cf2font.c revision 9c745321260bb728ab1cd1c8fd5f075854b2ad49
1/***************************************************************************/ 2/* */ 3/* cf2font.c */ 4/* */ 5/* Adobe's code for font instances (body). */ 6/* */ 7/* Copyright 2007-2014 Adobe Systems Incorporated. */ 8/* */ 9/* This software, and all works of authorship, whether in source or */ 10/* object code form as indicated by the copyright notice(s) included */ 11/* herein (collectively, the "Work") is made available, and may only be */ 12/* used, modified, and distributed under the FreeType Project License, */ 13/* LICENSE.TXT. Additionally, subject to the terms and conditions of the */ 14/* FreeType Project License, each contributor to the Work hereby grants */ 15/* to any individual or legal entity exercising permissions granted by */ 16/* the FreeType Project License and this section (hereafter, "You" or */ 17/* "Your") a perpetual, worldwide, non-exclusive, no-charge, */ 18/* royalty-free, irrevocable (except as stated in this section) patent */ 19/* license to make, have made, use, offer to sell, sell, import, and */ 20/* otherwise transfer the Work, where such license applies only to those */ 21/* patent claims licensable by such contributor that are necessarily */ 22/* infringed by their contribution(s) alone or by combination of their */ 23/* contribution(s) with the Work to which such contribution(s) was */ 24/* submitted. If You institute patent litigation against any entity */ 25/* (including a cross-claim or counterclaim in a lawsuit) alleging that */ 26/* the Work or a contribution incorporated within the Work constitutes */ 27/* direct or contributory patent infringement, then any patent licenses */ 28/* granted to You under this License for that Work shall terminate as of */ 29/* the date such litigation is filed. */ 30/* */ 31/* By using, modifying, or distributing the Work you indicate that you */ 32/* have read and understood the terms and conditions of the */ 33/* FreeType Project License as well as those provided in this section, */ 34/* and you accept them fully. */ 35/* */ 36/***************************************************************************/ 37 38 39#include "cf2ft.h" 40 41#include "cf2glue.h" 42#include "cf2font.h" 43#include "cf2error.h" 44#include "cf2intrp.h" 45 46 47 /* Compute a stem darkening amount in character space. */ 48 static void 49 cf2_computeDarkening( CF2_Fixed emRatio, 50 CF2_Fixed ppem, 51 CF2_Fixed stemWidth, 52 CF2_Fixed* darkenAmount, 53 CF2_Fixed boldenAmount, 54 FT_Bool stemDarkened, 55 FT_Int* darkenParams ) 56 { 57 /* 58 * Total darkening amount is computed in 1000 unit character space 59 * using the modified 5 part curve as Adobe's Avalon rasterizer. 60 * The darkening amount is smaller for thicker stems. 61 * It becomes zero when the stem is thicker than 2.333 pixels. 62 * 63 * By default, we use 64 * 65 * darkenAmount = 0.4 pixels if scaledStem <= 0.5 pixels, 66 * darkenAmount = 0.275 pixels if 1 <= scaledStem <= 1.667 pixels, 67 * darkenAmount = 0 pixel if scaledStem >= 2.333 pixels, 68 * 69 * and piecewise linear in-between: 70 * 71 * 72 * darkening 73 * ^ 74 * | 75 * | (x1,y1) 76 * |--------+ 77 * | \ 78 * | \ 79 * | \ (x3,y3) 80 * | +----------+ 81 * | (x2,y2) \ 82 * | \ 83 * | \ 84 * | +----------------- 85 * | (x4,y4) 86 * +---------------------------------------------> stem 87 * thickness 88 * 89 * 90 * This corresponds to the following values for the 91 * `darkening-parameters' property: 92 * 93 * (x1, y1) = (500, 400) 94 * (x2, y2) = (1000, 275) 95 * (x3, y3) = (1667, 275) 96 * (x4, y4) = (2333, 0) 97 * 98 */ 99 100 /* Internal calculations are done in units per thousand for */ 101 /* convenience. The x axis is scaled stem width in */ 102 /* thousandths of a pixel. That is, 1000 is 1 pixel. */ 103 /* The y axis is darkening amount in thousandths of a pixel.