CAlphaColour.hpp

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#ifndef __CAlphaColour__
#define __CAlphaColour__

#include "CColour.hpp"
using Exponent::GUI::Basics::CColour;

//  ===========================================================================

namespace Exponent
{
    namespace GUI
    {
        namespace Basics
        {
            class CAlphaColour : public CColour
            {
                EXPONENT_CLASS_DECLARATION;
//  ===========================================================================

            public:

//  ===========================================================================

                const static CAlphaColour CALPHACOLOUR_BLACK;           
                const static CAlphaColour CALPHACOLOUR_WHITE;           
                const static CAlphaColour CALPHACOLOUR_RED;             
                const static CAlphaColour CALPHACOLOUR_GREEN;           
                const static CAlphaColour CALPHACOLOUR_BLUE;            
                const static CAlphaColour CALPHACOLOUR_YELLOW;          
                const static CAlphaColour CALPHACOLOUR_ORANGE;          
                const static CAlphaColour CALPHACOLOUR_TURQUOISE;       
                const static CAlphaColour CALPHACOLOUR_PURPLE;          
                const static CAlphaColour CALPHACOLOUR_PINK;            
                const static CAlphaColour CALPHACOLOUR_LIGHT_GREY;      
                const static CAlphaColour CALPHACOLOUR_DARK_GREY;       
//  ===========================================================================

                CAlphaColour(const unsigned long red, const unsigned long green, const unsigned long blue, const unsigned long alpha = 255);

                CAlphaColour();

                CAlphaColour(const CAlphaColour &colour);

                virtual ~CAlphaColour();

//  ===========================================================================

                CAlphaColour &operator = (const CAlphaColour &colour);

                CAlphaColour &operator = (const CColour &colour);

                bool operator == (const CAlphaColour &colour) const;

//  ===========================================================================

                void setAlpha(const unsigned long alpha) { m_alpha = alpha; }

                unsigned long getAlpha() const { return m_alpha; }

//  ===========================================================================

                void darkenColour();

                void lightenColour();

//  ============================================================================

                virtual void setColour(const unsigned long red, const unsigned long green, const unsigned long blue, const unsigned long alpha);

                CColour *getAsColour() const;

                void getAsColour(CColour &colour) const;

//  ===========================================================================

                static FORCEINLINE void alphaBlend(CColour &destination, const CAlphaColour &background, const CAlphaColour &source)
                {
                    destination.setRed(CAlphaColour::alphaComposite(source.getRed(), background.getRed(), source.getAlpha()));
                    destination.setGreen(CAlphaColour::alphaComposite(source.getGreen(), background.getGreen(), source.getAlpha()));
                    destination.setBlue(CAlphaColour::alphaComposite(source.getBlue(), background.getBlue(), source.getAlpha()));
                }

                static FORCEINLINE void alphaBlend(CColour &destination, const CColour &background, const CColour &source, const unsigned long alpha)
                {
                    destination.setRed(CAlphaColour::alphaComposite(source.getRed(), background.getRed(), alpha));
                    destination.setGreen(CAlphaColour::alphaComposite(source.getGreen(), background.getGreen(), alpha));
                    destination.setBlue(CAlphaColour::alphaComposite(source.getBlue(), background.getBlue(), alpha));
                }

//  ===========================================================================

                virtual void getObjectDescription(char *string, const long size) const;

//  ===========================================================================

            protected:

//  ===========================================================================

                static FORCEINLINE unsigned long alphaComposite(const unsigned long foreground, const unsigned long background, const unsigned long alpha)
                {
                    unsigned long temp = ((unsigned long)(foreground)*(unsigned long)(alpha) + (unsigned long)(background)*(unsigned long)(255 - (unsigned long)(alpha)) + (unsigned long)128); 
                    return (unsigned long)((temp + (temp >> 8)) >> 8);
                }

//  ===========================================================================

                unsigned long m_alpha;      
            };
        }
    }
}
#endif  // end of CAlphaColour.hpp

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