include/core/SkColor.h

/*
 * Copyright 2006 The Android Open Source Project
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#ifndef SkColor_DEFINED
#define SkColor_DEFINED

#include "SkScalar.h"
#include "SkTypes.h"

/** \file SkColor.h

    Types and macros for colors
*/

/** 8-bit type for an alpha value. 0xFF is 100% opaque, 0x00 is 100% transparent.
*/
typedef uint8_t SkAlpha;
/** 32 bit ARGB color value, not premultiplied. The color components are always in
    a known order. This is different from SkPMColor, which has its bytes in a configuration
    dependent order, to match the format of kARGB32 bitmaps. SkColor is the type used to
    specify colors in SkPaint and in gradients.
*/
typedef uint32_t SkColor;

/** Return a SkColor value from 8 bit component values
*/
static constexpr inline SkColor SkColorSetARGB(U8CPU a, U8CPU r, U8CPU g, U8CPU b) {
    return SkASSERT(a <= 255 && r <= 255 && g <= 255 && b <= 255),
           (a << 24) | (r << 16) | (g << 8) | (b << 0);
}
// Legacy aliases.
#define SkColorSetARGBInline SkColorSetARGB
#define SkColorSetARGBMacro  SkColorSetARGB

/** Return a SkColor value from 8 bit component values, with an implied value
    of 0xFF for alpha (fully opaque)
*/
#define SkColorSetRGB(r, g, b)  SkColorSetARGB(0xFF, r, g, b)

/** return the alpha byte from a SkColor value */
#define SkColorGetA(color)      (((color) >> 24) & 0xFF)
/** return the red byte from a SkColor value */
#define SkColorGetR(color)      (((color) >> 16) & 0xFF)
/** return the green byte from a SkColor value */
#define SkColorGetG(color)      (((color) >>  8) & 0xFF)
/** return the blue byte from a SkColor value */
#define SkColorGetB(color)      (((color) >>  0) & 0xFF)

static constexpr inline SkColor SkColorSetA(SkColor c, U8CPU a) {
    return (c & 0x00FFFFFF) | (a << 24);
}

// common colors

/** transparent SkAlpha value */
#define SK_AlphaTRANSPARENT static_cast<SkAlpha>(0x00)
/** opaque SkAlpha value */
#define SK_AlphaOPAQUE      static_cast<SkAlpha>(0xFF)

/** transparent SkColor value */
#define SK_ColorTRANSPARENT static_cast<SkColor>(0x00000000)

/** black SkColor value */
#define SK_ColorBLACK       static_cast<SkColor>(0xFF000000)
/** dark gray SkColor value */
#define SK_ColorDKGRAY      static_cast<SkColor>(0xFF444444)
/** gray SkColor value */
#define SK_ColorGRAY        static_cast<SkColor>(0xFF888888)
/** light gray SkColor value */
#define SK_ColorLTGRAY      static_cast<SkColor>(0xFFCCCCCC)
/** white SkColor value */
#define SK_ColorWHITE       static_cast<SkColor>(0xFFFFFFFF)

/** red SkColor value */
#define SK_ColorRED         static_cast<SkColor>(0xFFFF0000)
/** green SkColor value */
#define SK_ColorGREEN       static_cast<SkColor>(0xFF00FF00)
/** blue SkColor value */
#define SK_ColorBLUE        static_cast<SkColor>(0xFF0000FF)
/** yellow SkColor value */
#define SK_ColorYELLOW      static_cast<SkColor>(0xFFFFFF00)
/** cyan SkColor value */
#define SK_ColorCYAN        static_cast<SkColor>(0xFF00FFFF)
/** magenta SkColor value */
#define SK_ColorMAGENTA     static_cast<SkColor>(0xFFFF00FF)

////////////////////////////////////////////////////////////////////////

/** Convert RGB components to HSV.
        hsv[0] is Hue [0 .. 360)
        hsv[1] is Saturation [0...1]
        hsv[2] is Value [0...1]
    @param red  red component value [0..255]
    @param green  green component value [0..255]
    @param blue  blue component value [0..255]
    @param hsv  3 element array which holds the resulting HSV components.
*/
SK_API void SkRGBToHSV(U8CPU red, U8CPU green, U8CPU blue, SkScalar hsv[3]);

/** Convert the argb color to its HSV components.
        hsv[0] is Hue [0 .. 360)
        hsv[1] is Saturation [0...1]
        hsv[2] is Value [0...1]
    @param color the argb color to convert. Note: the alpha component is ignored.
    @param hsv  3 element array which holds the resulting HSV components.
*/
static inline void SkColorToHSV(SkColor color, SkScalar hsv[3]) {
    SkRGBToHSV(SkColorGetR(color), SkColorGetG(color), SkColorGetB(color), hsv);
}

/** Convert HSV components to an ARGB color. The alpha component is passed through unchanged.
        hsv[0] is Hue [0 .. 360)
        hsv[1] is Saturation [0...1]
        hsv[2] is Value [0...1]
    If hsv values are out of range, they are pinned.
    @param alpha the alpha component of the returned argb color.
    @param hsv  3 element array which holds the input HSV components.
    @return the resulting argb color
*/
SK_API SkColor SkHSVToColor(U8CPU alpha, const SkScalar hsv[3]);

/** Convert HSV components to an ARGB color. The alpha component set to 0xFF.
        hsv[0] is Hue [0 .. 360)
        hsv[1] is Saturation [0...1]
        hsv[2] is Value [0...1]
    If hsv values are out of range, they are pinned.
    @param hsv  3 element array which holds the input HSV components.
    @return the resulting argb color
*/
static inline SkColor SkHSVToColor(const SkScalar hsv[3]) {
    return SkHSVToColor(0xFF, hsv);
}

////////////////////////////////////////////////////////////////////////

/** 32 bit ARGB color value, premultiplied. The byte order for this value is
    configuration dependent, matching the format of kARGB32 bitmaps. This is different
    from SkColor, which is nonpremultiplied, and is always in the same byte order.
*/
typedef uint32_t SkPMColor;

/** Return a SkPMColor value from unpremultiplied 8 bit component values
*/
SK_API SkPMColor SkPreMultiplyARGB(U8CPU a, U8CPU r, U8CPU g, U8CPU b);
/** Return a SkPMColor value from a SkColor value. This is done by multiplying the color
    components by the color's alpha, and by arranging the bytes in a configuration
    dependent order, to match the format of kARGB32 bitmaps.
*/
SK_API SkPMColor SkPreMultiplyColor(SkColor c);

///////////////////////////////////////////////////////////////////////////////////////////////////

struct SkPM4f;

/*
 *  The float values are 0...1 unpremultiplied
 */
struct SK_API SkColor4f {
    float fR;
    float fG;
    float fB;
    float fA;

    bool operator==(const SkColor4f& other) const {
        return fA == other.fA && fR == other.fR && fG == other.fG && fB == other.fB;
    }
    bool operator!=(const SkColor4f& other) const {
        return !(*this == other);
    }

    const float* vec() const { return &fR; }
    float* vec() { return &fR; }

    static SkColor4f Pin(float r, float g, float b, float a);
    /** Convert to SkColor4f, assuming SkColor is sRGB */
    static SkColor4f FromColor(SkColor);

    SkColor toSkColor() const;

    SkColor4f pin() const {
        return Pin(fR, fG, fB, fA);
    }

    SkPM4f premul() const;
};

#endif