PyWin32: detect "ready" before using SendKeys again?

Question

I'm using the following code to send keystrokes to an application:

import win32com.client
import time
process_id = 2032 # I change this value if needed
shell = win32com.client.Dispatch("WScript.Shell")
shell.AppActivate(process_id)
shell.SendKeys('^o')
time.sleep(.5)
# more input ...

The problem is: at some point everything goes downhill, meaning: the application is hanging (unpredictable for how long and when!) for whatever reason with unpleasant consequences. For example instead of clicking the "OK" button via the {ENTER} command, that keystroke does something else. After that all the keystrokes mess things up because they do not do what they were intended to do. Is there a difference between using time.sleep and win32api.sleep by the way? And is there a systematic way to check whether the application that I'm sending the keystrokes to, is in a stable ready-state again?

The functions of time.sleep and win32api.sleep are the same, except that time.sleep is in seconds and win32api.sleep is in milliseconds. — Strive Sun
– Strive Sun, Commented Sep 27, 2019 at 10:03
@David: it does help. I can use a sleep delay which gives the program the time it needs to open a file or make edits or save a modified file. I've had scenarios where it completely breaks without the delays. But instead of guessing which delay can handle any circumstances, I would prefer a more systematic solution. — Robert
– Robert, Commented Sep 30, 2019 at 7:33

Drake Wu · Accepted Answer · 2019-09-27 09:56:10Z

0

If the application is developed by you, you can use SendMessageTimeout to check the response of the app window. If the response times out, the application is considered to be hang on(not on ready-state).

answered Sep 27, 2019 at 9:56

Drake Wu

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5 Comments

Robert Over a year ago

If the application was developed by me I would not need to send keystrokes to it ;-) I'm trying to execute a program thousands of times (once for every file) and the program doesn't have an API nor can it be executed via the command line.

Drake Wu Over a year ago

Based on this answer and document, does Process.Responding Property help?

Robert Over a year ago

Saw the last comment just now: looks like Process.Responding is not available in pywin32. I have searched for "responding" in the documentation but I only find 2 items which seem to be unrelated :-/

Robert Over a year ago

I'm trying to find a way to port my code to C#, so that I can test Process.Responding, but it doesn't look like in C# it is as simple as shell = win32com.client.Dispatch("WScript.Shell")

Robert Over a year ago

I think I found (part of) the answer. It looks like I'm using AppActivate too much. Using AppActivate shortly before SendKeys seems to mess things up (swallowing letters etc). So what I do now instead is to check whether my app still has focus. If it doesn't, I refocus and sleep for 2 seconds before sending keys (or calling AppActivate again in case focus got lost again during the sleep).

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