1 /**************************************************************************** 2 * 3 * afloader.c 4 * 5 * Auto-fitter glyph loading routines (body). 6 * 7 * Copyright (C) 2003-2023 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 ) af_loader_init(AF_Loader loader,AF_GlyphHints hints)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 ) af_loader_reset(AF_Loader loader,AF_Module module,FT_Face face)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 = 59 (FT_Pointer)loader->globals; 60 face->autohint.finalizer = 61 (FT_Generic_Finalizer)af_face_globals_free; 62 } 63 } 64 65 return error; 66 } 67 68 69 /* Finalize glyph loader. */ 70 71 FT_LOCAL_DEF( void ) af_loader_done(AF_Loader loader)72 af_loader_done( AF_Loader loader ) 73 { 74 loader->face = NULL; 75 loader->globals = NULL; 76 loader->hints = NULL; 77 } 78 79 80 #define af_intToFixed( i ) \ 81 ( (FT_Fixed)( (FT_UInt32)(i) << 16 ) ) 82 #define af_fixedToInt( x ) \ 83 ( (FT_Short)( ( (FT_UInt32)(x) + 0x8000U ) >> 16 ) ) 84 #define af_floatToFixed( f ) \ 85 ( (FT_Fixed)( (f) * 65536.0 + 0.5 ) ) 86 87 88 static FT_Error af_loader_embolden_glyph_in_slot(AF_Loader loader,FT_Face face,AF_StyleMetrics style_metrics)89 af_loader_embolden_glyph_in_slot( AF_Loader loader, 90 FT_Face face, 91 AF_StyleMetrics style_metrics ) 92 { 93 FT_Error error = FT_Err_Ok; 94 95 FT_GlyphSlot slot = face->glyph; 96 AF_FaceGlobals globals = loader->globals; 97 AF_WritingSystemClass writing_system_class; 98 99 FT_Size_Metrics* size_metrics = &face->size->internal->autohint_metrics; 100 101 FT_Pos stdVW = 0; 102 FT_Pos stdHW = 0; 103 104 FT_Bool size_changed = size_metrics->x_ppem != 105 globals->stem_darkening_for_ppem; 106 107 FT_Fixed em_size = af_intToFixed( face->units_per_EM ); 108 109 FT_Matrix scale_down_matrix = { 0x10000L, 0, 0, 0x10000L }; 110 111 112 /* Skip stem darkening for broken fonts. */ 113 if ( !face->units_per_EM ) 114 { 115 error = FT_ERR( Corrupted_Font_Header ); 116 goto Exit; 117 } 118 119 /* 120 * We depend on the writing system (script analyzers) to supply 121 * standard widths for the script of the glyph we are looking at. If 122 * it can't deliver, stem darkening is disabled. 123 */ 124 writing_system_class = 125 af_writing_system_classes[style_metrics->style_class->writing_system]; 126 127 if ( writing_system_class->style_metrics_getstdw ) 128 writing_system_class->style_metrics_getstdw( style_metrics, 129 &stdHW, 130 &stdVW ); 131 else 132 { 133 error = FT_ERR( Unimplemented_Feature ); 134 goto Exit; 135 } 136 137 if ( size_changed || 138 ( stdVW > 0 && stdVW != globals->standard_vertical_width ) ) 139 { 140 FT_Fixed darken_by_font_units_x, darken_x; 141 142 143 darken_by_font_units_x = 144 af_loader_compute_darkening( loader, 145 face, 146 stdVW ) ; 147 darken_x = FT_MulFix( darken_by_font_units_x, 148 size_metrics->x_scale ); 149 150 globals->standard_vertical_width = stdVW; 151 globals->stem_darkening_for_ppem = size_metrics->x_ppem; 152 globals->darken_x = af_fixedToInt( darken_x ); 153 } 154 155 if ( size_changed || 156 ( stdHW > 0 && stdHW != globals->standard_horizontal_width ) ) 157 { 158 FT_Fixed darken_by_font_units_y, darken_y; 159 160 161 darken_by_font_units_y = 162 af_loader_compute_darkening( loader, 163 face, 164 stdHW ) ; 165 darken_y = FT_MulFix( darken_by_font_units_y, 166 size_metrics->y_scale ); 167 168 globals->standard_horizontal_width = stdHW; 169 globals->stem_darkening_for_ppem = size_metrics->x_ppem; 170 globals->darken_y = af_fixedToInt( darken_y ); 171 172 /* 173 * Scale outlines down on the Y-axis to keep them inside their blue 174 * zones. The stronger the emboldening, the stronger the downscaling 175 * (plus heuristical padding to prevent outlines still falling out 176 * their zones due to rounding). 