Re: About combination of thai and devanagrari

From: li bo <>
Date: Wed, 7 Sep 2011 17:06:25 +0800

If I use truetype font, Does it mean i need a higher-level layout engine to
layout the font?
I know that there are OpenType tables (GPOS and GSUB) to handle the shape
and combine for complex scripts.
But Is the OpenType tables support truetype font? I even don't know the
difference between the truetype font and opentype font.

On Tue, Sep 6, 2011 at 1:53 PM, Philippe Verdy <> wrote:

> Devanagari, not Decanagrari I suppose... Starts by looking at the
> TrueType and OpenType specifications:
> Then look at the details of the OpenType features needed for
> Devanagari and Thai.
> You'll immediately see that Thai is much less complex than Devanagari
> to implement.
> There are other competing technologies, base on TrueType (AAT for
> MacOS, Graphite portable across platforms, but not very well supported
> in applications).
> SVG fonts for now cannot support these scripts very well due to the
> impossibility to map precisely the contextual forms that are unified
> in Unicode (for Thai, well it could work with modern texts, but for
> Devanagari, it's impossible without additional data for mapping the
> contextual glyphs): there's still no specification in SVG fonts for
> "features" like in OpenType, AAT and Graphite. In addition, the DOM
> API for SVG fonts is not accessible in a documented way (only "opaque"
> interfaces are available; you have to rely to the XML DOM instead).
> There are tricks to support Devanagari with Type1 fonts, but this
> requires integratinf additional Postscript routines, specific to the
> PostScript engine, to keep context variables in some accessible global
> directory, such as the device context, normally not made for that, or
> by self modifying the font's directory (such trick is used to generate
> some Barcode fonts; font tools generally provide no help to integrate
> those routines).
> But you may want to create a composite font, in which case a SVG font
> can be built that combines two existing OpenType fonts (without
> modifying them and without importing or converting their glyph
> definitions), grouped under a single family-name and usable on the web
> for CSS. Of you can do that with CSS "@font{ ...}", for later use of
> the new family in a stylesheet or in HTML.
> -- Philippe --
> 2011/9/6 li bo <>:
> > I'd like to implement the combination of thai and decanagrari scripts
> using
> > vector font. But I have no idea about it. How do i adjust the position
> of
> > the combined glyph? Could anyone give some advices or references? Thanks
> a
> > lot!
> >
Received on Wed Sep 07 2011 - 04:10:39 CDT

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