1/*
2 * Copyright 2009 The Android Open Source Project
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
9#include "SkColorData.h"
10
11/*
12    Filter_32_opaque
13
14    There is no hard-n-fast rule that the filtering must produce
15    exact results for the color components, but if the 4 incoming colors are
16    all opaque, then the output color must also be opaque. Subsequent parts of
17    the drawing pipeline may rely on this (e.g. which blitrow proc to use).
18 */
19
20static inline void Filter_32_opaque(unsigned x, unsigned y,
21                                    SkPMColor a00, SkPMColor a01,
22                                    SkPMColor a10, SkPMColor a11,
23                                    SkPMColor* dstColor) {
24    SkASSERT((unsigned)x <= 0xF);
25    SkASSERT((unsigned)y <= 0xF);
26
27    int xy = x * y;
28    const uint32_t mask = 0xFF00FF;
29
30    int scale = 256 - 16*y - 16*x + xy;
31    uint32_t lo = (a00 & mask) * scale;
32    uint32_t hi = ((a00 >> 8) & mask) * scale;
33
34    scale = 16*x - xy;
35    lo += (a01 & mask) * scale;
36    hi += ((a01 >> 8) & mask) * scale;
37
38    scale = 16*y - xy;
39    lo += (a10 & mask) * scale;
40    hi += ((a10 >> 8) & mask) * scale;
41
42    lo += (a11 & mask) * xy;
43    hi += ((a11 >> 8) & mask) * xy;
44
45    *dstColor = ((lo >> 8) & mask) | (hi & ~mask);
46}
47
48static inline void Filter_32_alpha(unsigned x, unsigned y,
49                                   SkPMColor a00, SkPMColor a01,
50                                   SkPMColor a10, SkPMColor a11,
51                                   SkPMColor* dstColor,
52                                   unsigned alphaScale) {
53    SkASSERT((unsigned)x <= 0xF);
54    SkASSERT((unsigned)y <= 0xF);
55    SkASSERT(alphaScale <= 256);
56
57    int xy = x * y;
58    const uint32_t mask = 0xFF00FF;
59
60    int scale = 256 - 16*y - 16*x + xy;
61    uint32_t lo = (a00 & mask) * scale;
62    uint32_t hi = ((a00 >> 8) & mask) * scale;
63
64    scale = 16*x - xy;
65    lo += (a01 & mask) * scale;
66    hi += ((a01 >> 8) & mask) * scale;
67
68    scale = 16*y - xy;
69    lo += (a10 & mask) * scale;
70    hi += ((a10 >> 8) & mask) * scale;
71
72    lo += (a11 & mask) * xy;
73    hi += ((a11 >> 8) & mask) * xy;
74
75    lo = ((lo >> 8) & mask) * alphaScale;
76    hi = ((hi >> 8) & mask) * alphaScale;
77
78    *dstColor = ((lo >> 8) & mask) | (hi & ~mask);
79}
80
81// Two color version, where we filter only along 1 axis
82static inline void Filter_32_opaque(unsigned t,
83                                    SkPMColor color0,
84                                    SkPMColor color1,
85                                    SkPMColor* dstColor) {
86    SkASSERT((unsigned)t <= 0xF);
87
88    const uint32_t mask = 0xFF00FF;
89
90    int scale = 256 - 16*t;
91    uint32_t lo = (color0 & mask) * scale;
92    uint32_t hi = ((color0 >> 8) & mask) * scale;
93
94    scale = 16*t;
95    lo += (color1 & mask) * scale;
96    hi += ((color1 >> 8) & mask) * scale;
97
98    *dstColor = ((lo >> 8) & mask) | (hi & ~mask);
99}
100
101// Two color version, where we filter only along 1 axis
102static inline void Filter_32_alpha(unsigned t,
103                                   SkPMColor color0,
104                                   SkPMColor color1,
105                                   SkPMColor* dstColor,
106                                   unsigned alphaScale) {
107    SkASSERT((unsigned)t <= 0xF);
108    SkASSERT(alphaScale <= 256);
109
110    const uint32_t mask = 0xFF00FF;
111
112    int scale = 256 - 16*t;
113    uint32_t lo = (color0 & mask) * scale;
114    uint32_t hi = ((color0 >> 8) & mask) * scale;
115
116    scale = 16*t;
117    lo += (color1 & mask) * scale;
118    hi += ((color1 >> 8) & mask) * scale;
119
120    lo = ((lo >> 8) & mask) * alphaScale;
121    hi = ((hi >> 8) & mask) * alphaScale;
122
123    *dstColor = ((lo >> 8) & mask) | (hi & ~mask);
124}
125