177 * 178 * Reason: `FT_Outline_Embolden' works by shifting the rightmost 179 * points of stems farther to the right, and topmost points farther 180 * up. This positions points on the Y-axis outside their 181 * pre-computed blue zones and leads to distortion when applying the 182 * hints in the code further below. Code outside this emboldening 183 * block doesn't know we are presenting it with modified outlines the 184 * analyzer didn't see! 185 * 186 * An unfortunate side effect of downscaling is that the emboldening 187 * effect is slightly decreased. The loss becomes more pronounced 188 * versus the CFF driver at smaller sizes, e.g., at 9ppem and below. 189 */ 190 globals->scale_down_factor = 191 FT_DivFix( em_size - ( darken_by_font_units_y + af_intToFixed( 8 ) ), 192 em_size ); 193 } 194 195 FT_Outline_EmboldenXY( &slot->outline, 196 globals->darken_x, 197 globals->darken_y ); 198 199 scale_down_matrix.yy = globals->scale_down_factor; 200 FT_Outline_Transform( &slot->outline, &scale_down_matrix ); 201 202 Exit: 203 return error; 204 } 205 206 207 /* Load the glyph at index into the current slot of a face and hint it. */ 208 209 FT_LOCAL_DEF( FT_Error ) af_loader_load_glyph(AF_Loader loader,AF_Module module,FT_Face face,FT_UInt glyph_index,FT_Int32 load_flags)210 af_loader_load_glyph( AF_Loader loader, 211 AF_Module module, 212 FT_Face face, 213 FT_UInt glyph_index, 214 FT_Int32 load_flags ) 215 { 216 FT_Error error; 217 218 FT_Size size = face->size; 219 FT_Size_Internal size_internal = size->internal; 220 FT_GlyphSlot slot = face->glyph; 221 FT_Slot_Internal slot_internal = slot->internal; 222 FT_GlyphLoader gloader = slot_internal->loader; 223 224 AF_GlyphHints hints = loader->hints; 225 AF_ScalerRec scaler; 226 AF_StyleMetrics style_metrics; 227 FT_UInt style_options = AF_STYLE_NONE_DFLT; 228 AF_StyleClass style_class; 229 AF_WritingSystemClass writing_system_class; 230 231 232 FT_ZERO( &scaler ); 233 234 if ( !size_internal->autohint_metrics.x_scale || 235 size_internal->autohint_mode != FT_LOAD_TARGET_MODE( load_flags ) ) 236 { 237 /* switching between hinting modes usually means different scaling */ 238 /* values; this later on enforces recomputation of everything */ 239 /* related to the current size */ 240 241 size_internal->autohint_mode = FT_LOAD_TARGET_MODE( load_flags ); 242 size_internal->autohint_metrics = size->metrics; 243 244 #ifdef AF_CONFIG_OPTION_TT_SIZE_METRICS 245 { 246 FT_Size_Metrics* size_metrics = &size_internal->autohint_metrics; 247 248 249 /* set metrics to integer values and adjust scaling accordingly; */ 250 /* this is the same setup as with TrueType fonts, cf. function */ 251 /* `tt_size_reset' in file `ttobjs.c' */ 252 size_metrics->ascender = FT_PIX_ROUND( 253 FT_MulFix( face->ascender, 254 size_metrics->y_scale ) ); 255 size_metrics->descender = FT_PIX_ROUND( 256 FT_MulFix( face->descender, 257 size_metrics->y_scale ) ); 258 size_metrics->height = FT_PIX_ROUND( 259 FT_MulFix( face->height, 260 size_metrics->y_scale ) ); 261 262 size_metrics->x_scale = FT_DivFix( size_metrics->x_ppem << 6, 263 face->units_per_EM ); 264 size_metrics->y_scale = FT_DivFix( size_metrics->y_ppem << 6, 265 face->units_per_EM ); 266 size_metrics->max_advance = FT_PIX_ROUND( 267 FT_MulFix( face->max_advance_width, 268 size_metrics->x_scale ) ); 269 } 270 #endif /* AF_CONFIG_OPTION_TT_SIZE_METRICS */ 271 } 272 273 /* 274 * TODO: This code currently doesn't support fractional advance widths, 275 * i.e., placing hinted glyphs at anything other than integer 276 * x-positions. This is only relevant for the warper code, which 277 * scales and shifts glyphs to optimize blackness of stems (hinting on 278 * the x-axis by nature places things on pixel integers, hinting on the 279 * y-axis only, i.e., LIGHT mode, doesn't touch the x-axis). The delta 280 * values of the scaler would need to be adjusted. 281 */ 282 scaler.face = face; 283 scaler.x_scale = size_internal->autohint_metrics.x_scale; 284 scaler.x_delta = 0; 285 scaler.y_scale = size_internal->autohint_metrics.y_scale; 286 scaler.y_delta = 0; 287 288 scaler.render_mode = FT_LOAD_TARGET_MODE( load_flags ); 289 scaler.flags = 0; 290 291 /* note that the fallback style can't be changed anymore */ 292 /* after the first call of `af_loader_load_glyph' */ 293 error = af_loader_reset( loader, module, face ); 294 if ( error ) 295 goto Exit; 296 297 /* 298 * Glyphs (really code points) are assigned to scripts. Script 299 * analysis is done lazily: For each glyph that passes through here, 300 * the corresponding script analyzer is called, but returns immediately 301 * if it has been run already. 302 */ 303 error = af_face_globals_get_metrics( loader->globals, glyph_index, 304 style_options, &style_metrics ); 305 if ( error ) 306 goto Exit; 307 308 style_class = style_metrics->style_class; 309 writing_system_class = 310 af_writing_system_classes[style_class->writing_system]; 311 312 loader->metrics = style_metrics; 313 314 if ( writing_system_class->style_metrics_scale ) 315 writing_system_class->style_metrics_scale( style_metrics, &scaler ); 316 else 317 style_metrics->scaler = scaler; 318 319 if ( writing_system_class->style_hints_init ) 320 { 321 error = writing_system_class->style_hints_init( hints, 322 style_metrics ); 323 if ( error ) 324 goto Exit; 325 } 326 327 /* 328 * Do the main work of `af_loader_load_glyph'. Note that we never have 329 * to deal with composite glyphs as those get loaded into 330 * FT_GLYPH_FORMAT_OUTLINE by the recursed `FT_Load_Glyph' function. 331 * In the rare cases where FT_LOAD_NO_RECURSE is set, it implies 332 * FT_LOAD_NO_SCALE and as such the auto-hinter is never called. 333 */ 334 load_flags |= FT_LOAD_NO_SCALE | 335 FT_LOAD_IGNORE_TRANSFORM | 336 FT_LOAD_LINEAR_DESIGN; 337 load_flags &= ~FT_LOAD_RENDER; 338 339 error = FT_Load_Glyph( face, glyph_index, load_flags ); 340 if ( error ) 341 goto Exit; 342 343 /* 344 * Apply stem darkening (emboldening) here before hints are applied to 345 * the outline. Glyphs are scaled down proportionally to the 346 * emboldening so that curve points don't fall outside their 347 * precomputed blue zones. 348 * 349 * Any emboldening done by the font driver (e.g., the CFF driver) 350 * doesn't reach here because the autohinter loads the unprocessed 351 * glyphs in font units for analysis (functions `af_*_metrics_init_*') 352 * and then above to prepare it for the rasterizers by itself, 353 * independently of the font driver. So emboldening must be done here, 354 * within the autohinter. 