| 1 | #!/usr/bin/env python |
| 2 | |
| 3 | """ |
| 4 | Run wxPython in a second thread. |
| 5 | |
| 6 | Overview: |
| 7 | Importing this module creates a second thread and starts |
| 8 | wxPython in that thread. Its single method, |
| 9 | add_cone(), sends an event to the second thread |
| 10 | telling it to create a VTK viewer window with a cone in |
| 11 | it. |
| 12 | |
| 13 | This module is meant to be imported into the standard |
| 14 | Python interpreter. It also works with Pythonwin. |
| 15 | It doesn't seem to work with IDLE (on NT anyways). |
| 16 | It should also work in a wxPython application. |
| 17 | |
| 18 | Applications already running a wxPython app do not |
| 19 | need to start a second thread. In these cases, |
| 20 | viewer creates the cone windows in the current |
| 21 | thread. You can test this by running shell.py |
| 22 | that comes with wxPython, importing viewer and |
| 23 | calling add_cone. |
| 24 | |
| 25 | Usage: |
| 26 | [user]$ python |
| 27 | Python 1.5.2 (#1, Sep 17 1999, 20:15:36) ... |
| 28 | Copyright 1991-1995 Stichting Mathematisch Centrum, Amsterdam |
| 29 | >>> import viewer |
| 30 | >>> viewer.add_cone() # pop up a cone window |
| 31 | >>> a = 1 |
| 32 | 1 |
| 33 | >>> viewer.add_cone() # create another cone window |
| 34 | |
| 35 | Why would anyone do this?: |
| 36 | When using wxPython, the call to app.Mainloop() takes over |
| 37 | the thread from which it is called. This presents a |
| 38 | problem for applications that want to use the standard |
| 39 | Python command line user interface, while occasionally |
| 40 | creating a GUI window for viewing an image, plot, etc. |
| 41 | One solution is to manage the GUI in a second thread. |
| 42 | |
| 43 | wxPython does not behave well if windows are created in |
| 44 | a thread other than the one where wxPython was originally |
| 45 | imported. ( I assume importing wxPython initializes some |
| 46 | info in the thread). The current solution is to make the |
| 47 | original import of wxPython in the second thread and then |
| 48 | create all windows in that second thread. |
| 49 | |
| 50 | Methods in the main thread can create a new window by issuing |
| 51 | events to a "catcher" window in the second thread. This |
| 52 | catcher window has event handlers that actually create the |
| 53 | new window. |
| 54 | """ |
| 55 | |
| 56 | class viewer_thread: |
| 57 | def start(self): |
| 58 | """ start the GUI thread |
| 59 | """ |
| 60 | import time |
| 61 | import thread |
| 62 | thread.start_new_thread(self.run, ()) |
| 63 | |
| 64 | def run(self): |
| 65 | """ |
| 66 | Note that viewer_basices is first imported ***here***. |
| 67 | This is the second thread. viewer_basics imports |
| 68 | wxPython. if we imported it at |
| 69 | the module level instead of in this function, |
| 70 | the import would occur in the main thread and |
| 71 | wxPython wouldn't run correctly in the second thread. |
| 72 | """ |
| 73 | import viewer_basics |
| 74 | |
| 75 | try: |
| 76 | self.app = viewer_basics.SecondThreadApp(0) |
| 77 | self.app.MainLoop() |
| 78 | except TypeError: |
| 79 | self.app = None |
| 80 | |
| 81 | def add_cone(self): |
| 82 | """ |
| 83 | send an event to the catcher window in the |
| 84 | other thread and tell it to create a cone window. |
| 85 | """ |
| 86 | import viewer_basics |
| 87 | |
| 88 | if self.app: |
| 89 | evt = viewer_basics.AddCone() |
| 90 | viewer_basics.wxPostEvent(self.app.catcher, evt) |
| 91 | else: |
| 92 | viewer_basics.add_cone() |
| 93 | |
| 94 | viewer = viewer_thread() |
| 95 | viewer.start() |
| 96 | |
| 97 | def add_cone(): |
| 98 | viewer.add_cone() |
| 99 | |
| 100 | |