1 /***************************************************************************/ 2 /* */ 3 /* ftlcdfil.c */ 4 /* */ 5 /* FreeType API for color filtering of subpixel bitmap glyphs (body). */ 6 /* */ 7 /* Copyright 2006-2016 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_INTERNAL_DEBUG_H 21 22 #include FT_LCD_FILTER_H 23 #include FT_IMAGE_H 24 #include FT_INTERNAL_OBJECTS_H 25 26 27 #ifdef FT_CONFIG_OPTION_SUBPIXEL_RENDERING 28 29 /* define USE_LEGACY to implement the legacy filter */ 30 #define USE_LEGACY 31 32 /* FIR filter used by the default and light filters */ 33 static void 34 _ft_lcd_filter_fir( FT_Bitmap* bitmap, 35 FT_Render_Mode mode, 36 FT_Library library ) 37 { 38 FT_Byte* weights = library->lcd_weights; 39 FT_UInt width = (FT_UInt)bitmap->width; 40 FT_UInt height = (FT_UInt)bitmap->rows; 41 42 43 /* horizontal in-place FIR filter */ 44 if ( mode == FT_RENDER_MODE_LCD && width >= 4 ) 45 { 46 FT_Byte* line = bitmap->buffer; 47 48 49 /* take care of bitmap flow */ 50 if ( bitmap->pitch < 0 ) 51 line -= bitmap->pitch * (FT_Int)( bitmap->rows - 1 ); 52 53 /* `fir' and `pix' must be at least 32 bit wide, since the sum of */ 54 /* the values in `weights' can exceed 0xFF */ 55 56 for ( ; height > 0; height--, line += bitmap->pitch ) 57 { 58 FT_UInt fir[4]; /* below, `pix' is used as the 5th element */ 59 FT_UInt val1, xx; 60 61 62 val1 = line[0]; 63 fir[0] = weights[2] * val1; 64 fir[1] = weights[3] * val1; 65 fir[2] = weights[4] * val1; 66 fir[3] = 0; 67 68 val1 = line[1]; 69 fir[0] += weights[1] * val1; 70 fir[1] += weights[2] * val1; 71 fir[2] += weights[3] * val1; 72 fir[3] += weights[4] * val1; 73 74 for ( xx = 2; xx < width; xx++ ) 75 { 76 FT_UInt val, pix; 77 78 79 val = line[xx]; 80 pix = fir[0] + weights[0] * val; 81 fir[0] = fir[1] + weights[1] * val; 82 fir[1] = fir[2] + weights[2] * val; 83 fir[2] = fir[3] + weights[3] * val; 84 fir[3] = weights[4] * val; 85 86 pix >>= 8; 87 pix |= (FT_UInt)-(FT_Int)( pix >> 8 ); 88 line[xx - 2] = (FT_Byte)pix; 89 } 90 91 { 92 FT_UInt pix; 93 94 95 pix = fir[0] >> 8; 96 pix |= (FT_UInt)-(FT_Int)( pix >> 8 ); 97 line[xx - 2] = (FT_Byte)pix; 98 99 pix = fir[1] >> 8; 100 pix |= (FT_UInt)-(FT_Int)( pix >> 8 ); 101 line[xx - 1] = (FT_Byte)pix; 102 } 103 } 104 } 105 106 /* vertical in-place FIR filter */ 107 else if ( mode == FT_RENDER_MODE_LCD_V && height >= 4 ) 108 { 109 FT_Byte* column = bitmap->buffer; 110 FT_Int pitch = bitmap->pitch; 111 112 113 /* take care of bitmap flow */ 114 if ( bitmap->pitch < 0 ) 115 column -= bitmap->pitch * (FT_Int)( bitmap->rows - 1 ); 116 117 for ( ; width > 0; width--, column++ ) 118 { 119 FT_Byte* col = column; 120 FT_UInt fir[4]; /* below, `pix' is used as the 5th element */ 121 FT_UInt val1, yy; 122 123 124 val1 = col[0]; 125 fir[0] = weights[2] * val1; 126 fir[1] = weights[3] * val1; 127 