355 * 356 * All glyphs to be autohinted pass through here one by one. The 357 * standard widths can therefore change from one glyph to the next, 358 * depending on what script a glyph is assigned to (each script has its 359 * own set of standard widths and other metrics). The darkening amount 360 * must therefore be recomputed for each size and 361 * `standard_{vertical,horizontal}_width' change. 362 * 363 * Ignore errors and carry on without emboldening. 364 * 365 */ 366 367 /* stem darkening only works well in `light' mode */ 368 if ( scaler.render_mode == FT_RENDER_MODE_LIGHT && 369 ( !face->internal->no_stem_darkening || 370 ( face->internal->no_stem_darkening < 0 && 371 !module->no_stem_darkening ) ) ) 372 af_loader_embolden_glyph_in_slot( loader, face, style_metrics ); 373 374 loader->transformed = slot_internal->glyph_transformed; 375 if ( loader->transformed ) 376 { 377 FT_Matrix inverse; 378 379 380 loader->trans_matrix = slot_internal->glyph_matrix; 381 loader->trans_delta = slot_internal->glyph_delta; 382 383 inverse = loader->trans_matrix; 384 if ( !FT_Matrix_Invert( &inverse ) ) 385 FT_Vector_Transform( &loader->trans_delta, &inverse ); 386 } 387 388 switch ( slot->format ) 389 { 390 case FT_GLYPH_FORMAT_OUTLINE: 391 /* translate the loaded glyph when an internal transform is needed */ 392 if ( loader->transformed ) 393 FT_Outline_Translate( &slot->outline, 394 loader->trans_delta.x, 395 loader->trans_delta.y ); 396 397 /* compute original horizontal phantom points */ 398 /* (and ignore vertical ones) */ 399 loader->pp1.x = hints->x_delta; 400 loader->pp1.y = hints->y_delta; 401 loader->pp2.x = FT_MulFix( slot->metrics.horiAdvance, 402 hints->x_scale ) + hints->x_delta; 403 loader->pp2.y = hints->y_delta; 404 405 /* be sure to check for spacing glyphs */ 406 if ( slot->outline.n_points == 0 ) 407 goto Hint_Metrics; 408 409 /* now load the slot image into the auto-outline */ 410 /* and run the automatic hinting process */ 411 if ( writing_system_class->style_hints_apply ) 412 { 413 error = writing_system_class->style_hints_apply( 414 glyph_index, 415 hints, 416 &gloader->base.outline, 417 style_metrics ); 418 if ( error ) 419 goto Exit; 420 } 421 422 /* we now need to adjust the metrics according to the change in */ 423 /* width/positioning that occurred during the hinting process */ 424 if ( scaler.render_mode != FT_RENDER_MODE_LIGHT ) 425 { 426 AF_AxisHints axis = &hints->axis[AF_DIMENSION_HORZ]; 427 428 429 if ( axis->num_edges > 1 && AF_HINTS_DO_ADVANCE( hints ) ) 430 { 431 AF_Edge edge1 = axis->edges; /* leftmost edge */ 432 AF_Edge edge2 = edge1 + 433 axis->num_edges - 1; /* rightmost edge */ 434 435 FT_Pos old_rsb = loader->pp2.x - edge2->opos; 436 /* loader->pp1.x is always zero at this point of time */ 437 FT_Pos old_lsb = edge1->opos; /* - loader->pp1.x */ 438 FT_Pos new_lsb = edge1->pos; 439 440 /* remember unhinted values to later account */ 441 /* for rounding errors */ 442 FT_Pos pp1x_uh = new_lsb - old_lsb; 443 FT_Pos pp2x_uh = edge2->pos + old_rsb; 444 445 446 /* prefer too much space over too little space */ 447 /* for very small sizes */ 448 449 if ( old_lsb < 24 ) 450 pp1x_uh -= 8; 451 452 if ( old_rsb < 24 ) 453 pp2x_uh += 8; 454 455 loader->pp1.x = FT_PIX_ROUND( pp1x_uh ); 456 loader->pp2.x = FT_PIX_ROUND( pp2x_uh ); 457 458 if ( loader->pp1.x >= new_lsb && old_lsb > 0 ) 459 loader->pp1.x -= 64; 460 461 if ( loader->pp2.x <= edge2->pos && old_rsb > 0 ) 462 loader->pp2.x += 64; 463 464 