chromium/third_party/skia/include/core/SkColorPriv.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 SkColorPriv_DEFINED
#define SkColorPriv_DEFINED

#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>

/** 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
*/
static inline unsigned SkAlpha255To256(U8CPU alpha) { … }

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

static inline U8CPU SkUnitScalarClampToByte(SkScalar x) { … }

#define SK_A32_BITS …
#define SK_R32_BITS …
#define SK_G32_BITS …
#define SK_B32_BITS …

#define SK_A32_MASK …
#define SK_R32_MASK …
#define SK_G32_MASK …
#define SK_B32_MASK …

/*
 *  Skia's 32bit backend only supports 1 swizzle order at a time (compile-time).
 *  This is specified by SK_R32_SHIFT=0 or SK_R32_SHIFT=16.
 *
 *  For easier compatibility with Skia's GPU backend, we further restrict these
 *  to either (in memory-byte-order) RGBA or BGRA. Note that this "order" does
 *  not directly correspond to the same shift-order, since we have to take endianess
 *  into account.
 *
 *  Here we enforce this constraint.
 */

#define SK_RGBA_R32_SHIFT …
#define SK_RGBA_G32_SHIFT …
#define SK_RGBA_B32_SHIFT …
#define SK_RGBA_A32_SHIFT …

#define SK_BGRA_B32_SHIFT …
#define SK_BGRA_G32_SHIFT …
#define SK_BGRA_R32_SHIFT …
#define SK_BGRA_A32_SHIFT …

#if defined(SK_PMCOLOR_IS_RGBA) || defined(SK_PMCOLOR_IS_BGRA)
    #error "Configure PMCOLOR by setting SK_R32_SHIFT."
#endif

// Deduce which SK_PMCOLOR_IS_ to define from the _SHIFT defines

#if (SK_A32_SHIFT == SK_RGBA_A32_SHIFT && \
     SK_R32_SHIFT == SK_RGBA_R32_SHIFT && \
     SK_G32_SHIFT == SK_RGBA_G32_SHIFT && \
     SK_B32_SHIFT == SK_RGBA_B32_SHIFT)
    #define SK_PMCOLOR_IS_RGBA
#elif (SK_A32_SHIFT == SK_BGRA_A32_SHIFT && \
       SK_R32_SHIFT == SK_BGRA_R32_SHIFT && \
       SK_G32_SHIFT == SK_BGRA_G32_SHIFT && \
       SK_B32_SHIFT == SK_BGRA_B32_SHIFT)
    #define SK_PMCOLOR_IS_BGRA
#else
    #error "need 32bit packing to be either RGBA or BGRA"
#endif

#define SkGetPackedA32(packed) …
#define SkGetPackedR32(packed) …
#define SkGetPackedG32(packed) …
#define SkGetPackedB32(packed) …

#define SkA32Assert(a) …
#define SkR32Assert(r) …
#define SkG32Assert(g) …
#define SkB32Assert(b) …

/**
 *  Pack the components into a SkPMColor
 */
static inline SkPMColor SkPackARGB32(U8CPU a, U8CPU r, U8CPU g, U8CPU b) { … }

/**
 *  Legacy "NoCheck" version of SkPackARGB32. Remove this once all callers are updated.
 */
static inline SkPMColor SkPackARGB32NoCheck(U8CPU a, U8CPU r, U8CPU g, U8CPU b) { … }

static inline
SkPMColor SkPremultiplyARGBInline(U8CPU a, U8CPU r, U8CPU g, U8CPU b) { … }

// When Android is compiled optimizing for size, SkAlphaMulQ doesn't get
// inlined; forcing inlining significantly improves performance.
static SK_ALWAYS_INLINE uint32_t SkAlphaMulQ(uint32_t c, unsigned scale) { … }

static inline SkPMColor SkPMSrcOver(SkPMColor src, SkPMColor dst) { … }

#endif