SkColor.cpp File Reference

#include "include/core/SkColor.h"
#include "include/core/SkColorPriv.h"
#include "include/private/SkColorData.h"
#include "include/private/base/SkTPin.h"
#include "src/base/SkVx.h"
#include "src/core/SkSwizzlePriv.h"
#include <algorithm>

Go to the source code of this file.

Functions
SkPMColor	SkPreMultiplyARGB (U8CPU a, U8CPU r, U8CPU g, U8CPU b)
SkPMColor	SkPreMultiplyColor (SkColor c)
static SkScalar	ByteToScalar (U8CPU x)
static SkScalar	ByteDivToScalar (int numer, U8CPU denom)
void	SkRGBToHSV (U8CPU r, U8CPU g, U8CPU b, SkScalar hsv[3])
SkColor	SkHSVToColor (U8CPU a, const SkScalar hsv[3])

Function Documentation

ByteDivToScalar()

static SkScalar ByteDivToScalar ( int  numer, U8CPU  denom  )

inlinestatic

Definition at line 33 of file SkColor.cpp.

                                                               {
    // cast to keep the answer signed
    return SkIntToScalar(numer) / (int)denom;
}

ByteToScalar()

static SkScalar ByteToScalar ( U8CPU  x )

inlinestatic

Definition at line 28 of file SkColor.cpp.

                                             {
    SkASSERT(x <= 255);
    return SkIntToScalar(x) / 255;
}

SkHSVToColor()

SkColor SkHSVToColor	(	U8CPU	alpha,
		const SkScalar	hsv[3]
	)

Converts HSV components to an ARGB color. Alpha is passed through unchanged. hsv[0] represents hsv hue, an angle from zero to less than 360. hsv[1] represents hsv saturation, and varies from zero to one. hsv[2] represents hsv value, and varies from zero to one.

Out of range hsv values are pinned.

Parameters

alpha	alpha component of the returned ARGB color
hsv	three element array which holds the input HSV components

Returns

ARGB equivalent to HSV

Definition at line 78 of file SkColor.cpp.

                                                     {
    SkASSERT(hsv);
 
    SkScalar s = SkTPin(hsv[1], 0.0f, 1.0f);
    SkScalar v = SkTPin(hsv[2], 0.0f, 1.0f);
 
    U8CPU v_byte = SkScalarRoundToInt(v * 255);
 
    if (SkScalarNearlyZero(s)) { // shade of gray
        return SkColorSetARGB(a, v_byte, v_byte, v_byte);
    }
    SkScalar hx = (hsv[0] < 0 || hsv[0] >= SkIntToScalar(360)) ? 0 : hsv[0]/60;
    SkScalar w = SkScalarFloorToScalar(hx);
    SkScalar f = hx - w;
 
    unsigned p = SkScalarRoundToInt((SK_Scalar1 - s) * v * 255);
    unsigned q = SkScalarRoundToInt((SK_Scalar1 - (s * f)) * v * 255);
    unsigned t = SkScalarRoundToInt((SK_Scalar1 - (s * (SK_Scalar1 - f))) * v * 255);
 
    unsigned r, g, b;
 
    SkASSERT((unsigned)(w) < 6);
    switch ((unsigned)(w)) {
        case 0: r = v_byte;  g = t;      b = p; break;
        case 1: r = q;       g = v_byte; b = p; break;
        case 2: r = p;       g = v_byte; b = t; break;
        case 3: r = p;       g = q;      b = v_byte; break;
        case 4: r = t;       g = p;      b = v_byte; break;
        default: r = v_byte; g = p;      b = q; break;
    }
    return SkColorSetARGB(a, r, g, b);
}

SkPreMultiplyARGB()

SkPMColor SkPreMultiplyARGB	(	U8CPU	a,
		U8CPU	r,
		U8CPU	g,
		U8CPU	b
	)

Returns a SkPMColor value from unpremultiplied 8-bit component values.

Parameters

a	amount of alpha, from fully transparent (0) to fully opaque (255)
r	amount of red, from no red (0) to full red (255)
g	amount of green, from no green (0) to full green (255)
b	amount of blue, from no blue (0) to full blue (255)

Returns

premultiplied color

Definition at line 17 of file SkColor.cpp.

                                                                {
    return SkPremultiplyARGBInline(a, r, g, b);
}

SkPreMultiplyColor()

SkPMColor SkPreMultiplyColor

(

SkColor

c

)

Returns pmcolor closest to color c. Multiplies c RGB components by the c alpha, and arranges the bytes to match the format of kN32_SkColorType.

Parameters

c	unpremultiplied ARGB color

Returns

premultiplied color

Definition at line 21 of file SkColor.cpp.

                                        {
    return SkPremultiplyARGBInline(SkColorGetA(c), SkColorGetR(c),
                                   SkColorGetG(c), SkColorGetB(c));
}

SkRGBToHSV()

void SkRGBToHSV	(	U8CPU	red,
		U8CPU	green,
		U8CPU	blue,
		SkScalar	hsv[3]
	)

Converts RGB to its HSV components. hsv[0] contains hsv hue, a value from zero to less than 360. hsv[1] contains hsv saturation, a value from zero to one. hsv[2] contains hsv value, a value from zero to one.

Parameters

red	red component value from zero to 255
green	green component value from zero to 255
blue	blue component value from zero to 255
hsv	three element array which holds the resulting HSV components

Definition at line 38 of file SkColor.cpp.

                                                            {
    SkASSERT(hsv);
 
    unsigned min = std::min(r, std::min(g, b));
    unsigned max = std::max(r, std::max(g, b));
    unsigned delta = max - min;
 
    SkScalar v = ByteToScalar(max);
    SkASSERT(v >= 0 && v <= SK_Scalar1);
 
    if (0 == delta) { // we're a shade of gray
        hsv[0] = 0;
        hsv[1] = 0;
        hsv[2] = v;
        return;
    }
 
    SkScalar s = ByteDivToScalar(delta, max);
    SkASSERT(s >= 0 && s <= SK_Scalar1);
 
    SkScalar h;
    if (r == max) {
        h = ByteDivToScalar(g - b, delta);
    } else if (g == max) {
        h = SkIntToScalar(2) + ByteDivToScalar(b - r, delta);
    } else { // b == max
        h = SkIntToScalar(4) + ByteDivToScalar(r - g, delta);
    }
 
    h *= 60;
    if (h < 0) {
        h += SkIntToScalar(360);
    }
    SkASSERT(h >= 0 && h < SkIntToScalar(360));
 
    hsv[0] = h;
    hsv[1] = s;
    hsv[2] = v;
}