gecko-dev/layout/base/nsCSSColorUtils.h

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/* functions that manipulate colors */

#ifndef __nsCSSColorUtils_h
#define __nsCSSColorUtils_h

#include "nsColor.h"

// "Sufficient contrast" is determined by
// "Techniques For Accessibility Evalution And Repair Tools".
// See http://www.w3.org/TR/AERT#color-contrast
#define NS_SUFFICIENT_LUMINOSITY_DIFFERENCE 125000
#define NS_LUMINOSITY_DIFFERENCE(a, b) \
          PR_ABS(NS_GetLuminosity(a) - NS_GetLuminosity(b))

// Weird color computing code stolen from winfe which was stolen
// from the xfe which was written originally by Eric Bina. So there.
// To determin colors based on the background brightness
void NS_Get3DColors(nscolor aResult[2], nscolor aBackgroundColor);

// To determine colors based on the background brightness and border color
void NS_GetSpecial3DColors(nscolor aResult[2],
                           nscolor aBackgroundColor,
                           nscolor aBorderColor);

// Determins brightness for a specific color
int NS_GetBrightness(PRUint8 aRed, PRUint8 aGreen, PRUint8 aBlue);

// Get Luminosity of a specific color. That is same as Y of YIQ color space.
// The range of return value is 0 to 255000.
PRInt32 NS_GetLuminosity(nscolor aColor);

// function to convert from RGB color space to HSV color space 
void NS_RGB2HSV(nscolor aColor,PRUint16 &aHue,PRUint16 &aSat,PRUint16 &aValue);
// function to convert from HSV color space to RGB color space 
void NS_HSV2RGB(nscolor &aColor,PRUint16 aHue,PRUint16 aSat,PRUint16 aValue);

#endif