Re: Problems w/ Mangal?
- From: Owen Taylor <otaylor redhat com>
- To: Eric Mader <mader jtcsv com>
- Cc: gtk-i18n-list gnome org
- Subject: Re: Problems w/ Mangal?
- Date: Thu, 31 Jan 2002 18:11:56 -0500 (EST)
Eric Mader <mader jtcsv com> writes:
> I've got my indic-xft shaper limping along. It seems to shape well,
> but when I display Hindi text using an IBM Devanagari font
> ("Devanagari MT for IBM" - built for IBM's JDK) the text display looks
> pretty bad. In particular, the placement of the long-I matra looks way
> off. (And there's no hinting; TrueType Devanagari fonts tend to look
> pretty bad w/o hinting...)
Unfortunately, that is a problem we can't solve within the scope
of Pango since it's a legal one not a technical one.
(http://www.freetype.org/patents.html)
Its a reasonably simple matter to recompile FreeType with hinting on.
There have been some improvements in the FreeType autohinter recently
since the version shipped in Red Hat 7.2, but I suspect they probably
won't help much here since the autohinter is really tuned for
roman type.
> In an attempt to see if this was a font problem (though the font
> *does* display correctly on Windoze ;-) I tried using Mangal
> instead. With Mangal, I get this error: "Error loading GSUB table
> 4097" (TTO_Err_Invalid_SubTable)
>
> I've narrowed the error down to a bad ClassRangeRecord in
> Load_ClassDef2 in ftxopen.c. I've tried dumping the GSUB table using
> the tools on Windows, and I don't see the error that this code is
> reporting - I suspect that ftxopen is getting lost somehow and isn't
> really reading what it thinks it is...
>
> Has anyone else seem this kind of a problem with Mangal?
Without any shapers that could use Mangal, probably not. :-)
And if there is is any portion of the code I'd expect to have
bugs when not thoroughly tested, it would be the handling of
'GSUB Chaining Context Substitution Format 2: Class-based Chaining
Context Glyph Substitution', which is just about as complex
as OpenType gets. (And that's saying a lot...) :-(
Looking into this a little bit, I _think_ what is going on is that
pango/opentype/ftxgsub.c:Load_ChainContextSubst2() is not handling
that if lookahead_offset (and presumably the other similar offsets)
are 0, then the class is empty. I can't find any reference to that in
the docs for this particular table, but it seems to be a common
convention in the OpenType format and would make sense with the
values in mangal.ttf.
I tried fixing that, but then it died a bit later. It might be
useful to have the dump of the font when debugging this; otherwise,
it's probably just a lot of staring at the code. The diff I was
working with is attached ... most of it is just freeing some problems with
memory cleanup on error.
Regards,
Owen
Index: ftxgsub.c
===================================================================
RCS file: /cvs/gnome/pango/pango/opentype/ftxgsub.c,v
retrieving revision 1.2
diff -u -p -r1.2 ftxgsub.c
--- ftxgsub.c 2001/09/19 21:20:36 1.2
+++ ftxgsub.c 2002/01/31 23:10:28
@@ -827,7 +827,7 @@
FT_Error error;
FT_Memory memory = stream->memory;
- FT_UShort n, count;
+ FT_UShort n = 0, m, count;
FT_ULong cur_offset, new_offset, base_offset;
TTO_AlternateSet* aset;
@@ -882,8 +882,8 @@
return TT_Err_Ok;
Fail1:
- for ( n = 0; n < count; n++ )
- Free_AlternateSet( &aset[n], memory );
+ for ( m = 0; m < n; m++ )
+ Free_AlternateSet( &aset[m], memory );
FREE( aset );
@@ -1030,7 +1030,7 @@
FT_Error error;
FT_Memory memory = stream->memory;
- FT_UShort n, count;
+ FT_UShort n = 0, m, count;
FT_ULong cur_offset, new_offset, base_offset;
TTO_Ligature* l;
@@ -1071,8 +1071,8 @@
