[GRASS5] grass font

[Glynn Clements]

Radim Blazek wrote:

> I thing that the simplest solution for grass5.0.x, which should not bring new 
> bugs, would be conversion utility from other font formats (Type1, ..) to 
> Hershey Fonts format. Unfortunately I could not find such utility on the Web. 
> Anybody knows about such conversion program or why conversion to Hershey
> fonts is impossible? 

There are three basic types of fonts: stroked, outline and bitmap. 

GRASS fonts are stroked fonts; these correspond to the way in which
you write with a pen on paper.

PostScript and TrueType fonts are (usually) outline fonts; you could
convert these to stroked fonts, but the end result would be "hollow"
characters. Feed the following into ghostscript for an example:

	(Helvetica) findfont 72 scalefont setfont
	newpath 72 72 moveto
	(ABC) false charpath stroke
	showpage

BDF fonts are bitmap fonts; you can't reasonably convert these to
either stroked or outline fonts.

> 2. Long term solution 
> Let us define requirements first. I'll try to start:
> 
> - Labels (texts in map) must be identical (realy identical - the same font    
>    fonts with the same metrics) in:
>    - XDRIVER
>    - CELL, PNG, (and similar) drivers
>    - Postscript files created by ps.map
>    - all new possible clients/viewers: java, windows (not CygWin+Xfree)
> Is it possible to display (effectively) exactly the same fonts on many 
> platforms? Probably not. Where could we learn from - Acrobat , Ghostscript?)

You can display a font on any platform, if you can obtain the font
definition; the main issue here is copyright. Otherwise, you have to
limit yourself to fonts which you know will exist on any platform;
unfortunately this probably limits you to Helvetica, Times and
Courier. Users of languages which use encodings other than ISO-8859-1
are out of luck; many systems won't have any fonts for non-European
languages.

> - System fonts in some standard format should be used.  Fonts should not be
>    distributed in grass package.
> 
> - Vector fonts should be used. 
> 
> Please add new requrements and send your criticism. I am not fonts expert.
> 
> Glynn, is it solution for fonts so closely tied to new display architecture 
> or may be this task separated? 

Font handling will be a major factor in determining any new display
architecture.

At present, potential architectures can be split into two categories:

1. Generate PostScript; all drivers (apart from one for a PostScript
printer) would use ghostscript to do most of the work.

2. Do everything ourselves.

Option 1 saves us a lot of work, but also imposes some restrictions. 
Option 2 is much more work (to do it right), but doesn't impose any
restrictions.

One of the advantages of using PostScript is that it provides a lot of
desirable features "for free", e.g. affine transformations and
(decent) text rendering. However, internationalisation issues may
determine whether its text rendering is suitable; if it isn't, and we
have to implement our own text renderer, this eliminates one of the
biggest advantages of using it.

-- 
Glynn Clements <glynn.clements at virgin.net>