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1 /*
2  * Copyright 2012 Google Inc.
3  *
4  * Use of this source code is governed by a BSD-style license that can be
5  * found in the LICENSE file.
6  */
7 
8 #ifndef GrGaussianConvolutionFragmentProcessor_DEFINED
9 #define GrGaussianConvolutionFragmentProcessor_DEFINED
10 
11 #include "Gr1DKernelEffect.h"
12 
13 /**
14  * A 1D Gaussian convolution effect. The kernel is computed as an array of 2 * half-width weights.
15  * Each texel is multiplied by it's weight and summed to determine the filtered color. The output
16  * color is set to a modulation of the filtered and input colors.
17  */
18 class GrGaussianConvolutionFragmentProcessor : public Gr1DKernelEffect {
19 public:
20     /// Convolve with a Gaussian kernel
Make(GrResourceProvider * resourceProvider,sk_sp<GrTextureProxy> proxy,Direction dir,int halfWidth,float gaussianSigma,bool useBounds,int * bounds)21     static sk_sp<GrFragmentProcessor> Make(GrResourceProvider* resourceProvider,
22                                            sk_sp<GrTextureProxy> proxy,
23                                            Direction dir,
24                                            int halfWidth,
25                                            float gaussianSigma,
26                                            bool useBounds,
27                                            int* bounds) {
28         return sk_sp<GrFragmentProcessor>(new GrGaussianConvolutionFragmentProcessor(
29             resourceProvider, std::move(proxy), dir, halfWidth, gaussianSigma, useBounds, bounds));
30     }
31 
32     ~GrGaussianConvolutionFragmentProcessor() override;
33 
kernel()34     const float* kernel() const { return fKernel; }
35 
bounds()36     const int* bounds() const { return fBounds; }
useBounds()37     bool useBounds() const { return fUseBounds; }
38 
name()39     const char* name() const override { return "GaussianConvolution"; }
40 
41     // This was decided based on the min allowed value for the max texture
42     // samples per fragment program run in DX9SM2 (32). A sigma param of 4.0
43     // on a blur filter gives a kernel width of 25 while a sigma of 5.0
44     // would exceed a 32 wide kernel.
45     static const int kMaxKernelRadius = 12;
46     // With a C++11 we could have a constexpr version of WidthFromRadius()
47     // and not have to duplicate this calculation.
48     static const int kMaxKernelWidth = 2 * kMaxKernelRadius + 1;
49 
50 private:
51     /// Convolve with a Gaussian kernel
52     GrGaussianConvolutionFragmentProcessor(GrResourceProvider*, sk_sp<GrTextureProxy>, Direction,
53                                            int halfWidth, float gaussianSigma, bool useBounds,
54                                            int bounds[2]);
55 
56     GrGLSLFragmentProcessor* onCreateGLSLInstance() const override;
57 
58     void onGetGLSLProcessorKey(const GrShaderCaps&, GrProcessorKeyBuilder*) const override;
59 
60     bool onIsEqual(const GrFragmentProcessor&) const override;
61 
62     GR_DECLARE_FRAGMENT_PROCESSOR_TEST;
63 
64     // TODO: Inline the kernel constants into the generated shader code. This may involve pulling
65     // some of the logic from SkGpuBlurUtils into this class related to radius/sigma calculations.
66     float fKernel[kMaxKernelWidth];
67     bool  fUseBounds;
68     int   fBounds[2];
69 
70     typedef Gr1DKernelEffect INHERITED;
71 };
72 
73 #endif
74