From octave-graphics-request at bevo dot che dot wisc dot edu  Sun Mar 14 03:19:10 1999
Subject: Re: Canvas vs Plot Widget
From: Rafael Laboissiere <rafael at icp dot inpg dot fr>
To: octave-graphics at bevo dot che dot wisc dot edu
Date: 14 Mar 1999 10:19:11 +0100

>>>>> "JK" == Jonathan King <kingjw at missouri dot edu> writes:

    JK> I think it will be really tough to come up with a convincing
    JK> implementation using just pixmaps without other data
    JK> structures. This doesn't mean you can't use something like PLplot
    JK> as the basis for creating your pixmaps, only that you need to
    JK> compose those pixmaps with other stuff.

Let me just clarify my view on mouse interactivity associated with the Plot
Widget.  Even if the Plot Widget is going to be implemented as a pixmap in
which the pixels are drawn by a plotting library, the following
interactivity features should be present:

    - Ability to get the axis coordinates of mouse clicks and/or to show
      X-Y coordinates during mouse motion.

    - Zooming rectangular regions select with the mouse.

    - Scroll (when the pixmap is to big to fit in the parent window
      widget). 

I think that these features are implementable in a PLplot-based Plot
Widget.

OTOH, I do not see much sense (correct me if I am wrong, please) in
implementing some aspects of Handle Graphics, namely making all lines,
points and axes "clickable" and associating callbacks to them.  I guess
that Matlab users need this because they do not have a proper canvas widget
to play with.  If we think that Octave users will need this too, we just
include a canvas widget to the Octave GUI.

Although, if we are going to stay 100% compatible with Matlab legacy code,
the approach sketched above may be problematic.

--
Rafael Laboissière