afloader.c (24004B)
1 /**************************************************************************** 2 * 3 * afloader.c 4 * 5 * Auto-fitter glyph loading routines (body). 6 * 7 * Copyright (C) 2003-2025 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 25 #include <freetype/internal/ftcalc.h> 26 27 28 /* Initialize glyph loader. */ 29 30 FT_LOCAL_DEF( void ) 31 af_loader_init( AF_Loader loader, 32 AF_GlyphHints hints ) 33 { 34 FT_ZERO( loader ); 35 36 loader->hints = hints; 37 } 38 39 40 /* Reset glyph loader and compute globals if necessary. */ 41 42 FT_LOCAL_DEF( FT_Error ) 43 af_loader_reset( AF_Loader loader, 44 AF_Module module, 45 FT_Face face ) 46 { 47 FT_Error error = FT_Err_Ok; 48 49 50 loader->face = face; 51 loader->globals = (AF_FaceGlobals)face->autohint.data; 52 53 if ( !loader->globals ) 54 { 55 error = af_face_globals_new( face, &loader->globals, module ); 56 if ( !error ) 57 { 58 face->autohint.data = (FT_Pointer)loader->globals; 59 face->autohint.finalizer = af_face_globals_free; 60 } 61 } 62 63 return error; 64 } 65 66 67 /* Finalize glyph loader. */ 68 69 FT_LOCAL_DEF( void ) 70 af_loader_done( AF_Loader loader ) 71 { 72 loader->face = NULL; 73 loader->globals = NULL; 74 loader->hints = NULL; 75 } 76 77 78 #define af_intToFixed( i ) \ 79 ( (FT_Fixed)( (FT_UInt32)(i) << 16 ) ) 80 #define af_fixedToInt( x ) \ 81 ( (FT_Short)( ( (FT_UInt32)(x) + 0x8000U ) >> 16 ) ) 82 #define af_floatToFixed( f ) \ 83 ( (FT_Fixed)( (f) * 65536.0 + 0.5 ) ) 84 85 86 static FT_Error 87 af_loader_embolden_glyph_in_slot( AF_Loader loader, 88 FT_Face face, 89 AF_StyleMetrics style_metrics ) 90 { 91 FT_Error error = FT_Err_Ok; 92 93 FT_GlyphSlot slot = face->glyph; 94 AF_FaceGlobals globals = loader->globals; 95 AF_WritingSystemClass writing_system_class; 96 97 FT_Size_Metrics* size_metrics = &face->size->internal->autohint_metrics; 98 99 FT_Pos stdVW = 0; 100 FT_Pos stdHW = 0; 101 102 FT_Bool size_changed = size_metrics->x_ppem != 103 globals->stem_darkening_for_ppem; 104 105 FT_Fixed em_size = af_intToFixed( face->units_per_EM ); 106 107 FT_Matrix scale_down_matrix = { 0x10000L, 0, 0, 0x10000L }; 108 109 110 /* Skip stem darkening for broken fonts. */ 111 if ( !face->units_per_EM ) 112 { 113 error = FT_ERR( Corrupted_Font_Header ); 114 goto Exit; 115 } 116 117 /* 118 * We depend on the writing system (script analyzers) to supply 119 * standard widths for the script of the glyph we are looking at. If 120 * it can't deliver, stem darkening is disabled. 121 */ 122 writing_system_class = 123 af_writing_system_classes[style_metrics->style_class->writing_system]; 124 125 if ( writing_system_class->style_metrics_getstdw ) 126 writing_system_class->style_metrics_getstdw( style_metrics, 127 &stdHW, 128 &stdVW ); 129 else 130 { 131 error = FT_ERR( Unimplemented_Feature ); 132 goto Exit; 133 } 134 135 if ( size_changed || 136 ( stdVW > 0 && stdVW != globals->standard_vertical_width ) ) 137 { 138 FT_Fixed darken_by_font_units_x, darken_x; 139 140 141 darken_by_font_units_x = 142 af_loader_compute_darkening( loader, 143 face, 144 stdVW ) ; 145 darken_x = FT_MulFix( darken_by_font_units_x, 146 size_metrics->x_scale ); 147 148 globals->standard_vertical_width = stdVW; 149 globals->stem_darkening_for_ppem = size_metrics->x_ppem; 150 globals->darken_x = af_fixedToInt( darken_x ); 151 } 152 153 if ( size_changed || 154 ( stdHW > 0 && stdHW != globals->standard_horizontal_width ) ) 155 { 156 FT_Fixed darken_by_font_units_y, darken_y; 