Line data    Source code

       1             : /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
       2             : /* This Source Code Form is subject to the terms of the Mozilla Public
       3             :  * License, v. 2.0. If a copy of the MPL was not distributed with this
       4             :  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
       5             : 
       6             : #ifndef nsColor_h___
       7             : #define nsColor_h___
       8             : 
       9             : #include <stddef.h>                     // for size_t
      10             : #include <stdint.h>                     // for uint8_t, uint32_t
      11             : #include "nscore.h"                     // for nsAString
      12             : #include "nsCoord.h"                    // for NSToIntRound
      13             : 
      14             : class nsAString;
      15             : class nsString;
      16             : 
      17             : // A color is a 32 bit unsigned integer with four components: R, G, B
      18             : // and A.
      19             : typedef uint32_t nscolor;
      20             : 
      21             : // Make a color out of r,g,b values. This assumes that the r,g,b values are
      22             : // properly constrained to 0-255. This also assumes that a is 255.
      23             : #define NS_RGB(_r,_g,_b) \
      24             :   ((nscolor) ((255 << 24) | ((_b)<<16) | ((_g)<<8) | (_r)))
      25             : 
      26             : // Make a color out of r,g,b,a values. This assumes that the r,g,b,a
      27             : // values are properly constrained to 0-255.
      28             : #define NS_RGBA(_r,_g,_b,_a) \
      29             :   ((nscolor) (((_a) << 24) | ((_b)<<16) | ((_g)<<8) | (_r)))
      30             : 
      31             : // Extract color components from nscolor
      32             : #define NS_GET_R(_rgba) ((uint8_t) ((_rgba) & 0xff))
      33             : #define NS_GET_G(_rgba) ((uint8_t) (((_rgba) >> 8) & 0xff))
      34             : #define NS_GET_B(_rgba) ((uint8_t) (((_rgba) >> 16) & 0xff))
      35             : #define NS_GET_A(_rgba) ((uint8_t) (((_rgba) >> 24) & 0xff))
      36             : 
      37             : namespace mozilla {
      38             : 
      39             : template<typename T>
      40         177 : inline uint8_t ClampColor(T aColor)
      41             : {
      42         177 :   if (aColor >= 255) {
      43          93 :     return 255;
      44             :   }
      45          84 :   if (aColor <= 0) {
      46          12 :     return 0;
      47             :   }
      48          72 :   return NSToIntRound(aColor);
      49             : }
      50             : 
      51             : } // namespace mozilla
      52             : 
      53             : // Fast approximate division by 255. It has the property that
      54             : // for all 0 <= n <= 255*255, FAST_DIVIDE_BY_255(n) == n/255.
      55             : // But it only uses two adds and two shifts instead of an 
      56             : // integer division (which is expensive on many processors).
      57             : //
      58             : // equivalent to target=v/255
      59             : #define FAST_DIVIDE_BY_255(target,v)               \
      60             :   PR_BEGIN_MACRO                                   \
      61             :     unsigned tmp_ = v;                             \
      62             :     target = ((tmp_ << 8) + tmp_ + 255) >> 16;     \
      63             :   PR_END_MACRO
      64             : 
      65             : enum class nsHexColorType : uint8_t {
      66             :   NoAlpha, // 3 or 6 digit hex colors only
      67             :   AllowAlpha, // 3, 4, 6, or 8 digit hex colors
      68             : };
      69             : 
      70             : // Translate a hex string to a color. Return true if it parses ok,
      71             : // otherwise return false.
      72             : // This accepts the number of digits specified by aType.
      73             : bool
      74             : NS_HexToRGBA(const nsAString& aBuf, nsHexColorType aType, nscolor* aResult);
      75             : 
      76             : // Compose one NS_RGB color onto another. The result is what
      77             : // you get if you draw aFG on top of aBG with operator OVER.
      78             : nscolor NS_ComposeColors(nscolor aBG, nscolor aFG);
      79             : 
      80             : namespace mozilla {
      81             : 
      82           0 : inline uint32_t RoundingDivideBy255(uint32_t n)
      83             : {
      84             :   // There is an approximate alternative: ((n << 8) + n + 32896) >> 16
      85             :   // But that is actually slower than this simple expression on a modern
      86             :   // machine with a modern compiler.
      87           0 :   return (n + 127) / 255;
      88             : }
      89             : 
      90             : // Blend one RGBA color with another based on a given ratio.
      91             : // It is a linear interpolation on each channel with alpha premultipled.
      92             : nscolor LinearBlendColors(nscolor aBg, nscolor aFg, uint_fast8_t aFgRatio);
      93             : 
      94             : } // namespace mozilla
      95             : 
      96             : // Translate a hex string to a color. Return true if it parses ok,
      97             : // otherwise return false.
      98             : // This version accepts 1 to 9 digits (missing digits are 0)
      99             : bool NS_LooseHexToRGB(const nsString& aBuf, nscolor* aResult);
     100             : 
     101             : // There is no function to translate a color to a hex string, because
     102             : // the hex-string syntax does not support transparency.
     103             : 
     104             : // Translate a color name to a color. Return true if it parses ok,
     105             : // otherwise return false.
     106             : bool NS_ColorNameToRGB(const nsAString& aBuf, nscolor* aResult);
     107             : 
     108             : // Returns an array of all possible color names, and sets
     109             : // *aSizeArray to the size of that array. Do NOT call |free()| on this array.
     110             : const char * const * NS_AllColorNames(size_t *aSizeArray);
     111             : 
     112             : // function to convert from HSL color space to RGB color space
     113             : // the float parameters are all expected to be in the range 0-1
     114             : nscolor NS_HSL2RGB(float h, float s, float l);
     115             : 
     116             : // Return a color name for the given nscolor.  If there is no color
     117             : // name for it, returns null.  If there are multiple possible color
     118             : // names for the given color, the first one in nsColorNameList.h
     119             : // (which is generally the first one in alphabetical order) will be
     120             : // returned.
     121             : const char* NS_RGBToColorName(nscolor aColor);
     122             : 
     123             : #endif /* nsColor_h___ */