Re: the ConTeXt terminal

[Mojca M. <moj...@gm...>]

On 6/17/06, Daniel J Sebald wrote:
> Mojca Miklavec wrote:
>
> > I'm thinking about adding an option to use PostScript instead of
> > "quasi-native" graphics for the background, but many other things have
> > higher priority for now. (I would probably need to rewrite parts of
> > PostScript terminal and to study undocumented PS code as well as
> > supporting that inclusion in ConTeXt, so it could take me some time
> > that I don't feel worth investing yet.)
>
> But if you use something derivative of pslatex, you shouldn't have to study undocumented PS code.  That should be handled correctly already.  You'd need simply to supply the proper syntax for the text that ConTeXt requires as opposed to what LaTeX requires.

I know that I could ignore the PostScript graphic commands, but I need
to study the way how (La)TeX &.PostScript are integrated/how separate
files are handled inside Gnuplot, etc. I have to patch/integrate both
terminals in this case. I'm planning to do that, but it's not really
the priority unless someone confident with that code would be willing
to help. For the moment is was much easier to write my own code for
doing the graphic.

> Unless ConTeXt is improving on TeX graphics, from what I've seen PostScript is better than TeX graphics.  Much nicer looking and controllable arrows, etc.

What exactly do you mean by TeX graphics? \begin{picture} is useless
from my point of view, picTeX might be slightly better(?), but not
that much. What "ConTeXt graphic" means in this case is the following:

    \commandtostartgraphic
    ...
    drawing commands
    ...
    \commandtostopgraphic

drawing commands (ie. everything between the two commands for start
and stop the graphic) are written to a file, processed by MetaPost
which outputs a PostScript file which is postpocessed (converted to
PDF with special trickery) and included into final PDF literally. I
don't know how exactly it works if a flavour of TeX other than pdfTeX
is used, for example XeTeX, with DVI file as an intermediate step
(.tex -> .dvi -> PDF). But when XeTeX came out for the Linux platform
last monts, Hans was sitting the whole afternoon behind the laptop
trying to fix the existing code, so that transparency started to work
with XeTeX as well.

But the nice part of it is that I don't really have to care about what
is going on behind the scenes: it simply works (with exceptions of
bugs).

With MetaPost ("ConTeXt graphics") you can basically do everything
that you can do in PostScript: the code is converted to PostScript
indeed. You can't write literal PS code, but MetaPost is still a
programming language. You can draw exactly the same arrow in MetaPost
as you can do in PostScript.

Less supported (but conditionally possible) are shading and other
patterns introduced in later versions of PostScript. But on the other
hand you can use spot colors, transparency, ...

Mojca