1 /**************************************************************************** 2 * 3 * afloader.c 4 * 5 * Auto-fitter glyph loading routines (body). 6 * 7 * Copyright (C) 2003-2020 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 FT_Fixed em_ratio = FT_DivFix( af_intToFixed( 1000 ), em_size ); 109 110 FT_Matrix scale_down_matrix = { 0x10000L, 0, 0, 0x10000L }; 111 112 113 /* Skip stem darkening for broken fonts. */ 114 if ( !face->units_per_EM ) 115 { 116 error = FT_ERR( Corrupted_Font_Header ); 117 goto Exit; 118 } 119 120 /* 121 * We depend on the writing system (script analyzers) to supply 122 * standard widths for the script of the glyph we are looking at. If 123 * it can't deliver, stem darkening is disabled. 124 */ 125 writing_system_class = 126 af_writing_system_classes[style_metrics->style_class->writing_system]; 127 128 if ( writing_system_class->style_metrics_getstdw ) 129 writing_system_class->style_metrics_getstdw( style_metrics, 130 &stdHW, 131 &stdVW ); 132 else 133 { 134 error = FT_ERR( Unimplemented_Feature ); 135 goto Exit; 136 } 137 138 if ( size_changed || 139 ( stdVW > 0 && stdVW != globals->standard_vertical_width ) ) 140 { 141 FT_Fixed darken_by_font_units_x, darken_x; 142 143 144 darken_by_font_units_x = 145 af_intToFixed( af_loader_compute_darkening( loader, 146 face, 147 stdVW ) ); 148 darken_x = FT_DivFix( FT_MulFix( darken_by_font_units_x, 149 size_metrics->x_scale ), 150 em_ratio ); 151 152 globals->standard_vertical_width = stdVW; 153 globals->stem_darkening_for_ppem = size_metrics->x_ppem; 154 globals->darken_x = af_fixedToInt( darken_x ); 155 } 156 157 if ( size_changed || 158 ( stdHW > 0 && stdHW != globals->standard_horizontal_width ) ) 159 { 160 FT_Fixed darken_by_font_units_y, darken_y; 161 162 163 darken_by_font_units_y = 164 af_intToFixed( af_loader_compute_darkening( loader, 165 face, 166 stdHW ) ); 167 darken_y = FT_DivFix( FT_MulFix( darken_by_font_units_y, 168 size_metrics->y_scale ), 169 em_ratio ); 170 171 globals->standard_horizontal_width = stdHW; 172 globals->stem_darkening_for_ppem = size_metrics->x_ppem; 173 globals->darken_y = af_fixedToInt( darken_y ); 174 175 /* 176 * Scale outlines down on the Y-axis to keep them inside their blue 177 * zones. The stronger the emboldening, the stronger the downscaling 178 * (plus heuristical padding to prevent outlines still falling out 179 * their zones due to rounding). 180 * 181 * Reason: `FT_Outline_Embolden' works by shifting the rightmost 182 * points of stems farther to the right, and topmost points farther 183 * up. This positions points on the Y-axis outside their 184 * pre-computed blue zones and leads to distortion when applying the 185 * hints in the code further below. Code outside this emboldening 186 * block doesn't know we are presenting it with modified outlines the 187 * analyzer didn't see! 188 * 189 * An unfortunate side effect of downscaling is that the emboldening 190 * effect is slightly decreased. The loss becomes more pronounced 191 * versus the CFF driver at smaller sizes, e.g., at 9ppem and below. 