reed@android.com | 8a1c16f | 2008-12-17 15:59:43 +0000 | [diff] [blame^] | 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 | |
| 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 | |
| 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 | |
| 48 | static inline SkScalar ByteToScalar(U8CPU x) { |
| 49 | SkASSERT(x <= 255); |
| 50 | return SkIntToScalar(x) / 255; |
| 51 | } |
| 52 | |
| 53 | static inline SkScalar ByteDivToScalar(int numer, U8CPU denom) { |
| 54 | // cast to keep the answer signed |
| 55 | return SkIntToScalar(numer) / (int)denom; |
| 56 | } |
| 57 | |
| 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 | |
| 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 | |
| 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 | |