gfx/src/nsColor.h

   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 "gfxCore.h"                    // for NS_GFX_
  12 #include "nscore.h"                     // for nsAString
  13
  14 class nsAString;
  15 class nsString;
  16 class nsCString;
  17
  18 // A color is a 32 bit unsigned integer with four components: R, G, B
  19 // and A.
  20 typedef uint32_t nscolor;
  21
  22 // Make a color out of r,g,b values. This assumes that the r,g,b values are
  23 // properly constrained to 0-255. This also assumes that a is 255.
  24 #define NS_RGB(_r,_g,_b) \
  25   ((nscolor) ((255 << 24) | ((_b)<<16) | ((_g)<<8) | (_r)))
  26
  27 // Make a color out of r,g,b,a values. This assumes that the r,g,b,a
  28 // values are properly constrained to 0-255.
  29 #define NS_RGBA(_r,_g,_b,_a) \
  30   ((nscolor) (((_a) << 24) | ((_b)<<16) | ((_g)<<8) | (_r)))
  31
  32 // Extract color components from nscolor
  33 #define NS_GET_R(_rgba) ((uint8_t) ((_rgba) & 0xff))
  34 #define NS_GET_G(_rgba) ((uint8_t) (((_rgba) >> 8) & 0xff))
  35 #define NS_GET_B(_rgba) ((uint8_t) (((_rgba) >> 16) & 0xff))
  36 #define NS_GET_A(_rgba) ((uint8_t) (((_rgba) >> 24) & 0xff))
  37
  38 // Fast approximate division by 255. It has the property that
  39 // for all 0 <= n <= 255*255, FAST_DIVIDE_BY_255(n) == n/255.
  40 // But it only uses two adds and two shifts instead of an
  41 // integer division (which is expensive on many processors).
  42 //
  43 // equivalent to target=v/255
  44 #define FAST_DIVIDE_BY_255(target,v)               \
  45   PR_BEGIN_MACRO                                   \
  46     unsigned tmp_ = v;                             \
  47     target = ((tmp_ << 8) + tmp_ + 255) >> 16;     \
  48   PR_END_MACRO
  49
  50 // Translate a hex string to a color. Return true if it parses ok,
  51 // otherwise return false.
  52 // This accepts only 3 or 6 digits
  53 NS_GFX_(bool) NS_HexToRGB(const nsAString& aBuf, nscolor* aResult);
  54
  55 // Compose one NS_RGB color onto another. The result is what
  56 // you get if you draw aFG on top of aBG with operator OVER.
  57 NS_GFX_(nscolor) NS_ComposeColors(nscolor aBG, nscolor aFG);
  58
  59 // Translate a hex string to a color. Return true if it parses ok,
  60 // otherwise return false.
  61 // This version accepts 1 to 9 digits (missing digits are 0)
  62 NS_GFX_(bool) NS_LooseHexToRGB(const nsString& aBuf, nscolor* aResult);
  63
  64 // There is no function to translate a color to a hex string, because
  65 // the hex-string syntax does not support transparency.
  66
  67 // Translate a color name to a color. Return true if it parses ok,
  68 // otherwise return false.
  69 NS_GFX_(bool) NS_ColorNameToRGB(const nsAString& aBuf, nscolor* aResult);
  70
  71 // Returns an array of all possible color names, and sets
  72 // *aSizeArray to the size of that array. Do NOT call |free()| on this array.
  73 NS_GFX_(const char * const *) NS_AllColorNames(size_t *aSizeArray);
  74
  75 // function to convert from HSL color space to RGB color space
  76 // the float parameters are all expected to be in the range 0-1
  77 NS_GFX_(nscolor) NS_HSL2RGB(float h, float s, float l);
  78
  79 // Return a color name for the given nscolor.  If there is no color
  80 // name for it, returns null.  If there are multiple possible color
  81 // names for the given color, the first one in nsColorNameList.h
  82 // (which is generally the first one in alphabetical order) will be
  83 // returned.
  84 NS_GFX_(const char*) NS_RGBToColorName(nscolor aColor);
  85
  86 #endif /* nsColor_h___ */