157 158 159 darken_by_font_units_y = 160 af_loader_compute_darkening( loader, 161 face, 162 stdHW ) ; 163 darken_y = FT_MulFix( darken_by_font_units_y, 164 size_metrics->y_scale ); 165 166 globals->standard_horizontal_width = stdHW; 167 globals->stem_darkening_for_ppem = size_metrics->x_ppem; 168 globals->darken_y = af_fixedToInt( darken_y ); 169 170 /* 171 * Scale outlines down on the Y-axis to keep them inside their blue 172 * zones. The stronger the emboldening, the stronger the downscaling 173 * (plus heuristical padding to prevent outlines still falling out 174 * their zones due to rounding). 175 * 176 * Reason: `FT_Outline_Embolden' works by shifting the rightmost 177 * points of stems farther to the right, and topmost points farther 178 * up. This positions points on the Y-axis outside their 179 * pre-computed blue zones and leads to distortion when applying the 180 * hints in the code further below. Code outside this emboldening 181 * block doesn't know we are presenting it with modified outlines the 182 * analyzer didn't see! 183 * 184 * An unfortunate side effect of downscaling is that the emboldening 185 * effect is slightly decreased. The loss becomes more pronounced 186 * versus the CFF driver at smaller sizes, e.g., at 9ppem and below. 187 */ 188 globals->scale_down_factor = 189 FT_DivFix( em_size - ( darken_by_font_units_y + af_intToFixed( 8 ) ), 190 em_size ); 191 } 192 193 FT_Outline_EmboldenXY( &slot->outline, 194 globals->darken_x, 195 globals->darken_y ); 196 197 scale_down_matrix.yy = globals->scale_down_factor; 198 FT_Outline_Transform( &slot->outline, &scale_down_matrix ); 199 200 Exit: 201 return error; 202 } 203 204 205 /* Load the glyph at index into the current slot of a face and hint it. */ 206 207 FT_LOCAL_DEF( FT_Error ) 208 af_loader_load_glyph( AF_Loader loader, 209 AF_Module module, 210 FT_Face face, 211 FT_UInt glyph_index, 212 FT_Int32 load_flags ) 213 { 214 FT_Error error; 215 216 FT_Size size = face->size; 217 FT_Size_Internal size_internal = size->internal; 218 FT_GlyphSlot slot = face->glyph; 219 FT_Slot_Internal slot_internal = slot->internal; 220 FT_GlyphLoader gloader = slot_internal->loader; 221 222 AF_GlyphHints hints = loader->hints; 223 AF_ScalerRec scaler; 224 AF_StyleMetrics style_metrics; 225 FT_UInt style_options = AF_STYLE_NONE_DFLT; 226 AF_StyleClass style_class; 227 AF_WritingSystemClass writing_system_class; 228 229 230 FT_ZERO( &scaler ); 231 232 if ( !size_internal->autohint_metrics.x_scale || 233 size_internal->autohint_mode != FT_LOAD_TARGET_MODE( load_flags ) ) 234 { 235 /* switching between hinting modes usually means different scaling */ 236 /* values; this later on enforces recomputation of everything */ 237 /* related to the current size */ 238 239 size_internal->autohint_mode = FT_LOAD_TARGET_MODE( load_flags ); 240 size_internal->autohint_metrics = size->metrics; 241 242 #ifdef AF_CONFIG_OPTION_TT_SIZE_METRICS 243 { 244 FT_Size_Metrics* size_metrics = &size_internal->autohint_metrics; 245 246 247 /* set metrics to integer values and adjust scaling accordingly; */ 248 /* this is the same setup as with TrueType fonts, cf. function */ 249 /* `tt_size_reset' in file `ttobjs.c' */ 250 size_metrics->ascender = FT_PIX_ROUND( 251 FT_MulFix( face->ascender, 252 size_metrics->y_scale ) ); 253 size_metrics->descender = FT_PIX_ROUND( 254 FT_MulFix( face->descender, 255 size_metrics->y_scale ) ); 256 size_metrics->height = FT_PIX_ROUND( 257 