192 */ 193 globals->scale_down_factor = 194 FT_DivFix( em_size - ( darken_by_font_units_y + af_intToFixed( 8 ) ), 195 em_size ); 196 } 197 198 FT_Outline_EmboldenXY( &slot->outline, 199 globals->darken_x, 200 globals->darken_y ); 201 202 scale_down_matrix.yy = globals->scale_down_factor; 203 FT_Outline_Transform( &slot->outline, &scale_down_matrix ); 204 205 Exit: 206 return error; 207 } 208 209 210 /* Load the glyph at index into the current slot of a face and hint it. */ 211 212 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)213 af_loader_load_glyph( AF_Loader loader, 214 AF_Module module, 215 FT_Face face, 216 FT_UInt glyph_index, 217 FT_Int32 load_flags ) 218 { 219 FT_Error error; 220 221 FT_Size size = face->size; 222 FT_Size_Internal size_internal = size->internal; 223 FT_GlyphSlot slot = face->glyph; 224 FT_Slot_Internal slot_internal = slot->internal; 225 FT_GlyphLoader gloader = slot_internal->loader; 226 227 AF_GlyphHints hints = loader->hints; 228 AF_ScalerRec scaler; 229 AF_StyleMetrics style_metrics; 230 FT_UInt style_options = AF_STYLE_NONE_DFLT; 231 AF_StyleClass style_class; 232 AF_WritingSystemClass writing_system_class; 233 234 235 if ( !size ) 236 return FT_THROW( Invalid_Size_Handle ); 237 238 FT_ZERO( &scaler ); 239 240 if ( !size_internal->autohint_metrics.x_scale || 241 size_internal->autohint_mode != FT_LOAD_TARGET_MODE( load_flags ) ) 242 { 243 /* switching between hinting modes usually means different scaling */ 244 /* values; this later on enforces recomputation of everything */ 245 /* related to the current size */ 246 247 size_internal->autohint_mode = FT_LOAD_TARGET_MODE( load_flags ); 248 size_internal->autohint_metrics = size->metrics; 249 250 #ifdef AF_CONFIG_OPTION_TT_SIZE_METRICS 251 { 252 FT_Size_Metrics* size_metrics = &size_internal->autohint_metrics; 253 254 255 /* set metrics to integer values and adjust scaling accordingly; */ 256 /* this is the same setup as with TrueType fonts, cf. function */ 257 /* `tt_size_reset' in file `ttobjs.c' */ 258 size_metrics->ascender = FT_PIX_ROUND( 259 FT_MulFix( face->ascender, 260 size_metrics->y_scale ) ); 261 size_metrics->descender = FT_PIX_ROUND( 262 FT_MulFix( face->descender, 263 size_metrics->y_scale ) ); 264 size_metrics->height = FT_PIX_ROUND( 265 FT_MulFix( face->height, 266 size_metrics->y_scale ) ); 267 268 size_metrics->x_scale = FT_DivFix( size_metrics->x_ppem << 6, 269 face->units_per_EM ); 270 size_metrics->y_scale = FT_DivFix( size_metrics->y_ppem << 6, 271 face->units_per_EM ); 272 size_metrics->max_advance = FT_PIX_ROUND( 273 FT_MulFix( face->max_advance_width, 274 size_metrics->x_scale ) ); 275 } 276 #endif /* AF_CONFIG_OPTION_TT_SIZE_METRICS */ 277 } 278 279 /* 280 * TODO: This code currently doesn't support fractional advance widths, 281 * i.e., placing hinted glyphs at anything other than integer 282 * x-positions. This is only relevant for the warper code, which 283 * scales and shifts glyphs to optimize blackness of stems (hinting on 284 * the x-axis by nature places things on pixel integers, hinting on the 285 * y-axis only, i.e., LIGHT mode, doesn't touch the x-axis). The delta 286 * values of the scaler would need to be adjusted. 