1 /**************************************************************************** 2 * 3 * afloader.c 4 * 5 * Auto-fitter glyph loading routines (body). 6 * 7 * Copyright (C) 2003-2022 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 if ( !size ) 233 return FT_THROW( Invalid_Size_Handle ); 234 235 FT_ZERO( &scaler ); 236 237 if ( !size_internal->autohint_metrics.x_scale || 238 size_internal->autohint_mode != FT_LOAD_TARGET_MODE( load_flags ) ) 239 { 240 /* switching between hinting modes usually means different scaling */ 241 /* values; this later on enforces recomputation of everything */ 242 /* related to the current size */ 243 244 size_internal->autohint_mode = FT_LOAD_TARGET_MODE( load_flags ); 245 size_internal->autohint_metrics = size->metrics; 246 247 #ifdef AF_CONFIG_OPTION_TT_SIZE_METRICS 248 { 249 FT_Size_Metrics* size_metrics = &size_internal->autohint_metrics; 250 251 252 /* set metrics to integer values and adjust scaling accordingly; */ 253 /* this is the same setup as with TrueType fonts, cf. function */ 254 /* `tt_size_reset' in file `ttobjs.c' */ 255 size_metrics->ascender = FT_PIX_ROUND( 256 FT_MulFix( face->ascender, 257 size_metrics->y_scale ) ); 258 size_metrics->descender = FT_PIX_ROUND( 259 FT_MulFix( face->descender, 260 size_metrics->y_scale ) ); 261 size_metrics->height = FT_PIX_ROUND( 262 FT_MulFix( face->height, 263 size_metrics->y_scale ) ); 264 265 size_metrics->x_scale = FT_DivFix( size_metrics->x_ppem << 6, 266 face->units_per_EM ); 267 size_metrics->y_scale = FT_DivFix( size_metrics->y_ppem << 6, 268 face->units_per_EM ); 269 size_metrics->max_advance = FT_PIX_ROUND( 270 FT_MulFix( face->max_advance_width, 271 size_metrics->x_scale ) ); 272 } 273 #endif /* AF_CONFIG_OPTION_TT_SIZE_METRICS */ 274 } 275 276 /* 277 * TODO: This code currently doesn't support fractional advance widths, 278 * i.e., placing hinted glyphs at anything other than integer 279 * x-positions. This is only relevant for the warper code, which 280 * scales and shifts glyphs to optimize blackness of stems (hinting on 281 * the x-axis by nature places things on pixel integers, hinting on the 282 * y-axis only, i.e., LIGHT mode, doesn't touch the x-axis). The delta 283 * values of the scaler would need to be adjusted. 284 */ 285 scaler.face = face; 286 scaler.x_scale = size_internal->autohint_metrics.x_scale; 287 scaler.x_delta = 0; 288 scaler.y_scale = size_internal->autohint_metrics.y_scale; 289 scaler.y_delta = 0; 290 291 scaler.render_mode = FT_LOAD_TARGET_MODE( load_flags ); 292 scaler.flags = 0; 293 294 /* note that the fallback style can't be changed anymore */ 295 /* after the first call of `af_loader_load_glyph' */ 296 error = af_loader_reset( loader, module, face ); 297 if ( error ) 298 goto Exit; 299 300 /* 301 * Glyphs (really code points) are assigned to scripts. Script 302 * analysis is done lazily: For each glyph that passes through here, 303 * the corresponding script analyzer is called, but returns immediately 304 * if it has been run already. 