SkColorPriv.h File Reference

#include "include/core/SkColor.h"
#include "include/private/base/SkMath.h"
#include "include/private/base/SkTPin.h"
#include "include/private/base/SkTo.h"
#include <algorithm>

Go to the source code of this file.

Macros
#define	SkAlphaMul(value, alpha256)   (((value) * (alpha256)) >> 8)
#define	SK_A32_BITS   8
#define	SK_R32_BITS   8
#define	SK_G32_BITS   8
#define	SK_B32_BITS   8
#define	SK_A32_MASK   ((1 << SK_A32_BITS) - 1)
#define	SK_R32_MASK   ((1 << SK_R32_BITS) - 1)
#define	SK_G32_MASK   ((1 << SK_G32_BITS) - 1)
#define	SK_B32_MASK   ((1 << SK_B32_BITS) - 1)
#define	SK_RGBA_R32_SHIFT   0
#define	SK_RGBA_G32_SHIFT   8
#define	SK_RGBA_B32_SHIFT   16
#define	SK_RGBA_A32_SHIFT   24
#define	SK_BGRA_B32_SHIFT   0
#define	SK_BGRA_G32_SHIFT   8
#define	SK_BGRA_R32_SHIFT   16
#define	SK_BGRA_A32_SHIFT   24
#define	SkGetPackedA32(packed)   ((uint32_t)((packed) << (24 - SK_A32_SHIFT)) >> 24)
#define	SkGetPackedR32(packed)   ((uint32_t)((packed) << (24 - SK_R32_SHIFT)) >> 24)
#define	SkGetPackedG32(packed)   ((uint32_t)((packed) << (24 - SK_G32_SHIFT)) >> 24)
#define	SkGetPackedB32(packed)   ((uint32_t)((packed) << (24 - SK_B32_SHIFT)) >> 24)
#define	SkA32Assert(a)   SkASSERT((unsigned)(a) <= SK_A32_MASK)
#define	SkR32Assert(r)   SkASSERT((unsigned)(r) <= SK_R32_MASK)
#define	SkG32Assert(g)   SkASSERT((unsigned)(g) <= SK_G32_MASK)
#define	SkB32Assert(b)   SkASSERT((unsigned)(b) <= SK_B32_MASK)

Functions
static unsigned	SkAlpha255To256 (U8CPU alpha)
static U8CPU	SkUnitScalarClampToByte (SkScalar x)
static SkPMColor	SkPackARGB32 (U8CPU a, U8CPU r, U8CPU g, U8CPU b)
static SkPMColor	SkPackARGB32NoCheck (U8CPU a, U8CPU r, U8CPU g, U8CPU b)
static SkPMColor	SkPremultiplyARGBInline (U8CPU a, U8CPU r, U8CPU g, U8CPU b)
static SK_ALWAYS_INLINE uint32_t	SkAlphaMulQ (uint32_t c, unsigned scale)
static SkPMColor	SkPMSrcOver (SkPMColor src, SkPMColor dst)

Macro Definition Documentation

SK_A32_BITS

#define SK_A32_BITS   8

Definition at line 40 of file SkColorPriv.h.

SK_A32_MASK

#define SK_A32_MASK   ((1 << SK_A32_BITS) - 1)

Definition at line 45 of file SkColorPriv.h.

SK_B32_BITS

#define SK_B32_BITS   8

Definition at line 43 of file SkColorPriv.h.

SK_B32_MASK

#define SK_B32_MASK   ((1 << SK_B32_BITS) - 1)

Definition at line 48 of file SkColorPriv.h.

SK_BGRA_A32_SHIFT

#define SK_BGRA_A32_SHIFT   24

Definition at line 70 of file SkColorPriv.h.

SK_BGRA_B32_SHIFT

#define SK_BGRA_B32_SHIFT   0

Definition at line 67 of file SkColorPriv.h.

SK_BGRA_G32_SHIFT

#define SK_BGRA_G32_SHIFT   8

Definition at line 68 of file SkColorPriv.h.

SK_BGRA_R32_SHIFT

#define SK_BGRA_R32_SHIFT   16

Definition at line 69 of file SkColorPriv.h.

SK_G32_BITS

#define SK_G32_BITS   8

Definition at line 42 of file SkColorPriv.h.

SK_G32_MASK

#define SK_G32_MASK   ((1 << SK_G32_BITS) - 1)

Definition at line 47 of file SkColorPriv.h.

SK_R32_BITS

#define SK_R32_BITS   8

Definition at line 41 of file SkColorPriv.h.

SK_R32_MASK

#define SK_R32_MASK   ((1 << SK_R32_BITS) - 1)

Definition at line 46 of file SkColorPriv.h.

SK_RGBA_A32_SHIFT

#define SK_RGBA_A32_SHIFT   24

Definition at line 65 of file SkColorPriv.h.

SK_RGBA_B32_SHIFT

#define SK_RGBA_B32_SHIFT   16

Definition at line 64 of file SkColorPriv.h.

SK_RGBA_G32_SHIFT

#define SK_RGBA_G32_SHIFT   8

Definition at line 63 of file SkColorPriv.h.

SK_RGBA_R32_SHIFT

#define SK_RGBA_R32_SHIFT   0

Definition at line 62 of file SkColorPriv.h.

SkA32Assert

#define SkA32Assert

(

a

)

SkASSERT((unsigned)(a) <= SK_A32_MASK)

Definition at line 97 of file SkColorPriv.h.

SkAlphaMul

#define SkAlphaMul	(		value,
			alpha256
	)		(((value) * (alpha256)) >> 8)

Multiplify value by 0..256, and shift the result down 8 (i.e. return (value * alpha256) >> 8)

Definition at line 34 of file SkColorPriv.h.

