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[psaux] (1/2) Handle fonts that use SEAC for ligatures (#56580). 

As originally intended, a Type 1 SEAC charstring would be used for
an accented glyph (like `acaron' or `uumlaut'), where the advance
width of the SEAC glyph is the same as that of the `base' glyph
(like `a' or `u').  In this case it is not uncommon for the SEAC
glyph to not use an (H)SBW opcode of its own but to rely on the
value from the base glyph.

However, out-of-spec fonts also use SEAC glyphs for ligatures (like
`oe' or `fi'), and in those cases the overall advance width is
greater than that of the `base' glyph.  For this reason we have to
allow that the SEAC glyph can have an (H)SBW value of its own, and
if it has, retain this value, rather than the one from the base
glyph.

* src/psaux/psintrp.c (cf2_interpT2CharString) <cf2_escSEAC>:
Implement it.
This commit is contained in:
Chris Liddell 2019-07-04 14:04:52 +02:00 committed by Werner Lemberg
parent 8cf046c38d
commit f2b64583cb
2 changed files with 37 additions and 6 deletions
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21
ChangeLog
View File

@ -1,3 +1,24 @@
2019-07-04 Chris Liddell <chris.liddell@artifex.com>
[psaux] (1/2) Handle fonts that use SEAC for ligatures (#56580).
As originally intended, a Type 1 SEAC charstring would be used for
an accented glyph (like `acaron' or `uumlaut'), where the advance
width of the SEAC glyph is the same as that of the `base' glyph
(like `a' or `u'). In this case it is not uncommon for the SEAC
glyph to not use an (H)SBW opcode of its own but to rely on the
value from the base glyph.
However, out-of-spec fonts also use SEAC glyphs for ligatures (like
`oe' or `fi'), and in those cases the overall advance width is
greater than that of the `base' glyph. For this reason we have to
allow that the SEAC glyph can have an (H)SBW value of its own, and
if it has, retain this value, rather than the one from the base
glyph.
* src/psaux/psintrp.c (cf2_interpT2CharString) <cf2_escSEAC>:
Implement it.
2019-07-01 Werner Lemberg <wl@gnu.org>
* Version 2.10.1 released.

22
src/psaux/psintrp.c
View File

@ -1433,6 +1433,13 @@
lastError = error2; /* pass FreeType error through */
goto exit;
}
/* save the left bearing and width of the SEAC */
/* glyph as they will be erased by the next load */
left_bearing = *decoder->builder.left_bearing;
advance = *decoder->builder.advance;
cf2_interpT2CharString( font,
&component,
callbacks,
@ -1443,11 +1450,14 @@
&dummyWidth );
cf2_freeT1SeacComponent( decoder, &component );
/* save the left bearing and width of the base */
/* character as they will be erased by the next load */
/* If the SEAC glyph doesn't have a (H)SBW of its */
/* own use the values from the base glyph. */
left_bearing = *decoder->builder.left_bearing;
advance = *decoder->builder.advance;
if ( !haveWidth )
{
left_bearing = *decoder->builder.left_bearing;
advance = *decoder->builder.advance;
}
decoder->builder.left_bearing->x = 0;
decoder->builder.left_bearing->y = 0;
@ -1473,8 +1483,8 @@
&dummyWidth );
cf2_freeT1SeacComponent( decoder, &component );
/* restore the left side bearing and */
/* advance width of the base character */
/* restore the left side bearing and advance width */
/* of the SEAC glyph or base character (saved above) */
*decoder->builder.left_bearing = left_bearing;
*decoder->builder.advance = advance;