*/ 104 /* In the code, below, dividing by ppem and */ 105 /* adjusting for emRatio converts darkenAmount to character */ 106 /* space (font units). */ 107 CF2_Fixed stemWidthPer1000, scaledStem; 108 109 110 *darkenAmount = 0; 111 112 if ( boldenAmount == 0 && !stemDarkened ) 113 return; 114 115 /* protect against range problems and divide by zero */ 116 if ( emRatio < cf2_floatToFixed( .01 ) ) 117 return; 118 119 if ( stemDarkened ) 120 { 121 FT_Int x1 = darkenParams[0]; 122 FT_Int y1 = darkenParams[1]; 123 FT_Int x2 = darkenParams[2]; 124 FT_Int y2 = darkenParams[3]; 125 FT_Int x3 = darkenParams[4]; 126 FT_Int y3 = darkenParams[5]; 127 FT_Int x4 = darkenParams[6]; 128 FT_Int y4 = darkenParams[7]; 129 130 131 /* convert from true character space to 1000 unit character space; */ 132 /* add synthetic emboldening effect */ 133 134 /* we have to assure that the computation of `scaledStem' */ 135 /* and `stemWidthPer1000' don't overflow */ 136 137 stemWidthPer1000 = FT_MulFix( stemWidth + boldenAmount, emRatio ); 138 139 if ( emRatio > CF2_FIXED_ONE && 140 stemWidthPer1000 <= ( stemWidth + boldenAmount ) ) 141 { 142 stemWidthPer1000 = 0; /* to pacify compiler */ 143 scaledStem = cf2_intToFixed( x4 ); 144 } 145 else 146 { 147 scaledStem = FT_MulFix( stemWidthPer1000, ppem ); 148 149 if ( ppem > CF2_FIXED_ONE && 150 scaledStem <= stemWidthPer1000 ) 151 scaledStem = cf2_intToFixed( x4 ); 152 } 153 154 /* now apply the darkening parameters */ 155 156 if ( scaledStem < cf2_intToFixed( x1 ) ) 157 *darkenAmount = FT_DivFix( cf2_intToFixed( y1 ), ppem ); 158 159 else if ( scaledStem < cf2_intToFixed( x2 ) ) 160 { 161 FT_Int xdelta = x2 - x1; 162 FT_Int ydelta = y2 - y1; 163 FT_Int x = stemWidthPer1000 - 164 FT_DivFix( cf2_intToFixed( x1 ), ppem ); 165 166 167 if ( !xdelta ) 168 goto Try_x3; 169 170 *darkenAmount = FT_MulDiv( x, ydelta, xdelta ) + 171 FT_DivFix( cf2_intToFixed( y1 ), ppem ); 172 } 173 174 else if ( scaledStem < cf2_intToFixed( x3 ) ) 175 { 176 Try_x3: 177 { 178 FT_Int xdelta = x3 - x2; 179 FT_Int ydelta = y3 - y2; 180 FT_Int x = stemWidthPer1000 - 181 FT_DivFix( cf2_intToFixed( x2 ), ppem ); 182 183 184 if ( !xdelta ) 185 goto Try_x4; 186 187 *darkenAmount = FT_MulDiv( x, ydelta, xdelta ) + 188 FT_DivFix( cf2_intToFixed( y2 ), ppem ); 189 } 190 } 191 192 else if ( scaledStem < cf2_intToFixed( x4 ) ) 193 { 194 Try_x4: 195 { 196 FT_Int xdelta = x4 - x3; 197 FT_Int ydelta = y4 - y3; 198 FT_Int x = stemWidthPer1000 - 199 FT_DivFix( cf2_intToFixed( x3 ), ppem ); 200 201 202 if ( !xdelta ) 203 goto Use_y4; 204 205 *darkenAmount = FT_MulDiv( x, ydelta, xdelta ) + 206 FT_DivFix( cf2_intToFixed( y3 ), ppem ); 207 } 208 } 209 210 else 211 { 212 Use_y4: 213 *darkenAmount = FT_DivFix( cf2_intToFixed( y4 ), ppem ); 214 } 215 216 /* use half the amount on each side and convert back to true */ 217 /* character space */ 218 *darkenAmount = FT_DivFix( *darkenAmount, 2 * emRatio ); 219 } 220 221 /* add synthetic emboldening effect in character space */ 222 *darkenAmount += boldenAmount / 2; 223 } 224 225 226 /* set up values for the current FontDict and matrix */ 227 228 /* caller's transform is adjusted for subpixel positioning */ 229 static void 230 cf2_font_setup( CF2_Font font, 231 const CF2_Matrix* transform ) 232 { 233 /* pointer to parsed font object */ 234 CFF_Decoder* decoder = font->decoder; 235 236 FT_Bool needExtraSetup = FALSE; 237 238 /* character space units */ 239 CF2_Fixed boldenX = font->syntheticEmboldeningAmountX; 240 CF2_Fixed boldenY = font->syntheticEmboldeningAmountY; 241 242 CFF_SubFont subFont; 243 CF2_Fixed ppem; 244 245 246 /* clear previous error */ 247 font->error = FT_Err_Ok; 248 249 /* if a CID fontDict has changed, we need to recompute some cached */ 250 /* data */ 251 subFont = cf2_getSubfont( decoder ); 252 if ( font->lastSubfont != subFont ) 253 { 254 font->lastSubfont = subFont; 255 needExtraSetup = TRUE; 256 } 257 258 /* if ppem has changed, we need to recompute some cached data */ 259 /* note: because of CID font matrix concatenation, ppem and transform */ 260 /* do not necessarily track. */ 261 ppem = cf2_getPpemY( decoder ); 262 if ( font->ppem != ppem ) 263 { 264 font->ppem = ppem; 265 needExtraSetup = TRUE; 266 } 267 268 /* copy hinted flag on each call */ 269 font->hinted = (FT_Bool)( font->renderingFlags & CF2_FlagsHinted ); 270 271 /* determine if transform has changed; */ 272 /* include Fontmatrix but ignore translation */ 273 if ( ft_memcmp( transform, 274 &font->currentTransform, 275 4 * sizeof ( CF2_Fixed ) ) != 0 ) 276 { 277 /* save `key' information for `cache of one' matrix data; */ 278 /* save client transform, without the translation */ 279 font->currentTransform = *transform; 280 font->currentTransform.tx = 281 font->currentTransform.ty = cf2_intToFixed( 0 ); 282 283 /* TODO: FreeType transform is simple scalar; for now, use identity */ 284 /* for outer */ 285 font->innerTransform = *transform; 286 font->outerTransform.a = 287 font->outerTransform.d = cf2_intToFixed( 1 ); 288 font->outerTransform.b = 289 font->outerTransform.c = cf2_intToFixed( 0 ); 290 291 needExtraSetup = TRUE; 292 } 293 294 /* 295 * font->darkened is set to true if there is a stem darkening request or 296 * the font is synthetic emboldened. 297 * font->darkened controls whether to adjust blue zones, winding order, 298 * and hinting. 299 * 300 */ 301 if ( font->stemDarkened != ( font->renderingFlags & CF2_FlagsDarkened ) ) 302 { 303 font->stemDarkened = 304 (FT_Bool)( font->renderingFlags & CF2_FlagsDarkened ); 305 306 /* blue zones depend on darkened flag */ 307 needExtraSetup = TRUE; 308 } 309 310 /* recompute variables that are dependent on transform or FontDict or */ 311 /* darken flag */ 312 if ( needExtraSetup ) 313 { 314 /* StdVW is found in the private dictionary; */ 315 /* recompute darkening amounts whenever private dictionary or */ 316 /* transform change */ 317 /* Note: a rendering flag turns darkening on or off, so we want to */ 318 /* store the `on' amounts; */ 319 /* darkening amount is computed in character space */ 320 /* TODO: testing size-dependent darkening here; */ 321 /* what to do for rotations? */ 322 323 CF2_Fixed emRatio; 324 CF2_Fixed stdHW; 325 CF2_Int unitsPerEm = font->unitsPerEm; 326 327 328 if ( unitsPerEm == 0 ) 329 unitsPerEm = 1000; 330 331 ppem = FT_MAX( cf2_intToFixed( 4 ), 332 font->ppem ); /* use minimum ppem of 4 */ 333 334#if 0 335 /* since vstem is measured in the x-direction, we use the `a' member */ 336 /* of the fontMatrix */ 337 emRatio = cf2_fixedFracMul( cf2_intToFixed( 1000 ), fontMatrix->a ); 338#endif 339 340 /* Freetype does not preserve the fontMatrix when parsing; use */ 341 /* unitsPerEm instead. */ 342 /* TODO: check precision of this */ 343 emRatio = cf2_intToFixed( 1000 ) / unitsPerEm; 344 font->stdVW = cf2_getStdVW( decoder ); 345 346 if ( font->stdVW <= 0 ) 347 font->stdVW = FT_DivFix( cf2_intToFixed( 75 ), emRatio ); 348 349 if ( boldenX > 0 ) 350 { 351 /* Ensure that boldenX is at least 1 pixel for synthetic bold font */ 352 /* (similar to what Avalon does) */ 353 boldenX = FT_MAX( boldenX, 354 FT_DivFix( cf2_intToFixed( unitsPerEm ), ppem ) ); 355 356 /* Synthetic emboldening adds at least 1 pixel to darkenX, while */ 357 /* stem darkening adds at most half pixel. Since the purpose of */ 358 /* stem darkening (readability at small sizes) is met with */ 359 /* synthetic emboldening, no need to add stem darkening for a */ 360 /* synthetic bold font. */ 361 cf2_computeDarkening( emRatio, 362 ppem, 363 font->stdVW, 364 &font->darkenX, 365 boldenX, 366 FALSE, 367 font->darkenParams ); 368 } 369 else 370 cf2_computeDarkening( emRatio, 371 ppem, 372 font->stdVW, 373 &font->darkenX, 374 0, 375 font->stemDarkened, 376 font->darkenParams ); 377 378#if 0 379 /* since hstem is measured in the y-direction, we use the `d' member */ 380 /* of the fontMatrix */ 381 /* TODO: use the same units per em as above; check this */ 382 emRatio = cf2_fixedFracMul( cf2_intToFixed( 1000 ), fontMatrix->d ); 383#endif 384 385 /* set the default stem width, because it must be the same for all */ 386 /* family members; */ 387 /* choose a constant for StdHW that depends on font contrast */ 388 stdHW = cf2_getStdHW( decoder ); 389 390 if ( stdHW > 0 && font->stdVW > 2 * stdHW ) 391 font->stdHW = FT_DivFix( cf2_intToFixed( 75 ), emRatio ); 392 else 393 { 394 /* low contrast font gets less hstem darkening */ 395 font->stdHW = FT_DivFix( cf2_intToFixed( 110 ), emRatio ); 396 } 397 398 cf2_computeDarkening( emRatio, 399 ppem, 400 font->stdHW, 401 &font->darkenY, 402 boldenY, 403 font->stemDarkened, 404 font->darkenParams ); 405 406 if ( font->darkenX != 0 || font->darkenY != 0 ) 407 font->darkened = TRUE; 408 else 409 font->darkened = FALSE; 410 411 font->reverseWinding = FALSE; /* initial expectation is CCW */ 412 413 /* compute blue zones for this instance */ 414 cf2_blues_init( &font->blues, font ); 415 } 416 } 417 418 419 /* equivalent to AdobeGetOutline */ 420 FT_LOCAL_DEF( FT_Error ) 421 cf2_getGlyphOutline( CF2_Font font, 422 CF2_Buffer charstring, 423 const CF2_Matrix* transform, 424 CF2_F16Dot16* glyphWidth ) 425 { 426 FT_Error lastError = FT_Err_Ok; 427 428 FT_Vector translation; 429 430#if 0 431 FT_Vector advancePoint; 432#endif 433 434 CF2_Fixed advWidth = 0; 435 FT_Bool needWinding; 436 437 438 /* Note: use both integer and fraction for outlines. This allows bbox */ 439 /* to come out directly. */ 440 441 translation.x = transform->tx; 442 translation.y = transform->ty; 443 444 /* set up values based on transform */ 445 cf2_font_setup( font, transform ); 446 if ( font->error ) 447 goto exit; /* setup encountered an error */ 448 449 /* reset darken direction */ 450 font->reverseWinding = FALSE; 451 452 /* winding order only affects darkening */ 453 needWinding = font->darkened; 454 455 while ( 1 ) 456 { 457 /* reset output buffer */ 458 cf2_outline_reset( &font->outline ); 459 460 /* build the outline, passing the full translation */ 461 cf2_interpT2CharString( font, 462 charstring, 463 (CF2_OutlineCallbacks)&font->outline, 464 &translation, 465 FALSE, 466 0, 467 0, 468 &advWidth ); 469 470 if ( font->error ) 471 goto exit; 472 473 if ( !needWinding ) 474 break; 475 476 /* check winding order */ 477 if ( font->outline.root.windingMomentum >= 0 ) /* CFF is CCW */ 478 break; 479 480 /* invert darkening and render again */ 481 /* TODO: this should be a parameter to getOutline-computeOffset */ 482 font->reverseWinding = TRUE; 483 484 needWinding = FALSE; /* exit after next iteration */ 485 } 486 487 /* finish storing client outline */ 488 cf2_outline_close( &font->outline ); 489 490 exit: 491 /* FreeType just wants the advance width; there is no translation */ 492 *glyphWidth = advWidth; 493 494 /* free resources and collect errors from objects we've used */ 495 cf2_setError( &font->error, lastError ); 496 497 return font->error; 498 } 499 500 501/* END */ 502