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97            FreeType-2.12.1 API Reference
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100        <div class="md-header__topic" data-md-component="header-topic">
101          <span class="md-ellipsis">
102
103              External Debugging APIs
104
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108    </div>
109
110
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133            Initializing search
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168    </a>
169    FreeType-2.12.1 API Reference
170  </label>
171
172  <ul class="md-nav__list" data-md-scrollfix>
173
174
175
176
177
178
179
180
181    <li class="md-nav__item">
182      <a href="index.html" class="md-nav__link">
183        TOC
184      </a>
185    </li>
186
187
188
189
190
191
192
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194
195
196    <li class="md-nav__item">
197      <a href="ft2-index.html" class="md-nav__link">
198        Index
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202
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207
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209
210
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217      <label class="md-nav__link" for="__nav_3">
218        General Remarks
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220      </label>
221      <nav class="md-nav" aria-label="General Remarks" data-md-level="1">
222        <label class="md-nav__title" for="__nav_3">
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224          General Remarks
225        </label>
226        <ul class="md-nav__list" data-md-scrollfix>
227
228
229
230
231
232    <li class="md-nav__item">
233      <a href="ft2-preamble.html" class="md-nav__link">
234        Preamble
235      </a>
236    </li>
237
238
239
240
241
242
243
244    <li class="md-nav__item">
245      <a href="ft2-header_inclusion.html" class="md-nav__link">
246        FreeType's header inclusion scheme
247      </a>
248    </li>
249
250
251
252
253
254
255
256    <li class="md-nav__item">
257      <a href="ft2-user_allocation.html" class="md-nav__link">
258        User allocation
259      </a>
260    </li>
261
262
263
264        </ul>
265      </nav>
266    </li>
267
268
269
270
271
272
273
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280
281        <input class="md-nav__toggle md-toggle" data-md-toggle="__nav_4" type="checkbox" id="__nav_4" >
282
283      <label class="md-nav__link" for="__nav_4">
284        Core API
285        <span class="md-nav__icon md-icon"></span>
286      </label>
287      <nav class="md-nav" aria-label="Core API" data-md-level="1">
288        <label class="md-nav__title" for="__nav_4">
289          <span class="md-nav__icon md-icon"></span>
290          Core API
291        </label>
292        <ul class="md-nav__list" data-md-scrollfix>
293
294
295
296
297
298    <li class="md-nav__item">
299      <a href="ft2-version.html" class="md-nav__link">
300        FreeType Version
301      </a>
302    </li>
303
304
305
306
307
308
309
310    <li class="md-nav__item">
311      <a href="ft2-basic_types.html" class="md-nav__link">
312        Basic Data Types
313      </a>
314    </li>
315
316
317
318
319
320
321
322    <li class="md-nav__item">
323      <a href="ft2-base_interface.html" class="md-nav__link">
324        Base Interface
325      </a>
326    </li>
327
328
329
330
331
332
333
334    <li class="md-nav__item">
335      <a href="ft2-glyph_variants.html" class="md-nav__link">
336        Unicode Variation Sequences
337      </a>
338    </li>
339
340
341
342
343
344
345
346    <li class="md-nav__item">
347      <a href="ft2-color_management.html" class="md-nav__link">
348        Glyph Color Management
349      </a>
350    </li>
351
352
353
354
355
356
357
358    <li class="md-nav__item">
359      <a href="ft2-layer_management.html" class="md-nav__link">
360        Glyph Layer Management
361      </a>
362    </li>
363
364
365
366
367
368
369
370    <li class="md-nav__item">
371      <a href="ft2-glyph_management.html" class="md-nav__link">
372        Glyph Management
373      </a>
374    </li>
375
376
377
378
379
380
381
382    <li class="md-nav__item">
