1/*
2 * Copyright 2013 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 GrBicubicTextureEffect_DEFINED
9#define GrBicubicTextureEffect_DEFINED
10
11#include "src/gpu/effects/GrTextureDomain.h"
12#include "src/gpu/glsl/GrGLSLFragmentProcessor.h"
13
14class GrInvariantOutput;
15
16class GrBicubicEffect : public GrFragmentProcessor {
17public:
18 enum {
19 kFilterTexelPad = 2, // Given a src rect in texels to be filtered, this number of
20 // surrounding texels are needed by the kernel in x and y.
21 };
22
23 enum class Direction {
24 /** Apply bicubic kernel in local coord x, nearest neighbor in y. */
25 kX,
26 /** Apply bicubic kernel in local coord y, nearest neighbor in x. */
27 kY,
28 /** Apply bicubic in both x and y. */
29 kXY
30 };
31
32 const char* name() const override { return "Bicubic"; }
33
34 std::unique_ptr<GrFragmentProcessor> clone() const override {
35 return std::unique_ptr<GrFragmentProcessor>(new GrBicubicEffect(*this));
36 }
37
38 /**
39 * Create a Mitchell filter effect with specified texture matrix with clamp wrap mode.
40 */
41 static std::unique_ptr<GrFragmentProcessor> Make(GrSurfaceProxyView view,
42 SkAlphaType,
43 const SkMatrix&,
44 Direction direction);
45
46 /**
47 * Create a Mitchell filter effect for a texture with arbitrary wrap modes.
48 */
49 static std::unique_ptr<GrFragmentProcessor> Make(GrSurfaceProxyView view,
50 SkAlphaType,
51 const SkMatrix&,
52 const GrSamplerState::WrapMode wrapX,
53 const GrSamplerState::WrapMode wrapY,
54 Direction,
55 const GrCaps&);
56
57 /**
58 * Create a Mitchell filter effect for a subset of a texture, specified by a texture coordinate
59 * rectangle subset. The WrapModes apply to the subset.
60 */
61 static std::unique_ptr<GrFragmentProcessor> MakeSubset(GrSurfaceProxyView view,
62 SkAlphaType,
63 const SkMatrix&,
64 const GrSamplerState::WrapMode wrapX,
65 const GrSamplerState::WrapMode wrapY,
66 const SkRect& subset,
67 Direction,
68 const GrCaps&);
69
70 /**
71 * Make a Mitchell filter of a another fragment processor. The bicubic filter assumes that the
72 * discrete samples of the provided processor are at half-integer coords.
73 */
74 static std::unique_ptr<GrFragmentProcessor> Make(std::unique_ptr<GrFragmentProcessor>,
75 SkAlphaType,
76 const SkMatrix&,
77 Direction);
78
79 /**
80 * Determines whether the bicubic effect should be used based on the transformation from the
81 * local coords to the device. Returns true if the bicubic effect should be used. filterMode
82 * is set to appropriate filtering mode to use regardless of the return result (e.g. when this
83 * returns false it may indicate that the best fallback is to use kMipMap, kBilerp, or
84 * kNearest).
85 */
86 static bool ShouldUseBicubic(const SkMatrix& localCoordsToDevice,
87 GrSamplerState::Filter* filterMode);
88
89private:
90 class Impl;
91
92 enum class Clamp {
93 kUnpremul, // clamps rgba to 0..1
94 kPremul, // clamps a to 0..1 and rgb to 0..a
95 };
96
97 GrBicubicEffect(std::unique_ptr<GrFragmentProcessor>, const SkMatrix&, Direction, Clamp);
98
99 explicit GrBicubicEffect(const GrBicubicEffect&);
100
101 GrGLSLFragmentProcessor* onCreateGLSLInstance() const override;
102
103 void onGetGLSLProcessorKey(const GrShaderCaps&, GrProcessorKeyBuilder*) const override;
104
105 bool onIsEqual(const GrFragmentProcessor&) const override;
106
107 SkPMColor4f constantOutputForConstantInput(const SkPMColor4f&) const override;
108
109 GrCoordTransform fCoordTransform;
110 Direction fDirection;
111 Clamp fClamp;
112
113 GR_DECLARE_FRAGMENT_PROCESSOR_TEST
114
115 typedef GrFragmentProcessor INHERITED;
116};
117
118#endif
119