// Copyright (C) 2016 The Qt Company Ltd.

// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only

#ifndef QRGBA64_H

#define QRGBA64_H

#include <QtGui/qtguiglobal.h>

#include <QtCore/qprocessordetection.h>

QT_BEGIN_NAMESPACE

class QRgba64 {

    quint64 rgba;

    // Make sure that the representation always has the order: red green blue alpha, independent

    // of byte order. This way, vector operations that assume 4 16-bit values see the correct ones.

    enum Shifts {

#if Q_BYTE_ORDER == Q_BIG_ENDIAN

        RedShift = 48,

        GreenShift = 32,

        BlueShift = 16,

        AlphaShift = 0

#else // little endian:

        RedShift = 0,

        GreenShift = 16,

        BlueShift = 32,

        AlphaShift = 48

#endif

    };

    Q_ALWAYS_INLINE explicit constexpr QRgba64(quint64 c) : rgba(c) { }

public:

    QRgba64() = default;

    constexpr static

    QRgba64 fromRgba64(quint64 c)

    {

        return QRgba64(c);

    }

    constexpr static

    QRgba64 fromRgba64(quint16 red, quint16 green, quint16 blue, quint16 alpha)

    {

        return fromRgba64(quint64(red)   << RedShift

                        | quint64(green) << GreenShift

                        | quint64(blue)  << BlueShift

                        | quint64(alpha) << AlphaShift);

    }

    constexpr static QRgba64 fromRgba(quint8 red, quint8 green, quint8 blue, quint8 alpha)

    {

        QRgba64 rgb64 = fromRgba64(red, green, blue, alpha);

        // Expand the range so that 0x00 maps to 0x0000 and 0xff maps to 0xffff.

        rgb64.rgba |= rgb64.rgba << 8;

        return rgb64;

    }

    constexpr static

    QRgba64 fromArgb32(uint rgb)

    {

        return fromRgba(quint8(rgb >> 16), quint8(rgb >> 8), quint8(rgb), quint8(rgb >> 24));

    }

    constexpr bool isOpaque() const

    {

        return (rgba & alphaMask()) == alphaMask();

    }

    constexpr bool isTransparent() const

    {

        return (rgba & alphaMask()) == 0;

    }

    constexpr quint16 red()   const { return quint16(rgba >> RedShift);   }

    constexpr quint16 green() const { return quint16(rgba >> GreenShift); }

    constexpr quint16 blue()  const { return quint16(rgba >> BlueShift);  }

    constexpr quint16 alpha() const { return quint16(rgba >> AlphaShift); }

    void setRed(quint16 _red)     { rgba = (rgba & ~(Q_UINT64_C(0xffff) << RedShift))   | (quint64(_red) << RedShift); }

    void setGreen(quint16 _green) { rgba = (rgba & ~(Q_UINT64_C(0xffff) << GreenShift)) | (quint64(_green) << GreenShift); }

    void setBlue(quint16 _blue)   { rgba = (rgba & ~(Q_UINT64_C(0xffff) << BlueShift))  | (quint64(_blue) << BlueShift); }

    void setAlpha(quint16 _alpha) { rgba = (rgba & ~(Q_UINT64_C(0xffff) << AlphaShift)) | (quint64(_alpha) << AlphaShift); }

    constexpr quint8 red8()   const { return div_257(red()); }

    constexpr quint8 green8() const { return div_257(green()); }

    constexpr quint8 blue8()  const { return div_257(blue()); }

    constexpr quint8 alpha8() const { return div_257(alpha()); }

    constexpr uint toArgb32() const

    {

        quint64 br = rgba & Q_UINT64_C(0xffff0000ffff);

        quint64 ag = (rgba >> 16) & Q_UINT64_C(0xffff0000ffff);

        br += Q_UINT64_C(0x8000000080);

        ag += Q_UINT64_C(0x8000000080);

        br = (br - ((br >> 8) & Q_UINT64_C(0xffff0000ffff))) >> 8;

        ag = (ag - ((ag >> 8) & Q_UINT64_C(0xffff0000ffff)));

#if Q_BYTE_ORDER == Q_BIG_ENDIAN

        return ((br << 24) & 0xff000000)

             | ((ag >> 24) & 0xff0000)

             | ((br >> 24) & 0xff00)

             | ((ag >> 8)  & 0xff);

#else

        return ((ag >> 16) & 0xff000000)

             | ((br << 16) & 0xff0000)

             | (ag         & 0xff00)

             | ((br >> 32) & 0xff);