SkB32Assert

#define SkB32Assert

(

b

)

SkASSERT((unsigned)(b) <= SK_B32_MASK)

Definition at line 100 of file SkColorPriv.h.

SkG32Assert

#define SkG32Assert

(

g

)

SkASSERT((unsigned)(g) <= SK_G32_MASK)

Definition at line 99 of file SkColorPriv.h.

SkGetPackedA32

#define SkGetPackedA32

(

packed

)

((uint32_t)((packed) << (24 - SK_A32_SHIFT)) >> 24)

Definition at line 92 of file SkColorPriv.h.

SkGetPackedB32

#define SkGetPackedB32

(

packed

)

((uint32_t)((packed) << (24 - SK_B32_SHIFT)) >> 24)

Definition at line 95 of file SkColorPriv.h.

SkGetPackedG32

#define SkGetPackedG32

(

packed

)

((uint32_t)((packed) << (24 - SK_G32_SHIFT)) >> 24)

Definition at line 94 of file SkColorPriv.h.

SkGetPackedR32

#define SkGetPackedR32

(

packed

)

((uint32_t)((packed) << (24 - SK_R32_SHIFT)) >> 24)

Definition at line 93 of file SkColorPriv.h.

SkR32Assert

#define SkR32Assert

(

r

)

SkASSERT((unsigned)(r) <= SK_R32_MASK)

Definition at line 98 of file SkColorPriv.h.

Function Documentation

SkAlpha255To256()

static unsigned SkAlpha255To256 ( U8CPU  alpha )

inlinestatic

Turn 0..255 into 0..256 by adding 1 at the half-way point. Used to turn a byte into a scale value, so that we can say scale * value >> 8 instead of alpha * value / 255.

In debugging, asserts that alpha is 0..255

Definition at line 24 of file SkColorPriv.h.

                                                    {
    SkASSERT(SkToU8(alpha) == alpha);
    // this one assues that blending on top of an opaque dst keeps it that way
    // even though it is less accurate than a+(a>>7) for non-opaque dsts
    return alpha + 1;
}

SkAlphaMulQ()

static SK_ALWAYS_INLINE uint32_t SkAlphaMulQ ( uint32_t  c, unsigned  scale  )

static

Definition at line 142 of file SkColorPriv.h.

                                                                         {
    uint32_t mask = 0xFF00FF;
 
    uint32_t rb = ((c & mask) * scale) >> 8;
    uint32_t ag = ((c >> 8) & mask) * scale;
    return (rb & mask) | (ag & ~mask);
}

SkPackARGB32()

static SkPMColor SkPackARGB32 ( U8CPU  a, U8CPU  r, U8CPU  g, U8CPU  b  )

inlinestatic

Pack the components into a SkPMColor, checking (in the debug version) that the components are 0..255, and are already premultiplied (i.e. alpha >= color)

Definition at line 106 of file SkColorPriv.h.

                                                                         {
    SkA32Assert(a);
    SkASSERT(r <= a);
    SkASSERT(g <= a);
    SkASSERT(b <= a);
 
    return (a << SK_A32_SHIFT) | (r << SK_R32_SHIFT) |
           (g << SK_G32_SHIFT) | (b << SK_B32_SHIFT);
}

SkPackARGB32NoCheck()

static SkPMColor SkPackARGB32NoCheck ( U8CPU  a, U8CPU  r, U8CPU  g, U8CPU  b  )

inlinestatic

Same as SkPackARGB32, but this version guarantees to not check that the values are premultiplied in the debug version.

Definition at line 120 of file SkColorPriv.h.

                                                                                {
    return (a << SK_A32_SHIFT) | (r << SK_R32_SHIFT) |
           (g << SK_G32_SHIFT) | (b << SK_B32_SHIFT);
}

SkPMSrcOver()

static SkPMColor SkPMSrcOver ( SkPMColor  src, SkPMColor  dst  )

inlinestatic

Definition at line 150 of file SkColorPriv.h.

                                                                  {
    uint32_t scale = SkAlpha255To256(255 - SkGetPackedA32(src));
 
    uint32_t mask = 0xFF00FF;
    uint32_t rb = (((dst & mask) * scale) >> 8) & mask;
    uint32_t ag = (((dst >> 8) & mask) * scale) & ~mask;
 
    rb += (src &  mask);
    ag += (src & ~mask);
 
    // Color channels (but not alpha) can overflow, so we have to saturate to 0xFF in each lane.
    return std::min(rb & 0x000001FF, 0x000000FFU) |
           std::min(ag & 0x0001FF00, 0x0000FF00U) |
           std::min(rb & 0x01FF0000, 0x00FF0000U) |
                   (ag & 0xFF000000);
}

SkPremultiplyARGBInline()

static SkPMColor SkPremultiplyARGBInline ( U8CPU  a, U8CPU  r, U8CPU  g, U8CPU  b  )

inlinestatic

Definition at line 126 of file SkColorPriv.h.

                                                                      {
    SkA32Assert(a);
    SkR32Assert(r);
    SkG32Assert(g);
    SkB32Assert(b);
 
    if (a != 255) {
        r = SkMulDiv255Round(r, a);
        g = SkMulDiv255Round(g, a);
        b = SkMulDiv255Round(b, a);
    }
    return SkPackARGB32(a, r, g, b);
}

SkUnitScalarClampToByte()

static U8CPU SkUnitScalarClampToByte ( SkScalar  x )

inlinestatic

Definition at line 36 of file SkColorPriv.h.

                                                        {
    return static_cast<U8CPU>(SkTPin(x, 0.0f, 1.0f) * 255 + 0.5);
}