1/*
2 * Copyright 2016 Google Inc.
3 *
4 * Use of this source code is governed by a BSD-style license that can be
5 * found in the LICENSE file.
6 */
7
8#ifndef Sk4fGradientPriv_DEFINED
9#define Sk4fGradientPriv_DEFINED
10
11#include "include/core/SkColor.h"
12#include "include/core/SkImageInfo.h"
13#include "include/private/SkColorData.h"
14#include "include/private/SkHalf.h"
15#include "include/private/SkNx.h"
16#include "src/core/SkUtils.h"
17
18// Templates shared by various 4f gradient flavors.
19
20namespace { // NOLINT(google-build-namespaces)
21
22enum class ApplyPremul { True, False };
23
24template <ApplyPremul>
25struct PremulTraits;
26
27template <>
28struct PremulTraits<ApplyPremul::False> {
29 static Sk4f apply(const Sk4f& c) { return c; }
30};
31
32template <>
33struct PremulTraits<ApplyPremul::True> {
34 static Sk4f apply(const Sk4f& c) {
35 const float alpha = c[3];
36 // FIXME: portable swizzle?
37 return c * Sk4f(alpha, alpha, alpha, 1);
38 }
39};
40
41// Struct encapsulating various dest-dependent ops:
42//
43// - load() Load a SkPMColor4f value into Sk4f. Normally called once per interval
44// advance. Also applies a scale and swizzle suitable for DstType.
45//
46// - store() Store one Sk4f to dest. Optionally handles premul, color space
47// conversion, etc.
48//
49// - store(count) Store the Sk4f value repeatedly to dest, count times.
50//
51// - store4x() Store 4 Sk4f values to dest (opportunistic optimization).
52//
53
54template <ApplyPremul premul>
55struct DstTraits {
56 using PM = PremulTraits<premul>;
57
58 // For L32, prescaling by 255 saves a per-pixel multiplication when premul is not needed.
59 static Sk4f load(const SkPMColor4f& c) {
60 Sk4f c4f = swizzle_rb_if_bgra(Sk4f::Load(c.vec()));
61 return premul == ApplyPremul::False
62 ? c4f * Sk4f(255)
63 : c4f;
64 }
65
66 static void store(const Sk4f& c, SkPMColor* dst, const Sk4f& bias) {
67 if (premul == ApplyPremul::False) {
68 // c is pre-scaled by 255 and pre-biased, just store.
69 SkNx_cast<uint8_t>(c).store(dst);
70 } else {
71 *dst = Sk4f_toL32(PM::apply(c) + bias);
72 }
73 }
74
75 static void store(const Sk4f& c, SkPMColor* dst, int n) {
76 SkPMColor pmc;
77 store(c, &pmc, Sk4f(0));
78 sk_memset32(dst, pmc, n);
79 }
80
81 static void store4x(const Sk4f& c0, const Sk4f& c1,
82 const Sk4f& c2, const Sk4f& c3,
83 SkPMColor* dst,
84 const Sk4f& bias0,
85 const Sk4f& bias1) {
86 if (premul == ApplyPremul::False) {
87 // colors are pre-scaled and pre-biased.
88 Sk4f_ToBytes((uint8_t*)dst, c0, c1, c2, c3);
89 } else {
90 store(c0, dst + 0, bias0);
91 store(c1, dst + 1, bias1);
92 store(c2, dst + 2, bias0);
93 store(c3, dst + 3, bias1);
94 }
95 }
96
97 static Sk4f pre_lerp_bias(const Sk4f& bias) {
98 // We can apply the bias before interpolation when the colors are premultiplied.
99 return premul == ApplyPremul::False ? bias : 0;
100 }
101};
102
103} // anonymous namespace
104
105#endif // Sk4fGradientPriv_DEFINED
106