Adding graphic capabilities to Gnumeric

[Miguel de Icaza <miguel nuclecu unam mx>]

Hello guys,

    Yesterday I played a little with Excel 97 plotting functions just
to learn what sort of stuff we should do for Gnumeric. 

    The graphics can be inserted either in the spreadsheet or in a
separate page.  Doing both approaches in Gnumeric is trivial.  Now,
the interesting thing is that the actual graphic page inserted is not
just the plotting region, it is some sort of drawing canvas which has
various components: the title, the axis descriptions, the annotations,
and Excel can even stick a table of the values plotted on the graphics
region (go figure the reasons for that) the data tags and on top of
that you can add drawings and text to it everywere in this drawing
canvas region. 

    So, Gnumeric will have to provide a graphic object that will be
this basic user-level canvas where we would be sticking all of the
decorations and of course, the actual graphic.

    This complex thing here is that the user can actually grab with
the mouse the data points being plotted and move them freely (with the
obvious constraints).  Once the motion has finished, the value on the
spreadsheet is modified accordingly (and of course, this can invoke
the solver for computed values).

     So, my goal is to be able to use Guppi for the emebedded graphic
inside the graphic region, but I dont think Guppi is quite ready for
this setup.  So we would have two modes of operation: Graphic modes
that are fully Gnumeric aware (by using the gnome canvas as their
engine) and the external plot-only widgets.

Comments?

Miguel.