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[autofit] Don't distort (latin) glyphs too much (#46195).

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* src/autofit/aflatin.h (AF_LatinBlueRec): Add `ascender' and
`descender' fields.

* src/autofit/aflatin.c (af_latin_metrics_init_blues): Collect
ascender and descender data for blue zones.
(af_latin_metrics_scale_dim): Reject vertical scaling values that
change the result by more than two pixels.
This commit is contained in:
Philipp Knechtges 2015-11-08 08:37:51 +01:00 committed by Werner Lemberg
parent 7363414b9d
commit be32b168ac
3 changed files with 76 additions and 11 deletions
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12
ChangeLog
View File

@ -1,3 +1,15 @@
2015-11-06 Philipp Knechtges <philipp-dev@knechtges.com>
[autofit] Don't distort (latin) glyphs too much (#46195).
* src/autofit/aflatin.h (AF_LatinBlueRec): Add `ascender' and
`descender' fields.
* src/autofit/aflatin.c (af_latin_metrics_init_blues): Collect
ascender and descender data for blue zones.
(af_latin_metrics_scale_dim): Reject vertical scaling values that
change the result by more than two pixels.
2015-11-05 Werner Lemberg <wl@gnu.org>
[sfnt] Ignore embedded bitmaps with zero size (#46379).

73
src/autofit/aflatin.c
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@ -293,6 +293,8 @@
const char* p = &af_blue_strings[bs->string];
FT_Pos* blue_ref;
FT_Pos* blue_shoot;
FT_Pos ascender;
FT_Pos descender;
#ifdef FT_DEBUG_LEVEL_TRACE
@ -344,6 +346,8 @@
num_flats = 0;
num_rounds = 0;
ascender = 0;
descender = 0;
while ( *p )
{
@ -405,20 +409,30 @@
if ( AF_LATIN_IS_TOP_BLUE( bs ) )
{
for ( pp = first; pp <= last; pp++ )
{
if ( best_point < 0 || points[pp].y > best_y )
{
best_point = pp;
best_y = points[pp].y;
ascender = FT_MAX( ascender, best_y + y_offset );
}
else
descender = FT_MIN( descender, points[pp].y + y_offset );
}
}
else
{
for ( pp = first; pp <= last; pp++ )
{
if ( best_point < 0 || points[pp].y < best_y )
{
best_point = pp;
best_y = points[pp].y;
descender = FT_MIN( descender, best_y + y_offset );
}
else
ascender = FT_MAX( ascender, points[pp].y + y_offset );
}
}
if ( best_point != old_best_point )
@ -791,6 +805,9 @@
}
}
blue->ascender = ascender;
blue->descender = descender;
blue->flags = 0;
if ( AF_LATIN_IS_TOP_BLUE( bs ) )
blue->flags |= AF_LATIN_BLUE_TOP;
@ -973,18 +990,52 @@
#endif
if ( dim == AF_DIMENSION_VERT )
{
scale = FT_MulDiv( scale, fitted, scaled );
FT_Pos max_height;
FT_Pos dist;
FT_Fixed new_scale;
FT_TRACE5((
"af_latin_metrics_scale_dim:"
" x height alignment (style `%s'):\n"
" "
" vertical scaling changed from %.4f to %.4f (by %d%%)\n"
"\n",
af_style_names[metrics->root.style_class->style],
axis->org_scale / 65536.0,
scale / 65536.0,
( fitted - scaled ) * 100 / scaled ));
new_scale = FT_MulDiv( scale, fitted, scaled );
/* the scaling should not change the result by more than two pixels */
max_height = metrics->units_per_em;
for ( nn = 0; nn < Axis->blue_count; nn++ )
{
max_height = FT_MAX( max_height, Axis->blues[nn].ascender );
max_height = FT_MAX( max_height, -Axis->blues[nn].descender );
}
dist = FT_ABS( FT_MulFix( max_height, new_scale - scale ) );
dist &= ~127;
if ( dist == 0 )
{
scale = new_scale;
FT_TRACE5((
"af_latin_metrics_scale_dim:"
" x height alignment (style `%s'):\n"
" "
" vertical scaling changed from %.4f to %.4f (by %d%%)\n"
"\n",
af_style_names[metrics->root.style_class->style],
axis->org_scale / 65536.0,
scale / 65536.0,
( fitted - scaled ) * 100 / scaled ));
}
#ifdef FT_DEBUG_LEVEL_TRACE
else
{
FT_TRACE5((
"af_latin_metrics_scale_dim:"
" x height alignment (style `%s'):\n"
" "
" excessive vertical scaling abandoned\n"
"\n",
af_style_names[metrics->root.style_class->style] ));
}
#endif
}
}
}

2
src/autofit/aflatin.h
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@ -74,6 +74,8 @@ FT_BEGIN_HEADER
{
AF_WidthRec ref;
AF_WidthRec shoot;
FT_Pos ascender;
FT_Pos descender;
FT_UInt flags;
} AF_LatinBlueRec, *AF_LatinBlue;