slot->lsb_delta = loader->pp1.x - pp1x_uh; 465 slot->rsb_delta = loader->pp2.x - pp2x_uh; 466 } 467 else 468 { 469 FT_Pos pp1x = loader->pp1.x; 470 FT_Pos pp2x = loader->pp2.x; 471 472 473 loader->pp1.x = FT_PIX_ROUND( pp1x ); 474 loader->pp2.x = FT_PIX_ROUND( pp2x ); 475 476 slot->lsb_delta = loader->pp1.x - pp1x; 477 slot->rsb_delta = loader->pp2.x - pp2x; 478 } 479 } 480 /* `light' mode uses integer advance widths */ 481 /* but sets `lsb_delta' and `rsb_delta' */ 482 else 483 { 484 FT_Pos pp1x = loader->pp1.x; 485 FT_Pos pp2x = loader->pp2.x; 486 487 488 loader->pp1.x = FT_PIX_ROUND( pp1x ); 489 loader->pp2.x = FT_PIX_ROUND( pp2x ); 490 491 slot->lsb_delta = loader->pp1.x - pp1x; 492 slot->rsb_delta = loader->pp2.x - pp2x; 493 } 494 495 break; 496 497 default: 498 /* we don't support other formats (yet?) */ 499 error = FT_THROW( Unimplemented_Feature ); 500 } 501 502 Hint_Metrics: 503 { 504 FT_BBox bbox; 505 FT_Vector vvector; 506 507 508 vvector.x = slot->metrics.vertBearingX - slot->metrics.horiBearingX; 509 vvector.y = slot->metrics.vertBearingY - slot->metrics.horiBearingY; 510 vvector.x = FT_MulFix( vvector.x, style_metrics->scaler.x_scale ); 511 vvector.y = FT_MulFix( vvector.y, style_metrics->scaler.y_scale ); 512 513 /* transform the hinted outline if needed */ 514 if ( loader->transformed ) 515 { 516 FT_Outline_Transform( &gloader->base.outline, &loader->trans_matrix ); 517 FT_Vector_Transform( &vvector, &loader->trans_matrix ); 518 } 519 520 /* we must translate our final outline by -pp1.x and compute */ 521 /* the new metrics */ 522 if ( loader->pp1.x ) 523 FT_Outline_Translate( &gloader->base.outline, -loader->pp1.x, 0 ); 524 525 FT_Outline_Get_CBox( &gloader->base.outline, &bbox ); 526 527 bbox.xMin = FT_PIX_FLOOR( bbox.xMin ); 528 bbox.yMin = FT_PIX_FLOOR( bbox.yMin ); 529 bbox.xMax = FT_PIX_CEIL( bbox.xMax ); 530 bbox.yMax = FT_PIX_CEIL( bbox.yMax ); 531 532 slot->metrics.width = bbox.xMax - bbox.xMin; 533 slot->metrics.height = bbox.yMax - bbox.yMin; 534 slot->metrics.horiBearingX = bbox.xMin; 535 slot->metrics.horiBearingY = bbox.yMax; 536 537 slot->metrics.vertBearingX = FT_PIX_FLOOR( bbox.xMin + vvector.x ); 538 slot->metrics.vertBearingY = FT_PIX_FLOOR( bbox.yMax + vvector.y ); 539 540 /* for mono-width fonts (like Andale, Courier, etc.) we need */ 541 /* to keep the original rounded advance width; ditto for */ 542 /* digits if all have the same advance width */ 543 if ( scaler.render_mode != FT_RENDER_MODE_LIGHT && 544 ( FT_IS_FIXED_WIDTH( slot->face ) || 545 ( af_face_globals_is_digit( loader->globals, glyph_index ) && 546 style_metrics->digits_have_same_width ) ) ) 547 { 548 slot->metrics.horiAdvance = 549 FT_MulFix( slot->metrics.horiAdvance, 550 style_metrics->scaler.x_scale ); 551 552 /* Set delta values to 0. Otherwise code that uses them is */ 553 /* going to ruin the fixed advance width. */ 554 slot->lsb_delta = 0; 555 slot->rsb_delta = 0; 556 } 557 else 558 { 559 /* non-spacing glyphs must stay as-is */ 560 if ( slot->metrics.horiAdvance ) 561 slot->metrics.horiAdvance = loader->pp2.x - loader->pp1.x; 562 } 563 564 slot->metrics.vertAdvance = FT_MulFix( slot->metrics.vertAdvance, 565 style_metrics->scaler.y_scale ); 566 567 slot->metrics.horiAdvance = FT_PIX_ROUND( slot->metrics.horiAdvance ); 568 slot->metrics.vertAdvance = FT_PIX_ROUND( slot->metrics.vertAdvance ); 569 570 slot->format = FT_GLYPH_FORMAT_OUTLINE; 571 } 572 573 Exit: 574 return error; 575 } 576 577 578 /* 579 * Compute amount of font units the face should be emboldened by, in 580 * analogy to the CFF driver's `cf2_computeDarkening' function. See there 581 * for details of the algorithm. 