[Freetype] Re: PS Type1 vs. TrueType

[David Turner]

Hello Vadim,

I've removed the "render" list from this reply, since I'm unsure
that they'll really appreciate this thread..
> 
> Is "PostScript Type1" rendering is free of such *surprises*?
>
I don't know, I'm unsure that the MS patent is TrueType specific.
This needs careful review of the patent, and I lack the time to
do that currently..

> I found that with recent FreeType release, FT 2.0.3, and AA enabled (in
> XFree86), rendering quality of Type1 fonts is very good.
> So, may be it's time to use Type1 fonts instead of TrueType?
> Are there any patents surrounding rendering of Type1 fonts?
>
Well, the auto-hinter has been rather significantly enhanced in 2.0.3,
though there is still more work to do (after all, we live in an unperfect
world :-)

I'm currently working on adding native Type 1 support to FT2, as well
as a new auto-hinting sub-system (works better, but also a lot slower
than the current one :-()
 
> ***
> I was trying to recall why I stopped using Type1 fonts. To be correct, I have
> tried to recall why I was *never* using Type1 fonts running Windows.
> (I am running Linux from Aug.2000, while I was Windows user since 1989-1990)
> Explantations are very simple:
> - Adobe Type Manager costs money, and it is more than $100 (ATM Deluxe) with
> good selection of fonts.

Actually, ATM is now distributed as a free plug-in on Windows and Mac.
It has also been integrated within Windows 2000, Me and XP I believe,
so these OSes already support Type 1 fonts natively !!

(NT4 also supports them but with a rather strange scheme. Installing
 a Postscript font in the "System/Fonts" folder will automatically
 "convert" it to an equivalent hidden TrueType font file. I'm unsure
  that this was a good idea..)


> - there were no good Cyrillic fonts (1993-1995) available in Type1 format,
> with good hinting. Adobe never localized ATM for Russian market, so it was
> really not an option at all.
>
That's probably the biggest problem now..
 
> At a moment:
> - *free* Type1 rasterizer is part of XFree86, Type1 fonts supported by
> FreeType2

Yes, and anti-aliased too. Xft is not about TrueType only.. there seems
to be confusion about that in the XRender documents available on the
web :-)


> - URW fonts, part of GhostScript distribution, are of rather good quality.
>  They are limited to Latin-1 and Latin-2 encodings, but it's better than
> nothing. At leats, those fonts are free and do not require licensing.
> -there are some Cyrillic fonts available nowdays, and it's possible to hint
> them for better rendering quality.
>
Be careful not to enter into copyright violation issues. If the fonts
are under the GPL, that's OK. For the newest fonts available with XFree86 4
(i.e. the "Lucidux" family of fonts), I think things are a bit different.

Some people on the Render list should be able to give more information
on these..
 
> Well, Type1 will not find its way to Windows (already...), but there are good
> opportunities on Linux/UNIX'es. I found that hinting process for Type1 fonts
> is much more simple than for TrueType, and it can be done (even by one
> person) in realistic timeframe.
> 
Definitely, definitely, definitely :o)


> What do you think about this?
> Does TrueType have some advantages over Type1, especially when you *disabled*
> TrueType Bytecode interpreter (due to patent issues...) ?
>
Yes, the Type 1 format inherits from many of the annoyances of the
Postscript language, which means:

  - limited to 256 characters per encoding. D'oh..
    Of course, you can have more glyphs, but you need to
    parse glyph name strings in order to build a correct
    Unicode charmap for these (done automatically by FT2 though)

  - atrocious file structure, and up to four different files
    for a single font !! You basically cannot parse directly
    a font file in memory, since you'll need to "decode" the
    ridiculous "encryption" and hex strings before. This means
    larger memory footprints !!

  - Forth-like syntax. Clumsy, hard to write, hard to parse and
    hard to debug. Fortunately, some pretty clever regexp help
    a lot for fonts and speed things _tremendously_ :-)

The CID format is similar to Type 1 but can be parsed directly
in memory (not surprising since the fonts can be several megabytes :-)

The CFF format is a compressed variant of Type 1. You can theorically
convert between these two formats without any losses, though I haven't
tested this.. Funnily, it's a lot

The "OpenType Outline" format is really good, because its embeds
a CFF font with other important tables (like Unicode charmaps,
OpenType Layout extensions, etc..) that cannot be easily fitted
in a Type 1 font, and can be parsed much more easily (they're
binary, pre-sorted, etc..). I find it a lot better than TrueType
itself..

And yes, CFF and OpenType are supported by FT2. We just need the
tools to convert our fonts to them..

Now, if someone wants to sponsor the development of such tools,
I'm available as a software consultant. That's just not my current
priority with FreeType.

Regards,

- David