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Prevent hinting if there are too many segments.

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This speeds up handling of broken glyphs.

Reported as

  https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=35309

* src/autofit/aflatin.c (af_latin_hints_compute_segments): Implement
it.
This commit is contained in:
Werner Lemberg 2021-06-19 06:32:29 +02:00
parent 61bac75963
commit 232243e749
2 changed files with 38 additions and 0 deletions
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13
ChangeLog
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@ -1,3 +1,16 @@
2021-06-19 Werner Lemberg <david@freetype.org>
[autofit] Prevent hinting if there are too many segments.
This speeds up handling of broken glyphs.
Reported as
https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=35309
* src/autofit/aflatin.c (af_latin_hints_compute_segments): Implement
it.
2021-06-18 Alexei Podtelezhnikov <apodtele@gmail.com>
* src/sdf/ftsdfrend.c (ft_(b)sdf_render): Do not FT_ERROR routinely.

25
src/autofit/aflatin.c
View File

@ -1847,6 +1847,31 @@
( FT_ABS( point->out_dir ) == major_dir ||
point == point->prev ) )
{
/*
* For efficiency, we restrict the number of segments to 1000,
* which is a heuristic value: it is very unlikely that a glyph
* with so many segments can be hinted in a sensible way.
* Reasons:
*
* - The glyph has really 1000 segments; this implies that it has
* at least 2000 outline points. Assuming 'normal' fonts that
* have superfluous points optimized away, viewing such a glyph
* only makes sense at large magnifications where hinting
* isn't applied anyway.
*
* - We have a broken glyph. Hinting doesn't make sense in this
* case either.
*/
if ( axis->num_segments > 1000 )
{
FT_TRACE0(( "af_latin_hints_compute_segments:"
" more than 1000 segments in this glyph;\n" ));
FT_TRACE0(( " "
" hinting is suppressed\n" ));
axis->num_segments = 0;
return FT_Err_Ok;
}
/* this is the start of a new segment! */
segment_dir = (AF_Direction)point->out_dir;