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f6bcfd97 BP |
1 | #!/usr/bin/env python |
2 | """ | |
3 | Run wxPython in a second thread. | |
4 | ||
5 | Overview: | |
6 | Importing this module creates a second thread and starts | |
7 | wxPython in that thread. Its single method, | |
8 | add_cone(), sends an event to the second thread | |
9 | telling it to create a VTK viewer window with a cone in | |
10 | it. | |
11 | ||
12 | This module is meant to be imported into the standard | |
13 | Python interpreter. It also works with Pythonwin. | |
14 | It doesn't seem to work with IDLE (on NT anyways). | |
15 | It should also work in a wxPython application. | |
16 | ||
17 | Applications already running a wxPython app do not | |
18 | need to start a second thread. In these cases, | |
19 | viewer creates the cone windows in the current | |
20 | thread. You can test this by running shell.py | |
21 | that comes with wxPython, importing viewer and | |
22 | calling add_cone. | |
23 | ||
24 | Usage: | |
25 | [user]$ python | |
26 | Python 1.5.2 (#1, Sep 17 1999, 20:15:36) ... | |
27 | Copyright 1991-1995 Stichting Mathematisch Centrum, Amsterdam | |
28 | >>> import viewer | |
29 | >>> viewer.add_cone() # pop up a cone window | |
30 | >>> a = 1 | |
31 | 1 | |
32 | >>> viewer.add_cone() # create another cone window | |
33 | ||
34 | Why would anyone do this?: | |
35 | When using wxPython, the call to app.Mainloop() takes over | |
36 | the thread from which it is called. This presents a | |
37 | problem for applications that want to use the standard | |
8b9a4190 | 38 | Python command line user interface, while occasionally |
f6bcfd97 | 39 | creating a GUI window for viewing an image, plot, etc. |
8b9a4190 | 40 | One solution is to manage the GUI in a second thread. |
f6bcfd97 BP |
41 | |
42 | wxPython does not behave well if windows are created in | |
43 | a thread other than the one where wxPython was originally | |
44 | imported. ( I assume importing wxPython initializes some | |
45 | info in the thread). The current solution is to make the | |
46 | original import of wxPython in the second thread and then | |
47 | create all windows in that second thread. | |
48 | ||
49 | Methods in the main thread can create a new window by issuing | |
50 | events to a "catcher" window in the second thread. This | |
51 | catcher window has event handlers that actually create the | |
52 | new window. | |
53 | """ | |
54 | ||
55 | class viewer_thread: | |
56 | def start(self): | |
57 | """ start the GUI thread | |
58 | """ | |
59 | import thread,time | |
60 | thread.start_new_thread(self.run, ()) | |
61 | ||
62 | def run(self): | |
63 | """ | |
64 | Note that viewer_basices is first imported ***here***. | |
65 | This is the second thread. viewer_basics imports | |
66 | wxPython. if we imported it at | |
67 | the module level instead of in this function, | |
68 | the import would occur in the main thread and | |
69 | wxPython wouldn't run correctly in the second thread. | |
70 | """ | |
71 | from viewer_basics import * | |
72 | try: | |
73 | self.app = SecondThreadApp(0) | |
74 | self.app.MainLoop() | |
75 | except TypeError: | |
76 | self.app = None | |
77 | ||
78 | def add_cone(self): | |
79 | """ | |
80 | send an event to the catcher window in the | |
81 | other thread and tell it to create a cone window. | |
82 | """ | |
83 | import viewer_basics | |
84 | if self.app: | |
85 | evt = viewer_basics.AddCone() | |
86 | viewer_basics.wxPostEvent(self.app.catcher, evt) | |
87 | else: | |
88 | viewer_basics.add_cone() | |
89 | ||
90 | viewer = viewer_thread() | |
91 | viewer.start() | |
92 | ||
93 | def add_cone(): | |
94 | viewer.add_cone() | |
95 | ||
96 |