1 /* libs/graphics/sgl/SkColor.cpp
2 **
3 ** Copyright 2006, The Android Open Source Project
4 **
5 ** Licensed under the Apache License, Version 2.0 (the "License");
6 ** you may not use this file except in compliance with the License.
7 ** You may obtain a copy of the License at
8 **
9 ** http://www.apache.org/licenses/LICENSE-2.0
10 **
11 ** Unless required by applicable law or agreed to in writing, software
12 ** distributed under the License is distributed on an "AS IS" BASIS,
13 ** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 ** See the License for the specific language governing permissions and
15 ** limitations under the License.
16 */
17
18 #include "SkColor.h"
19 #include "SkColorPriv.h"
20
SkPreMultiplyARGB(U8CPU a,U8CPU r,U8CPU g,U8CPU b)21 SkPMColor SkPreMultiplyARGB(U8CPU a, U8CPU r, U8CPU g, U8CPU b) {
22 if (a != 255) {
23 #if 0
24 unsigned scale = SkAlpha255To256(a);
25 r = SkAlphaMul(r, scale);
26 g = SkAlphaMul(g, scale);
27 b = SkAlphaMul(b, scale);
28 #else
29 r = SkMulDiv255Round(r, a);
30 g = SkMulDiv255Round(g, a);
31 b = SkMulDiv255Round(b, a);
32 #endif
33 }
34 return SkPackARGB32(a, r, g, b);
35 }
36
SkPreMultiplyColor(SkColor c)37 SkPMColor SkPreMultiplyColor(SkColor c) {
38 unsigned a = SkColorGetA(c);
39 unsigned r = SkColorGetR(c);
40 unsigned g = SkColorGetG(c);
41 unsigned b = SkColorGetB(c);
42
43 return SkPreMultiplyARGB(a, r, g, b);
44 }
45
46 //////////////////////////////////////////////////////////////////////////////////////////////
47
ByteToScalar(U8CPU x)48 static inline SkScalar ByteToScalar(U8CPU x) {
49 SkASSERT(x <= 255);
50 return SkIntToScalar(x) / 255;
51 }
52
ByteDivToScalar(int numer,U8CPU denom)53 static inline SkScalar ByteDivToScalar(int numer, U8CPU denom) {
54 // cast to keep the answer signed
55 return SkIntToScalar(numer) / (int)denom;
56 }
57
SkRGBToHSV(U8CPU r,U8CPU g,U8CPU b,SkScalar hsv[3])58 void SkRGBToHSV(U8CPU r, U8CPU g, U8CPU b, SkScalar hsv[3]) {
59 SkASSERT(hsv);
60
61 unsigned min = SkMin32(r, SkMin32(g, b));
62 unsigned max = SkMax32(r, SkMax32(g, b));
63 unsigned delta = max - min;
64
65 SkScalar v = ByteToScalar(max);
66 SkASSERT(v >= 0 && v <= SK_Scalar1);
67
68 if (0 == delta) { // we're a shade of gray
69 hsv[0] = 0;
70 hsv[1] = 0;
71 hsv[2] = v;
72 return;
73 }
74
75 SkScalar s = ByteDivToScalar(delta, max);
76 SkASSERT(s >= 0 && s <= SK_Scalar1);
77
78 SkScalar h;
79 if (r == max) {
80 h = ByteDivToScalar(g - b, delta);
81 } else if (g == max) {
82 h = SkIntToScalar(2) + ByteDivToScalar(b - r, delta);
83 } else { // b == max
84 h = SkIntToScalar(4) + ByteDivToScalar(r - g, delta);
85 }
86
87 h *= 60;
88 if (h < 0) {
89 h += SkIntToScalar(360);
90 }
91 SkASSERT(h >= 0 && h < SkIntToScalar(360));
92
93 hsv[0] = h;
94 hsv[1] = s;
95 hsv[2] = v;
96 }
97
UnitScalarToByte(SkScalar x)98 static inline U8CPU UnitScalarToByte(SkScalar x) {
99 if (x < 0) {
100 return 0;
101 }
102 if (x >= SK_Scalar1) {
103 return 255;
104 }
105 return SkScalarToFixed(x) >> 8;
106 }
107
SkHSVToColor(U8CPU a,const SkScalar hsv[3])108 SkColor SkHSVToColor(U8CPU a, const SkScalar hsv[3]) {
109 SkASSERT(hsv);
110
111 U8CPU s = UnitScalarToByte(hsv[1]);
112 U8CPU v = UnitScalarToByte(hsv[2]);
113
114 if (0 == s) { // shade of gray
115 return SkColorSetARGB(a, v, v, v);
116 }
117 SkFixed hx = (hsv[0] < 0 || hsv[0] >= SkIntToScalar(360)) ? 0 : SkScalarToFixed(hsv[0]/60);
118 SkFixed f = hx & 0xFFFF;
119
120 unsigned v_scale = SkAlpha255To256(v);
121 unsigned p = SkAlphaMul(255 - s, v_scale);
122 unsigned q = SkAlphaMul(255 - (s * f >> 16), v_scale);
123 unsigned t = SkAlphaMul(255 - (s * (SK_Fixed1 - f) >> 16), v_scale);
124
125 unsigned r, g, b;
126
127 SkASSERT((unsigned)(hx >> 16) < 6);
128 switch (hx >> 16) {
129 case 0: r = v; g = t; b = p; break;
130 case 1: r = q; g = v; b = p; break;
131 case 2: r = p; g = v; b = t; break;
132 case 3: r = p; g = q; b = v; break;
133 case 4: r = t; g = p; b = v; break;
134 default: r = v; g = p; b = q; break;
135 }
136 return SkColorSetARGB(a, r, g, b);
137 }
138
139