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Re: FT2 design question

From: Stefan Seefeld
Subject: Re: FT2 design question
Date: Mon, 28 Feb 2000 08:50:01 -0500

Werner LEMBERG wrote:

> IMHO the layout of a text is always dependent on the particular font
> you use.  I don't know exactly what your problem is.  Are you talking
> about the situation where a font for printing is not the same used for
> displaying on the screen, and you want to approximate the text layout,
> i.e., having identical line and page breaks both on the screen and
> paper?

Yes. Berlin uses a DrawingKit interface which encapsulates a device and
a renderer for it. You set individual font attributes such as family, point 
size, weight etc.
On the other hand there is the scene graph. You can do a lot of things
with it, not just drawing. So we have an abstract traversal operation for it
with two particularly important variants, draw traversal and pick traversal. 
Both need detailed layout information of the nodes (characters/glyphs are nodes
in this scene graph as well) to be able to pick and modify the scene. Drawing
can then be done to different devices. Screen, printer etc.
Therefore the hope is that we can initialize the region requirements of the 
with some 'canonical' value (say, the size to be used by the canonical 
which is the one to be used most opten, namely to draw on screen) and then only
adjust/compensate if another DrawingKit is used such as for printing.
The aim is not to be able to replace one font with another without changing the
layout (line break etc.) but to allow this abstract formulation of fonts, which 
matched by different font renderers in the openGL driver (based on FreeType) and
PostScript (ghostscript). WYSIWYG should be the aim not only for very 
DTP tools but for the whole windowing system.

The architecture is based on research at Stanford university/the X Consortium.
The paper which describes the basic ideas of such a fine grained scene graph 
glyphs, please have a look at the paper 

"Glyphs: Flyweight Objects for User Interfaces" which you can find at

Best regards,   Stefan
Stefan Seefeld
Departement de Physique
Universite de Montreal
email: address@hidden


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