287 */ 288 scaler.face = face; 289 scaler.x_scale = size_internal->autohint_metrics.x_scale; 290 scaler.x_delta = 0; 291 scaler.y_scale = size_internal->autohint_metrics.y_scale; 292 scaler.y_delta = 0; 293 294 scaler.render_mode = FT_LOAD_TARGET_MODE( load_flags ); 295 scaler.flags = 0; 296 297 /* note that the fallback style can't be changed anymore */ 298 /* after the first call of `af_loader_load_glyph' */ 299 error = af_loader_reset( loader, module, face ); 300 if ( error ) 301 goto Exit; 302 303 #ifdef FT_OPTION_AUTOFIT2 304 /* XXX: undocumented hook to activate the latin2 writing system. */ 305 if ( load_flags & ( 1UL << 20 ) ) 306 style_options = AF_STYLE_LTN2_DFLT; 307 #endif 308 309 /* 310 * Glyphs (really code points) are assigned to scripts. Script 311 * analysis is done lazily: For each glyph that passes through here, 312 * the corresponding script analyzer is called, but returns immediately 313 * if it has been run already. 314 */ 315 error = af_face_globals_get_metrics( loader->globals, glyph_index, 316 style_options, &style_metrics ); 317 if ( error ) 318 goto Exit; 319 320 style_class = style_metrics->style_class; 321 writing_system_class = 322 af_writing_system_classes[style_class->writing_system]; 323 324 loader->metrics = style_metrics; 325 326 if ( writing_system_class->style_metrics_scale ) 327 writing_system_class->style_metrics_scale( style_metrics, &scaler ); 328 else 329 style_metrics->scaler = scaler; 330 331 if ( writing_system_class->style_hints_init ) 332 { 333 error = writing_system_class->style_hints_init( hints, 334 style_metrics ); 335 if ( error ) 336 goto Exit; 337 } 338 339 /* 340 * Do the main work of `af_loader_load_glyph'. Note that we never have 341 * to deal with composite glyphs as those get loaded into 342 * FT_GLYPH_FORMAT_OUTLINE by the recursed `FT_Load_Glyph' function. 343 * In the rare cases where FT_LOAD_NO_RECURSE is set, it implies 344 * FT_LOAD_NO_SCALE and as such the auto-hinter is never called. 345 */ 346 load_flags |= FT_LOAD_NO_SCALE | 347 FT_LOAD_IGNORE_TRANSFORM | 348 FT_LOAD_LINEAR_DESIGN; 349 load_flags &= ~FT_LOAD_RENDER; 350 351 error = FT_Load_Glyph( face, glyph_index, load_flags ); 352 if ( error ) 353 goto Exit; 354 355 /* 356 * Apply stem darkening (emboldening) here before hints are applied to 357 * the outline. Glyphs are scaled down proportionally to the 358 * emboldening so that curve points don't fall outside their 359 * precomputed blue zones. 360 * 361 * Any emboldening done by the font driver (e.g., the CFF driver) 362 * doesn't reach here because the autohinter loads the unprocessed 363 * glyphs in font units for analysis (functions `af_*_metrics_init_*') 364 * and then above to prepare it for the rasterizers by itself, 365 * independently of the font driver. So emboldening must be done here, 366 * within the autohinter. 367 * 368 * All glyphs to be autohinted pass through here one by one. The 369 * standard widths can therefore change from one glyph to the next, 370 * depending on what script a glyph is assigned to (each script has its 371 * own set of standard widths and other metrics). The darkening amount 372 * must therefore be recomputed for each size and 373 * `standard_{vertical,horizontal}_width' change. 374 * 375 * Ignore errors and carry on without emboldening. 