Re: [Plplot-devel] plGetCursor() return value (was Should plgetpos ...)

[Maurice L. <mj...@ga...>]

Alan W. Irwin writes:
 > On Wed, 27 Feb 2002, Maurice LeBrun wrote:
 > 
 > > I don't really think the return code should be overloaded with window number.
 > > To me it's better/clearer to put it in a separate PLGraphicsIn struct entry.
 > 
 > That's okay if you are talking about plTranslateCursor, but I hope you
 > ignore that completely for now since it is a separate issue.  c_plcalc_world

Right, I was talking about plTranslateCursor.  My message was more relevant
when I wrote it, quite a few hours before it actually appeared.

 > does not use PLGraphicsIn data since it is common API where the various
 > front ends typically demand simple variable or array argument lists.  Its
 > purpose is to convert relative device coordinates to world coordinates with
 > no assumptions about what the front ends will use that data for.  Is there
 > any reason in the c_plcalc_world case not to return -1 for the subpage
 > number when there is no valid subpage?

Sounds fine.
 > I understand the first part, but I don't see the problem since each subpage
 > (or window or subwindow, grrr) is registered as you say.  But I am not sure
 > what you mean by "per-page list of windows".  Is that a list of sub-pages
 > for the current page?  If so, isn't that exactly what your registering
 > already does so that to get data for each subpage you simply walk through
 > the list?  For example, c_plcalc_windows does this by the following
 > fragment of code:
 > 
 > for (i = lastwin; i >= firstwin; i--) {
 >       w = &plsc->plwin[i % PL_MAXWINDOWS];

Whoops, I forgot that was in there.. cool.  OK, so forget about that
part of my message as it's already done.  Then if you are returning the
window number as found above, I'm happy.

 > One concern I still have with c_plcalc_world is whether it gives good
 > results for multiple viewports per (sub-)page.  Geoffrey, I hope you will
 > test that directly since you brought up this case originally (;-)) and you
 > apparently had several examples of this you were concerned about.

It should.  The plsc->plwin struct only cares about windows "registered"
through the plwind call, so it's nicely general.  Doesn't care if it's
in a subwindow or not.

 > Also, to move to a related topic, can anybody explain the cursor freeze
 > I encountered when outside a viewport?  I assume it is an x01c.c problem or
 > else a problem in the xwin, tk, and ntk drivers.

Hmm.. never noticed it before.  Crappy error handling probably. :)
If you invoke locate with the "L" key binding there's no problem.
I'll look into it when I get a chance.

 > This thread has been confused today because the e-mail delivery for
 > plplot_devel has been extraordinarily erratic (one of my key messages about
 > the cursor freeze, etc. got held up for many hours while later messages
 > sailed through). Thus, I am going to send extra copies of this directly to
 > the principal contributors (Maurice, Geoffrey, and Joao) to make sure
 > they get it in a timely manner.
 > 
 > Alan

-- 
Maurice LeBrun    mj...@ga...