383      <a href="ft2-mac_specific.html" class="md-nav__link">
384        Mac Specific Interface
385      </a>
386    </li>
387
388
389
390
391
392
393
394    <li class="md-nav__item">
395      <a href="ft2-sizes_management.html" class="md-nav__link">
396        Size Management
397      </a>
398    </li>
399
400
401
402
403
404
405
406    <li class="md-nav__item">
407      <a href="ft2-header_file_macros.html" class="md-nav__link">
408        Header File Macros
409      </a>
410    </li>
411
412
413
414        </ul>
415      </nav>
416    </li>
417
418
419
420
421
422
423
424
425
426
427
428    <li class="md-nav__item md-nav__item--nested">
429
430
431        <input class="md-nav__toggle md-toggle" data-md-toggle="__nav_5" type="checkbox" id="__nav_5" >
432
433      <label class="md-nav__link" for="__nav_5">
434        Format-Specific API
435        <span class="md-nav__icon md-icon"></span>
436      </label>
437      <nav class="md-nav" aria-label="Format-Specific API" data-md-level="1">
438        <label class="md-nav__title" for="__nav_5">
439          <span class="md-nav__icon md-icon"></span>
440          Format-Specific API
441        </label>
442        <ul class="md-nav__list" data-md-scrollfix>
443
444
445
446
447
448    <li class="md-nav__item">
449      <a href="ft2-multiple_masters.html" class="md-nav__link">
450        Multiple Masters
451      </a>
452    </li>
453
454
455
456
457
458
459
460    <li class="md-nav__item">
461      <a href="ft2-truetype_tables.html" class="md-nav__link">
462        TrueType Tables
463      </a>
464    </li>
465
466
467
468
469
470
471
472    <li class="md-nav__item">
473      <a href="ft2-type1_tables.html" class="md-nav__link">
474        Type 1 Tables
475      </a>
476    </li>
477
478
479
480
481
482
483
484    <li class="md-nav__item">
485      <a href="ft2-sfnt_names.html" class="md-nav__link">
486        SFNT Names
487      </a>
488    </li>
489
490
491
492
493
494
495
496    <li class="md-nav__item">
497      <a href="ft2-bdf_fonts.html" class="md-nav__link">
498        BDF and PCF Files
499      </a>
500    </li>
501
502
503
504
505
506
507
508    <li class="md-nav__item">
509      <a href="ft2-cid_fonts.html" class="md-nav__link">
510        CID Fonts
511      </a>
512    </li>
513
514
515
516
517
518
519
520    <li class="md-nav__item">
521      <a href="ft2-pfr_fonts.html" class="md-nav__link">
522        PFR Fonts
523      </a>
524    </li>
525
526
527
528
529
530
531
532    <li class="md-nav__item">
533      <a href="ft2-winfnt_fonts.html" class="md-nav__link">
534        Window FNT Files
535      </a>
536    </li>
537
538
539
540
541
542
543
544    <li class="md-nav__item">
545      <a href="ft2-svg_fonts.html" class="md-nav__link">
546        OpenType SVG Fonts
547      </a>
548    </li>
549
550
551
552
553
554
555
556    <li class="md-nav__item">
557      <a href="ft2-font_formats.html" class="md-nav__link">
558        Font Formats
559      </a>
560    </li>
561
562
563
564
565
566
567
568    <li class="md-nav__item">
569      <a href="ft2-gasp_table.html" class="md-nav__link">
570        Gasp Table
571      </a>
572    </li>
573
574
575
576        </ul>
577      </nav>
578    </li>
579
580
581
582
583
584
585
586
587
588
589
590    <li class="md-nav__item md-nav__item--nested">
591
592
593        <input class="md-nav__toggle md-toggle" data-md-toggle="__nav_6" type="checkbox" id="__nav_6" >
594
595      <label class="md-nav__link" for="__nav_6">
596        Controlling FreeType Modules
597        <span class="md-nav__icon md-icon"></span>
598      </label>
599      <nav class="md-nav" aria-label="Controlling FreeType Modules" data-md-level="1">
600        <label class="md-nav__title" for="__nav_6">
601          <span class="md-nav__icon md-icon"></span>
602          Controlling FreeType Modules
603        </label>
604        <ul class="md-nav__list" data-md-scrollfix>
605
606
607
608
609
610    <li class="md-nav__item">
611      <a href="ft2-auto_hinter.html" class="md-nav__link">
612        The auto-hinter
613      </a>
614    </li>
615
616
617
618
619
620
621
622    <li class="md-nav__item">
623      <a href="ft2-cff_driver.html" class="md-nav__link">
624        The CFF driver
