1 /***************************************************************************/ 2 /* */ 3 /* afloader.c */ 4 /* */ 5 /* Auto-fitter glyph loading routines (body). */ 6 /* */ 7 /* Copyright 2003-2015 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 "afglobal.h" 20 #include "afloader.h" 21 #include "afhints.h" 22 #include "aferrors.h" 23 #include "afmodule.h" 24 #include "afpic.h" 25 26 #include FT_INTERNAL_CALC_H 27 28 29 /* Initialize glyph loader. */ 30 31 FT_LOCAL_DEF( void ) af_loader_init(AF_Loader loader,AF_GlyphHints hints)32 af_loader_init( AF_Loader loader, 33 AF_GlyphHints hints ) 34 { 35 FT_ZERO( loader ); 36 37 loader->hints = hints; 38 } 39 40 41 /* Reset glyph loader and compute globals if necessary. */ 42 43 FT_LOCAL_DEF( FT_Error ) af_loader_reset(AF_Loader loader,AF_Module module,FT_Face face)44 af_loader_reset( AF_Loader loader, 45 AF_Module module, 46 FT_Face face ) 47 { 48 FT_Error error = FT_Err_Ok; 49 50 51 loader->face = face; 52 loader->globals = (AF_FaceGlobals)face->autohint.data; 53 54 if ( loader->globals == NULL ) 55 { 56 error = af_face_globals_new( face, &loader->globals, module ); 57 if ( !error ) 58 { 59 face->autohint.data = 60 (FT_Pointer)loader->globals; 61 face->autohint.finalizer = 62 (FT_Generic_Finalizer)af_face_globals_free; 63 } 64 } 65 66 return error; 67 } 68 69 70 /* Finalize glyph loader. */ 71 72 FT_LOCAL_DEF( void ) af_loader_done(AF_Loader loader)73 af_loader_done( AF_Loader loader ) 74 { 75 loader->face = NULL; 76 loader->globals = NULL; 77 loader->hints = NULL; 78 } 79 80 81 #define af_intToFixed( i ) \ 82 ( (FT_Fixed)( (FT_UInt32)(i) << 16 ) ) 83 #define af_fixedToInt( x ) \ 84 ( (FT_Short)( ( (FT_UInt32)(x) + 0x8000U ) >> 16 ) ) 85 #define af_floatToFixed( f ) \ 86 ( (FT_Fixed)( (f) * 65536.0 + 0.5 ) ) 87 88 89 /* Do the main work of `af_loader_load_glyph'. Note that we never */ 90 /* have to deal with composite glyphs as those get loaded into */ 91 /* FT_GLYPH_FORMAT_OUTLINE by the recursed `FT_Load_Glyph' function. */ 92 /* In the rare cases where FT_LOAD_NO_RECURSE is set, it implies */ 93 /* FT_LOAD_NO_SCALE and as such the auto-hinter is never called. */ 94 95 static FT_Error af_loader_load_g(AF_Loader loader,AF_Scaler scaler,FT_UInt glyph_index,FT_Int32 load_flags)96 af_loader_load_g( AF_Loader loader, 97 AF_Scaler scaler, 98 FT_UInt glyph_index, 99 FT_Int32 load_flags ) 100 { 101 AF_Module module = loader->globals->module; 102 103 FT_Error error; 104 FT_Face face = loader->face; 105 AF_StyleMetrics metrics = loader->metrics; 106 AF_GlyphHints hints = loader->hints; 107 FT_GlyphSlot slot = face->glyph; 108 FT_Slot_Internal internal = slot->internal; 109 FT_GlyphLoader gloader = internal->loader; 110 FT_Int32 flags; 111 112 113 flags = load_flags | FT_LOAD_LINEAR_DESIGN; 114 error = FT_Load_Glyph( face, glyph_index, flags ); 115 if ( error ) 116 goto Exit; 117 118 /* 119 * Apply stem darkening (emboldening) here before hints are applied to 120 * the outline. Glyphs are scaled down proportionally to the 121 * emboldening so that curve points don't fall outside their precomputed 122 * blue zones. 123 * 124 * Any emboldening done by the font driver (e.g., the CFF driver) 125 * doesn't reach here because the autohinter loads the unprocessed 126 * glyphs in font units for analysis (functions `af_*_metrics_init_*') 127 * and then above to prepare it for the rasterizers by itself, 128 * independently of the font driver. So emboldening must be done here, 129 * within the autohinter. 