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[reactos.git] / lib / 3rdparty / freetype / src / base / ftlcdfil.c
1 /***************************************************************************/
2 /* */
3 /* ftlcdfil.c */
4 /* */
5 /* FreeType API for color filtering of subpixel bitmap glyphs (body). */
6 /* */
7 /* Copyright 2006, 2008, 2009 by */
8 /* David Turner, Robert Wilhelm, and Werner Lemberg. */
9 /* */
10 /* This file is part of the FreeType project, and may only be used, */
11 /* modified, and distributed under the terms of the FreeType project */
12 /* license, LICENSE.TXT. By continuing to use, modify, or distribute */
13 /* this file you indicate that you have read the license and */
14 /* understand and accept it fully. */
15 /* */
16 /***************************************************************************/
17
18
19 #include <ft2build.h>
20 #include FT_LCD_FILTER_H
21 #include FT_IMAGE_H
22 #include FT_INTERNAL_OBJECTS_H
23
24
25 #ifdef FT_CONFIG_OPTION_SUBPIXEL_RENDERING
26
27 /* define USE_LEGACY to implement the legacy filter */
28 #define USE_LEGACY
29
30 /* FIR filter used by the default and light filters */
31 static void
32 _ft_lcd_filter_fir( FT_Bitmap* bitmap,
33 FT_Render_Mode mode,
34 FT_Library library )
35 {
36 FT_Byte* weights = library->lcd_weights;
37 FT_UInt width = (FT_UInt)bitmap->width;
38 FT_UInt height = (FT_UInt)bitmap->rows;
39
40
41 /* horizontal in-place FIR filter */
42 if ( mode == FT_RENDER_MODE_LCD && width >= 4 )
43 {
44 FT_Byte* line = bitmap->buffer;
45
46
47 for ( ; height > 0; height--, line += bitmap->pitch )
48 {
49 FT_UInt fir[5];
50 FT_UInt val1, xx;
51
52
53 val1 = line[0];
54 fir[0] = weights[2] * val1;
55 fir[1] = weights[3] * val1;
56 fir[2] = weights[4] * val1;
57 fir[3] = 0;
58 fir[4] = 0;
59
60 val1 = line[1];
61 fir[0] += weights[1] * val1;
62 fir[1] += weights[2] * val1;
63 fir[2] += weights[3] * val1;
64 fir[3] += weights[4] * val1;
65
66 for ( xx = 2; xx < width; xx++ )
67 {
68 FT_UInt val, pix;
69
70
71 val = line[xx];
72 pix = fir[0] + weights[0] * val;
73 fir[0] = fir[1] + weights[1] * val;
74 fir[1] = fir[2] + weights[2] * val;
75 fir[2] = fir[3] + weights[3] * val;
76 fir[3] = weights[4] * val;
77
78 pix >>= 8;
79 pix |= -( pix >> 8 );
80 line[xx - 2] = (FT_Byte)pix;
81 }
82
83 {
84 FT_UInt pix;
85
86
87 pix = fir[0] >> 8;
88 pix |= -( pix >> 8 );
89 line[xx - 2] = (FT_Byte)pix;
90
91 pix = fir[1] >> 8;
92 pix |= -( pix >> 8 );
93 line[xx - 1] = (FT_Byte)pix;
94 }
95 }
96 }
97
98 /* vertical in-place FIR filter */
99 else if ( mode == FT_RENDER_MODE_LCD_V && height >= 4 )
100 {
101 FT_Byte* column = bitmap->buffer;
102 FT_Int pitch = bitmap->pitch;
103
104
105 for ( ; width > 0; width--, column++ )
106 {
107 FT_Byte* col = column;
108 FT_UInt fir[5];
109 FT_UInt val1, yy;
110
111
112 val1 = col[0];
113 fir[0] = weights[2] * val1;
114 fir[1] = weights[3] * val1;
115 fir[2] = weights[4] * val1;
116 fir[3] = 0;
117 fir[4] = 0;
118 col += pitch;
119
120 val1 = col[0];
121 fir[0] += weights[1] * val1;
122 fir[1] += weights[2] * val1;
123 fir[2] += weights[3] * val1;
124 fir[3] += weights[4] * val1;
125 col += pitch;
126
127 for ( yy = 2; yy < height; yy++ )
128 {
129 FT_UInt val, pix;
130
131
132 val = col[0];
133 pix = fir[0] + weights[0] * val;
134 fir[0] = fir[1] + weights[1] * val;
135 fir[1] = fir[2] + weights[2] * val;
136 fir[2] = fir[3] + weights[3] * val;
137 fir[3] = weights[4] * val;
138
139 pix >>= 8;
140 pix |= -( pix >> 8 );
141 col[-2 * pitch] = (FT_Byte)pix;
142 col += pitch;
143 }
144
145 {
146 FT_UInt pix;
147
148
149 pix = fir[0] >> 8;
150 pix |= -( pix >> 8 );
151 col[-2 * pitch] = (FT_Byte)pix;
152
153 pix = fir[1] >> 8;
154 pix |= -( pix >> 8 );
155 col[-pitch] = (FT_Byte)pix;
156 }
157 }
158 }
159 }
160
161
162 #ifdef USE_LEGACY
163
164 /* intra-pixel filter used by the legacy filter */
165 static void
166 _ft_lcd_filter_legacy( FT_Bitmap* bitmap,
167 FT_Render_Mode mode,
168 FT_Library library )
169 {
