skia/src/include/core/SkColor.h

/*
 * Copyright (C) 2006 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#ifndef SkColor_DEFINED
#define SkColor_DEFINED

#include "SkScalar.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 inline SkColor SkColorSetARGB(U8CPU a, U8CPU r, U8CPU g, U8CPU b)
{
    SkASSERT(a <= 255 && r <= 255 && g <= 255 && b <= 255);

    return (a << 24) | (r << 16) | (g << 8) | (b << 0);
}

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

// common colors

#define SK_ColorBLACK   0xFF000000  //!< black SkColor value
#define SK_ColorDKGRAY  0xFF444444  //!< dark gray SkColor value
#define SK_ColorGRAY    0xFF888888  //!< gray SkColor value
#define SK_ColorLTGRAY  0xFFCCCCCC  //!< light gray SkColor value
#define SK_ColorWHITE   0xFFFFFFFF  //!< white SkColor value

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

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

/** 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.
*/
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
*/
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
*/
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.
*/
SkPMColor SkPreMultiplyColor(SkColor c);

/** Define a function pointer type for combining two premultiplied colors
*/
typedef SkPMColor (*SkXfermodeProc)(SkPMColor src, SkPMColor dst);

/** Define a function pointer type for combining a premultiplied src color
    and a 16bit device color.
*/
typedef uint16_t (*SkXfermodeProc16)(SkPMColor src, uint16_t dst);

#endif