130 * 131 * All glyphs to be autohinted pass through here one by one. The 132 * standard widths can therefore change from one glyph to the next, 133 * depending on what script a glyph is assigned to (each script has its 134 * own set of standard widths and other metrics). The darkening amount 135 * must therefore be recomputed for each size and 136 * `standard_{vertical,horizontal}_width' change. 137 */ 138 if ( !module->no_stem_darkening ) 139 { 140 AF_FaceGlobals globals = loader->globals; 141 AF_WritingSystemClass writing_system_class; 142 143 FT_Pos stdVW = 0; 144 FT_Pos stdHW = 0; 145 146 FT_Bool size_changed = face->size->metrics.x_ppem 147 != globals->stem_darkening_for_ppem; 148 149 FT_Fixed em_size = af_intToFixed( face->units_per_EM ); 150 FT_Fixed em_ratio = FT_DivFix( af_intToFixed( 1000 ), em_size ); 151 152 FT_Matrix scale_down_matrix = { 0x10000L, 0, 0, 0x10000L }; 153 154 155 /* Skip stem darkening for broken fonts. */ 156 if ( !face->units_per_EM ) 157 goto After_Emboldening; 158 159 /* 160 * We depend on the writing system (script analyzers) to supply 161 * standard widths for the script of the glyph we are looking at. If 162 * it can't deliver, stem darkening is effectively disabled. 163 */ 164 writing_system_class = 165 AF_WRITING_SYSTEM_CLASSES_GET[metrics->style_class->writing_system]; 166 167 if ( writing_system_class->style_metrics_getstdw ) 168 writing_system_class->style_metrics_getstdw( metrics, 169 &stdHW, 170 &stdVW ); 171 else 172 goto After_Emboldening; 173 174 175 if ( size_changed || 176 ( stdVW > 0 && stdVW != globals->standard_vertical_width ) ) 177 { 178 FT_Fixed darken_by_font_units_x, darken_x; 179 180 181 darken_by_font_units_x = 182 af_intToFixed( af_loader_compute_darkening( loader, 183 face, 184 stdVW ) ); 185 darken_x = FT_DivFix( FT_MulFix( darken_by_font_units_x, 186 face->size->metrics.x_scale ), 187 em_ratio ); 188 189 globals->standard_vertical_width = stdVW; 190 globals->stem_darkening_for_ppem = face->size->metrics.x_ppem; 191 globals->darken_x = af_fixedToInt( darken_x ); 192 } 193 194 if ( size_changed || 195 ( stdHW > 0 && stdHW != globals->standard_horizontal_width ) ) 196 { 197 FT_Fixed darken_by_font_units_y, darken_y; 198 199 200 darken_by_font_units_y = 201 af_intToFixed( af_loader_compute_darkening( loader, 202 face, 203 stdHW ) ); 204 darken_y = FT_DivFix( FT_MulFix( darken_by_font_units_y, 205 face->size->metrics.y_scale ), 206 em_ratio ); 207 208 globals->standard_horizontal_width = stdHW; 209 globals->stem_darkening_for_ppem = face->size->metrics.x_ppem; 210 globals->darken_y = af_fixedToInt( darken_y ); 211 212 /* 213 * Scale outlines down on the Y-axis to keep them inside their blue 214 * zones. The stronger the emboldening, the stronger the 215 * downscaling (plus heuristical padding to prevent outlines still 216 * falling out their zones due to rounding). 