FT_MulFix( face->height, 258 size_metrics->y_scale ) ); 259 260 size_metrics->x_scale = FT_DivFix( size_metrics->x_ppem << 6, 261 face->units_per_EM ); 262 size_metrics->y_scale = FT_DivFix( size_metrics->y_ppem << 6, 263 face->units_per_EM ); 264 size_metrics->max_advance = FT_PIX_ROUND( 265 FT_MulFix( face->max_advance_width, 266 size_metrics->x_scale ) ); 267 } 268 #endif /* AF_CONFIG_OPTION_TT_SIZE_METRICS */ 269 } 270 271 /* 272 * TODO: This code currently doesn't support fractional advance widths, 273 * i.e., placing hinted glyphs at anything other than integer 274 * x-positions. This is only relevant for the warper code, which 275 * scales and shifts glyphs to optimize blackness of stems (hinting on 276 * the x-axis by nature places things on pixel integers, hinting on the 277 * y-axis only, i.e., LIGHT mode, doesn't touch the x-axis). The delta 278 * values of the scaler would need to be adjusted. 279 */ 280 scaler.face = face; 281 scaler.x_scale = size_internal->autohint_metrics.x_scale; 282 scaler.x_delta = 0; 283 scaler.y_scale = size_internal->autohint_metrics.y_scale; 284 scaler.y_delta = 0; 285 286 scaler.render_mode = FT_LOAD_TARGET_MODE( load_flags ); 287 scaler.flags = 0; 288 289 /* note that the fallback style can't be changed anymore */ 290 /* after the first call of `af_loader_load_glyph' */ 291 error = af_loader_reset( loader, module, face ); 292 if ( error ) 293 goto Exit; 294 295 /* 296 * Glyphs (really code points) are assigned to scripts. Script 297 * analysis is done lazily: For each glyph that passes through here, 298 * the corresponding script analyzer is called, but returns immediately 299 * if it has been run already. 300 */ 301 error = af_face_globals_get_metrics( loader->globals, glyph_index, 302 style_options, &style_metrics ); 303 if ( error ) 304 goto Exit; 305 306 style_class = style_metrics->style_class; 307 writing_system_class = 308 af_writing_system_classes[style_class->writing_system]; 309 310 loader->metrics = style_metrics; 311 312 if ( writing_system_class->style_metrics_scale ) 313 writing_system_class->style_metrics_scale( style_metrics, &scaler ); 314 else 315 style_metrics->scaler = scaler; 316 317 if ( writing_system_class->style_hints_init ) 318 { 319 error = writing_system_class->style_hints_init( hints, 320 style_metrics ); 321 if ( error ) 322 goto Exit; 323 } 324 325 /* 326 * Do the main work of `af_loader_load_glyph'. Note that we never have 327 * to deal with composite glyphs as those get loaded into 328 * FT_GLYPH_FORMAT_OUTLINE by the recursed `FT_Load_Glyph' function. 329 * In the rare cases where FT_LOAD_NO_RECURSE is set, it implies 330 * FT_LOAD_NO_SCALE and as such the auto-hinter is never called. 331 */ 332 load_flags |= FT_LOAD_NO_SCALE | 333 FT_LOAD_IGNORE_TRANSFORM | 334 FT_LOAD_LINEAR_DESIGN; 335 load_flags &= ~FT_LOAD_RENDER; 336 337 error = FT_Load_Glyph( face, glyph_index, load_flags ); 338 if ( error ) 339 goto Exit; 340 341 /* 342 * Apply stem darkening (emboldening) here before hints are applied to 343 * the outline. Glyphs are scaled down proportionally to the 344 * emboldening so that curve points don't fall outside their 345 * precomputed blue zones. 346 * 347 * Any emboldening done by the font driver (e.g., the CFF driver) 348 * doesn't reach here because the autohinter loads the unprocessed 349 * glyphs in font units for analysis (functions `af_*_metrics_init_*') 350 * and then above to prepare it for the rasterizers by itself, 351 * independently of the font driver. So emboldening must be done here, 352 * within the autohinter. 