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| 1 |
| 2 /* |
| 3 * Copyright 2013 Google Inc. |
| 4 * |
| 5 * Use of this source code is governed by a BSD-style license that can be |
| 6 * found in the LICENSE file. |
| 7 */ |
| 8 |
| 9 #include "GrBlend.h" |
| 10 |
| 11 static inline GrBlendCoeff swap_coeff_src_dst(GrBlendCoeff coeff) { |
| 12 switch (coeff) { |
| 13 case kDC_GrBlendCoeff: |
| 14 return kSC_GrBlendCoeff; |
| 15 case kIDC_GrBlendCoeff: |
| 16 return kISC_GrBlendCoeff; |
| 17 case kDA_GrBlendCoeff: |
| 18 return kSA_GrBlendCoeff; |
| 19 case kIDA_GrBlendCoeff: |
| 20 return kISA_GrBlendCoeff; |
| 21 case kSC_GrBlendCoeff: |
| 22 return kDC_GrBlendCoeff; |
| 23 case kISC_GrBlendCoeff: |
| 24 return kIDC_GrBlendCoeff; |
| 25 case kSA_GrBlendCoeff: |
| 26 return kDA_GrBlendCoeff; |
| 27 case kISA_GrBlendCoeff: |
| 28 return kIDA_GrBlendCoeff; |
| 29 default: |
| 30 return coeff; |
| 31 } |
| 32 } |
| 33 |
| 34 static inline unsigned saturated_add(unsigned a, unsigned b) { |
| 35 SkASSERT(a <= 255); |
| 36 SkASSERT(b <= 255); |
| 37 unsigned sum = a + b; |
| 38 if (sum > 255) { |
| 39 sum = 255; |
| 40 } |
| 41 return sum; |
| 42 } |
| 43 |
| 44 static GrColor add_colors(GrColor src, GrColor dst) { |
| 45 unsigned r = saturated_add(GrColorUnpackR(src), GrColorUnpackR(dst)); |
| 46 unsigned g = saturated_add(GrColorUnpackG(src), GrColorUnpackG(dst)); |
| 47 unsigned b = saturated_add(GrColorUnpackB(src), GrColorUnpackB(dst)); |
| 48 unsigned a = saturated_add(GrColorUnpackA(src), GrColorUnpackA(dst)); |
| 49 return GrColorPackRGBA(r, g, b, a); |
| 50 } |
| 51 |
| 52 static inline bool valid_color(uint32_t compFlags) { |
| 53 return (kRGBA_GrColorComponentFlags & compFlags) == kRGBA_GrColorComponentF
lags; |
| 54 } |
| 55 |
| 56 static GrColor simplify_blend_term(GrBlendCoeff* srcCoeff, |
| 57 GrColor srcColor, uint32_t srcCompFlags, |
| 58 GrColor dstColor, uint32_t dstCompFlags, |
| 59 GrColor constantColor) { |
| 60 |
| 61 GrAssert(!GrBlendCoeffRefsSrc(*srcCoeff)); |
| 62 GrAssert(NULL != srcCoeff); |
| 63 |
| 64 // Check whether srcCoeff can be reduced to kOne or kZero based on known col
or inputs. |
| 65 // We could pick out the coeff r,g,b,a values here and use them to compute t
he blend term color, |
| 66 // if possible, below but that is not implemented now. |
| 67 switch (*srcCoeff) { |
| 68 case kIDC_GrBlendCoeff: |
| 69 dstColor = ~dstColor; // fallthrough |
| 70 case kDC_GrBlendCoeff: |
| 71 if (valid_color(dstCompFlags)) { |
| 72 if (0xffffffff == dstColor) { |
| 73 *srcCoeff = kOne_GrBlendCoeff; |
| 74 } else if (0 == dstColor) { |
| 75 *srcCoeff = kZero_GrBlendCoeff; |
| 76 } |
| 77 } |
| 78 break; |
| 79 |
| 80 case kIDA_GrBlendCoeff: |
| 81 dstColor = ~dstColor; // fallthrough |
| 82 case kDA_GrBlendCoeff: |
| 83 if (kA_GrColorComponentFlag & dstCompFlags) { |
| 84 if (0xff == GrColorUnpackA(dstColor)) { |
| 85 *srcCoeff = kOne_GrBlendCoeff; |
| 86 } else if (0 == GrColorUnpackA(dstColor)) { |
| 87 *srcCoeff = kZero_GrBlendCoeff; |
| 88 } |
| 89 } |
| 90 break; |
| 91 |
| 92 case kIConstC_GrBlendCoeff: |
| 93 constantColor = ~constantColor; // fallthrough |
| 94 case kConstC_GrBlendCoeff: |
| 95 if (0xffffffff == constantColor) { |
| 96 *srcCoeff = kOne_GrBlendCoeff; |
| 97 } else if (0 == constantColor) { |
| 98 *srcCoeff = kZero_GrBlendCoeff; |
| 99 } |
| 100 break; |
| 101 |
| 102 case kIConstA_GrBlendCoeff: |
| 103 constantColor = ~constantColor; // fallthrough |
| 104 case kConstA_GrBlendCoeff: |
| 105 if (0xff == GrColorUnpackA(constantColor)) { |
| 106 *srcCoeff = kOne_GrBlendCoeff; |
| 107 } else if (0 == GrColorUnpackA(constantColor)) { |
| 108 *srcCoeff = kZero_GrBlendCoeff; |
| 109 } |
| 110 break; |
| 111 |
| 112 default: |
| 113 break; |
| 114 } |
| 115 // We may have invalidated these above and shouldn't read them again. |
| 116 GR_DEBUGCODE(dstColor = constantColor = GrColor_ILLEGAL;) |
| 117 |
| 118 if (kZero_GrBlendCoeff == *srcCoeff || (valid_color(srcCompFlags) && 0 == sr
cColor)) { |
| 119 *srcCoeff = kZero_GrBlendCoeff; |
| 120 return 0; |
| 121 } |
| 122 |
| 123 if (kOne_GrBlendCoeff == *srcCoeff && valid_color(srcCompFlags)) { |
| 124 return srcColor; |
| 125 } else { |
| 126 return GrColor_ILLEGAL; |
| 127 } |
| 128 } |
| 129 |
| 130 GrColor GrSimplifyBlend(GrBlendCoeff* srcCoeff, |
| 131 GrBlendCoeff* dstCoeff, |
| 132 GrColor srcColor, uint32_t srcCompFlags, |
| 133 GrColor dstColor, uint32_t dstCompFlags, |
| 134 GrColor constantColor) { |
| 135 GrColor srcTermColor = simplify_blend_term(srcCoeff, |
| 136 srcColor, srcCompFlags, |
| 137 dstColor, dstCompFlags, |
| 138 constantColor); |
| 139 |
| 140 // We call the same function to simplify the dst blend coeff. We trick it ou
t by swapping the |
| 141 // src and dst. |
| 142 GrBlendCoeff spoofedCoeff = swap_coeff_src_dst(*dstCoeff); |
| 143 GrColor dstTermColor = simplify_blend_term(&spoofedCoeff, |
| 144 dstColor, dstCompFlags, |
| 145 srcColor, srcCompFlags, |
| 146 constantColor); |
| 147 *dstCoeff = swap_coeff_src_dst(spoofedCoeff); |
| 148 |
| 149 if (GrColor_ILLEGAL != srcTermColor && GrColor_ILLEGAL != dstTermColor) { |
| 150 return add_colors(srcTermColor, dstTermColor); |
| 151 } else { |
| 152 return GrColor_ILLEGAL; |
| 153 } |
| 154 } |
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