305 */ 306 error = af_face_globals_get_metrics( loader->globals, glyph_index, 307 style_options, &style_metrics ); 308 if ( error ) 309 goto Exit; 310 311 style_class = style_metrics->style_class; 312 writing_system_class = 313 af_writing_system_classes[style_class->writing_system]; 314 315 loader->metrics = style_metrics; 316 317 if ( writing_system_class->style_metrics_scale ) 318 writing_system_class->style_metrics_scale( style_metrics, &scaler ); 319 else 320 style_metrics->scaler = scaler; 321 322 if ( writing_system_class->style_hints_init ) 323 { 324 error = writing_system_class->style_hints_init( hints, 325 style_metrics ); 326 if ( error ) 327 goto Exit; 328 } 329 330 /* 331 * Do the main work of `af_loader_load_glyph'. Note that we never have 332 * to deal with composite glyphs as those get loaded into 333 * FT_GLYPH_FORMAT_OUTLINE by the recursed `FT_Load_Glyph' function. 334 * In the rare cases where FT_LOAD_NO_RECURSE is set, it implies 335 * FT_LOAD_NO_SCALE and as such the auto-hinter is never called. 336 */ 337 load_flags |= FT_LOAD_NO_SCALE | 338 FT_LOAD_IGNORE_TRANSFORM | 339 FT_LOAD_LINEAR_DESIGN; 340 load_flags &= ~FT_LOAD_RENDER; 341 342 error = FT_Load_Glyph( face, glyph_index, load_flags ); 343 if ( error ) 344 goto Exit; 345 346 /* 347 * Apply stem darkening (emboldening) here before hints are applied to 348 * the outline. Glyphs are scaled down proportionally to the 349 * emboldening so that curve points don't fall outside their 350 * precomputed blue zones. 351 * 352 * Any emboldening done by the font driver (e.g., the CFF driver) 353 * doesn't reach here because the autohinter loads the unprocessed 354 * glyphs in font units for analysis (functions `af_*_metrics_init_*') 355 * and then above to prepare it for the rasterizers by itself, 356 * independently of the font driver. So emboldening must be done here, 357 * within the autohinter. 358 * 359 * All glyphs to be autohinted pass through here one by one. The 360 * standard widths can therefore change from one glyph to the next, 361 * depending on what script a glyph is assigned to (each script has its 362 * own set of standard widths and other metrics). The darkening amount 363 * must therefore be recomputed for each size and 364 * `standard_{vertical,horizontal}_width' change. 365 * 366 * Ignore errors and carry on without emboldening. 367 * 368 */ 369 370 /* stem darkening only works well in `light' mode */ 371 if ( scaler.render_mode == FT_RENDER_MODE_LIGHT && 372 ( !face->internal->no_stem_darkening || 373 ( face->internal->no_stem_darkening < 0 && 374 !module->no_stem_darkening ) ) ) 375 af_loader_embolden_glyph_in_slot( loader, face, style_metrics ); 376 377 loader->transformed = slot_internal->glyph_transformed; 378 if ( loader->transformed ) 379 { 380 FT_Matrix inverse; 381 382 383 loader->trans_matrix = slot_internal->glyph_matrix; 384 loader->trans_delta = slot_internal->glyph_delta; 385 386 inverse = loader->trans_matrix; 387 if ( !FT_Matrix_Invert( &inverse ) ) 388 FT_Vector_Transform( &loader->trans_delta, &inverse ); 389 } 390 391 switch ( slot->format ) 392 { 393 case FT_GLYPH_FORMAT_OUTLINE: 394 /* translate the loaded glyph when an internal transform is needed */ 395 if ( loader->transformed ) 396 FT_Outline_Translate( &slot->outline, 397 loader->trans_delta.x, 398 loader->trans_delta.y ); 399 400 /* compute original horizontal phantom points */ 401 /* (and ignore vertical ones) */ 402 loader->pp1.x = hints->x_delta; 403 loader->pp1.y = hints->y_delta; 404 loader->pp2.x = FT_MulFix( slot->metrics.horiAdvance, 405 hints->x_scale ) + hints->x_delta; 406 loader->pp2.y = hints->y_delta; 407 408 /* be sure to check for spacing glyphs */ 409 if ( slot->outline.n_points == 0 ) 410 goto Hint_Metrics; 411 412 /* now load the slot image into the auto-outline */ 413 /* and run the automatic hinting process */ 414 if ( writing_system_class->style_hints_apply ) 415 { 416 error = writing_system_class->style_hints_apply( 417 glyph_index, 418 hints, 419 &gloader->base.outline, 420 style_metrics ); 421 if ( error ) 422 goto Exit; 423 } 424 425 /* we now need to adjust the metrics according to the change in */ 426 /* width/positioning that occurred during the hinting process */ 427 if ( scaler.render_mode != FT_RENDER_MODE_LIGHT ) 428 { 429 AF_AxisHints axis = &hints->axis[AF_DIMENSION_HORZ]; 430 431 432 if ( axis->num_edges > 1 && AF_HINTS_DO_ADVANCE( hints ) ) 433 { 434 AF_Edge edge1 = axis->edges; /* leftmost edge */ 435 AF_Edge edge2 = edge1 + 436 axis->num_edges - 1; /* rightmost edge */ 437 438 FT_Pos old_rsb = loader->pp2.x - edge2->opos; 439 /* loader->pp1.x is always zero at this point of time */ 440 FT_Pos old_lsb = edge1->opos; /* - loader->pp1.x */ 441 FT_Pos new_lsb = edge1->pos; 442 443 /* remember unhinted values to later account */ 444 /* for rounding errors */ 445 FT_Pos pp1x_uh = new_lsb - old_lsb; 446 FT_Pos pp2x_uh = edge2->pos + old_rsb; 447 448 449 /* prefer too much space over too little space */ 450 /* for very small sizes */ 451 452 if ( old_lsb < 24 ) 453 pp1x_uh -= 8; 454 455 if ( old_rsb < 24 ) 456 pp2x_uh += 8; 457 458 loader->pp1.x = FT_PIX_ROUND( pp1x_uh ); 459 loader->pp2.x = FT_PIX_ROUND( pp2x_uh ); 460 461 if ( loader->pp1.x >= new_lsb && old_lsb > 0 ) 462 loader->pp1.x -= 64; 463 464 if ( loader->pp2.x <= edge2->pos && old_rsb > 0 ) 465 loader->pp2.x += 64; 466 467 slot->lsb_delta = loader->pp1.x - pp1x_uh; 468 slot->rsb_delta = loader->pp2.x - pp2x_uh; 469 } 470 else 471 { 472 FT_Pos pp1x = loader->pp1.x; 473 FT_Pos pp2x = loader->pp2.x; 474 475 476 loader->pp1.x = FT_PIX_ROUND( pp1x ); 477 loader->pp2.x = FT_PIX_ROUND( pp2x ); 478 479 slot->lsb_delta = loader->pp1.x - pp1x; 480 slot->rsb_delta = loader->pp2.x - pp2x; 481 } 482 } 483 /* `light' mode uses integer advance widths */ 484 /* but sets `lsb_delta' and `rsb_delta' */ 485 else 486 { 487 FT_Pos pp1x = loader->pp1.x; 488 FT_Pos pp2x = loader->pp2.x; 489 490 491 loader->pp1.x = FT_PIX_ROUND( pp1x ); 492 loader->pp2.x = FT_PIX_ROUND( pp2x ); 493 494 slot->lsb_delta = loader->pp1.x - pp1x; 495 slot->rsb_delta = loader->pp2.x - pp2x; 496 } 497 498 break; 499 500 default: 501 /* we