From: Andrew Dunbar (hippietrail@yahoo.com)
Date: Tue Feb 26 2002 - 18:58:49 GMT
> I have been looking into using the FreeType font
> renderer
Cool!
> (www.freetype.org) , 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:
Is FreeType available on all our current platforms and
all platforms that might be targeted in the future -
I'm thinking palmtops. Maybe worth a thought.
Also I'm wondering if this decision should be taken
seperately from deciding whether we should use Pango
at some point. Will that be a second change or should
we look into the effects of both before redesigning
a new API/architecture etc?
> (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
> solution.
>
>
> 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.
>
> Tomas
=====
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