Re: [ft-devel] Understanding Type1 fonts

[mpsuzuki]

On Wed, 9 Jan 2008 13:32:29 +0200
Donn <address@hidden> wrote:
>> [In the following, I assume that you want to get metrics, right?]
>As a quick summary: Fonty Python is meant to, acting independently of 
>fontconfig:
>1. Let one browse to any folder and see (rendered via PIL) what fonts are in 
>it. What is considered a font, right now, is based entirely on the extension 
>of the filename. ".ttf",".otf",".ttc",".pfb" with ".pfa" in the works.
>2. Allow one to 'collect' fonts into groups.
>3. Allow one to 'install' the fonts in a group in one go. This is done by 
>making soft links in ~/.fonts to wherever those fonts live.
>
>So, from FP's pov the metrics are not important in as much as I leave all the 
>font voodoo to PIL (which works via Freetype). But the metrics *may* be 
>important to other apps (like Inkscape) which are run after FP is used and 
>then pick-up the fonts in ~/.fonts for use.

Sorry, yet I've never used Fonty Python, Inkscape, Scribus etc.
Please let me know the expected applications that Fonty Python
manages the fonts for, and whether they (will) use fontconfig
/or not. I guess fontconfig is the reason why you choose ~/.fonts,
but I'm not sure.

About kerning support, I note: FreeType2 provides fundamental
APIs to get kerning vector from the font files, but complex
kerning computation is not provided.

Just 1 year ago, the possibility of Win32-like pair
kerning API was discussed in this list. At that time,
FreeType2 decided to participate to provide the access
to the memory image of "kern" table, but the detailed
handling of its contents is left to the application.
Please check the thread from:
http://lists.gnu.org/archive/html/freetype-devel/2006-01/msg00023.html

In fact, when Masatake Yamato and I had developed TrueType
"kern" table validator in FreeType, we found that the design
of unified/portable API to retrieve kerning informations
even if we restrict the scope to TrueType fonts, because
newest Apple's kern table requires state machine.
Please check the section 5 of freetype2/src/gxvalid/README.
Also OpenType provides kerning feature by GPOS table, but
parsing and kerning computation by GPOS table is now
expected to be the role of Unicode text layout libraries
like Pango/HarfBuzz, ICU, etc.

# I wish if such informations (OpenType extension
# availability) are available from fontconfig database.

Do you have any favorite software supporting AFM/PFM
or TrueType kerning?

Regards,
mpsuzuki