217 * 218 * Reason: `FT_Outline_Embolden' works by shifting the rightmost 219 * points of stems farther to the right, and topmost points farther 220 * up. This positions points on the Y-axis outside their 221 * pre-computed blue zones and leads to distortion when applying the 222 * hints in the code further below. Code outside this emboldening 223 * block doesn't know we are presenting it with modified outlines 224 * the analyzer didn't see! 225 * 226 * An unfortunate side effect of downscaling is that the emboldening 227 * effect is slightly decreased. The loss becomes more pronounced 228 * versus the CFF driver at smaller sizes, e.g., at 9ppem and below. 229 */ 230 globals->scale_down_factor = 231 FT_DivFix( em_size - ( darken_by_font_units_y + af_intToFixed( 8 ) ), 232 em_size ); 233 } 234 235 FT_Outline_EmboldenXY( &slot->outline, 236 globals->darken_x, 237 globals->darken_y ); 238 239 scale_down_matrix.yy = globals->scale_down_factor; 240 FT_Outline_Transform( &slot->outline, &scale_down_matrix ); 241 } 242 243 After_Emboldening: 244 loader->transformed = internal->glyph_transformed; 245 if ( loader->transformed ) 246 { 247 FT_Matrix inverse; 248 249 250 loader->trans_matrix = internal->glyph_matrix; 251 loader->trans_delta = internal->glyph_delta; 252 253 inverse = loader->trans_matrix; 254 if ( !FT_Matrix_Invert( &inverse ) ) 255 FT_Vector_Transform( &loader->trans_delta, &inverse ); 256 } 257 258 switch ( slot->format ) 259 { 260 case FT_GLYPH_FORMAT_OUTLINE: 261 /* translate the loaded glyph when an internal transform is needed */ 262 if ( loader->transformed ) 263 FT_Outline_Translate( &slot->outline, 264 loader->trans_delta.x, 265 loader->trans_delta.y ); 266 267 /* compute original horizontal phantom points (and ignore */ 268 /* vertical ones) */ 269 loader->pp1.x = hints->x_delta; 270 loader->pp1.y = hints->y_delta; 271 loader->pp2.x = FT_MulFix( slot->metrics.horiAdvance, 272 hints->x_scale ) + hints->x_delta; 273 loader->pp2.y = hints->y_delta; 274 275 /* be sure to check for spacing glyphs */ 276 if ( slot->outline.n_points == 0 ) 277 goto Hint_Metrics; 278 279 /* now load the slot image into the auto-outline and run the */ 280 /* automatic hinting process */ 281 { 282 #ifdef FT_CONFIG_OPTION_PIC 283 AF_FaceGlobals globals = loader->globals; 284 #endif 285 AF_StyleClass style_class = metrics->style_class; 286 AF_WritingSystemClass writing_system_class = 287 AF_WRITING_SYSTEM_CLASSES_GET[style_class->writing_system]; 288 289 290 if ( writing_system_class->style_hints_apply ) 291 writing_system_class->style_hints_apply( glyph_index, 292 hints, 293 &gloader->base.outline, 294 metrics ); 295 } 296 297 /* we now need to adjust the metrics according to the change in */ 298 /* width/positioning that occurred during the hinting process */ 299 if ( scaler->render_mode != FT_RENDER_MODE_LIGHT ) 300 { 301 FT_Pos old_rsb, old_lsb, new_lsb; 302 FT_Pos pp1x_uh, pp2x_uh; 303 AF_AxisHints axis = &hints->axis[AF_DIMENSION_HORZ]; 304 AF_Edge edge1 = axis->edges; /* leftmost edge */ 305 AF_Edge edge2 = edge1 + 306 axis->num_edges - 1; /* rightmost edge */ 307 308 309 if ( axis->num_edges > 1 && AF_HINTS_DO_ADVANCE( hints ) ) 310 { 311 old_rsb = loader->pp2.x - edge2->opos; 312 old_lsb = edge1->opos; 313 new_lsb = edge1->pos; 314 315 /* remember unhinted values to later account */ 316 /* for rounding errors */ 317 318 pp1x_uh = new_lsb - old_lsb; 319 pp2x_uh = edge2->pos + old_rsb; 320 321 /* prefer too much space over too little space */ 322 /* for very small sizes */ 323 324 if ( old_lsb < 24 ) 325 pp1x_uh -= 8; 326 327 if ( old_rsb < 24 ) 328 pp2x_uh += 8; 329 330 loader->pp1.x = FT_PIX_ROUND( pp1x_uh ); 331 loader->pp2.x = FT_PIX_ROUND( pp2x_uh ); 332 333 if ( loader->pp1.x >= new_lsb && old_lsb > 0 ) 334 loader->pp1.x -= 64; 335 336 if ( loader->pp2.x <= edge2->pos && old_rsb > 0 ) 337 loader->pp2.x += 64; 338 339 slot->lsb_delta = loader->pp1.x - pp1x_uh; 340 slot->rsb_delta = loader->pp2.x - pp2x_uh; 341 } 342 else 343 { 344 FT_Pos pp1x = loader->pp1.x; 345 FT_Pos pp2x = loader->pp2.x; 346 347 348 loader->pp1.x = FT_PIX_ROUND( pp1x ); 349 loader->pp2.x = FT_PIX_ROUND( pp2x ); 350 351 slot->lsb_delta = loader->pp1.x - pp1x; 352 slot->rsb_delta = loader->pp2.x - pp2x; 353 } 354 } 355 else 356 { 357 FT_Pos pp1x = loader->pp1.x; 358 FT_Pos pp2x = loader->pp2.x; 359 360 361 loader->pp1.x = FT_PIX_ROUND( pp1x + hints->xmin_delta ); 362 loader->pp2.x = FT_PIX_ROUND( pp2x + hints->xmax_delta ); 363 364 slot->lsb_delta = loader->pp1.x - pp1x; 365 slot->rsb_delta = loader->pp2.x - pp2x; 366 } 367 368 break; 369 370 default: 371 /* we don't support other formats (yet?) */ 372 error = FT_THROW( Unimplemented_Feature ); 373 } 374 375 Hint_Metrics: 376 { 377 FT_BBox bbox; 378 FT_Vector vvector; 379 380 381 vvector.x = slot->metrics.vertBearingX - slot->metrics.horiBearingX; 382 vvector.y = slot->metrics.vertBearingY - slot->metrics.horiBearingY; 383 vvector.x = FT_MulFix( vvector.x, metrics->scaler.x_scale ); 384 vvector.y = FT_MulFix( vvector.y, metrics->scaler.y_scale ); 385 386 /* transform the hinted outline if needed */ 387 if ( loader->transformed ) 388 { 389 FT_Outline_Transform( &gloader->base.outline, &loader->trans_matrix ); 390 FT_Vector_Transform( &vvector, &loader->trans_matrix ); 391 } 392 #if 1 393 /* we must translate our final outline by -pp1.x and compute */ 394 /* the new metrics */ 395 if ( loader->pp1.x ) 396 FT_Outline_Translate( &gloader->base.outline, -loader->pp1.x, 0 ); 397 #endif 398 FT_Outline_Get_CBox( &gloader->base.outline, &bbox ); 399 400 bbox.xMin = FT_PIX_FLOOR( bbox.xMin ); 401 bbox.yMin = FT_PIX_FLOOR( bbox.yMin ); 402 bbox.xMax = FT_PIX_CEIL( bbox.xMax ); 403 bbox.yMax = FT_PIX_CEIL( bbox.yMax ); 404 405 slot->metrics.width = bbox.xMax - bbox.xMin; 406 slot->metrics.height = bbox.yMax - bbox.yMin; 407 slot->metrics.horiBearingX = bbox.xMin; 408 slot->metrics.horiBearingY = bbox.yMax; 409 410 slot->metrics.vertBearingX = FT_PIX_FLOOR( bbox.xMin + vvector.x ); 411 slot->metrics.vertBearingY = FT_PIX_FLOOR( bbox.yMax + vvector.y ); 412 413 /* for mono-width fonts (like Andale, Courier, etc.) we need */ 414 /* to keep the original rounded advance width; ditto for */ 415 /* digits if all have the same advance width */ 416 #if 0 417 if ( !FT_IS_FIXED_WIDTH( slot->face ) ) 418 slot->metrics.horiAdvance = loader->pp2.x - loader->pp1.x; 419 else 420 slot->metrics.horiAdvance = FT_MulFix( slot->metrics.horiAdvance, 421 x_scale ); 422 #else 423 if ( scaler->render_mode != FT_RENDER_MODE_LIGHT && 424 ( FT_IS_FIXED_WIDTH( slot->face ) || 425 ( af_face_globals_is_digit( loader->globals, glyph_index ) && 426 metrics->digits_have_same_width ) ) ) 427 { 428 slot->metrics.horiAdvance = FT_MulFix( slot->metrics.horiAdvance, 429 metrics->scaler.x_scale ); 430 431 /* Set delta values to 0. Otherwise code that uses them is */ 432 /* going to ruin the fixed advance width. */ 433 