kernel constants into the generated shader code. This may involve pulling
// some of the logic from SkGpuBlurUtils into this class related to radius/sigma calculations.
float fKernel[kMaxKernelWidth];
int fBounds[2];
int fRadius;
Direction fDirection;
GrTextureDomain::Mode fMode;
typedef GrFragmentProcessor INHERITED;