#endif

    }

    constexpr ushort toRgb16() const

    {

        return ushort((red() & 0xf800) | ((green() >> 10) << 5) | (blue() >> 11));

    }

    constexpr QRgba64 premultiplied() const

    {

        if (isOpaque())

            return *this;

        if (isTransparent())

            return QRgba64::fromRgba64(0);

        const quint64 a = alpha();

        quint64 br = (rgba & Q_UINT64_C(0xffff0000ffff)) * a;

        quint64 ag = ((rgba >> 16) & Q_UINT64_C(0xffff0000ffff)) * a;

        br = (br + ((br >> 16) & Q_UINT64_C(0xffff0000ffff)) + Q_UINT64_C(0x800000008000));

        ag = (ag + ((ag >> 16) & Q_UINT64_C(0xffff0000ffff)) + Q_UINT64_C(0x800000008000));

#if Q_BYTE_ORDER == Q_BIG_ENDIAN

        ag = ag & Q_UINT64_C(0xffff0000ffff0000);

        br = (br >> 16) & Q_UINT64_C(0xffff00000000);

        return fromRgba64(a | br | ag);

#else

        br = (br >> 16) & Q_UINT64_C(0xffff0000ffff);

        ag = ag & Q_UINT64_C(0xffff0000);

        return fromRgba64((a << 48) | br | ag);

#endif

    }

    constexpr QRgba64 unpremultiplied() const

    {

#if Q_PROCESSOR_WORDSIZE < 8

        return unpremultiplied_32bit();

#else

        return unpremultiplied_64bit();

#endif

    }

    constexpr operator quint64() const

    {

        return rgba;

    }

    QRgba64 &operator=(quint64 _rgba) noexcept

    {

        rgba = _rgba;

        return *this;

    }

private:

    Q_ALWAYS_INLINE static constexpr quint64 alphaMask() { return Q_UINT64_C(0xffff) << AlphaShift; }

    Q_ALWAYS_INLINE static constexpr quint8 div_257_floor(uint x) { return quint8((x - (x >> 8)) >> 8); }

    Q_ALWAYS_INLINE static constexpr quint8 div_257(quint16 x) { return div_257_floor(x + 128U); }

    Q_ALWAYS_INLINE constexpr QRgba64 unpremultiplied_32bit() const

    {

        if (isOpaque() || isTransparent())

            return *this;

        const quint32 a = alpha();

        const quint16 r = quint16((red()   * 0xffff + a/2) / a);

        const quint16 g = quint16((green() * 0xffff + a/2) / a);

        const quint16 b = quint16((blue()  * 0xffff + a/2) / a);

        return fromRgba64(r, g, b, quint16(a));

    }

    Q_ALWAYS_INLINE constexpr QRgba64 unpremultiplied_64bit() const

    {

        if (isOpaque() || isTransparent())

            return *this;

        const quint64 a = alpha();

        const quint64 fa = (Q_UINT64_C(0xffff00008000) + a/2) / a;

        const quint16 r = quint16((red()   * fa + 0x80000000) >> 32);

        const quint16 g = quint16((green() * fa + 0x80000000) >> 32);

        const quint16 b = quint16((blue()  * fa + 0x80000000) >> 32);

        return fromRgba64(r, g, b, quint16(a));

    }

};

Q_DECLARE_TYPEINFO(QRgba64, Q_PRIMITIVE_TYPE);

constexpr inline QRgba64 qRgba64(quint16 r, quint16 g, quint16 b, quint16 a)

{

    return QRgba64::fromRgba64(r, g, b, a);

}

constexpr inline QRgba64 qRgba64(quint64 c)

{

    return QRgba64::fromRgba64(c);

}

constexpr inline QRgba64 qPremultiply(QRgba64 c)

{

    return c.premultiplied();

}

constexpr inline QRgba64 qUnpremultiply(QRgba64 c)

{

    return c.unpremultiplied();

}

inline constexpr uint qRed(QRgba64 rgb)

{ return rgb.red8(); }

inline constexpr uint qGreen(QRgba64 rgb)

{ return rgb.green8(); }

inline constexpr uint qBlue(QRgba64 rgb)

{ return rgb.blue8(); }

inline constexpr uint qAlpha(QRgba64 rgb)

{ return rgb.alpha8(); }

QT_END_NAMESPACE

#endif // QRGBA64_H