don't support other formats (yet?) */ 502 error = FT_THROW( Unimplemented_Feature ); 503 } 504 505 Hint_Metrics: 506 { 507 FT_BBox bbox; 508 FT_Vector vvector; 509 510 511 vvector.x = slot->metrics.vertBearingX - slot->metrics.horiBearingX; 512 vvector.y = slot->metrics.vertBearingY - slot->metrics.horiBearingY; 513 vvector.x = FT_MulFix( vvector.x, style_metrics->scaler.x_scale ); 514 vvector.y = FT_MulFix( vvector.y, style_metrics->scaler.y_scale ); 515 516 /* transform the hinted outline if needed */ 517 if ( loader->transformed ) 518 { 519 FT_Outline_Transform( &gloader->base.outline, &loader->trans_matrix ); 520 FT_Vector_Transform( &vvector, &loader->trans_matrix ); 521 } 522 523 /* we must translate our final outline by -pp1.x and compute */ 524 /* the new metrics */ 525 if ( loader->pp1.x ) 526 FT_Outline_Translate( &gloader->base.outline, -loader->pp1.x, 0 ); 527 528 FT_Outline_Get_CBox( &gloader->base.outline, &bbox ); 529 530 bbox.xMin = FT_PIX_FLOOR( bbox.xMin ); 531 bbox.yMin = FT_PIX_FLOOR( bbox.yMin ); 532 bbox.xMax = FT_PIX_CEIL( bbox.xMax ); 533 bbox.yMax = FT_PIX_CEIL( bbox.yMax ); 534 535 slot->metrics.width = bbox.xMax - bbox.xMin; 536 slot->metrics.height = bbox.yMax - bbox.yMin; 537 slot->metrics.horiBearingX = bbox.xMin; 538 slot->metrics.horiBearingY = bbox.yMax; 539 540 slot->metrics.vertBearingX = FT_PIX_FLOOR( bbox.xMin + vvector.x ); 541 slot->metrics.vertBearingY = FT_PIX_FLOOR( bbox.yMax + vvector.y ); 542 543 /* for mono-width fonts (like Andale, Courier, etc.) we need */ 544 /* to keep the original rounded advance width; ditto for */ 545 /* digits if all have the same advance width */ 546 if ( scaler.render_mode != FT_RENDER_MODE_LIGHT && 547 ( FT_IS_FIXED_WIDTH( slot->face ) || 548 ( af_face_globals_is_digit( loader->globals, glyph_index ) && 549 style_metrics->digits_have_same_width ) ) ) 550 { 551 slot->metrics.horiAdvance = 552 FT_MulFix( slot->metrics.horiAdvance, 553 style_metrics->scaler.x_scale ); 554 555 /* Set delta values to 0. Otherwise code that uses them is */ 556 /* going to ruin the fixed advance width. */ 557 slot->lsb_delta = 0; 558 slot->rsb_delta = 0; 559 } 560 else 561 { 562 /* non-spacing glyphs must stay as-is */ 563 if ( slot->metrics.horiAdvance ) 564 slot->metrics.horiAdvance = loader->pp2.x - loader->pp1.x; 565 } 566 567 slot->metrics.vertAdvance = FT_MulFix( slot->metrics.vertAdvance, 568 style_metrics->scaler.y_scale ); 569 570 slot->metrics.horiAdvance = FT_PIX_ROUND( slot->metrics.horiAdvance ); 571 slot->metrics.vertAdvance = FT_PIX_ROUND( slot->metrics.vertAdvance ); 572 573 slot->format = FT_GLYPH_FORMAT_OUTLINE; 574 } 575 576 Exit: 577 return error; 578 } 579 580 581 /* 582 * Compute amount of font units the face should be emboldened by, in 583 * analogy to the CFF driver's `cf2_computeDarkening' function. See there 584 * for details of the algorithm. 585 * 586 * XXX: Currently a crude adaption of the original algorithm. Do better? 