slot->lsb_delta = 0; 434 slot->rsb_delta = 0; 435 } 436 else 437 { 438 /* non-spacing glyphs must stay as-is */ 439 if ( slot->metrics.horiAdvance ) 440 slot->metrics.horiAdvance = loader->pp2.x - loader->pp1.x; 441 } 442 #endif 443 444 slot->metrics.vertAdvance = FT_MulFix( slot->metrics.vertAdvance, 445 metrics->scaler.y_scale ); 446 447 slot->metrics.horiAdvance = FT_PIX_ROUND( slot->metrics.horiAdvance ); 448 slot->metrics.vertAdvance = FT_PIX_ROUND( slot->metrics.vertAdvance ); 449 450 #if 0 451 /* reassign all outline fields except flags to protect them */ 452 slot->outline.n_contours = internal->loader->base.outline.n_contours; 453 slot->outline.n_points = internal->loader->base.outline.n_points; 454 slot->outline.points = internal->loader->base.outline.points; 455 slot->outline.tags = internal->loader->base.outline.tags; 456 slot->outline.contours = internal->loader->base.outline.contours; 457 #endif 458 459 slot->format = FT_GLYPH_FORMAT_OUTLINE; 460 } 461 462 Exit: 463 return error; 464 } 465 466 467 /* Load a glyph. */ 468 469 FT_LOCAL_DEF( FT_Error ) af_loader_load_glyph(AF_Loader loader,AF_Module module,FT_Face face,FT_UInt gindex,FT_Int32 load_flags)470 af_loader_load_glyph( AF_Loader loader, 471 AF_Module module, 472 FT_Face face, 473 FT_UInt gindex, 474 FT_Int32 load_flags ) 475 { 476 FT_Error error; 477 FT_Size size = face->size; 478 AF_ScalerRec scaler; 479 480 481 if ( !size ) 482 return FT_THROW( Invalid_Size_Handle ); 483 484 FT_ZERO( &scaler ); 485 486 scaler.face = face; 487 scaler.x_scale = size->metrics.x_scale; 488 scaler.x_delta = 0; /* XXX: TODO: add support for sub-pixel hinting */ 489 scaler.y_scale = size->metrics.y_scale; 490 scaler.y_delta = 0; /* XXX: TODO: add support for sub-pixel hinting */ 491 492 scaler.render_mode = FT_LOAD_TARGET_MODE( load_flags ); 493 scaler.flags = 0; /* XXX: fix this */ 494 495 error = af_loader_reset( loader, module, face ); 496 if ( !error ) 497 { 498 AF_StyleMetrics metrics; 499 FT_UInt options = AF_STYLE_NONE_DFLT; 500 501 502 #ifdef FT_OPTION_AUTOFIT2 503 /* XXX: undocumented hook to activate the latin2 writing system */ 504 if ( load_flags & ( 1UL << 20 ) ) 505 options = AF_STYLE_LTN2_DFLT; 506 #endif 507 508 error = af_face_globals_get_metrics( loader->globals, gindex, 509 options, &metrics ); 510 if ( !error ) 511 { 512 #ifdef FT_CONFIG_OPTION_PIC 513 AF_FaceGlobals globals = loader->globals; 514 #endif 515 AF_StyleClass style_class = metrics->style_class; 516 AF_WritingSystemClass writing_system_class = 517 AF_WRITING_SYSTEM_CLASSES_GET[style_class->writing_system]; 518 519 520 loader->metrics = metrics; 521 522 if ( writing_system_class->style_metrics_scale ) 523 writing_system_class->style_metrics_scale( metrics, &scaler ); 524 else 525 metrics->scaler = scaler; 526 527 load_flags |= FT_LOAD_NO_SCALE | FT_LOAD_IGNORE_TRANSFORM; 528 load_flags &= ~FT_LOAD_RENDER; 529 530 if ( writing_system_class->style_hints_init ) 531 { 532 error = writing_system_class->style_hints_init( loader->hints, 533 metrics ); 534 if ( error ) 535 goto Exit; 536 } 537 538 error = af_loader_load_g( loader, &scaler, gindex, load_flags ); 539 } 540 } 541 Exit: 542 return error; 543 } 544 545 546 /* 547 * Compute amount of font units the face should be emboldened by, in 548 * analogy to the CFF driver's `cf2_computeDarkening' function. See there 549 * for details of the algorithm. 