1 /*
2 * Copyright (C) 2008 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 #ifndef SkDither_DEFINED
18 #define SkDither_DEFINED
19
20 #include "SkColorPriv.h"
21
22 #define SK_DitherValueMax4444 15
23 #define SK_DitherValueMax565 7
24
25 /* need to use macros for bit-counts for each component, and then
26 move these into SkColorPriv.h
27 */
28
29 #define SkDITHER_R32_FOR_565_MACRO(r, d) (r + d - (r >> 5))
30 #define SkDITHER_G32_FOR_565_MACRO(g, d) (g + (d >> 1) - (g >> 6))
31 #define SkDITHER_B32_FOR_565_MACRO(b, d) (b + d - (b >> 5))
32
33 #define SkDITHER_A32_FOR_4444_MACRO(a, d) (a + 15 - (a >> 4))
34 #define SkDITHER_R32_FOR_4444_MACRO(r, d) (r + d - (r >> 4))
35 #define SkDITHER_G32_FOR_4444_MACRO(g, d) (g + d - (g >> 4))
36 #define SkDITHER_B32_FOR_4444_MACRO(b, d) (b + d - (b >> 4))
37
38 #ifdef SK_DEBUG
SkDITHER_R32_FOR_565(unsigned r,unsigned d)39 inline unsigned SkDITHER_R32_FOR_565(unsigned r, unsigned d)
40 {
41 SkASSERT(d <= SK_DitherValueMax565);
42 SkA32Assert(r);
43 r = SkDITHER_R32_FOR_565_MACRO(r, d);
44 SkA32Assert(r);
45 return r;
46 }
SkDITHER_G32_FOR_565(unsigned g,unsigned d)47 inline unsigned SkDITHER_G32_FOR_565(unsigned g, unsigned d)
48 {
49 SkASSERT(d <= SK_DitherValueMax565);
50 SkG32Assert(g);
51 g = SkDITHER_G32_FOR_565_MACRO(g, d);
52 SkG32Assert(g);
53 return g;
54 }
SkDITHER_B32_FOR_565(unsigned b,unsigned d)55 inline unsigned SkDITHER_B32_FOR_565(unsigned b, unsigned d)
56 {
57 SkASSERT(d <= SK_DitherValueMax565);
58 SkB32Assert(b);
59 b = SkDITHER_B32_FOR_565_MACRO(b, d);
60 SkB32Assert(b);
61 return b;
62 }
63 #else
64 #define SkDITHER_R32_FOR_565(r, d) SkDITHER_R32_FOR_565_MACRO(r, d)
65 #define SkDITHER_G32_FOR_565(g, d) SkDITHER_G32_FOR_565_MACRO(g, d)
66 #define SkDITHER_B32_FOR_565(b, d) SkDITHER_B32_FOR_565_MACRO(b, d)
67 #endif
68
69 #define SkDITHER_R32To565(r, d) SkR32ToR16(SkDITHER_R32_FOR_565(r, d))
70 #define SkDITHER_G32To565(g, d) SkG32ToG16(SkDITHER_G32_FOR_565(g, d))
71 #define SkDITHER_B32To565(b, d) SkB32ToB16(SkDITHER_B32_FOR_565(b, d))
72
73 #define SkDITHER_A32To4444(a, d) SkA32To4444(SkDITHER_A32_FOR_4444_MACRO(a, d))
74 #define SkDITHER_R32To4444(r, d) SkR32To4444(SkDITHER_R32_FOR_4444_MACRO(r, d))
75 #define SkDITHER_G32To4444(g, d) SkG32To4444(SkDITHER_G32_FOR_4444_MACRO(g, d))
76 #define SkDITHER_B32To4444(b, d) SkB32To4444(SkDITHER_B32_FOR_4444_MACRO(b, d))
77
SkDitherARGB32For565(SkPMColor c,unsigned dither)78 static inline SkPMColor SkDitherARGB32For565(SkPMColor c, unsigned dither)
79 {
80 SkASSERT(dither <= SK_DitherValueMax565);
81
82 unsigned sa = SkGetPackedA32(c);
83 dither = SkAlphaMul(dither, SkAlpha255To256(sa));
84
85 unsigned sr = SkGetPackedR32(c);
86 unsigned sg = SkGetPackedG32(c);
87 unsigned sb = SkGetPackedB32(c);
88 sr = SkDITHER_R32_FOR_565(sr, dither);
89 sg = SkDITHER_G32_FOR_565(sg, dither);
90 sb = SkDITHER_B32_FOR_565(sb, dither);
91
92 return SkPackARGB32(sa, sr, sg, sb);
93 }
94
SkDitherRGB32For565(SkPMColor c,unsigned dither)95 static inline SkPMColor SkDitherRGB32For565(SkPMColor c, unsigned dither)
96 {
97 SkASSERT(dither <= SK_DitherValueMax565);
98
99 unsigned sr = SkGetPackedR32(c);
100 unsigned sg = SkGetPackedG32(c);
101 unsigned sb = SkGetPackedB32(c);
102 sr = SkDITHER_R32_FOR_565(sr, dither);
103 sg = SkDITHER_G32_FOR_565(sg, dither);
104 sb = SkDITHER_B32_FOR_565(sb, dither);
105
106 return SkPackARGB32(0xFF, sr, sg, sb);
