[Octave-bug-tracker] [bug #51645] zoom to singular region dumps core

[Dan Sebald]

Follow-up Comment #10, bug #51645 (project octave):

OK.  If users complain about the warning message messing up their screen
output (because I myself often highlight text in shell window and use center
mouse button to paste), we'll just remove the message.  In a follow-up post I
will point out another warning message.

Attached are two changesets.

The first one--with the tag "INTOLERABLE_LAG"--is the implementation which
uses QTimers to confirm there is no double click before drawing.  Because the
timer needs a slot, there has to be something derived from QObject on the
receiving end.  Hence , this sort of construct has to go in GLCanvas, not
Canvas.  Anyway, it works, and I've included it here more for reference of how
to do such a thing, but honestly it doesn't make the grade.  Double click time
is a LONG time.  Do a single click and wait 0.4 seconds; yikes, unresponsive. 
Add to that the fact that this sort of delay effectively re-arranges the order
of events, which could be very important with regard to key-qualifiers.  This
isn't the way to go.

However, in the sequence of PRESS | RELEASE | PRESS | DOUBLE-CLICK | RELEASE,
one can ignore that second RELEASE event using an m_doubleClickActive state
variable (and it need not be in GLCanvas).  So I've included a second, much
smaller changeset to do just that.  I'd say this is much better and tolerable.
 In some sense having DOUBLE-CLICK action in Z+ and Z- mode is the source of
problem.  There is an Autoscale button easily near by after all.  It might be
nicer and faster if someone could quickly repeat zooming without the double
click behavior getting in the way.

So, I'd say let's make the smaller of these two changesets the tentative
modification, but hold off a little bit and let's think about this.  I mean,
I've pushed this new state variable to the lowest level so that it only
affects the repeated zooming.  But who knows?  Maybe there are other
double-click operations in the plot modes that also suffer from the follow-up
RELEASE event.

(file #41426, file #41427)
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Additional Item Attachment:

File name:
octave-qt_toolkit_debounce_doubleclick_INTOLERABLE_LAG-djs2017aug05.patch
Size:5 KB
File name: octave-qt_toolkit_debounce_doubleclick-djs2017aug05.patch Size:2 KB


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