353 * 354 * All glyphs to be autohinted pass through here one by one. The 355 * standard widths can therefore change from one glyph to the next, 356 * depending on what script a glyph is assigned to (each script has its 357 * own set of standard widths and other metrics). The darkening amount 358 * must therefore be recomputed for each size and 359 * `standard_{vertical,horizontal}_width' change. 360 * 361 * Ignore errors and carry on without emboldening. 362 * 363 */ 364 365 /* stem darkening only works well in `light' mode */ 366 if ( scaler.render_mode == FT_RENDER_MODE_LIGHT && 367 ( !face->internal->no_stem_darkening || 368 ( face->internal->no_stem_darkening < 0 && 369 !module->no_stem_darkening ) ) ) 370 af_loader_embolden_glyph_in_slot( loader, face, style_metrics ); 371 372 loader->transformed = slot_internal->glyph_transformed; 373 if ( loader->transformed ) 374 { 375 FT_Matrix inverse; 376 377 378 loader->trans_matrix = slot_internal->glyph_matrix; 379 loader->trans_delta = slot_internal->glyph_delta; 380 381 inverse = loader->trans_matrix; 382 if ( !FT_Matrix_Invert( &inverse ) ) 383 FT_Vector_Transform( &loader->trans_delta, &inverse ); 384 } 385 386 switch ( slot->format ) 387 { 388 case FT_GLYPH_FORMAT_OUTLINE: 389 /* translate the loaded glyph when an internal transform is needed */ 390 if ( loader->transformed ) 391 FT_Outline_Translate( &slot->outline, 392 loader->trans_delta.x, 393 loader->trans_delta.y ); 394 395 /* compute original horizontal phantom points */ 396 /* (and ignore vertical ones) */ 397 loader->pp1.x = hints->x_delta; 398 loader->pp1.y = hints->y_delta; 399 loader->pp2.x = FT_MulFix( slot->metrics.horiAdvance, 400 hints->x_scale ) + hints->x_delta; 401 loader->pp2.y = hints->y_delta; 402 403 /* be sure to check for spacing glyphs */ 404 if ( slot->outline.n_points == 0 ) 405 goto Hint_Metrics; 406 407 /* now load the slot image into the auto-outline */ 408 /* and run the automatic hinting process */ 409 if ( writing_system_class->style_hints_apply ) 410 { 411 error = writing_system_class->style_hints_apply( 412 glyph_index, 413 hints, 414 &gloader->base.outline, 415 style_metrics ); 416 if ( error ) 417 goto Exit; 418 } 419 420 /* we now need to adjust the metrics according to the change in */ 421 /* width/positioning that occurred during the hinting process */ 422 if ( scaler.render_mode != FT_RENDER_MODE_LIGHT ) 423 { 424 AF_AxisHints axis = &hints->axis[AF_DIMENSION_HORZ]; 425 426 427 if ( axis->num_edges > 1 && AF_HINTS_DO_ADVANCE( hints ) ) 428 { 429 AF_Edge edge1 = axis->edges; /* leftmost edge */ 430 AF_Edge edge2 = edge1 + 431 axis->num_edges - 1; /* rightmost edge */ 432 433 FT_Pos old_rsb = loader->pp2.x - edge2->opos; 434 /* loader->pp1.x is always zero at this point of time */ 435 FT_Pos old_lsb = edge1->opos; /* - loader->pp1.x */ 436 FT_Pos new_lsb = edge1->pos; 437 438 /* remember unhinted values to later account */ 439 /* for rounding errors */ 440 FT_Pos pp1x_uh = new_lsb - old_lsb; 441 FT_Pos pp2x_uh = edge2->pos + old_rsb; 442 443 444 /* prefer too much space over too little space */ 445 /* for very small sizes */ 446 447 if ( old_lsb < 24 ) 448 pp1x_uh -= 8; 449 450 if ( old_rsb < 24 ) 451 pp2x_uh += 8; 452 453 loader->pp1.x = FT_PIX_ROUND( pp1x_uh ); 454 loader->pp2.x = FT_PIX_ROUND( pp2x_uh ); 455 456 if ( loader->pp1.x >= new_lsb && old_lsb > 0 ) 457 loader->pp1.x -= 64; 458 459 if ( loader->pp2.x <= edge2->pos && old_rsb > 0 ) 460 loader->pp2.x += 64; 461 462 slot->lsb_delta = loader->pp1.x - pp1x_uh; 463 slot->rsb_delta = loader->pp2.x - pp2x_uh; 464 } 465 else 466 { 467 FT_Pos pp1x = loader->pp1.x; 468 FT_Pos pp2x = loader->pp2.x; 469 470 471 loader->pp1.x = FT_PIX_ROUND( pp1x ); 472 loader->pp2.x = FT_PIX_ROUND( pp2x ); 473 474 slot->lsb_delta = loader->pp1.x - pp1x; 475 slot->rsb_delta = loader->pp2.x - pp2x; 476 } 477 } 478 /* `light' mode uses integer advance widths */ 479 /* but sets `lsb_delta' and `rsb_delta' */ 480 else 481 { 482 FT_Pos pp1x = loader->pp1.x; 483 FT_Pos pp2x = loader->pp2.x; 484 485 486 loader->pp1.x = FT_PIX_ROUND( pp1x ); 487 loader->pp2.x = FT_PIX_ROUND( pp2x ); 488 489 slot->lsb_delta = loader->pp1.x - pp1x; 490 slot->rsb_delta = loader->pp2.x - pp2x; 491 } 492 493 break; 494 495 default: 496 /* we don't support other formats (yet?) */ 497 error = FT_THROW( Unimplemented_Feature ); 498 } 499 500 Hint_Metrics: 501 { 502 FT_BBox bbox; 503 FT_Vector vvector; 504 505 506 vvector.x = slot->metrics.vertBearingX - slot->metrics.horiBearingX; 507 vvector.y = slot->metrics.vertBearingY - slot->metrics.horiBearingY; 508 vvector.x = FT_MulFix( vvector.x, style_metrics->scaler.x_scale ); 509 vvector.y = FT_MulFix( vvector.y, style_metrics->scaler.y_scale ); 510 511 /* transform the hinted outline if needed */ 512 if ( loader->transformed ) 513 { 514 FT_Outline_Transform( &gloader->base.outline, &loader->trans_matrix ); 515 FT_Vector_Transform( &vvector, &loader->trans_matrix ); 516 } 517 518 /* we must translate our final outline by -pp1.x and compute */ 519 /* the new metrics */ 520 if ( loader->pp1.x ) 521 FT_Outline_Translate( &gloader->base.outline, -loader->pp1.x, 0 ); 522 523 FT_Outline_Get_CBox( &gloader->base.outline, &bbox ); 524 525 bbox.xMin = FT_PIX_FLOOR( bbox.xMin ); 526 bbox.yMin = FT_PIX_FLOOR( bbox.yMin ); 527 bbox.xMax = FT_PIX_CEIL( bbox.xMax ); 528 bbox.yMax = FT_PIX_CEIL( bbox.yMax ); 529 530 slot->metrics.width = bbox.xMax - bbox.xMin; 531 slot->metrics.height = bbox.yMax - bbox.yMin; 532 slot->metrics.horiBearingX = bbox.xMin; 533 slot->metrics.horiBearingY = bbox.yMax; 534 535 slot->metrics.vertBearingX = FT_PIX_FLOOR( bbox.xMin + vvector.x ); 536 slot->metrics.vertBearingY = FT_PIX_FLOOR( bbox.yMax + vvector.y ); 537 538 /* for mono-width fonts (like Andale, Courier, etc.) we need */ 539 /* to keep the original rounded advance width; ditto for */ 540 /* digits if all have the same advance width */ 541 if ( scaler.render_mode != FT_RENDER_MODE_LIGHT && 542 ( FT_IS_FIXED_WIDTH( slot->face ) || 543 ( af_face_globals_is_digit( loader->globals, glyph_index ) && 544 style_metrics->digits_have_same_width ) ) ) 545 { 546 slot->metrics.horiAdvance = 547 FT_MulFix( slot->metrics.horiAdvance, 548 style_metrics->scaler.x_scale ); 549 550 /* Set delta values to 0. Otherwise code that uses them is */ 551 /* going to ruin the fixed advance width. */ 552 slot->lsb_delta = 0; 553 slot->rsb_delta = 0; 554 } 555 else 556 { 557 /* non-spacing glyphs must stay as-is */ 558 if ( slot->metrics.horiAdvance ) 559 slot->metrics.horiAdvance = loader->pp2.x - loader->pp1.x; 560 } 561 562 slot->metrics.vertAdvance = FT_MulFix( slot->metrics.vertAdvance, 563 style_metrics->scaler.y_scale ); 564 565 slot->metrics.horiAdvance = FT_PIX_ROUND( slot->metrics.horiAdvance ); 566 slot->metrics.vertAdvance = FT_PIX_ROUND( slot->metrics.vertAdvance ); 567 568 slot->format = FT_GLYPH_FORMAT_OUTLINE; 569 } 570 571 Exit: 572 return error; 573 } 574 575 576 /* 577 * Compute amount of font units the face should be emboldened by, in 578 * analogy to the CFF driver's `cf2_computeDarkening' function. See there 579 * for details of the algorithm. 