582 * 583 * XXX: Currently a crude adaption of the original algorithm. Do better? 584 */ 585 FT_LOCAL_DEF( FT_Fixed ) af_loader_compute_darkening(AF_Loader loader,FT_Face face,FT_Pos standard_width)586 af_loader_compute_darkening( AF_Loader loader, 587 FT_Face face, 588 FT_Pos standard_width ) 589 { 590 AF_Module module = loader->globals->module; 591 592 FT_UShort units_per_EM; 593 FT_Fixed ppem, em_ratio; 594 FT_Fixed stem_width, stem_width_per_1000, scaled_stem, darken_amount; 595 FT_Int log_base_2; 596 FT_Int x1, y1, x2, y2, x3, y3, x4, y4; 597 598 599 ppem = FT_MAX( af_intToFixed( 4 ), 600 af_intToFixed( face->size->metrics.x_ppem ) ); 601 units_per_EM = face->units_per_EM; 602 603 em_ratio = FT_DivFix( af_intToFixed( 1000 ), 604 af_intToFixed ( units_per_EM ) ); 605 if ( em_ratio < af_floatToFixed( .01 ) ) 606 { 607 /* If something goes wrong, don't embolden. */ 608 return 0; 609 } 610 611 x1 = module->darken_params[0]; 612 y1 = module->darken_params[1]; 613 x2 = module->darken_params[2]; 614 y2 = module->darken_params[3]; 615 x3 = module->darken_params[4]; 616 y3 = module->darken_params[5]; 617 x4 = module->darken_params[6]; 618 y4 = module->darken_params[7]; 619 620 if ( standard_width <= 0 ) 621 { 622 stem_width = af_intToFixed( 75 ); /* taken from cf2font.c */ 623 stem_width_per_1000 = stem_width; 624 } 625 else 626 { 627 stem_width = af_intToFixed( standard_width ); 628 stem_width_per_1000 = FT_MulFix( stem_width, em_ratio ); 629 } 630 631 log_base_2 = FT_MSB( (FT_UInt32)stem_width_per_1000 ) + 632 FT_MSB( (FT_UInt32)ppem ); 633 634 if ( log_base_2 >= 46 ) 635 { 636 /* possible overflow */ 637 scaled_stem = af_intToFixed( x4 ); 638 } 639 else 640 scaled_stem = FT_MulFix( stem_width_per_1000, ppem ); 641 642 /* now apply the darkening parameters */ 643 if ( scaled_stem < af_intToFixed( x1 ) ) 644 darken_amount = FT_DivFix( af_intToFixed( y1 ), ppem ); 645 646 else if ( scaled_stem < af_intToFixed( x2 ) ) 647 { 648 FT_Int xdelta = x2 - x1; 649 FT_Int ydelta = y2 - y1; 650 FT_Int x = stem_width_per_1000 - 651 FT_DivFix( af_intToFixed( x1 ), ppem ); 652 653 654 if ( !xdelta ) 655 goto Try_x3; 656 657 darken_amount = FT_MulDiv( x, ydelta, xdelta ) + 658 FT_DivFix( af_intToFixed( y1 ), ppem ); 659 } 660 661 else if ( scaled_stem < af_intToFixed( x3 ) ) 662 { 663 Try_x3: 664 { 665 FT_Int xdelta = x3 - x2; 666 FT_Int ydelta = y3 - y2; 667 FT_Int x = stem_width_per_1000 - 668 FT_DivFix( af_intToFixed( x2 ), ppem ); 669 670 671 if ( !xdelta ) 672 goto Try_x4; 673 674 darken_amount = FT_MulDiv( x, ydelta, xdelta ) + 675 FT_DivFix( af_intToFixed( y2 ), ppem ); 676 } 677 } 678 679 else if ( scaled_stem < af_intToFixed( x4 ) ) 680 { 681 Try_x4: 682 { 683 FT_Int xdelta = x4 - x3; 684 FT_Int ydelta = y4 - y3; 685 FT_Int x = stem_width_per_1000 - 686 FT_DivFix( af_intToFixed( x3 ), ppem ); 687 688 689 if ( !xdelta ) 690 goto Use_y4; 691 692 darken_amount = FT_MulDiv( x, ydelta, xdelta ) + 693 FT_DivFix( af_intToFixed( y3 ), ppem ); 694 } 695 } 696 697 else 698 { 699 Use_y4: 700 darken_amount = FT_DivFix( af_intToFixed( y4 ), ppem ); 701 } 702 703 /* Convert darken_amount from per 1000 em to true character space. */ 704 return FT_DivFix( darken_amount, em_ratio ); 705 } 706 707 708 /* END */ 709