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Improve documentation of the 'BDF ' table as used in X11 .otb files.

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Also do some minor code formatting.
This commit is contained in:
Werner Lemberg 2025-12-04 07:30:06 +01:00
parent 85161d7622
commit 5751c184cc
6 changed files with 48 additions and 27 deletions
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8
devel/ftoption.h
View file

@ -759,7 +759,13 @@ FT_BEGIN_HEADER
/**************************************************************************
*
* Define `TT_CONFIG_OPTION_BDF` if you want to include support for an
* embedded 'BDF~' table within SFNT-based bitmap formats.
* embedded 'BDF~' table within an SFNT-based `.otb` font file. This table
* is an extension used by X11 to preserve BDF properties after conversion
* to SFNT containers. See
*
* https://fontforge.org/docs/techref/non-standard.html#non-standard-bdf
*
* for more details.
*/
#define TT_CONFIG_OPTION_BDF

8
docs/formats.txt
View file

@ -86,8 +86,8 @@ which isn't supported yet please send a mail too.
SFNT PS CFF SYNTHETIC --- OT spec, 5176.CFF.pdf
SFNT PS CFF2 --- cff OT spec 1.8
SFNT TT SBIT --- sfnt XFree86 (bitmaps only;
with `head' table)
SFNT TT SBIT --- sfnt X11 (bitmaps only;
with `head' table) [8]
SFNT TT MACSBIT --- sfnt OT spec (for the Mac;
bitmaps only; `bhed' table)
SFNT TT --- --- truetype OT spec (`normal' TT font)
@ -204,6 +204,10 @@ which isn't supported yet please send a mail too.
versions of FreeType don't not support this format, but FontForge
can load it.
[8] Such fonts also contain a 'BDF ' table to hold BDF properties; see
https://fontforge.org/docs/techref/non-standard.html#non-standard-bdf
------------------------------------------------------------------------
Copyright (C) 2004-2025 by

8
include/freetype/config/ftoption.h
View file

@ -759,7 +759,13 @@ FT_BEGIN_HEADER
/**************************************************************************
*
* Define `TT_CONFIG_OPTION_BDF` if you want to include support for an
* embedded 'BDF~' table within SFNT-based bitmap formats.
* embedded 'BDF~' table within an SFNT-based `.otb` font file. This table
* is an extension used by X11 to preserve BDF properties after conversion
* to SFNT containers. See
*
* https://fontforge.org/docs/techref/non-standard.html#non-standard-bdf
*
* for more details.
*/
#define TT_CONFIG_OPTION_BDF

12
include/freetype/ftbdf.h
View file

@ -44,7 +44,8 @@ FT_BEGIN_HEADER
*
* @description:
* This section contains the declaration of functions specific to BDF and
* PCF fonts.
* PCF fonts. They also work for SFNT bitmap fonts that contain a 'BDF~'
* table like X11's `.otb` fonts.
*
*/
@ -151,7 +152,9 @@ FT_BEGIN_HEADER
* FreeType error code. 0~means success.
*
* @note:
* This function only works with BDF faces, returning an error otherwise.
* This function only works with BDF faces and SFNT fonts that have a
* 'BDF~' table, returning an error otherwise. For the latter, a bitmap
* strike size must be selected first.
*/
FT_EXPORT( FT_Error )
FT_Get_BDF_Charset_ID( FT_Face face,
@ -165,7 +168,7 @@ FT_BEGIN_HEADER
* FT_Get_BDF_Property
*
* @description:
* Retrieve a BDF property from a BDF or PCF font file.
* Retrieve a BDF property from a BDF or PCF font.
*
* @input:
* face ::
@ -196,6 +199,9 @@ FT_BEGIN_HEADER
*
* In case of error, `aproperty->type` is always set to
* @BDF_PROPERTY_TYPE_NONE.
*
* This also with SFNT fonts that have a 'BDF~' table, after a bitmap
* strike size has been selected.
*/
FT_EXPORT( FT_Error )
FT_Get_BDF_Property( FT_Face face,

7
src/sfnt/sfdriver.c
View file

@ -1142,12 +1142,7 @@
FT_Error error;
/* XXX: I don't know whether this is correct, since
* tt_face_find_bdf_prop only returns something correct if we have
* previously selected a size that is listed in the BDF table.
* Should we change the BDF table format to include single offsets
* for `CHARSET_REGISTRY' and `CHARSET_ENCODING'?
*/
/* We expect that a bitmap strike has been selected. */
error = tt_face_find_bdf_prop( face, "CHARSET_REGISTRY", &registry );
if ( !error )
{

32
src/sfnt/ttbdf.c
View file

@ -16,6 +16,12 @@
*/
/*
* The 'BDF ' SFNT table is described in the FontForge documentation, see
*
* https://fontforge.org/docs/techref/non-standard.html#non-standard-bdf
*/
#include <freetype/internal/ftdebug.h>
#include <freetype/internal/ftstream.h>
#include <freetype/tttags.h>
@ -80,21 +86,19 @@
bdf->table_end = bdf->table + length;
{
FT_Byte* p = bdf->table;
FT_UInt version = FT_NEXT_USHORT( p );
FT_UInt num_strikes = FT_NEXT_USHORT( p );
FT_ULong strings = FT_NEXT_ULONG ( p );
FT_UInt count;
FT_Byte* strike;
FT_Byte* p = bdf->table;
FT_UInt version = FT_NEXT_USHORT( p );
FT_UInt num_strikes = FT_NEXT_USHORT( p );
FT_ULong strings = FT_NEXT_ULONG ( p );
FT_UInt count;
FT_Byte* strike;
if ( version != 0x0001 ||
strings < 8 ||
( strings - 8 ) / 4 < num_strikes ||
strings + 1 > length )
{
goto BadTable;
}
bdf->num_strikes = num_strikes;
bdf->strings = bdf->table + strings;
@ -104,15 +108,14 @@
p = bdf->table + 8;
strike = p + count * 4;
/* Check table length. */
for ( ; count > 0; count-- )
{
FT_UInt num_items = FT_PEEK_USHORT( p + 2 );
/*
* We don't need to check the value sets themselves, since this
* is done later.
*/
/* We don't check the value sets themselves; */
/* this is done while accessing a property. */
strike += 10 * num_items;
p += 4;
@ -200,6 +203,7 @@
FT_UInt32 name_offset = FT_PEEK_ULONG( p );
FT_UInt32 value = FT_PEEK_ULONG( p + 6 );
/* be a bit paranoid for invalid entries here */
if ( name_offset < bdf->strings_size &&
property_len < bdf->strings_size - name_offset &&
@ -212,7 +216,7 @@
case 0x00: /* string */
case 0x01: /* atoms */
/* check that the content is really 0-terminated */
if ( value < bdf->strings_size &&
if ( value < bdf->strings_size &&
ft_memchr( bdf->strings + value, 0, bdf->strings_size ) )
{
aprop->type = BDF_PROPERTY_TYPE_ATOM;