587 */ 588 FT_LOCAL_DEF( FT_Fixed ) af_loader_compute_darkening(AF_Loader loader,FT_Face face,FT_Pos standard_width)589 af_loader_compute_darkening( AF_Loader loader, 590 FT_Face face, 591 FT_Pos standard_width ) 592 { 593 AF_Module module = loader->globals->module; 594 595 FT_UShort units_per_EM; 596 FT_Fixed ppem, em_ratio; 597 FT_Fixed stem_width, stem_width_per_1000, scaled_stem, darken_amount; 598 FT_Int log_base_2; 599 FT_Int x1, y1, x2, y2, x3, y3, x4, y4; 600 601 602 ppem = FT_MAX( af_intToFixed( 4 ), 603 af_intToFixed( face->size->metrics.x_ppem ) ); 604 units_per_EM = face->units_per_EM; 605 606 em_ratio = FT_DivFix( af_intToFixed( 1000 ), 607 af_intToFixed ( units_per_EM ) ); 608 if ( em_ratio < af_floatToFixed( .01 ) ) 609 { 610 /* If something goes wrong, don't embolden. */ 611 return 0; 612 } 613 614 x1 = module->darken_params[0]; 615 y1 = module->darken_params[1]; 616 x2 = module->darken_params[2]; 617 y2 = module->darken_params[3]; 618 x3 = module->darken_params[4]; 619 y3 = module->darken_params[5]; 620 x4 = module->darken_params[6]; 621 y4 = module->darken_params[7]; 622 623 if ( standard_width <= 0 ) 624 { 625 stem_width = af_intToFixed( 75 ); /* taken from cf2font.c */ 626 stem_width_per_1000 = stem_width; 627 } 628 else 629 { 630 stem_width = af_intToFixed( standard_width ); 631 stem_width_per_1000 = FT_MulFix( stem_width, em_ratio ); 632 } 633 634 log_base_2 = FT_MSB( (FT_UInt32)stem_width_per_1000 ) + 635 FT_MSB( (FT_UInt32)ppem ); 636 637 if ( log_base_2 >= 46 ) 638 { 639 /* possible overflow */ 640 scaled_stem = af_intToFixed( x4 ); 641 } 642 else 643 scaled_stem = FT_MulFix( stem_width_per_1000, ppem ); 644 645 /* now apply the darkening parameters */ 646 if ( scaled_stem < af_intToFixed( x1 ) ) 647 darken_amount = FT_DivFix( af_intToFixed( y1 ), ppem ); 648 649 else if ( scaled_stem < af_intToFixed( x2 ) ) 650 { 651 FT_Int xdelta = x2 - x1; 652 FT_Int ydelta = y2 - y1; 653 FT_Int x = stem_width_per_1000 - 654 FT_DivFix( af_intToFixed( x1 ), ppem ); 655 656 657 if ( !xdelta ) 658 goto Try_x3; 659 660 darken_amount = FT_MulDiv( x, ydelta, xdelta ) + 661 FT_DivFix( af_intToFixed( y1 ), ppem ); 662 } 663 664 else if ( scaled_stem < af_intToFixed( x3 ) ) 665 { 666 Try_x3: 667 { 668 FT_Int xdelta = x3 - x2; 669 FT_Int ydelta = y3 - y2; 670 FT_Int x = stem_width_per_1000 - 671 FT_DivFix( af_intToFixed( x2 ), ppem ); 672 673 674 if ( !xdelta ) 675 goto Try_x4; 676 677 darken_amount = FT_MulDiv( x, ydelta, xdelta ) + 678 FT_DivFix( af_intToFixed( y2 ), ppem ); 679 } 680 } 681 682 else if ( scaled_stem < af_intToFixed( x4 ) ) 683 { 684 Try_x4: 685 { 686 FT_Int xdelta = x4 - x3; 687 FT_Int ydelta = y4 - y3; 688 FT_Int x = stem_width_per_1000 - 689 FT_DivFix( af_intToFixed( x3 ), ppem ); 690 691 692 if ( !xdelta ) 693 goto Use_y4; 694 695 darken_amount = FT_MulDiv( x, ydelta, xdelta ) + 696 FT_DivFix( af_intToFixed( y3 ), ppem ); 697 } 698 } 699 700 else 701 { 702 Use_y4: 703 darken_amount = FT_DivFix( af_intToFixed( y4 ), ppem ); 704 } 705 706 /* Convert darken_amount from per 1000 em to true character space. */ 707 return FT_DivFix( darken_amount, em_ratio ); 708 } 709 710 711 /* END */ 712