376 * 377 */ 378 379 /* stem darkening only works well in `light' mode */ 380 if ( scaler.render_mode == FT_RENDER_MODE_LIGHT && 381 ( !face->internal->no_stem_darkening || 382 ( face->internal->no_stem_darkening < 0 && 383 !module->no_stem_darkening ) ) ) 384 af_loader_embolden_glyph_in_slot( loader, face, style_metrics ); 385 386 loader->transformed = slot_internal->glyph_transformed; 387 if ( loader->transformed ) 388 { 389 FT_Matrix inverse; 390 391 392 loader->trans_matrix = slot_internal->glyph_matrix; 393 loader->trans_delta = slot_internal->glyph_delta; 394 395 inverse = loader->trans_matrix; 396 if ( !FT_Matrix_Invert( &inverse ) ) 397 FT_Vector_Transform( &loader->trans_delta, &inverse ); 398 } 399 400 switch ( slot->format ) 401 { 402 case FT_GLYPH_FORMAT_OUTLINE: 403 /* translate the loaded glyph when an internal transform is needed */ 404 if ( loader->transformed ) 405 FT_Outline_Translate( &slot->outline, 406 loader->trans_delta.x, 407 loader->trans_delta.y ); 408 409 /* compute original horizontal phantom points */ 410 /* (and ignore vertical ones) */ 411 loader->pp1.x = hints->x_delta; 412 loader->pp1.y = hints->y_delta; 413 loader->pp2.x = FT_MulFix( slot->metrics.horiAdvance, 414 hints->x_scale ) + hints->x_delta; 415 loader->pp2.y = hints->y_delta; 416 417 /* be sure to check for spacing glyphs */ 418 if ( slot->outline.n_points == 0 ) 419 goto Hint_Metrics; 420 421 /* now load the slot image into the auto-outline */ 422 /* and run the automatic hinting process */ 423 if ( writing_system_class->style_hints_apply ) 424 { 425 error = writing_system_class->style_hints_apply( 426 glyph_index, 427 hints, 428 &gloader->base.outline, 429 style_metrics ); 430 if ( error ) 431 goto Exit; 432 } 433 434 /* we now need to adjust the metrics according to the change in */ 435 /* width/positioning that occurred during the hinting process */ 436 if ( scaler.render_mode != FT_RENDER_MODE_LIGHT ) 437 { 438 AF_AxisHints axis = &hints->axis[AF_DIMENSION_HORZ]; 439 440 441 if ( axis->num_edges > 1 && AF_HINTS_DO_ADVANCE( hints ) ) 442 { 443 AF_Edge edge1 = axis->edges; /* leftmost edge */ 444 AF_Edge edge2 = edge1 + 445 axis->num_edges - 1; /* rightmost edge */ 446 447 FT_Pos old_rsb = loader->pp2.x - edge2->opos; 448 /* loader->pp1.x is always zero at this point of time */ 449 FT_Pos old_lsb = edge1->opos; /* - loader->pp1.x */ 450 FT_Pos new_lsb = edge1->pos; 451 452 /* remember unhinted values to later account */ 453 /* for rounding errors */ 454 FT_Pos pp1x_uh = new_lsb - old_lsb; 455 FT_Pos pp2x_uh = edge2->pos + old_rsb; 456 457 458 /* prefer too much space over too little space */ 459 /* for very small sizes */ 460 461 if ( old_lsb < 24 ) 462 pp1x_uh -= 8; 463 464 if ( old_rsb < 24 ) 465 pp2x_uh += 8; 466 467 loader->pp1.x = FT_PIX_ROUND( pp1x_uh ); 468 loader->pp2.x = FT_PIX_ROUND( pp2x_uh ); 469 470 if ( loader->pp1.x >= new_lsb && old_lsb > 0 ) 471 loader->pp1.x -= 64; 472 473 if ( loader->pp2.x <= edge2->pos && old_rsb > 0 ) 474 loader->pp2.x += 64; 475 476 slot->lsb_delta = loader->pp1.x - pp1x_uh; 477 slot->rsb_delta = loader->pp2.x - pp2x_uh; 478 } 479 else 480 { 481 FT_Pos pp1x = loader->pp1.x; 482 FT_Pos pp2x = loader->pp2.x; 483 484 485 loader->pp1.x = FT_PIX_ROUND( pp1x + hints->xmin_delta ); 486 loader->pp2.x = FT_PIX_ROUND( pp2x + hints->xmax_delta ); 487 488 slot->lsb_delta = loader->pp1.x - pp1x; 489 slot->rsb_delta = loader->pp2.x - pp2x; 490 } 491 } 492 /* `light' mode uses