return TT_Err_Ok;
Fail:
- for ( n = 0; n < count; n++ )
- Free_Ligature( &l[n], memory );
+ for ( m = 0; m < n; m++ )
+ Free_Ligature( &l[m], memory );
FREE( l );
return error;
@@ -1108,7 +1108,7 @@
FT_Error error;
FT_Memory memory = stream->memory;
- FT_UShort n, count;
+ FT_UShort n = 0, m, count;
FT_ULong cur_offset, new_offset, base_offset;
TTO_LigatureSet* lset;
@@ -1163,8 +1163,8 @@
return TT_Err_Ok;
Fail1:
- for ( n = 0; n < count; n++ )
- Free_LigatureSet( &lset[n], memory );
+ for ( m = 0; m < n; m++ )
+ Free_LigatureSet( &lset[m], memory );
FREE( lset );
@@ -1478,7 +1478,7 @@
FT_Error error;
FT_Memory memory = stream->memory;
- FT_UShort n, count;
+ FT_UShort n = 0, m, count;
FT_ULong cur_offset, new_offset, base_offset;
TTO_SubRule* sr;
@@ -1519,8 +1519,8 @@
return TT_Err_Ok;
Fail:
- for ( n = 0; n < count; n++ )
- Free_SubRule( &sr[n], memory );
+ for ( m = 0; m < n; m++ )
+ Free_SubRule( &sr[m], memory );
FREE( sr );
return error;
@@ -1556,7 +1556,7 @@
FT_Error error;
FT_Memory memory = stream->memory;
- FT_UShort n, count;
+ FT_UShort n = 0, m, count;
FT_ULong cur_offset, new_offset, base_offset;
TTO_SubRuleSet* srs;
@@ -1610,8 +1610,8 @@
return TT_Err_Ok;
Fail1:
- for ( n = 0; n < count; n++ )
- Free_SubRuleSet( &srs[n], memory );
+ for ( m = 0; m < n; m++ )
+ Free_SubRuleSet( &srs[m], memory );
FREE( srs );
@@ -1823,7 +1823,7 @@
FT_Error error;
FT_Memory memory = stream->memory;
- FT_UShort n, count;
+ FT_UShort n = 0, m, count;
FT_ULong cur_offset, new_offset, base_offset;
TTO_SubClassSet* scs;
@@ -1901,8 +1901,8 @@
return TT_Err_Ok;
Fail1:
- for ( n = 0; n < count; n++ )
- Free_SubClassSet( &scs[n], memory );
+ for ( m = 0; m < n; m++ )
+ Free_SubClassSet( &scs[m], memory );
FREE( scs );
@@ -2519,7 +2519,7 @@
FT_Error error;
FT_Memory memory = stream->memory;
- FT_UShort n, count;
+ FT_UShort n = 0, m, count;
FT_ULong cur_offset, new_offset, base_offset;
TTO_ChainSubRule* csr;
@@ -2560,8 +2560,8 @@
return TT_Err_Ok;
Fail:
- for ( n = 0; n < count; n++ )
- Free_ChainSubRule( &csr[n], memory );
+ for ( m = 0; m < n; m++ )
+ Free_ChainSubRule( &csr[m], memory );
FREE( csr );
return error;
@@ -2598,7 +2598,7 @@
FT_Error error;
FT_Memory memory = stream->memory;
- FT_UShort n, count;
+ FT_UShort n = 0, m, count;
FT_ULong cur_offset, new_offset, base_offset;
TTO_ChainSubRuleSet* csrs;
@@ -2652,8 +2652,8 @@
return TT_Err_Ok;
Fail1:
- for ( n = 0; n < count; n++ )
- Free_ChainSubRuleSet( &csrs[n], memory );
+ for ( m = 0; m < n; m++ )
+ Free_ChainSubRuleSet( &csrs[m], memory );
FREE( csrs );
@@ -2872,7 +2872,7 @@
FT_Error error;
FT_Memory memory = stream->memory;
- FT_UShort n, count;
+ FT_UShort n = 0, m, count;
FT_ULong cur_offset, new_offset, base_offset;
TTO_ChainSubClassRule* cscr;
@@ -2915,8 +2915,8 @@
return TT_Err_Ok;
Fail:
- for ( n = 0; n < count; n++ )
- Free_ChainSubClassRule( &cscr[n], memory );
+ for ( m = 0; m < n; n++ )
+ Free_ChainSubClassRule( &cscr[m], memory );
FREE( cscr );
return error;
@@ -2943,7 +2943,31 @@
}
}
+ static FT_Error Load_EmptyOrClassDefinition( TTO_ClassDefinition* cd,
+ FT_UShort limit,
+ FT_ULong class_offset,
+ FT_ULong base_offset,
+ FT_Stream stream )
+ {
+ FT_Error error;
+ FT_ULong cur_offset;
+ cur_offset = FILE_Pos();
+
+ if ( class_offset )
+ {
+ if ( FILE_Seek( class_offset + base_offset ) )
+ error = Load_ClassDefinition( cd, limit, stream ) == TT_Err_Ok;
+ }
+ else
+ error = Load_EmptyClassDefinition ( cd, stream );
+
+ (void)FILE_Seek( cur_offset );
+
+ return error;
+ }
+
+
/* ChainContextSubstFormat2 */
static FT_Error Load_ChainContextSubst2(
@@ -2953,7 +2977,7 @@
FT_Error error;
FT_Memory memory = stream->memory;
