Re: [Plplot-general] GetCursor and multiple subwindows..

[Alan W. I. <ir...@be...>]

On 2005-02-28 17:42-0700 R. V. Urvashi wrote:

> Hi
>
> I'm using the C++ API for PLPLOT, and trying to use "GetCursor" to record
> the world co-ordinates and subwindow index from a cursor event. Following
> this event, I need to 'advance' to the chosen subwindow, and overlay a
> plot.  This entire process needs to be done repeatedly.
>
> Given a valid subwindow 'n', I am able to get the overlay plot on the
> correct subwindow by doing the following
>
> pls->adv(n)
> pls->vpor(...)
> pls->wind(...)
> ...plot
>
> However, when this is put into a loop and done repeatedly, the
> 'subwindow' member returned via GetCursor does NOT always have the correct
> subwindow index. Could someone please tell me if I'm missing something, or
> if this could this be a bug ?

The underlying C plGetCursor ultimately calls plcalc_world to get all the
required information.  That latter routine is documented at 
http://plplot.sourceforge.net/docbook-manual/plplot-html-5.3.1/plcalc_world.html.
Note, the documentation there of the returned window index.  You may be
violating one of the many documented assumptions in obtaining that index.
Also, please look at
http://plplot.sourceforge.net/docbook-manual/plplot-html-5.3.1/viewport_window.html
for an explanation of the hierarchy of viewing surfaces, (sub-)pages,
viewports, and windows.

I believe your above logic should work if you create sub-pages with plssub
(note in CVS I have just changed that documentation to refer to the proper
subpage term rather than sub-window) with one viewport and corresponding
window on each, and if you mouse click _inside_ the viewport/window and not
in the outer areas where the text labels go which is outside the
viewport/window for the subpage.

If after this explanation and reading the documentation you are still having
difficulty understanding the results from GetCursor, try as a simple test
calling calc_world, the C++ wrapped version of plcalc_world using
appropriate relative device coordinate that are inside/outside the window of
each sub-page.  What window indices are returned by such an experiment?  If
you are not getting the indices you expect from that experiment, please post
the complete simple test code here.

Alan
__________________________
Alan W. Irwin
email: ir...@be...
phone: 250-727-2902

Astronomical research affiliation with Department of Physics and Astronomy,
University of Victoria (astrowww.phys.uvic.ca).

Programming affiliations with the FreeEOS equation-of-state implementation
for stellar interiors (freeeos.sf.net); PLplot scientific plotting software
package (plplot.org); the Yorick front-end to PLplot (yplot.sf.net); the
Loads of Linux Links project (loll.sf.net); and the Linux Brochure Project
(lbproject.sf.net).
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