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 GrConvolutionEffect_DEFINED
9#define GrConvolutionEffect_DEFINED
10
11#include "Gr1DKernelEffect.h"
12
13class GrGLConvolutionEffect;
14
15/**
16 * A convolution effect. The kernel is specified as an array of 2 * half-width
17 * + 1 weights. Each texel is multiplied by it's weight and summed to determine
18 * the output color. The output color is modulated by the input color.
19 */
20class GrConvolutionEffect : public Gr1DKernelEffect {
21
22public:
23
24    /// Convolve with an arbitrary user-specified kernel
25    static GrFragmentProcessor* Create(GrTexture* tex,
26                                       Direction dir,
27                                       int halfWidth,
28                                       const float* kernel,
29                                       bool useBounds,
30                                       float bounds[2]) {
31        return SkNEW_ARGS(GrConvolutionEffect, (tex,
32                                                dir,
33                                                halfWidth,
34                                                kernel,
35                                                useBounds,
36                                                bounds));
37    }
38
39    /// Convolve with a Gaussian kernel
40    static GrFragmentProcessor* CreateGaussian(GrTexture* tex,
41                                               Direction dir,
42                                               int halfWidth,
43                                               float gaussianSigma,
44                                               bool useBounds,
45                                               float bounds[2]) {
46        return SkNEW_ARGS(GrConvolutionEffect, (tex,
47                                                dir,
48                                                halfWidth,
49                                                gaussianSigma,
50                                                useBounds,
51                                                bounds));
52    }
53
54    virtual ~GrConvolutionEffect();
55
56    const float* kernel() const { return fKernel; }
57
58    const float* bounds() const { return fBounds; }
59    bool useBounds() const { return fUseBounds; }
60
61    static const char* Name() { return "Convolution"; }
62
63    typedef GrGLConvolutionEffect GLProcessor;
64
65    virtual const GrBackendFragmentProcessorFactory& getFactory() const SK_OVERRIDE;
66
67    virtual void getConstantColorComponents(GrColor*, uint32_t* validFlags) const {
68        // If the texture was opaque we could know that the output color if we knew the sum of the
69        // kernel values.
70        *validFlags = 0;
71    }
72
73    enum {
74        // This was decided based on the min allowed value for the max texture
75        // samples per fragment program run in DX9SM2 (32). A sigma param of 4.0
76        // on a blur filter gives a kernel width of 25 while a sigma of 5.0
77        // would exceed a 32 wide kernel.
78        kMaxKernelRadius = 12,
79        // With a C++11 we could have a constexpr version of WidthFromRadius()
80        // and not have to duplicate this calculation.
81        kMaxKernelWidth = 2 * kMaxKernelRadius + 1,
82    };
83
84protected:
85
86    float fKernel[kMaxKernelWidth];
87    bool fUseBounds;
88    float fBounds[2];
89
90private:
91    GrConvolutionEffect(GrTexture*, Direction,
92                        int halfWidth,
93                        const float* kernel,
94                        bool useBounds,
95                        float bounds[2]);
96
97    /// Convolve with a Gaussian kernel
98    GrConvolutionEffect(GrTexture*, Direction,
99                        int halfWidth,
100                        float gaussianSigma,
101                        bool useBounds,
102                        float bounds[2]);
103
104    virtual bool onIsEqual(const GrProcessor&) const SK_OVERRIDE;
105
106    GR_DECLARE_FRAGMENT_PROCESSOR_TEST;
107
108    typedef Gr1DKernelEffect INHERITED;
109};
110
111#endif
112