625      </a>
626    </li>
627
628
629
630
631
632
633
634    <li class="md-nav__item">
635      <a href="ft2-t1_cid_driver.html" class="md-nav__link">
636        The Type 1 and CID drivers
637      </a>
638    </li>
639
640
641
642
643
644
645
646    <li class="md-nav__item">
647      <a href="ft2-tt_driver.html" class="md-nav__link">
648        The TrueType driver
649      </a>
650    </li>
651
652
653
654
655
656
657
658    <li class="md-nav__item">
659      <a href="ft2-pcf_driver.html" class="md-nav__link">
660        The PCF driver
661      </a>
662    </li>
663
664
665
666
667
668
669
670    <li class="md-nav__item">
671      <a href="ft2-ot_svg_driver.html" class="md-nav__link">
672        The SVG driver
673      </a>
674    </li>
675
676
677
678
679
680
681
682    <li class="md-nav__item">
683      <a href="ft2-properties.html" class="md-nav__link">
684        Driver properties
685      </a>
686    </li>
687
688
689
690
691
692
693
694    <li class="md-nav__item">
695      <a href="ft2-parameter_tags.html" class="md-nav__link">
696        Parameter Tags
697      </a>
698    </li>
699
700
701
702
703
704
705
706    <li class="md-nav__item">
707      <a href="ft2-lcd_rendering.html" class="md-nav__link">
708        Subpixel Rendering
709      </a>
710    </li>
711
712
713
714        </ul>
715      </nav>
716    </li>
717
718
719
720
721
722
723
724
725
726
727
728    <li class="md-nav__item md-nav__item--nested">
729
730
731        <input class="md-nav__toggle md-toggle" data-md-toggle="__nav_7" type="checkbox" id="__nav_7" >
732
733      <label class="md-nav__link" for="__nav_7">
734        Cache Sub-System
735        <span class="md-nav__icon md-icon"></span>
736      </label>
737      <nav class="md-nav" aria-label="Cache Sub-System" data-md-level="1">
738        <label class="md-nav__title" for="__nav_7">
739          <span class="md-nav__icon md-icon"></span>
740          Cache Sub-System
741        </label>
742        <ul class="md-nav__list" data-md-scrollfix>
743
744
745
746
747
748    <li class="md-nav__item">
749      <a href="ft2-cache_subsystem.html" class="md-nav__link">
750        Cache Sub-System
751      </a>
752    </li>
753
754
755
756        </ul>
757      </nav>
758    </li>
759
760
761
762
763
764
765
766
767
768
769
770
771
772    <li class="md-nav__item md-nav__item--active md-nav__item--nested">
773
774
775        <input class="md-nav__toggle md-toggle" data-md-toggle="__nav_8" type="checkbox" id="__nav_8" checked>
776
777      <label class="md-nav__link" for="__nav_8">
778        Support API
779        <span class="md-nav__icon md-icon"></span>
780      </label>
781      <nav class="md-nav" aria-label="Support API" data-md-level="1">
782        <label class="md-nav__title" for="__nav_8">
783          <span class="md-nav__icon md-icon"></span>
784          Support API
785        </label>
786        <ul class="md-nav__list" data-md-scrollfix>
787
788
789
790
791
792    <li class="md-nav__item">
793      <a href="ft2-computations.html" class="md-nav__link">
794        Computations
795      </a>
796    </li>
797
798
799
800
801
802
803
804    <li class="md-nav__item">
805      <a href="ft2-list_processing.html" class="md-nav__link">
806        List Processing
807      </a>
808    </li>
809
810
811
812
813
814
815
816    <li class="md-nav__item">
817      <a href="ft2-outline_processing.html" class="md-nav__link">
818        Outline Processing
819      </a>
820    </li>
821
822
823
824
825
826
827
828    <li class="md-nav__item">
829      <a href="ft2-quick_advance.html" class="md-nav__link">
830        Quick retrieval of advance values
831      </a>
832    </li>
833
834
835
836
837
838
839
840    <li class="md-nav__item">
841      <a href="ft2-bitmap_handling.html" class="md-nav__link">
842        Bitmap Handling
843      </a>
844    </li>
845
846
847
848
849
850
851
852    <li class="md-nav__item">
853      <a href="ft2-raster.html" class="md-nav__link">
854        Scanline Converter
855      </a>
856    </li>
857
858
859
860
861
862
863
864    <li class="md-nav__item">
865      <a href="ft2-glyph_stroker.html" class="md-nav__link">
866        Glyph Stroker
867      </a>
868    </li>
869
870
871
872
873
874
875
