Re: [ft] Accessing font tables?

[mpsuzuki]

Hi,

I understand your touble as following:

1. ICU wants to access the memory mapped image of
   OpenType table which is specified by 4-letter tag
   (e.g. "kern", "GSUB", etc)

2. But FT_Get_Sfnt_Table() requires FT2-specific
   number, FT_Sfnt_Tag, to specify TrueType table.

3. So a conversion from 4-letter tag to FT_Sfnt_Tag
   is required. Which function does the conversion?

If I'm misunderstanding, please correct.

I guess, ICU can want to access the OpenType table
which cannot be specified by FT_Sfnt_Tag (e.g. "GSUB"),
so another function FT_Load_Sfnt_Table() can be better.
FT_Load_Sfnt_Table() receives 4-letter tag to specify
the table in the font. How do you think of?

Regards,
mpsuzuki


On Mon, 09 Jun 2008 16:35:30 -0300
Ian Britten <address@hidden> wrote:
>Hi all,
>I'm in the process of upgrading some v2.1.7 code to the latest
>version (2.3.5), and was wondering if someone could point me in
>the right direction regarding accessing font tables?
>
><Background>
>The relevant code is bridging ICU and FreeType.  I'm not sure
>why ICU wants the font tables (Kerning probably?), but I'm just
>trying to get them back to the caller.  See
>http://www.icu-project.org/apiref/icu4c/classLEFontInstance.html#af1da7510c05deebcab885b4f351db33
>for the C++ baseclass interface I need to implement.
>
>It provides a single input (LETag == uint32_t), and wants a
>void* back.  It's called from deep within ICU if/when necessary
></Background>
>
>The original code seems to only support TT tables, and looks
>something like this:
>         LETag tableTag = // whatever
>         TT_Face ttFace =  // whatever
>         FT_ULong length = 0;
>         FT_Error error = ttFace->goto_table(
>                 ttFace, tableTag, ttFace->stream, &length);
>         if (error)
>                 // whatever
>
>         unsigned char *outBuffer = // whatever
>         error = FT_Stream_Read(ttFace->stream, outBuffer, length);
>         if (error)
>                 // whatever
>
>With the removal of the FT_INTERNAL header files, this code no
>longer compiles, and needs to be upgraded to the proper public
>FT interfaces.
>
>Now, am I correct in my understanding that this stuff is referred
>to as SFNT?  And that it's accessed via some of the functions
>like FT_Get_Sfnt_Table()
>(http://freetype.sourceforge.net/freetype2/docs/reference/ft2-truetype_tables.html#FT_Get_Sfnt_Table)
>
>If that's the case, does anyone know how I might convert/map the
>given LETag integer to a FT_Sfnt_Tag enum?
>If this isn't the correct approach, can someone point me in the
>right direction?
>
>Many thanks for any help!
>Ian