blob: 1599a2f97eea31f8629318c0a944d2c58cf5594f [file] [log] [blame]
/*
* 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 Sk4fGradientPriv_DEFINED
#define Sk4fGradientPriv_DEFINED
#include "include/core/SkColor.h"
#include "include/core/SkImageInfo.h"
#include "include/private/SkColorData.h"
#include "include/private/SkHalf.h"
#include "include/private/SkNx.h"
#include "src/core/SkOpts.h"
// Templates shared by various 4f gradient flavors.
namespace { // NOLINT(google-build-namespaces)
enum class ApplyPremul { True, False };
template <ApplyPremul>
struct PremulTraits;
template <>
struct PremulTraits<ApplyPremul::False> {
static Sk4f apply(const Sk4f& c) { return c; }
};
template <>
struct PremulTraits<ApplyPremul::True> {
static Sk4f apply(const Sk4f& c) {
const float alpha = c[3];
// FIXME: portable swizzle?
return c * Sk4f(alpha, alpha, alpha, 1);
}
};
// Struct encapsulating various dest-dependent ops:
//
// - load() Load a SkPMColor4f value into Sk4f. Normally called once per interval
// advance. Also applies a scale and swizzle suitable for DstType.
//
// - store() Store one Sk4f to dest. Optionally handles premul, color space
// conversion, etc.
//
// - store(count) Store the Sk4f value repeatedly to dest, count times.
//
// - store4x() Store 4 Sk4f values to dest (opportunistic optimization).
//
template <ApplyPremul premul>
struct DstTraits {
using PM = PremulTraits<premul>;
// For L32, prescaling by 255 saves a per-pixel multiplication when premul is not needed.
static Sk4f load(const SkPMColor4f& c) {
Sk4f c4f = swizzle_rb_if_bgra(Sk4f::Load(c.vec()));
return premul == ApplyPremul::False
? c4f * Sk4f(255)
: c4f;
}
static void store(const Sk4f& c, SkPMColor* dst, const Sk4f& bias) {
if (premul == ApplyPremul::False) {
// c is pre-scaled by 255 and pre-biased, just store.
SkNx_cast<uint8_t>(c).store(dst);
} else {
*dst = Sk4f_toL32(PM::apply(c) + bias);
}
}
static void store(const Sk4f& c, SkPMColor* dst, int n) {
SkPMColor pmc;
store(c, &pmc, Sk4f(0));
sk_memset32(dst, pmc, n);
}
static void store4x(const Sk4f& c0, const Sk4f& c1,
const Sk4f& c2, const Sk4f& c3,
SkPMColor* dst,
const Sk4f& bias0,
const Sk4f& bias1) {
if (premul == ApplyPremul::False) {
// colors are pre-scaled and pre-biased.
Sk4f_ToBytes((uint8_t*)dst, c0, c1, c2, c3);
} else {
store(c0, dst + 0, bias0);
store(c1, dst + 1, bias1);
store(c2, dst + 2, bias0);
store(c3, dst + 3, bias1);
}
}
static Sk4f pre_lerp_bias(const Sk4f& bias) {
// We can apply the bias before interpolation when the colors are premultiplied.
return premul == ApplyPremul::False ? bias : 0;
}
};
} // anonymous namespace
#endif // Sk4fGradientPriv_DEFINED