integer advance widths */ 493 /* but sets `lsb_delta' and `rsb_delta' */ 494 else 495 { 496 FT_Pos pp1x = loader->pp1.x; 497 FT_Pos pp2x = loader->pp2.x; 498 499 500 loader->pp1.x = FT_PIX_ROUND( pp1x ); 501 loader->pp2.x = FT_PIX_ROUND( pp2x ); 502 503 slot->lsb_delta = loader->pp1.x - pp1x; 504 slot->rsb_delta = loader->pp2.x - pp2x; 505 } 506 507 break; 508 509 default: 510 /* we don't support other formats (yet?) */ 511 error = FT_THROW( Unimplemented_Feature ); 512 } 513 514 Hint_Metrics: 515 { 516 FT_BBox bbox; 517 FT_Vector vvector; 518 519 520 vvector.x = slot->metrics.vertBearingX - slot->metrics.horiBearingX; 521 vvector.y = slot->metrics.vertBearingY - slot->metrics.horiBearingY; 522 vvector.x = FT_MulFix( vvector.x, style_metrics->scaler.x_scale ); 523 vvector.y = FT_MulFix( vvector.y, style_metrics->scaler.y_scale ); 524 525 /* transform the hinted outline if needed */ 526 if ( loader->transformed ) 527 { 528 FT_Outline_Transform( &gloader->base.outline, &loader->trans_matrix ); 529 FT_Vector_Transform( &vvector, &loader->trans_matrix ); 530 } 531 532 /* we must translate our final outline by -pp1.x and compute */ 533 /* the new metrics */ 534 if ( loader->pp1.x ) 535 FT_Outline_Translate( &gloader->base.outline, -loader->pp1.x, 0 ); 536 537 FT_Outline_Get_CBox( &gloader->base.outline, &bbox ); 538 539 bbox.xMin = FT_PIX_FLOOR( bbox.xMin ); 540 bbox.yMin = FT_PIX_FLOOR( bbox.yMin ); 541 bbox.xMax = FT_PIX_CEIL( bbox.xMax ); 542 bbox.yMax = FT_PIX_CEIL( bbox.yMax ); 543 544 slot->metrics.width = bbox.xMax - bbox.xMin; 545 slot->metrics.height = bbox.yMax - bbox.yMin; 546 slot->metrics.horiBearingX = bbox.xMin; 547 slot->metrics.horiBearingY = bbox.yMax; 548 549 slot->metrics.vertBearingX = FT_PIX_FLOOR( bbox.xMin + vvector.x ); 550 slot->metrics.vertBearingY = FT_PIX_FLOOR( bbox.yMax + vvector.y ); 551 552 /* for mono-width fonts (like Andale, Courier, etc.) we need */ 553 /* to keep the original rounded advance width; ditto for */ 554 /* digits if all have the same advance width */ 555 if ( scaler.render_mode != FT_RENDER_MODE_LIGHT && 556 ( FT_IS_FIXED_WIDTH( slot->face ) || 557 ( af_face_globals_is_digit( loader->globals, glyph_index ) && 558 style_metrics->digits_have_same_width ) ) ) 559 { 560 slot->metrics.horiAdvance = 561 FT_MulFix( slot->metrics.horiAdvance, 562 style_metrics->scaler.x_scale ); 563 564 /* Set delta values to 0. Otherwise code that uses them is */ 565 /* going to ruin the fixed advance width. */ 566 slot->lsb_delta = 0; 567 slot->rsb_delta = 0; 568 } 569 else 570 { 571 /* non-spacing glyphs must stay as-is */ 572 if ( slot->metrics.horiAdvance ) 573 slot->metrics.horiAdvance = loader->pp2.x - loader->pp1.x; 574 } 575 576 slot->metrics.vertAdvance = FT_MulFix( slot->metrics.vertAdvance, 577 style_metrics->scaler.y_scale ); 578 579 slot->metrics.horiAdvance = FT_PIX_ROUND( slot->metrics.horiAdvance ); 580 slot->metrics.vertAdvance = FT_PIX_ROUND( slot->metrics.vertAdvance ); 581 582 slot->format = FT_GLYPH_FORMAT_OUTLINE; 583 } 584 585 Exit: 586 return error; 587 } 588 589 590 /* 591 * Compute amount of font units the face should be emboldened by, in 592 * analogy to the CFF driver's `cf2_computeDarkening' function. See there 593 * for details of the algorithm. 