John Pote wrote:
Hi all,
I’m new to wxpython and so far finding it pretty good. Mainly because
Glade (came with Stani’s Python Editor) makes GUI design and moding much
easier than hand hacking tkinter code. I have some questions about idle
time:
- If an idle event causes a handler function to be invoked does the
window freeze (ie not respond to mouse clicks etc) until the handler
returns?
Yes. The idle event handlers are called in the same thread as any other
event handler, and so just as in those cases the handler needs to return
in order for more events to be sent.
- Assuming the window does not freeze (or unfrozen via a yield() call
which I assume turns the function into a generator a la python) could
the handler be re-entered in the following scenario:
a. idle event causes handler to be entered
b. while running some event happens, eg click on a button, which
does something and then finishes putting the window into the idle state
again and hence the issuing of another idle event.
c. this event propagates through the event tables as before and
causes a second instance of the idle handler to be started.
While any event handler is running no more events are dispatched unless
you do something that allows them to be. For example, calling
wx.Yield() (or any of the similar functions) will essentially run
iterations of the MainLoop until there are no more pending events, and
wx.Dialog.ShowModal will enter a nested event loop that restricts mouse
and UI interaction to the dialog, but other kinds of events (paint,
timers, idle, etc.) can still be sent to other windows.
So I now have two handler events running. This would not be what I want
and would put an instance count into the handler class and return
immediately if an instance was already running.
- How would you advise using wxPython as a GUI front end to an app that
needs continuous running. eg monitoring and responding to a serial port
stream. I found tkinter far to slow to do everything in the idle loop.
So I did the serial port stuff in a separate thread and queued messages
for the GUI to/from an idle handler. No speed problems now and GUI
update fast enough.
That same approach would work well with wxPython.
See also: http://wiki.wxpython.org/index.cgi/LongRunningTasks
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Robin Dunn
Software Craftsman
http://wxPython.org Java give you jitters? Relax with wxPython!
Robin,
Wow! such a quick and helpful response. Long running tasks link very useful - printed and filed for future ref.
Many thanks
John