[Devel] Help me understand this... I'm loosing my sanity. Please.

[Maurizio Colucci]

Hello everybody,

Excuse me if I am writing such a long message, but I've spent days
trying to understand this. I have also read many messages from this
list, without solving my problem. You are my last resource.

I am using the latest unstable debian, the one that depends on
libfreetype6_2.1.3+2.1.4rc2-5_i386.deb.

Basically, I am trying to figure out why the antialiased fonts in the
debian (KDE 3.1.1) are so much worse than in redhat 8 and 9.

The problem is difficult to explain, and I don't have a web site where
I can post some pictures. Anyway, it looks like in debian the color of
the antialiased fonts is unevenly distributed, resulting in some very
thin lines and some very thick ones, in the same font. Sometimes you
can even see what look like spots of ink on a font. The effect is
similar to the one posted in

  http://www.freetype.org/patents.html

(the nopatents.png picture)

but a bit less evident (due to auto-hinting, I suppose. See below).

The problem is particularly evident in the luxy fonts, which are
beautiful in redhat and awful in debian.  But, to be honest, the only
decent fonts in debian are helvetica and arial, and there is not a
single serif fonts which doesn't look messy.

Searching the net for a solution, I've found many misleading
informations: xfs, xfs-tt, xfsft, xfstt, debian font deuglification
howto, debian true type fonts howto, TT-Xfree86 howto, DPI, startx --
-dpi 75, /etc/U /usr/X11R6/lib/X11/fs/config,
/usr/X11R6/lib/X11/fs-xtt/config, even Xft2, /etc/fonts/fonts.conf.

I have lost DAYS trying to understand these softwares, but I could not
solve the problem by tweaking any of them.


At last, I have found the patents page at freetype.org, and some
messages from the developer's mailing list.

My current understanding is:

1. TTF files have both a data part and a code part. The code part is
made of bytecode, which describes how to deform the font in order to
render them better with low-resolutions. The byte-code interpreter can
be used with both antialiased and unantialiased fonts.

2. For patents problems, freetype2 introduces an auto-hinting module,
which IGNORES the bytecode BUT tries to achieve a decent hinting
effect nevertheless. This auto-hinting module can also be used BOTH in
antialiased and unantialiased fonts.

3. The freetype2 implementation can EITHER use the bytecode
interpreter OR the auto-hinting, but not both at the same time. And
the choice is made at compile time, with

       #define TT_CONFIG_OPTION_BYTECODE_INTERPRETER


Is that correct?

So I guess have found the source of the problem:

4.  maybe redhat 8-9 activates the bytecode interpreter, whereas
debian doesn't?  That would explain the better rendering of fonts in
redhat.

5. maybe debian uses auto-hinting in replace. That would explain why
the fonts are not as awful as in the nopatents.png picture.

Are points 1, 2, 3, 4 and 5 true?

But there are other things I don't understand:

6. how can I know if the debian libfreetype6 package I am using
activates the byte-code interpreter? I DID read
/usr/share/docs/libfreetype6/README.Debian but there is no mention.

7. I noticed that redhat 8 sets the following resources by default:

Xft.dpi:        96
Xft.hinting:    true
Xft.hintstyle:  hintmedium

What do they mean? What reads them? Where can I find more info about
them?

8.  I can't see why in redhat 9, openoffice.org's menus are
antialiased, and in debian this is not the case. I don't know if the
problems are related, so I just thought to mention it.


Thanks for any help, with all my heart.

Maurizio Colucci.