using FreeType post 1.0

From: Tomas Frydrych (
Date: Tue Feb 26 2002 - 17:24:53 GMT

  • Next message: F J Franklin: "Re: using FreeType post 1.0"

    I have been looking into using the FreeType font renderer
    ( , and I was rather suprprised how simple it
    would be to implement our drawChars and measureCharWidth
    functions with it.

    I was initially looking at this as a means to solve our Unix font
    problems, and there is no doubt in my mind that this is the way to
    go -- not only would using FreeType completely resolve the font
    mess, but we would also get rid off the Unicode->8-bit-locale
    translation that we currently have to do at every text-drawing and
    text-measuring operation.

    As I have been examining what FreeType offers, I came to the
    conclusion that we would in fact be well advised to use it from our
    XP code, getting rid off the platform specific measureCharWidth
    and drawChars functions. There are several good reasons for this:

    (1) We should be able to improve the WYSIWIGness of our screen
    output; on win32 in particular we currently struggle with
    cummulative truncating errors in width calculations for which there
    is no simple cure -- with FreeType we should be able to get a
    better precision.

    (2) We would be able to add font aliasing to all our platforms.

    (3) We would be able to use proper kerning on all platforms with
    very little coding effort. This is very desirable and at present would
    be lot of work to implement (in platform code).

    (4) We would be able to use the scalable fonts supported by
    FreeType on all our platforms -- i.e., you could use pfa/pfb fonts on
    Windows, if you wanted to. FreeType supports TrueType,
    OpenType, PostScript, CID keyed fonts, and others.

    (5) Finally, and IMO most importantly, having an xp font renderer
    would greatly simplify maintanance and further development. What
    has proved to be the worst nightmare in the bidi work, is getting
    RTL text out on the screen correctly under different OS's. For
    instance, the capbilities of the various flavours of win32 differ
    widely, with no standard way of determining what they are; inspite
    of hours of work and long nights, RTL text still does not display
    correctly on some flavours of win32 when using some fonts. We
    end up with unreliable heurstics trying to convince the system to
    do what we want it to do. We will have to relive this again and again
    when someone will get to getting bidi work on Mac, BeOS, QNX ...
    With FreeType we would have a single layout engine with single
    set of bugs and equal (and excellent) capabilities on all platforms.

    There is one drawback -- we may loose some OS specific
    capabilities. For instance some bidi-enabled win32 can do
    glyphshaping using OpenType fonts; FreeType2 at the moment
    cannot. I consider this a small price to pay. At the moment we do
    not make use of it, and will not in forseeable future. We will want
    this in the medium to long-term, but even then to do glyphshaping
    in the platform code would be a maintanance nightmare; the
    FreeType folk started a separate project on a layout library that will
    provide this functionality, so in long term there will be an xp

    It seems to me that the benefits of using FreeType far outweight
    any drawbacks. If we can agree on this, then migrating to FreeType
    should be one of the first things to do after the 1.0 release.


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