src/core/SkPM4fPriv.h

/*
 * Copyright 2016 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#ifndef SkPM4fPriv_DEFINED
#define SkPM4fPriv_DEFINED

#include "SkColorData.h"
#include "SkColorSpace.h"
#include "SkColorSpacePriv.h"
#include "SkColorSpaceXformSteps.h"
#include "SkArenaAlloc.h"
#include "SkPM4f.h"
#include "SkRasterPipeline.h"
#include "../jumper/SkJumper.h"

// This file is mostly helper routines for doing color space management.
// It probably wants a new name, and they likely don't need to be inline.
//
// There are two generations of routines in here, the old ones that assumed linear blending,
// and the new ones assuming as-encoded blending.  We're trying to move to the new as-encoded
// ones and will hopefully eventually remove all the linear routines.
//
// We'll start with the new as-encoded routines first,
// and shove all the old broken routines towards the bottom.

static inline Sk4f Sk4f_fromL32(uint32_t px) {
    return SkNx_cast<float>(Sk4b::Load(&px)) * (1/255.0f);
}

static inline uint32_t Sk4f_toL32(const Sk4f& px) {
    uint32_t l32;
    SkNx_cast<uint8_t>(Sk4f_round(px * 255.0f)).store(&l32);
    return l32;
}

static inline SkPM4f premul_in_dst_colorspace(SkColor4f color4f,
                                              SkColorSpace* srcCS, SkColorSpace* dstCS) {
    // TODO: In the very common case of srcCS being sRGB,
    // can we precompute an sRGB -> dstCS SkColorSpaceXformSteps for each device and use it here?
    SkColorSpaceXformSteps(srcCS, kUnpremul_SkAlphaType,
                           dstCS, kPremul_SkAlphaType)
        .apply(color4f.vec());

    return {{color4f.fR, color4f.fG, color4f.fB, color4f.fA}};
}

static inline SkPM4f premul_in_dst_colorspace(SkColor c, SkColorSpace* dstCS) {
    SkColor4f color4f;
    swizzle_rb(Sk4f_fromL32(c)).store(color4f.vec());

    // SkColors are always sRGB.
    return premul_in_dst_colorspace(color4f, sk_srgb_singleton(), dstCS);
}

#endif