107 }
108
SkDitherRGBTo565(U8CPU r,U8CPU g,U8CPU b,unsigned dither)109 static inline uint16_t SkDitherRGBTo565(U8CPU r, U8CPU g, U8CPU b,
110 unsigned dither)
111 {
112 SkASSERT(dither <= SK_DitherValueMax565);
113 r = SkDITHER_R32To565(r, dither);
114 g = SkDITHER_G32To565(g, dither);
115 b = SkDITHER_B32To565(b, dither);
116 return SkPackRGB16(r, g, b);
117 }
118
SkDitherRGB32To565(SkPMColor c,unsigned dither)119 static inline uint16_t SkDitherRGB32To565(SkPMColor c, unsigned dither)
120 {
121 SkASSERT(dither <= SK_DitherValueMax565);
122
123 unsigned sr = SkGetPackedR32(c);
124 unsigned sg = SkGetPackedG32(c);
125 unsigned sb = SkGetPackedB32(c);
126 sr = SkDITHER_R32To565(sr, dither);
127 sg = SkDITHER_G32To565(sg, dither);
128 sb = SkDITHER_B32To565(sb, dither);
129
130 return SkPackRGB16(sr, sg, sb);
131 }
132
SkDitherARGB32To565(U8CPU sa,SkPMColor c,unsigned dither)133 static inline uint16_t SkDitherARGB32To565(U8CPU sa, SkPMColor c, unsigned dither)
134 {
135 SkASSERT(dither <= SK_DitherValueMax565);
136 dither = SkAlphaMul(dither, SkAlpha255To256(sa));
137
138 unsigned sr = SkGetPackedR32(c);
139 unsigned sg = SkGetPackedG32(c);
140 unsigned sb = SkGetPackedB32(c);
141 sr = SkDITHER_R32To565(sr, dither);
142 sg = SkDITHER_G32To565(sg, dither);
143 sb = SkDITHER_B32To565(sb, dither);
144
145 return SkPackRGB16(sr, sg, sb);
146 }
147
148 ///////////////////////// 4444
149
SkDitherARGB32To4444(U8CPU a,U8CPU r,U8CPU g,U8CPU b,unsigned dither)150 static inline SkPMColor16 SkDitherARGB32To4444(U8CPU a, U8CPU r, U8CPU g,
151 U8CPU b, unsigned dither)
152 {
153 dither = SkAlphaMul(dither, SkAlpha255To256(a));
154
155 a = SkDITHER_A32To4444(a, dither);
156 r = SkDITHER_R32To4444(r, dither);
157 g = SkDITHER_G32To4444(g, dither);
158 b = SkDITHER_B32To4444(b, dither);
159
160 return SkPackARGB4444(a, r, g, b);
161 }
162
SkDitherARGB32To4444(SkPMColor c,unsigned dither)163 static inline SkPMColor16 SkDitherARGB32To4444(SkPMColor c, unsigned dither)
164 {
165 unsigned a = SkGetPackedA32(c);
166 unsigned r = SkGetPackedR32(c);
167 unsigned g = SkGetPackedG32(c);
168 unsigned b = SkGetPackedB32(c);
169
170 dither = SkAlphaMul(dither, SkAlpha255To256(a));
171
172 a = SkDITHER_A32To4444(a, dither);
173 r = SkDITHER_R32To4444(r, dither);
174 g = SkDITHER_G32To4444(g, dither);
175 b = SkDITHER_B32To4444(b, dither);
176
177 return SkPackARGB4444(a, r, g, b);
178 }
179
180 // TODO: need dither routines for 565 -> 4444
181
182 // this toggles between a 4x4 and a 1x4 array
183 //#define ENABLE_DITHER_MATRIX_4X4
184
185 #ifdef ENABLE_DITHER_MATRIX_4X4
186 extern const uint8_t gDitherMatrix_4Bit_4X4[4][4];
187 extern const uint8_t gDitherMatrix_3Bit_4X4[4][4];
188
189 #define DITHER_4444_SCAN(y) const uint8_t* dither_scan = gDitherMatrix_4Bit_4X4[(y) & 3]
190 #define DITHER_565_SCAN(y) const uint8_t* dither_scan = gDitherMatrix_3Bit_4X4[(y) & 3]
191
192 #define DITHER_VALUE(x) dither_scan[(x) & 3]
193 #else
194 extern const uint16_t gDitherMatrix_4Bit_16[4];
195 extern const uint16_t gDitherMatrix_3Bit_16[4];
196
197 #define DITHER_4444_SCAN(y) const uint16_t dither_scan = gDitherMatrix_4Bit_16[(y) & 3]
198 #define DITHER_565_SCAN(y) const uint16_t dither_scan = gDitherMatrix_3Bit_16[(y) & 3]
199
200 #define DITHER_VALUE(x) ((dither_scan >> (((x) & 3) << 2)) & 0xF)
201 #endif
202
203 #define DITHER_INC_X(x) ++(x)
204
205 #endif
206