876    <li class="md-nav__item">
877      <a href="ft2-system_interface.html" class="md-nav__link">
878        System Interface
879      </a>
880    </li>
881
882
883
884
885
886
887
888    <li class="md-nav__item">
889      <a href="ft2-module_management.html" class="md-nav__link">
890        Module Management
891      </a>
892    </li>
893
894
895
896
897
898
899
900    <li class="md-nav__item">
901      <a href="ft2-gzip.html" class="md-nav__link">
902        GZIP Streams
903      </a>
904    </li>
905
906
907
908
909
910
911
912    <li class="md-nav__item">
913      <a href="ft2-lzw.html" class="md-nav__link">
914        LZW Streams
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971    Synopsis
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973
974</li>
975
976        <li class="md-nav__item">
977  <a href="#ft_trace_set_level" class="md-nav__link">
978    FT_Trace_Set_Level
979  </a>
980
981</li>
982
983        <li class="md-nav__item">
984  <a href="#ft_trace_set_default_level" class="md-nav__link">
985    FT_Trace_Set_Default_Level
986  </a>
987
988</li>
989
990        <li class="md-nav__item">
991  <a href="#ft_custom_log_handler" class="md-nav__link">
992    FT_Custom_Log_Handler
993  </a>
994
995</li>
996
997        <li class="md-nav__item">
998  <a href="#ft_set_log_handler" class="md-nav__link">
999    FT_Set_Log_Handler
1000  </a>
1001
1002</li>
1003
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1005  <a href="#ft_set_default_log_handler" class="md-nav__link">
1006    FT_Set_Default_Log_Handler
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1184    Synopsis
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1186
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1189        <li class="md-nav__item">
1190  <a href="#ft_trace_set_level" class="md-nav__link">
1191    FT_Trace_Set_Level
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1193
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1195
1196        <li class="md-nav__item">
1197  <a href="#ft_trace_set_default_level" class="md-nav__link">
1198    FT_Trace_Set_Default_Level
1199  </a>
1200
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1204  <a href="#ft_custom_log_handler" class="md-nav__link">
1205    FT_Custom_Log_Handler
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1207
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1209
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1211  <a href="#ft_set_log_handler" class="md-nav__link">
1212    FT_Set_Log_Handler
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1214
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1216
1217        <li class="md-nav__item">
1218  <a href="#ft_set_default_log_handler" class="md-nav__link">
1219    FT_Set_Default_Log_Handler
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1234
1235
1236
1237                <p><a href="https://www.freetype.org">FreeType</a> &raquo; <a href="../">Docs</a> &raquo; <a href="index.html#support-api">Support API</a> &raquo; External Debugging APIs</p>
1238<hr />
1239<h1 id="external-debugging-apis">External Debugging APIs<a class="headerlink" href="#external-debugging-apis" title="Permanent link">&para;</a></h1>
1240<h2 id="synopsis">Synopsis<a class="headerlink" href="#synopsis" title="Permanent link">&para;</a></h2>
1241<p>This section contains the declarations of public functions that enables fine control of what the <code>FT_DEBUG_LOGGING</code> macro outputs.</p>
1242<h2 id="ft_trace_set_level">FT_Trace_Set_Level<a class="headerlink" href="#ft_trace_set_level" title="Permanent link">&para;</a></h2>
1243<div class = "codehilite"><pre><code>  FT_EXPORT( <span class="keyword">void</span> )
1244  <b>FT_Trace_Set_Level</b>( <span class="keyword">const</span> <span class="keyword">char</span>*  tracing_level );
1245</code></pre></div>
1246
1247<p>Change the levels of tracing components of FreeType at run time.</p>
1248<h4>input</h4>
1249<table class="fields">
1250<tr><td class="val" id="tracing_level">tracing_level</td><td class="desc">
1251<p>New tracing value.</p>
1252</td></tr>
1253</table>
1254
1255<h4>example</h4>
1256
1257<p>The following call makes FreeType trace everything but the &lsquo;memory&rsquo; component.