170 FT_UInt width = (FT_UInt)bitmap->width;
171 FT_UInt height = (FT_UInt)bitmap->rows;
172 FT_Int pitch = bitmap->pitch;
173
174 static const int filters[3][3] =
175 {
176 { 65538 * 9/13, 65538 * 1/6, 65538 * 1/13 },
177 { 65538 * 3/13, 65538 * 4/6, 65538 * 3/13 },
178 { 65538 * 1/13, 65538 * 1/6, 65538 * 9/13 }
179 };
180
181 FT_UNUSED( library );
182
183
184 /* horizontal in-place intra-pixel filter */
185 if ( mode == FT_RENDER_MODE_LCD && width >= 3 )
186 {
187 FT_Byte* line = bitmap->buffer;
188
189
190 for ( ; height > 0; height--, line += pitch )
191 {
192 FT_UInt xx;
193
194
195 for ( xx = 0; xx < width; xx += 3 )
196 {
197 FT_UInt r = 0;
198 FT_UInt g = 0;
199 FT_UInt b = 0;
200 FT_UInt p;
201
202
203 p = line[xx];
204 r += filters[0][0] * p;
205 g += filters[0][1] * p;
206 b += filters[0][2] * p;
207
208 p = line[xx + 1];
209 r += filters[1][0] * p;
210 g += filters[1][1] * p;
211 b += filters[1][2] * p;
212
213 p = line[xx + 2];
214 r += filters[2][0] * p;
215 g += filters[2][1] * p;
216 b += filters[2][2] * p;
217
218 line[xx] = (FT_Byte)( r / 65536 );
219 line[xx + 1] = (FT_Byte)( g / 65536 );
220 line[xx + 2] = (FT_Byte)( b / 65536 );
221 }
222 }
223 }
224 else if ( mode == FT_RENDER_MODE_LCD_V && height >= 3 )
225 {
226 FT_Byte* column = bitmap->buffer;
227
228
229 for ( ; width > 0; width--, column++ )
230 {
231 FT_Byte* col = column;
232 FT_Byte* col_end = col + height * pitch;
233
234
235 for ( ; col < col_end; col += 3 * pitch )
236 {
237 FT_UInt r = 0;
238 FT_UInt g = 0;
239 FT_UInt b = 0;
240 FT_UInt p;
241
242
243 p = col[0];
244 r += filters[0][0] * p;
245 g += filters[0][1] * p;
246 b += filters[0][2] * p;
247
248 p = col[pitch];
249 r += filters[1][0] * p;
250 g += filters[1][1] * p;
251 b += filters[1][2] * p;
252
253 p = col[pitch * 2];
254 r += filters[2][0] * p;
255 g += filters[2][1] * p;
256 b += filters[2][2] * p;
257
258 col[0] = (FT_Byte)( r / 65536 );
259 col[pitch] = (FT_Byte)( g / 65536 );
260 col[2 * pitch] = (FT_Byte)( b / 65536 );
261 }
262 }
263 }
264 }
265
266 #endif /* USE_LEGACY */
267
268
269 FT_EXPORT_DEF( FT_Error )
270 FT_Library_SetLcdFilter( FT_Library library,
271 FT_LcdFilter filter )
272 {
273 static const FT_Byte light_filter[5] =
274 { 0, 85, 86, 85, 0 };
275 /* the values here sum up to a value larger than 256, */
276 /* providing a cheap gamma correction */
277 static const FT_Byte default_filter[5] =
278 { 0x10, 0x40, 0x70, 0x40, 0x10 };
279
280
281 if ( library == NULL )
282 return FT_Err_Invalid_Argument;
283
284 switch ( filter )
285 {
286 case FT_LCD_FILTER_NONE:
287 library->lcd_filter_func = NULL;
288 library->lcd_extra = 0;
289 break;
290
291 case FT_LCD_FILTER_DEFAULT:
292 #if defined( FT_FORCE_LEGACY_LCD_FILTER )
293
294 library->lcd_filter_func = _ft_lcd_filter_legacy;
295 library->lcd_extra = 0;
296
297 #elif defined( FT_FORCE_LIGHT_LCD_FILTER )
298
299 ft_memcpy( library->lcd_weights, light_filter, 5 );
300 library->lcd_filter_func = _ft_lcd_filter_fir;
301 library->lcd_extra = 2;
302
303 #else
304
305 ft_memcpy( library->lcd_weights, default_filter, 5 );
306 library->lcd_filter_func = _ft_lcd_filter_fir;
307 library->lcd_extra = 2;
308
309 #endif
310
311 break;
312
313 case FT_LCD_FILTER_LIGHT:
314 ft_memcpy( library->lcd_weights, light_filter, 5 );
315 library->lcd_filter_func = _ft_lcd_filter_fir;
316 library->lcd_extra = 2;
317 break;
318
319 #ifdef USE_LEGACY
320
321 case FT_LCD_FILTER_LEGACY:
322 library->lcd_filter_func = _ft_lcd_filter_legacy;
323 library->lcd_extra = 0;
324 break;
325
326 #endif
327
328 default:
329 return FT_Err_Invalid_Argument;
330 }
331
332 library->lcd_filter = filter;
333 return 0;
334 }
335
336 #else /* !FT_CONFIG_OPTION_SUBPIXEL_RENDERING */
337
338 FT_EXPORT_DEF( FT_Error )
339 FT_Library_SetLcdFilter( FT_Library library,
340 FT_LcdFilter filter )
341 {
342 FT_UNUSED( library );
343 FT_UNUSED( filter );
344
345 return FT_Err_Unimplemented_Feature;
346 }
347
348 #endif /* !FT_CONFIG_OPTION_SUBPIXEL_RENDERING */
349
350
351 /* END */