bcolortools.cxx

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 *   Licensed to the Apache Software Foundation (ASF) under one or more
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#include <basegfx/numeric/ftools.hxx>
#include <basegfx/color/bcolor.hxx>
#include <basegfx/color/bcolortools.hxx>
#include <rtl/math.hxx>
 
namespace basegfx::utils
{
    BColor rgb2hsl(const BColor& rRGBColor)
    {
        const double r=rRGBColor.getRed(), g=rRGBColor.getGreen(), b=rRGBColor.getBlue();
        const double minVal = std::min( std::min( r, g ), b );
        const double maxVal = std::max( std::max( r, g ), b );
        const double d = maxVal - minVal;
 
        double h=0, s=0, l=0;
 
        l = (maxVal + minVal) / 2.0;
 
        if( ::basegfx::fTools::equalZero(d) )
        {
            s = h = 0; // hue undefined (achromatic case)
        }
        else
        {
            s = l > 0.5 ? d/(2.0-maxVal-minVal) :
                d/(maxVal + minVal);
 
            if( rtl::math::approxEqual(r, maxVal) )
                h = (g - b)/d;
            else if( rtl::math::approxEqual(g, maxVal) )
                h = 2.0 + (b - r)/d;
            else
                h = 4.0 + (r - g)/d;
 
            h *= 60.0;
 
            if( h < 0.0 )
                h += 360.0;
        }
 
        return BColor(h,s,l);
    }
 
    static double hsl2rgbHelper( double nValue1, double nValue2, double nHue )
    {
        // clamp hue to [0,360]
        nHue = fmod( nHue, 360.0 );
 
        // cope with wrap-arounds
        if( nHue < 0.0 )
            nHue += 360.0;
 
        if( nHue < 60.0 )
            return nValue1 + (nValue2 - nValue1)*nHue/60.0;
        else if( nHue < 180.0 )
            return nValue2;
        else if( nHue < 240.0 )
            return nValue1 + (nValue2 - nValue1)*(240.0 - nHue)/60.0;
        else
            return nValue1;
    }
 
    BColor hsl2rgb(const BColor& rHSLColor)
    {
        const double h=rHSLColor.getRed(), s=rHSLColor.getGreen(), l=rHSLColor.getBlue();
 
        if( fTools::equalZero(s) )
            return BColor(l, l, l ); // achromatic case
 
        const double nVal1( l <= 0.5 ? l*(1.0 + s) : l + s - l*s );
        const double nVal2( 2.0*l - nVal1 );
 
        return BColor(
            hsl2rgbHelper(nVal2,
                          nVal1,
                          h + 120.0),
            hsl2rgbHelper(nVal2,
                          nVal1,
                          h),
            hsl2rgbHelper(nVal2,
                          nVal1,
                          h - 120.0) );
    }
 
    BColor rgb2hsv(const BColor& rRGBColor)
    {
        const double r=rRGBColor.getRed(), g=rRGBColor.getGreen(), b=rRGBColor.getBlue();
        const double maxVal = std::max(std::max(r,g),b);
        const double minVal = std::min(std::min(r,g),b);
        const double delta = maxVal-minVal;
 
        double h=0, s=0, v=0;
 
        v = maxVal;
        if( fTools::equalZero(v) )
            s = 0;
        else
            s = delta / v;
 
        if( !fTools::equalZero(s) )
        {
            if( rtl::math::approxEqual(maxVal, r) )
            {
                h = (g - b) / delta;
            }
            else if( rtl::math::approxEqual(maxVal, g) )
            {
                h = 2.0 + (b - r) / delta;
            }
            else
            {
                h = 4.0 + (r - g) / delta;
            }
 
            h *= 60.0;
 
            if( h < 0 )
                h += 360;
        }
 
        return BColor(h,s,v);
    }
 
    BColor hsv2rgb(const BColor& rHSVColor)
    {
        double h=rHSVColor.getRed();
        const double s=rHSVColor.getGreen(), v=rHSVColor.getBlue();
 
        if( fTools::equalZero(s) )
        {
            // achromatic case: no hue.
            return BColor(v,v,v);
        }
        else
        {
            if( fTools::equal(h, 360.0) )
                h = 0; // 360 degrees is equivalent to 0 degrees
 
            h /= 60.0;
            const sal_Int32 intval = static_cast< sal_Int32 >( h );
            const double f = h - intval;
            const double p = v*(1.0-s);
            const double q = v*(1.0-(s*f));
            const double t = v*(1.0-(s*(1.0-f)));
 
            /* which hue area? */
            switch( intval )
            {
                case 0:
                    return BColor(v,t,p);
 
                case 1:
                    return BColor(q,v,p);
 
                case 2:
                    return BColor(p,v,t);
 
                case 3:
                    return BColor(p,q,v);
 
                case 4:
                    return BColor(t,p,v);
 
                case 5:
                    return BColor(v,p,q);
 
                default:
                    // hue overflow
                    return BColor();
            }
        }
    }
 
} // end of namespace
 
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