Re: [guppi-list] Re: piechart component project

[Bernhard Reiter <bernhard uwm edu>]

On Thu, Mar 11, 1999 at 08:07:07PM -0500, Havoc Pennington wrote:
> > The guppi project seems to be the one most closely related.

> Guppi consists of several components:

We also look forward to oo-model the data and control handling 
which will be need to represent in drawing piecharts (and maybe charts).

>  - "Plot state" objects, which contain information like the data to 
>     be plotted, what range the axes cover, etc. All the parameters 
>     for the plot.
> 
>  - A Gnome frontend; this is a way to represent plot state objects 
>    via a canvas item, first, and second a bunch of container glue
>    that is used only when Guppi is standalone (in "component"
>    mode, only the canvas item is used and the container application
>    will provide the glue).
> 
>  - Guile scripting; there are two levels of this, Guile scripting 
>    for the backend "plot state" objects and Guile scripting for 
>    the Gnome frontend in particular.
> 
>  - The Goose statistical library; Goose provides a bunch of statistical 
>    operations, and is available from within Guppi. It also has 
>    Guile bindings.
> 
>  - A "data pool" which can store numeric data and lets you keep 
>    track of it and browse it in various ways.

If I understand this correctly, this sepereated the data into
values (data pool) and label, axis describtion and parameters (plot state).
This occurs to be as not keeping the methods and the corresponding 
data together. I still have to do some thinking to it.

Currently Frank, Jan and I are setting up our development environments
and learning to use them, because we all might work on different 
operating systems.  (UWM here uses OSF1/alpha machines and most 
development tools are not installed.)
We will definetly have a look at guppi, though it seems to 
be a bit difficult to get the develpment version out of CVS and running.

> The above components are all implemented to some extent for bar charts and
> scatter plots. No pie chart so far. :-)

This is, what I read out of the webpages. Good to know it is correct. ;)
We will probably take our time to come up with some design for piecharts
then.

> For printing, I (or we, perhaps :-) will be using the gnome-print library
> to render each "plot state" object. We could add libplot support too, as
> yet another way to represent the plot state objects (PostScript, Gnome,
> Guile, ...). 

Making the objects available is very important.
I also think that libplot might be a very good idea.

> For saving to a file, I'm using Daniel Veillard's gnome-xml package. Right
> now Guppi only saves its numeric data, but once the plots are more stable
> they will be able to save in XML format as well.
An XML format also seems to be a good idea.

The two important things different from our goals with creating
a piechart package are:
	- A general API of using chart programs with other programs
		two levels:
			file communication for data and commands
			direct communication over CORBA or COM
	- Portability
		All the gome components used are fine,
		but we would need them seperately.
		This especially holds true for the GUI part.
		And the scripting part.

> So to do a pie chart you would need to create PieState, the
> GnomeCanvasItem for representing the pie chart, to start.  Then Guile
> bindings for your PieState, and the ability to convert to XML and to
> render via gnome-print or libplot. 

We three do not have much experience with guile and GnomeCanvas at
all, so expect slow progress. 

> Unfortunately the Guppi source code is not very well organized right now;
Which would help in get us started faster.

So this is my first brain dump on the issues,
sorry that it took so long!

	Bernhard

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