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95 lines
3.7 KiB
95 lines
3.7 KiB
6 years ago
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# A sample originally provided by Richard Bell, and modified by Mark Hammond.
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# This sample demonstrates how to use COM events in an aparment-threaded
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# world. In this world, COM itself ensures that all calls to and events
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# from an object happen on the same thread that created the object, even
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# if they originated from different threads. For this cross-thread
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# marshalling to work, this main thread *must* run a "message-loop" (ie,
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# a loop fetching and dispatching Windows messages). Without such message
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# processing, dead-locks can occur.
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# See also eventsFreeThreaded.py for how to do this in a free-threaded
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# world where these marshalling considerations do not exist.
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# NOTE: This example uses Internet Explorer, but it should not be considerd
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# a "best-practices" for writing against IE events, but for working with
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# events in general. For example:
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# * The first OnDocumentComplete event is not a reliable indicator that the
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# URL has completed loading
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# * As we are demonstrating the most efficient way of handling events, when
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# running this sample you will see an IE Windows briefly appear, but
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# vanish without ever being repainted.
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import sys
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import os
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import win32com.client
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import win32api
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import win32event
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# sys.coinit_flags not set, so pythoncom initializes apartment-threaded.
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import pythoncom
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import time
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class ExplorerEvents:
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def __init__(self):
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self.event = win32event.CreateEvent(None, 0, 0, None)
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def OnDocumentComplete(self,
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pDisp=pythoncom.Empty,
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URL=pythoncom.Empty):
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thread = win32api.GetCurrentThreadId()
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print("OnDocumentComplete event processed on thread %d"%thread)
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# Set the event our main thread is waiting on.
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win32event.SetEvent(self.event)
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def OnQuit(self):
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thread = win32api.GetCurrentThreadId()
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print("OnQuit event processed on thread %d"%thread)
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win32event.SetEvent(self.event)
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def WaitWhileProcessingMessages(event, timeout = 2):
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start = time.clock()
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while True:
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# Wake 4 times a second - we can't just specify the
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# full timeout here, as then it would reset for every
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# message we process.
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rc = win32event.MsgWaitForMultipleObjects( (event,), 0,
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250,
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win32event.QS_ALLEVENTS)
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if rc == win32event.WAIT_OBJECT_0:
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# event signalled - stop now!
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return True
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if (time.clock() - start) > timeout:
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# Timeout expired.
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return False
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# must be a message.
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pythoncom.PumpWaitingMessages()
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def TestExplorerEvents():
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iexplore = win32com.client.DispatchWithEvents(
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"InternetExplorer.Application", ExplorerEvents)
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thread = win32api.GetCurrentThreadId()
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print('TestExplorerEvents created IE object on thread %d'%thread)
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iexplore.Visible = 1
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try:
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iexplore.Navigate(win32api.GetFullPathName('..\\readme.htm'))
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except pythoncom.com_error as details:
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print("Warning - could not open the test HTML file", details)
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# Wait for the event to be signalled while pumping messages.
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if not WaitWhileProcessingMessages(iexplore.event):
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print("Document load event FAILED to fire!!!")
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iexplore.Quit()
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#
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# Give IE a chance to shutdown, else it can get upset on fast machines.
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# Note, Quit generates events. Although this test does NOT catch them
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# it is NECESSARY to pump messages here instead of a sleep so that the Quit
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# happens properly!
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if not WaitWhileProcessingMessages(iexplore.event):
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print("OnQuit event FAILED to fire!!!")
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iexplore = None
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if __name__=='__main__':
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TestExplorerEvents()
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