594 * 595 * XXX: Currently a crude adaption of the original algorithm. Do better? 596 */ 597 FT_LOCAL_DEF( FT_Int32 ) af_loader_compute_darkening(AF_Loader loader,FT_Face face,FT_Pos standard_width)598 af_loader_compute_darkening( AF_Loader loader, 599 FT_Face face, 600 FT_Pos standard_width ) 601 { 602 AF_Module module = loader->globals->module; 603 604 FT_UShort units_per_EM; 605 FT_Fixed ppem, em_ratio; 606 FT_Fixed stem_width, stem_width_per_1000, scaled_stem, darken_amount; 607 FT_Int log_base_2; 608 FT_Int x1, y1, x2, y2, x3, y3, x4, y4; 609 610 611 ppem = FT_MAX( af_intToFixed( 4 ), 612 af_intToFixed( face->size->metrics.x_ppem ) ); 613 units_per_EM = face->units_per_EM; 614 615 em_ratio = FT_DivFix( af_intToFixed( 1000 ), 616 af_intToFixed ( units_per_EM ) ); 617 if ( em_ratio < af_floatToFixed( .01 ) ) 618 { 619 /* If something goes wrong, don't embolden. */ 620 return 0; 621 } 622 623 x1 = module->darken_params[0]; 624 y1 = module->darken_params[1]; 625 x2 = module->darken_params[2]; 626 y2 = module->darken_params[3]; 627 x3 = module->darken_params[4]; 628 y3 = module->darken_params[5]; 629 x4 = module->darken_params[6]; 630 y4 = module->darken_params[7]; 631 632 if ( standard_width <= 0 ) 633 { 634 stem_width = af_intToFixed( 75 ); /* taken from cf2font.c */ 635 stem_width_per_1000 = stem_width; 636 } 637 else 638 { 639 stem_width = af_intToFixed( standard_width ); 640 stem_width_per_1000 = FT_MulFix( stem_width, em_ratio ); 641 } 642 643 log_base_2 = FT_MSB( (FT_UInt32)stem_width_per_1000 ) + 644 FT_MSB( (FT_UInt32)ppem ); 645 646 if ( log_base_2 >= 46 ) 647 { 648 /* possible overflow */ 649 scaled_stem = af_intToFixed( x4 ); 650 } 651 else 652 scaled_stem = FT_MulFix( stem_width_per_1000, ppem ); 653 654 /* now apply the darkening parameters */ 655 if ( scaled_stem < af_intToFixed( x1 ) ) 656 darken_amount = FT_DivFix( af_intToFixed( y1 ), ppem ); 657 658 else if ( scaled_stem < af_intToFixed( x2 ) ) 659 { 660 FT_Int xdelta = x2 - x1; 661 FT_Int ydelta = y2 - y1; 662 FT_Int x = stem_width_per_1000 - 663 FT_DivFix( af_intToFixed( x1 ), ppem ); 664 665 666 if ( !xdelta ) 667 goto Try_x3; 668 669 darken_amount = FT_MulDiv( x, ydelta, xdelta ) + 670 FT_DivFix( af_intToFixed( y1 ), ppem ); 671 } 672 673 else if ( scaled_stem < af_intToFixed( x3 ) ) 674 { 675 Try_x3: 676 { 677 FT_Int xdelta = x3 - x2; 678 FT_Int ydelta = y3 - y2; 679 FT_Int x = stem_width_per_1000 - 680 FT_DivFix( af_intToFixed( x2 ), ppem ); 681 682 683 if ( !xdelta ) 684 goto Try_x4; 685 686 darken_amount = FT_MulDiv( x, ydelta, xdelta ) + 687 FT_DivFix( af_intToFixed( y2 ), ppem ); 688 } 689 } 690 691 else if ( scaled_stem < af_intToFixed( x4 ) ) 692 { 693 Try_x4: 694 { 695 FT_Int xdelta = x4 - x3; 696 FT_Int ydelta = y4 - y3; 697 FT_Int x = stem_width_per_1000 - 698 FT_DivFix( af_intToFixed( x3 ), ppem ); 699 700 701 if ( !xdelta ) 702 goto Use_y4; 703 704 darken_amount = FT_MulDiv( x, ydelta, xdelta ) + 705 FT_DivFix( af_intToFixed( y3 ), ppem ); 706 } 707 } 708 709 else 710 { 711 Use_y4: 712 darken_amount = FT_DivFix( af_intToFixed( y4 ), ppem ); 713 } 714 715 /* Convert darken_amount from per 1000 em to true character space. */ 716 return af_fixedToInt( FT_DivFix( darken_amount, em_ratio ) ); 717 } 718 719 720 /* END */ 721