- FT_UShort n, count;
+ FT_UShort n = 0, m, count;
FT_ULong cur_offset, new_offset, base_offset;
FT_ULong backtrack_offset, input_offset, lookahead_offset;
@@ -2978,9 +3002,9 @@
if ( ACCESS_Frame( 8L ) )
goto Fail5;
- backtrack_offset = GET_UShort() + base_offset;
- input_offset = GET_UShort() + base_offset;
- lookahead_offset = GET_UShort() + base_offset;
+ backtrack_offset = GET_UShort();
+ input_offset = GET_UShort();
+ lookahead_offset = GET_UShort();
/* `ChainSubClassSetCount' is the upper limit for input class values,
thus we read it now to make an additional safety check. */
@@ -2989,18 +3013,18 @@
FORGET_Frame();
- cur_offset = FILE_Pos();
- if ( FILE_Seek( backtrack_offset ) ||
- ( error = Load_ClassDefinition( &ccsf2->BacktrackClassDef, count,
- stream ) ) != TT_Err_Ok )
- goto Fail5;
- if ( FILE_Seek( input_offset ) ||
- ( error = Load_ClassDefinition( &ccsf2->InputClassDef, count,
- stream ) ) != TT_Err_Ok )
- goto Fail4;
- if ( FILE_Seek( lookahead_offset ) ||
- ( error = Load_ClassDefinition( &ccsf2->LookaheadClassDef, count,
- stream ) ) != TT_Err_Ok )
+ if ( ( error = Load_EmptyOrClassDefinition( &ccsf2->BacktrackClassDef, count,
+ backtrack_offset, base_offset,
+ stream ) ) != TT_Err_Ok )
+ goto Fail5;
+
+ if ( ( error = Load_EmptyOrClassDefinition( &ccsf2->InputClassDef, count,
+ input_offset, base_offset,
+ stream ) ) != TT_Err_Ok )
+ goto Fail4;
+ if ( ( error = Load_EmptyOrClassDefinition( &ccsf2->LookaheadClassDef, count,
+ lookahead_offset, base_offset,
+ stream ) ) != TT_Err_Ok )
goto Fail3;
(void)FILE_Seek( cur_offset );
@@ -3044,8 +3068,8 @@
return TT_Err_Ok;
Fail1:
- for ( n = 0; n < count; n++ )
- Free_ChainSubClassSet( &cscs[n], memory );
+ for ( m = 0; m < n; m++ )
+ Free_ChainSubClassSet( &cscs[m], memory );
FREE( cscs );
Index: ftxopen.c
===================================================================
RCS file: /cvs/gnome/pango/pango/opentype/ftxopen.c,v
retrieving revision 1.3
diff -u -p -r1.3 ftxopen.c
--- ftxopen.c 2001/09/19 21:20:36 1.3
+++ ftxopen.c 2002/01/31 23:10:28
@@ -569,7 +569,7 @@
FT_Error error;
FT_Memory memory = stream->memory;
- FT_UShort n, count;
+ FT_UShort n = 0, m, count;
FT_ULong cur_offset, new_offset, base_offset;
TTO_SubTable* st;
@@ -613,8 +613,8 @@
return TT_Err_Ok;
Fail:
- for ( n = 0; n < count; n++ )
- Free_SubTable( &st[n], type, l->LookupType, memory );
+ for ( m = 0; m < n; m++ )
+ Free_SubTable( &st[m], type, l->LookupType, memory );
FREE( l->SubTable );
return error;
@@ -1203,6 +1203,29 @@
return error;
}
+
+ FT_Error Load_EmptyClassDefinition( TTO_ClassDefinition* cd,
+ FT_Stream stream )
+ {
+ FT_Error error;
+ FT_Memory memory = stream->memory;
+
+
+ if ( ALLOC_ARRAY( cd->Defined, 1, FT_Bool ) )
+ return error;
+
+ cd->ClassFormat = 1; /* Meaningless */
+ cd->Defined[0] = FALSE;
+
+ if ( ALLOC_ARRAY( cd->cd.cd1.ClassValueArray, 1, FT_UShort ) )
+ goto Fail;
+
+ return TT_Err_Ok;
+
+ Fail:
+ FREE( cd->Defined );
+ return error;
+ }
void Free_ClassDefinition( TTO_ClassDefinition* cd,
FT_Memory memory )
Index: ftxopenf.h
===================================================================
RCS file: /cvs/gnome/pango/pango/opentype/ftxopenf.h,v
retrieving revision 1.1
diff -u -p -r1.1 ftxopenf.h
--- ftxopenf.h 2000/12/20 04:41:36 1.1
+++ ftxopenf.h 2002/01/31 23:10:28
@@ -39,6 +39,8 @@ extern "C" {
FT_Error Load_ClassDefinition( TTO_ClassDefinition* cd,
FT_UShort limit,
FT_Stream input );
+ FT_Error Load_EmptyClassDefinition( TTO_ClassDefinition* cd,
+ FT_Stream input );
FT_Error Load_Device( TTO_Device* d,
FT_Stream input );
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