550 * 551 * XXX: Currently a crude adaption of the original algorithm. Do better? 552 */ 553 FT_LOCAL_DEF( FT_Int32 ) af_loader_compute_darkening(AF_Loader loader,FT_Face face,FT_Pos standard_width)554 af_loader_compute_darkening( AF_Loader loader, 555 FT_Face face, 556 FT_Pos standard_width ) 557 { 558 AF_Module module = loader->globals->module; 559 560 FT_UShort units_per_EM; 561 FT_Fixed ppem, em_ratio; 562 FT_Fixed stem_width, stem_width_per_1000, scaled_stem, darken_amount; 563 FT_Int log_base_2; 564 FT_Int x1, y1, x2, y2, x3, y3, x4, y4; 565 566 567 ppem = FT_MAX( af_intToFixed( 4 ), 568 af_intToFixed( face->size->metrics.x_ppem ) ); 569 units_per_EM = face->units_per_EM; 570 571 em_ratio = FT_DivFix( af_intToFixed( 1000 ), 572 af_intToFixed ( units_per_EM ) ); 573 if ( em_ratio < af_floatToFixed( .01 ) ) 574 { 575 /* If something goes wrong, don't embolden. */ 576 return 0; 577 } 578 579 x1 = module->darken_params[0]; 580 y1 = module->darken_params[1]; 581 x2 = module->darken_params[2]; 582 y2 = module->darken_params[3]; 583 x3 = module->darken_params[4]; 584 y3 = module->darken_params[5]; 585 x4 = module->darken_params[6]; 586 y4 = module->darken_params[7]; 587 588 if ( standard_width <= 0 ) 589 { 590 stem_width = af_intToFixed( 75 ); /* taken from cf2font.c */ 591 stem_width_per_1000 = stem_width; 592 } 593 else 594 { 595 stem_width = af_intToFixed( standard_width ); 596 stem_width_per_1000 = FT_MulFix( stem_width, em_ratio ); 597 } 598 599 log_base_2 = FT_MSB( (FT_UInt32)stem_width_per_1000 ) + 600 FT_MSB( (FT_UInt32)ppem ); 601 602 if ( log_base_2 >= 46 ) 603 { 604 /* possible overflow */ 605 scaled_stem = af_intToFixed( x4 ); 606 } 607 else 608 scaled_stem = FT_MulFix( stem_width_per_1000, ppem ); 609 610 /* now apply the darkening parameters */ 611 if ( scaled_stem < af_intToFixed( x1 ) ) 612 darken_amount = FT_DivFix( af_intToFixed( y1 ), ppem ); 613 614 else if ( scaled_stem < af_intToFixed( x2 ) ) 615 { 616 FT_Int xdelta = x2 - x1; 617 FT_Int ydelta = y2 - y1; 618 FT_Int x = stem_width_per_1000 - 619 FT_DivFix( af_intToFixed( x1 ), ppem ); 620 621 622 if ( !xdelta ) 623 goto Try_x3; 624 625 darken_amount = FT_MulDiv( x, ydelta, xdelta ) + 626 FT_DivFix( af_intToFixed( y1 ), ppem ); 627 } 628 629 else if ( scaled_stem < af_intToFixed( x3 ) ) 630 { 631 Try_x3: 632 { 633 FT_Int xdelta = x3 - x2; 634 FT_Int ydelta = y3 - y2; 635 FT_Int x = stem_width_per_1000 - 636 FT_DivFix( af_intToFixed( x2 ), ppem ); 637 638 639 if ( !xdelta ) 640 goto Try_x4; 641 642 darken_amount = FT_MulDiv( x, ydelta, xdelta ) + 643 FT_DivFix( af_intToFixed( y2 ), ppem ); 644 } 645 } 646 647 else if ( scaled_stem < af_intToFixed( x4 ) ) 648 { 649 Try_x4: 650 { 651 FT_Int xdelta = x4 - x3; 652 FT_Int ydelta = y4 - y3; 653 FT_Int x = stem_width_per_1000 - 654 FT_DivFix( af_intToFixed( x3 ), ppem ); 655 656 657 if ( !xdelta ) 658 goto Use_y4; 659 660 darken_amount = FT_MulDiv( x, ydelta, xdelta ) + 661 FT_DivFix( af_intToFixed( y3 ), ppem ); 662 } 663 } 664 665 else 666 { 667 Use_y4: 668 darken_amount = FT_DivFix( af_intToFixed( y4 ), ppem ); 669 } 670 671 /* Convert darken_amount from per 1000 em to true character space. */ 672 return af_fixedToInt( FT_DivFix( darken_amount, em_ratio ) ); 673 } 674 675 676 /* END */ 677