gecko/layout/base/nsCSSColorUtils.h

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

/* functions that manipulate colors */

#ifndef __nsCSSColorUtils_h
#define __nsCSSColorUtils_h

#include "nsColor.h"
#include <cstdlib> // for std::abs(int/long)
#include <cmath> // for std::abs(float/double)

// "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) \
          std::abs(NS_GetLuminosity(a) - NS_GetLuminosity(b))

// 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(uint8_t aRed, uint8_t aGreen, uint8_t 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.
int32_t NS_GetLuminosity(nscolor aColor);

// function to convert from RGBA color space to HSVA color space 
void NS_RGB2HSV(nscolor aColor, uint16_t &aHue, uint16_t &aSat,
                uint16_t &aValue, uint8_t &aAlpha);

// function to convert from HSVA color space to RGBA color space 
void NS_HSV2RGB(nscolor &aColor, uint16_t aHue, uint16_t aSat, uint16_t aValue,
                uint8_t aAlpha);

#endif