#!/usr/bin/env python
"""
Run wxPython in a second thread.
Overview:
Importing this module creates a second thread and starts
wxPython in that thread. Its single method,
add_cone(), sends an event to the second thread
telling it to create a VTK viewer window with a cone in
it.
This module is meant to be imported into the standard
Python interpreter. It also works with Pythonwin.
It doesn't seem to work with IDLE (on NT anyways).
It should also work in a wxPython application.
Applications already running a wxPython app do not
need to start a second thread. In these cases,
viewer creates the cone windows in the current
thread. You can test this by running shell.py
that comes with wxPython, importing viewer and
calling add_cone.
Usage:
[user]$ python
Python 1.5.2 (#1, Sep 17 1999, 20:15:36) ...
Copyright 1991-1995 Stichting Mathematisch Centrum, Amsterdam
>>> import viewer
>>> viewer.add_cone() # pop up a cone window
>>> a = 1
1
>>> viewer.add_cone() # create another cone window
Why would anyone do this?:
When using wxPython, the call to app.Mainloop() takes over
the thread from which it is called. This presents a
problem for applications that want to use the standard
Python command line user interface, while occasionally
creating a GUI window for viewing an image, plot, etc.
One solution is to manage the GUI in a second thread.
wxPython does not behave well if windows are created in
a thread other than the one where wxPython was originally
imported. ( I assume importing wxPython initializes some
info in the thread). The current solution is to make the
original import of wxPython in the second thread and then
create all windows in that second thread.
Methods in the main thread can create a new window by issuing
events to a "catcher" window in the second thread. This
catcher window has event handlers that actually create the
new window.
"""
class viewer_thread:
def start(self):
""" start the GUI thread
"""
import time
import thread
thread.start_new_thread(self.run, ())
def run(self):
"""
Note that viewer_basices is first imported ***here***.
This is the second thread. viewer_basics imports
wxPython. if we imported it at
the module level instead of in this function,
the import would occur in the main thread and
wxPython wouldn't run correctly in the second thread.
"""
import viewer_basics
try:
self.app = viewer_basics.SecondThreadApp(0)
self.app.MainLoop()
except TypeError:
self.app = None
def add_cone(self):
"""
send an event to the catcher window in the
other thread and tell it to create a cone window.
"""
import viewer_basics
if self.app:
evt = viewer_basics.AddCone()
viewer_basics.wxPostEvent(self.app.catcher, evt)
else:
viewer_basics.add_cone()
viewer = viewer_thread()
viewer.start()
def add_cone():
viewer.add_cone()
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