580 * 581 * XXX: Currently a crude adaption of the original algorithm. Do better? 582 */ 583 FT_LOCAL_DEF( FT_Fixed ) 584 af_loader_compute_darkening( AF_Loader loader, 585 FT_Face face, 586 FT_Pos standard_width ) 587 { 588 AF_Module module = loader->globals->module; 589 590 FT_UShort units_per_EM; 591 FT_Fixed ppem, em_ratio; 592 FT_Fixed stem_width, stem_width_per_1000, scaled_stem, darken_amount; 593 FT_Int log_base_2; 594 FT_Int x1, y1, x2, y2, x3, y3, x4, y4; 595 596 597 ppem = FT_MAX( af_intToFixed( 4 ), 598 af_intToFixed( face->size->metrics.x_ppem ) ); 599 units_per_EM = face->units_per_EM; 600 601 em_ratio = FT_DivFix( af_intToFixed( 1000 ), 602 af_intToFixed ( units_per_EM ) ); 603 if ( em_ratio < af_floatToFixed( .01 ) ) 604 { 605 /* If something goes wrong, don't embolden. */ 606 return 0; 607 } 608 609 x1 = module->darken_params[0]; 610 y1 = module->darken_params[1]; 611 x2 = module->darken_params[2]; 612 y2 = module->darken_params[3]; 613 x3 = module->darken_params[4]; 614 y3 = module->darken_params[5]; 615 x4 = module->darken_params[6]; 616 y4 = module->darken_params[7]; 617 618 if ( standard_width <= 0 ) 619 { 620 stem_width = af_intToFixed( 75 ); /* taken from cf2font.c */ 621 stem_width_per_1000 = stem_width; 622 } 623 else 624 { 625 stem_width = af_intToFixed( standard_width ); 626 stem_width_per_1000 = FT_MulFix( stem_width, em_ratio ); 627 } 628 629 log_base_2 = FT_MSB( (FT_UInt32)stem_width_per_1000 ) + 630 FT_MSB( (FT_UInt32)ppem ); 631 632 if ( log_base_2 >= 46 ) 633 { 634 /* possible overflow */ 635 scaled_stem = af_intToFixed( x4 ); 636 } 637 else 638 scaled_stem = FT_MulFix( stem_width_per_1000, ppem ); 639 640 /* now apply the darkening parameters */ 641 if ( scaled_stem < af_intToFixed( x1 ) ) 642 darken_amount = FT_DivFix( af_intToFixed( y1 ), ppem ); 643 644 else if ( scaled_stem < af_intToFixed( x2 ) ) 645 { 646 FT_Int xdelta = x2 - x1; 647 FT_Int ydelta = y2 - y1; 648 FT_Int x = stem_width_per_1000 - 649 FT_DivFix( af_intToFixed( x1 ), ppem ); 650 651 652 if ( !xdelta ) 653 goto Try_x3; 654 655 darken_amount = FT_MulDiv( x, ydelta, xdelta ) + 656 FT_DivFix( af_intToFixed( y1 ), ppem ); 657 } 658 659 else if ( scaled_stem < af_intToFixed( x3 ) ) 660 { 661 Try_x3: 662 { 663 FT_Int xdelta = x3 - x2; 664 FT_Int ydelta = y3 - y2; 665 FT_Int x = stem_width_per_1000 - 666 FT_DivFix( af_intToFixed( x2 ), ppem ); 667 668 669 if ( !xdelta ) 670 goto Try_x4; 671 672 darken_amount = FT_MulDiv( x, ydelta, xdelta ) + 673 FT_DivFix( af_intToFixed( y2 ), ppem ); 674 } 675 } 676 677 else if ( scaled_stem < af_intToFixed( x4 ) ) 678 { 679 Try_x4: 680 { 681 FT_Int xdelta = x4 - x3; 682 FT_Int ydelta = y4 - y3; 683 FT_Int x = stem_width_per_1000 - 684 FT_DivFix( af_intToFixed( x3 ), ppem ); 685 686 687 if ( !xdelta ) 688 goto Use_y4; 689 690 darken_amount = FT_MulDiv( x, ydelta, xdelta ) + 691 FT_DivFix( af_intToFixed( y3 ), ppem ); 692 } 693 } 694 695 else 696 { 697 Use_y4: 698 darken_amount = FT_DivFix( af_intToFixed( y4 ), ppem ); 699 } 700 701 /* Convert darken_amount from per 1000 em to true character space. */ 702 return FT_DivFix( darken_amount, em_ratio ); 703 } 704 705 706 /* END */