nsColor.h (2779B)
1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ 2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */ 3 /* This Source Code Form is subject to the terms of the Mozilla Public 4 * License, v. 2.0. If a copy of the MPL was not distributed with this 5 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ 6 7 #ifndef nsColor_h___ 8 #define nsColor_h___ 9 10 #include <stdint.h> // for uint8_t, uint32_t 11 #include "nsCoord.h" // for NSToIntRound 12 #include "nsStringFwd.h" 13 14 // A color is a 32 bit unsigned integer with four components: R, G, B 15 // and A. 16 typedef uint32_t nscolor; 17 18 // Make a color out of r,g,b values. This assumes that the r,g,b values are 19 // properly constrained to 0-255. This also assumes that a is 255. 20 #define NS_RGB(_r, _g, _b) \ 21 ((nscolor)((255 << 24) | ((_b) << 16) | ((_g) << 8) | (_r))) 22 23 // Make a color out of r,g,b,a values. This assumes that the r,g,b,a 24 // values are properly constrained to 0-255. 25 #define NS_RGBA(_r, _g, _b, _a) \ 26 ((nscolor)(((_a) << 24) | ((_b) << 16) | ((_g) << 8) | (_r))) 27 28 // Extract color components from nscolor 29 #define NS_GET_R(_rgba) ((uint8_t)((_rgba) & 0xff)) 30 #define NS_GET_G(_rgba) ((uint8_t)(((_rgba) >> 8) & 0xff)) 31 #define NS_GET_B(_rgba) ((uint8_t)(((_rgba) >> 16) & 0xff)) 32 #define NS_GET_A(_rgba) ((uint8_t)(((_rgba) >> 24) & 0xff)) 33 34 namespace mozilla { 35 36 template <typename T> 37 inline uint8_t ClampColor(T aColor) { 38 if (aColor >= 255) { 39 return 255; 40 } 41 if (aColor <= 0) { 42 return 0; 43 } 44 return NSToIntRound(aColor); 45 } 46 47 } // namespace mozilla 48 49 enum class nsHexColorType : uint8_t { 50 NoAlpha, // 3 or 6 digit hex colors only 51 AllowAlpha, // 3, 4, 6, or 8 digit hex colors 52 }; 53 54 // Translate a hex string to a color. Return true if it parses ok, 55 // otherwise return false. 56 // This accepts the number of digits specified by aType. 57 bool NS_HexToRGBA(const nsAString& aBuf, nsHexColorType aType, 58 nscolor* aResult); 59 60 // Compose one NS_RGB color onto another. The result is what 61 // you get if you draw aFG on top of aBG with operator OVER. 62 nscolor NS_ComposeColors(nscolor aBG, nscolor aFG); 63 64 namespace mozilla { 65 66 inline uint32_t RoundingDivideBy255(uint32_t n) { 67 // There is an approximate alternative: ((n << 8) + n + 32896) >> 16 68 // But that is actually slower than this simple expression on a modern 69 // machine with a modern compiler. 70 return (n + 127) / 255; 71 } 72 73 } // namespace mozilla 74 75 // Translate a hex string to a color. Return true if it parses ok, 76 // otherwise return false. 77 // This version accepts 1 to 9 digits (missing digits are 0) 78 bool NS_LooseHexToRGB(const nsString& aBuf, nscolor* aResult); 79 80 // There is no function to translate a color to a hex string, because 81 // the hex-string syntax does not support transparency. 82 83 #endif /* nsColor_h___ */