1 /*
2 * Copyright 2015 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 #include "GrBlend.h"
9
10 /**
11 * MaskedColor is used to evaluate the color and valid color component flags through the
12 * blending equation. Could possibly extend this to be used more broadly.
13 */
14 class MaskedColor {
15 public:
MaskedColor(GrColor color,GrColorComponentFlags flags)16 MaskedColor(GrColor color, GrColorComponentFlags flags)
17 : fColor(color)
18 , fFlags(flags) {}
19
MaskedColor()20 MaskedColor() {}
21
set(GrColor color,GrColorComponentFlags flags)22 void set(GrColor color, GrColorComponentFlags flags) {
23 fColor = color;
24 fFlags = flags;
25 }
26
Invert(const MaskedColor & in)27 static MaskedColor Invert(const MaskedColor& in) {
28 return MaskedColor(GrInvertColor(in.fColor), in.fFlags);
29 }
30
ExtractAlpha(const MaskedColor & in)31 static MaskedColor ExtractAlpha(const MaskedColor& in) {
32 GrColorComponentFlags flags = (in.fFlags & kA_GrColorComponentFlag) ?
33 kRGBA_GrColorComponentFlags : kNone_GrColorComponentFlags;
34 return MaskedColor(GrColorPackA4(GrColorUnpackA(in.fColor)), flags);
35 }
36
ExtractInverseAlpha(const MaskedColor & in)37 static MaskedColor ExtractInverseAlpha(const MaskedColor& in) {
38 GrColorComponentFlags flags = (in.fFlags & kA_GrColorComponentFlag) ?
39 kRGBA_GrColorComponentFlags : kNone_GrColorComponentFlags;
40 return MaskedColor(GrColorPackA4(0xFF - GrColorUnpackA(in.fColor)), flags);
41 }
42
Mul(const MaskedColor & a,const MaskedColor & b)43 static MaskedColor Mul(const MaskedColor& a, const MaskedColor& b) {
44 GrColorComponentFlags outFlags = (a.fFlags & b.fFlags) | a.componentsWithValue(0) |
45 b.componentsWithValue(0);
46 return MaskedColor(GrColorMul(a.fColor, b.fColor), outFlags);
47 }
48
SatAdd(const MaskedColor & a,const MaskedColor & b)49 static MaskedColor SatAdd(const MaskedColor& a, const MaskedColor& b) {
50 GrColorComponentFlags outFlags = (a.fFlags & b.fFlags) | a.componentsWithValue(0xFF) |
51 b.componentsWithValue(0xFF);
52 return MaskedColor(GrColorSatAdd(a.fColor, b.fColor), outFlags);
53 }
54
color() const55 GrColor color() const { return fColor; }
56
validFlags() const57 GrColorComponentFlags validFlags () const { return fFlags; }
58
59 private:
componentsWithValue(unsigned value) const60 GrColorComponentFlags componentsWithValue(unsigned value) const {
61 GrColorComponentFlags flags = kNone_GrColorComponentFlags;
62 if ((kR_GrColorComponentFlag & fFlags) && value == GrColorUnpackR(fColor)) {
63 flags |= kR_GrColorComponentFlag;
64 }
65 if ((kG_GrColorComponentFlag & fFlags) && value == GrColorUnpackG(fColor)) {
66 flags |= kG_GrColorComponentFlag;
67 }
68 if ((kB_GrColorComponentFlag & fFlags) && value == GrColorUnpackB(fColor)) {
69 flags |= kB_GrColorComponentFlag;
70 }
71 if ((kA_GrColorComponentFlag & fFlags) && value == GrColorUnpackA(fColor)) {
72 flags |= kA_GrColorComponentFlag;
73 }
74 return flags;
75 }
76
77 GrColor fColor;
78 GrColorComponentFlags fFlags;
79 };
80
get_term(GrBlendCoeff coeff,const MaskedColor & src,const MaskedColor & dst,const MaskedColor & value)81 static MaskedColor get_term(GrBlendCoeff coeff, const MaskedColor& src, const MaskedColor& dst,
82 const MaskedColor& value) {
83 switch (coeff) {
84 case kZero_GrBlendCoeff:
85 return MaskedColor(0, kRGBA_GrColorComponentFlags);
86 case kOne_GrBlendCoeff:
87 return value;
88 case kDC_GrBlendCoeff:
89 return MaskedColor::Mul(dst, value);
90 case kIDC_GrBlendCoeff:
91 return MaskedColor::Mul(MaskedColor::Invert(dst), value);
92 case kDA_GrBlendCoeff:
93 return MaskedColor::Mul(MaskedColor::ExtractAlpha(dst), value);
94 case kIDA_GrBlendCoeff:
95 return MaskedColor::Mul(MaskedColor::ExtractInverseAlpha(dst), value);
96 case kSC_GrBlendCoeff:
97 return MaskedColor::Mul(src, value);
98 case kISC_GrBlendCoeff:
99 return MaskedColor::Mul(MaskedColor::Invert(src), value);
100 case kSA_GrBlendCoeff:
101 return MaskedColor::Mul(MaskedColor::ExtractAlpha(src), value);
102 case kISA_GrBlendCoeff:
103 return MaskedColor::Mul(MaskedColor::ExtractInverseAlpha(src), value);
104 default:
105 SkFAIL("Illegal coefficient");
106 return MaskedColor();
107 }
108 }
109
GrGetCoeffBlendKnownComponents(GrBlendCoeff srcCoeff,GrBlendCoeff dstCoeff,GrColor srcColor,GrColorComponentFlags srcColorFlags,GrColor dstColor,GrColorComponentFlags dstColorFlags,GrColor * outColor,GrColorComponentFlags * outFlags)110 void GrGetCoeffBlendKnownComponents(GrBlendCoeff srcCoeff, GrBlendCoeff dstCoeff,
111 GrColor srcColor, GrColorComponentFlags srcColorFlags,
112 GrColor dstColor, GrColorComponentFlags dstColorFlags,
113 GrColor* outColor,
114 GrColorComponentFlags* outFlags) {
115 MaskedColor src(srcColor, srcColorFlags);
116 MaskedColor dst(dstColor, dstColorFlags);
117
118 MaskedColor srcTerm = get_term(srcCoeff, src, dst, src);
119 MaskedColor dstTerm = get_term(dstCoeff, src, dst, dst);
120
121 MaskedColor output = MaskedColor::SatAdd(srcTerm, dstTerm);
122 *outColor = output.color();
123 *outFlags = output.validFlags();
124 }
125