1258<div class="highlight"><pre><span></span><code>FT_Trace_Set_Level( &quot;any:7 memory:0 );
1259</code></pre></div></p>
1260<h4>note</h4>
1261
1262<p>This function does nothing if compilation option <code>FT_DEBUG_LOGGING</code> isn't set.</p>
1263<h4>since</h4>
1264
1265<p>2.11</p>
1266<hr>
1267
1268<h2 id="ft_trace_set_default_level">FT_Trace_Set_Default_Level<a class="headerlink" href="#ft_trace_set_default_level" title="Permanent link">&para;</a></h2>
1269<div class = "codehilite"><pre><code>  FT_EXPORT( <span class="keyword">void</span> )
1270  <b>FT_Trace_Set_Default_Level</b>( <span class="keyword">void</span> );
1271</code></pre></div>
1272
1273<p>Reset tracing value of FreeType's components to the default value (i.e., to the value of the <code>FT2_DEBUG</code> environment value or to NULL if <code>FT2_DEBUG</code> is not set).</p>
1274<h4>note</h4>
1275
1276<p>This function does nothing if compilation option <code>FT_DEBUG_LOGGING</code> isn't set.</p>
1277<h4>since</h4>
1278
1279<p>2.11</p>
1280<hr>
1281
1282<h2 id="ft_custom_log_handler">FT_Custom_Log_Handler<a class="headerlink" href="#ft_custom_log_handler" title="Permanent link">&para;</a></h2>
1283<div class = "codehilite"><pre><code>  <span class="keyword">typedef</span> <span class="keyword">void</span>
1284  (*<b>FT_Custom_Log_Handler</b>)( <span class="keyword">const</span> <span class="keyword">char</span>*  ft_component,
1285                            <span class="keyword">const</span> <span class="keyword">char</span>*  fmt,
1286                            va_list      args );
1287</code></pre></div>
1288
1289<p>A function typedef that is used to handle the logging of tracing and debug messages on a file system.</p>
1290<h4>input</h4>
1291<table class="fields">
1292<tr><td class="val" id="ft_component">ft_component</td><td class="desc">
1293<p>The name of <code>FT_COMPONENT</code> from which the current debug or error message is produced.</p>
1294</td></tr>
1295<tr><td class="val" id="fmt">fmt</td><td class="desc">
1296<p>Actual debug or tracing message.</p>
1297</td></tr>
1298<tr><td class="val" id="args">args</td><td class="desc">
1299<p>Arguments of debug or tracing messages.</p>
1300</td></tr>
1301</table>
1302
1303<h4>since</h4>
1304
1305<p>2.11</p>
1306<hr>
1307
1308<h2 id="ft_set_log_handler">FT_Set_Log_Handler<a class="headerlink" href="#ft_set_log_handler" title="Permanent link">&para;</a></h2>
1309<div class = "codehilite"><pre><code>  FT_EXPORT( <span class="keyword">void</span> )
1310  <b>FT_Set_Log_Handler</b>( <a href="ft2-debugging_apis.html#ft_custom_log_handler">FT_Custom_Log_Handler</a>  handler );
1311</code></pre></div>
1312
1313<p>A function to set a custom log handler.</p>
1314<h4>input</h4>
1315<table class="fields">
1316<tr><td class="val" id="handler">handler</td><td class="desc">
1317<p>New logging function.</p>
1318</td></tr>
1319</table>
1320
1321<h4>note</h4>
1322
1323<p>This function does nothing if compilation option <code>FT_DEBUG_LOGGING</code> isn't set.</p>
1324<h4>since</h4>
1325
1326<p>2.11</p>
1327<hr>
1328
1329<h2 id="ft_set_default_log_handler">FT_Set_Default_Log_Handler<a class="headerlink" href="#ft_set_default_log_handler" title="Permanent link">&para;</a></h2>
1330<div class = "codehilite"><pre><code>  FT_EXPORT( <span class="keyword">void</span> )
1331  <b>FT_Set_Default_Log_Handler</b>( <span class="keyword">void</span> );
1332</code></pre></div>
1333
1334<p>A function to undo the effect of <code><a href="ft2-debugging_apis.html#ft_set_log_handler">FT_Set_Log_Handler</a></code>, resetting the log handler to FreeType's built-in version.</p>
1335<h4>note</h4>
1336
1337<p>This function does nothing if compilation option <code>FT_DEBUG_LOGGING</code> isn't set.</p>
1338<h4>since</h4>
1339
1340<p>2.11</p>
1341<hr>
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