gfx/public/nsColor.h

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  37
  38 #ifndef nsColor_h___
  39 #define nsColor_h___
  40
  41 #include "gfxCore.h"
  42 #include "nscore.h"
  43
  44 class nsAString;
  45 class nsString;
  46 class nsCString;
  47
  48 // A color is a 32 bit unsigned integer with four components: R, G, B
  49 // and A.
  50 typedef PRUint32 nscolor;
  51
  52 // Make a color out of r,g,b values. This assumes that the r,g,b values are
  53 // properly constrained to 0-255. This also assumes that a is 255.
  54 #define NS_RGB(_r,_g,_b) \
  55   ((nscolor) ((255 << 24) | ((_b)<<16) | ((_g)<<8) | (_r)))
  56
  57 // Make a color out of r,g,b,a values. This assumes that the r,g,b,a
  58 // values are properly constrained to 0-255.
  59 #define NS_RGBA(_r,_g,_b,_a) \
  60   ((nscolor) (((_a) << 24) | ((_b)<<16) | ((_g)<<8) | (_r)))
  61
  62 // Extract color components from nscolor
  63 #define NS_GET_R(_rgba) ((PRUint8) ((_rgba) & 0xff))
  64 #define NS_GET_G(_rgba) ((PRUint8) (((_rgba) >> 8) & 0xff))
  65 #define NS_GET_B(_rgba) ((PRUint8) (((_rgba) >> 16) & 0xff))
  66 #define NS_GET_A(_rgba) ((PRUint8) (((_rgba) >> 24) & 0xff))
  67
  68 // Fast approximate division by 255. It has the property that
  69 // for all 0 <= n <= 255*255, FAST_DIVIDE_BY_255(n) == n/255.
  70 // But it only uses two adds and two shifts instead of an
  71 // integer division (which is expensive on many processors).
  72 //
  73 // equivalent to target=v/255
  74 #define FAST_DIVIDE_BY_255(target,v)               \
  75   PR_BEGIN_MACRO                                   \
  76     unsigned tmp_ = v;                             \
  77     target = ((tmp_ << 8) + tmp_ + 255) >> 16;     \
  78   PR_END_MACRO
  79
  80 // Blending macro
  81 //
  82 // equivalent to target=(bg*(255-alpha)+fg*alpha)/255
  83 #define MOZ_BLEND(target, bg, fg, alpha) \
  84         FAST_DIVIDE_BY_255(target, (bg)*(255-(alpha)) + (fg)*(alpha))
  85
  86 // Translate a hex string to a color. Return true if it parses ok,
  87 // otherwise return false.
  88 // This accepts only 3 or 6 digits
  89 NS_GFX_(PRBool) NS_HexToRGB(const nsString& aBuf, nscolor* aResult);
  90
  91 // Compose one NS_RGB color onto another. The result is what you get
  92 // if you draw aBG onto RGBA(0,0,0,0) and then aFG on top of that,
  93 // with operator OVER.
  94 NS_GFX_(nscolor) NS_ComposeColors(nscolor aBG, nscolor aFG);
  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 NS_GFX_(PRBool) NS_LooseHexToRGB(const nsString& aBuf, nscolor* aResult);
 100
 101 // Translate a color to a hex string and prepend a '#'.
 102 // The returned string is always 7 characters including a '#' character.
 103 NS_GFX_(void) NS_RGBToHex(nscolor aColor, nsAString& aResult);
 104
 105 // Translate a color name to a color. Return true if it parses ok,
 106 // otherwise return false.
 107 NS_GFX_(PRBool) NS_ColorNameToRGB(const nsAString& aBuf, nscolor* aResult);
 108
 109 // function to convert from HSL color space to RGB color space
 110 // the float parameters are all expected to be in the range 0-1
 111 NS_GFX_(nscolor) NS_HSL2RGB(float h, float s, float l);
 112
 113 #endif /* nsColor_h___ */