fir[2] = weights[4] * val1; 128 fir[3] = 0; 129 col += pitch; 130 131 val1 = col[0]; 132 fir[0] += weights[1] * val1; 133 fir[1] += weights[2] * val1; 134 fir[2] += weights[3] * val1; 135 fir[3] += weights[4] * val1; 136 col += pitch; 137 138 for ( yy = 2; yy < height; yy++ ) 139 { 140 FT_UInt val, pix; 141 142 143 val = col[0]; 144 pix = fir[0] + weights[0] * val; 145 fir[0] = fir[1] + weights[1] * val; 146 fir[1] = fir[2] + weights[2] * val; 147 fir[2] = fir[3] + weights[3] * val; 148 fir[3] = weights[4] * val; 149 150 pix >>= 8; 151 pix |= (FT_UInt)-(FT_Int)( pix >> 8 ); 152 col[-2 * pitch] = (FT_Byte)pix; 153 col += pitch; 154 } 155 156 { 157 FT_UInt pix; 158 159 160 pix = fir[0] >> 8; 161 pix |= (FT_UInt)-(FT_Int)( pix >> 8 ); 162 col[-2 * pitch] = (FT_Byte)pix; 163 164 pix = fir[1] >> 8; 165 pix |= (FT_UInt)-(FT_Int)( pix >> 8 ); 166 col[-pitch] = (FT_Byte)pix; 167 } 168 } 169 } 170 } 171 172 173 #ifdef USE_LEGACY 174 175 /* intra-pixel filter used by the legacy filter */ 176 static void 177 _ft_lcd_filter_legacy( FT_Bitmap* bitmap, 178 FT_Render_Mode mode, 179 FT_Library library ) 180 { 181 FT_UInt width = (FT_UInt)bitmap->width; 182 FT_UInt height = (FT_UInt)bitmap->rows; 183 FT_Int pitch = bitmap->pitch; 184 185 static const unsigned int filters[3][3] = 186 { 187 { 65538 * 9/13, 65538 * 1/6, 65538 * 1/13 }, 188 { 65538 * 3/13, 65538 * 4/6, 65538 * 3/13 }, 189 { 65538 * 1/13, 65538 * 1/6, 65538 * 9/13 } 190 }; 191 192 FT_UNUSED( library ); 193 194 195 /* horizontal in-place intra-pixel filter */ 196 if ( mode == FT_RENDER_MODE_LCD && width >= 3 ) 197 { 198 FT_Byte* line = bitmap->buffer; 199 200 201 /* take care of bitmap flow */ 202 if ( bitmap->pitch < 0 ) 203 line -= bitmap->pitch * (FT_Int)( bitmap->rows - 1 ); 204 205 for ( ; height > 0; height--, line += pitch ) 206 { 207 FT_UInt xx; 208 209 210 for ( xx = 0; xx < width; xx += 3 ) 211 { 212 FT_UInt r = 0; 213 FT_UInt g = 0; 214 FT_UInt b = 0; 215 FT_UInt p; 216 217 218 p = line[xx]; 219 r += filters[0][0] * p; 220 g += filters[0][1] * p; 221 b += filters[0][2] * p; 222 223 p = line[xx + 1]; 224 r += filters[1][0] * p; 225 g += filters[1][1] * p; 226 b += filters[1][2] * p; 227 228 p = line[xx + 2]; 229 r += filters[2][0] * p; 230 g += filters[2][1] * p; 231 b += filters[2][2] * p; 232 233 line[xx] = (FT_Byte)( r / 65536 ); 234 line[xx + 1] = (FT_Byte)( g / 65536 ); 235 line[xx + 2] = (FT_Byte)( b / 65536 ); 236 } 237 } 238 } 239 else if ( mode == FT_RENDER_MODE_LCD_V && height >= 3 ) 240 { 241 FT_Byte* column = bitmap->buffer; 242 243 244 /* take care of bitmap flow */ 245 if ( bitmap->pitch < 0 ) 246 column -= bitmap->pitch * (FT_Int)( bitmap->rows - 1 ); 247 248 for ( ; width > 0; width--, column++ ) 249 { 250 FT_Byte* col = column; 251 FT_Byte* col_end = col + (FT_Int)height * pitch; 252 253 254 for ( ; col < col_end; col += 3 * pitch ) 255 { 256 FT_UInt r = 0; 257 FT_UInt g = 0; 258 FT_UInt b = 0; 259 FT_UInt p; 260 261 262 p = col[0]; 263 r += filters[0][0] * p; 264 g += filters[0][1] * p; 265 b += filters[0][2] * p; 266 267 p = col[pitch]; 268 r += filters[1][0] * p; 269 g += filters[1][1] * p; 270 b += filters[1][2] * p; 271 272 p = col[pitch * 2]; 273 r += filters[2][0] * p; 274 g += filters[2][1] * p; 275 b += filters[2][2] * p; 276 277 col[0] = (FT_Byte)( r / 65536 ); 278 col[pitch] = (FT_Byte)( g / 65536 ); 279 col[2 * pitch] = (FT_Byte)( b / 65536 ); 280 } 281 } 282 } 283 } 284 285 #endif /* USE_LEGACY */ 286 287 288 FT_EXPORT_DEF( FT_Error ) 289 FT_Library_SetLcdFilterWeights( FT_Library library, 290 unsigned char *weights ) 291 { 292 if ( !library ) 293 return FT_THROW( Invalid_Library_Handle ); 294 295 if ( !weights ) 296 return FT_THROW( Invalid_Argument ); 297 298 ft_memcpy( library->lcd_weights, weights, 5 ); 299 library->lcd_filter_func = _ft_lcd_filter_fir; 300 library->lcd_extra = 2; 301 302 return FT_Err_Ok; 303 } 304 305 306 FT_EXPORT_DEF( FT_Error ) 307 FT_Library_SetLcdFilter( FT_Library library, 308 FT_LcdFilter filter ) 309 { 310 static const FT_Byte default_filter[5] = 311 { 0x08, 0x4d, 0x56, 0x4d, 0x08 }; 312 static const FT_Byte light_filter[5] = 313 { 0x00, 0x55, 0x56, 0x55, 0x00 }; 314 315 316 if ( !library ) 317 return FT_THROW( Invalid_Library_Handle ); 318 319 switch ( filter ) 320 { 321 case FT_LCD_FILTER_NONE: 322 library->lcd_filter_func = NULL; 323 library->lcd_extra = 0; 324 break; 325 326 case FT_LCD_FILTER_DEFAULT: 327 ft_memcpy( library->lcd_weights, default_filter, 5 ); 328 library->lcd_filter_func = _ft_lcd_filter_fir; 329 library->lcd_extra = 2; 330 break; 331 332 case FT_LCD_FILTER_LIGHT: 333 ft_memcpy( library->lcd_weights, light_filter, 5 ); 334 library->lcd_filter_func = _ft_lcd_filter_fir; 335 library->lcd_extra = 2; 336 break; 337 338 #ifdef USE_LEGACY 339 340 case FT_LCD_FILTER_LEGACY: 341 case FT_LCD_FILTER_LEGACY1: 342 library->lcd_filter_func = _ft_lcd_filter_legacy; 343 library->lcd_extra = 0; 344 break; 345 346 #endif 347 348 default: 349 return FT_THROW( Invalid_Argument ); 350 } 351 352 library->lcd_filter = filter; 353 354 return FT_Err_Ok; 355 } 356 357 #else /* !FT_CONFIG_OPTION_SUBPIXEL_RENDERING */ 358 359 FT_EXPORT_DEF( FT_Error ) 360 FT_Library_SetLcdFilterWeights( FT_Library library, 361 unsigned char *weights ) 362 { 363 FT_UNUSED( library ); 364 FT_UNUSED( weights ); 365 366 return FT_THROW( Unimplemented_Feature ); 367 } 368 369 370 FT_EXPORT_DEF( FT_Error ) 371 FT_Library_SetLcdFilter( FT_Library library, 372 FT_LcdFilter filter ) 373 { 374 FT_UNUSED( library ); 375 FT_UNUSED( filter ); 376 377 return FT_THROW( Unimplemented_Feature ); 378 } 379 380 #endif /* !FT_CONFIG_OPTION_SUBPIXEL_RENDERING */ 381 382 383 /* END */ 384
