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ShellExecute window...

Posted on 2001-07-31
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Last Modified: 2012-06-27
I open files using ShellExecute command. The command opens application, according to file type. Can I get window handle of starting application?

For example,
 I open txt file.
 Notepad started.
 Now I want get window handle of notepad (to change size, location etc. of the window)
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Question by:Slavak
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by:Madshi
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If you know how the title and/or class of the new window will be, you can use FindWindow. If you don't know that, using ShellExecute(Ex) is not the correct solution. In that case you should use FindExecutable to find the exe which is registered for the file type (in your example *.txt). Then you should call CreateProcess. You'll get a processID from CreateProcess. After CreateProcess returned you should wait a bit to let the application start. Then you can use EnumWindows to enumerate all windows. For each enumerated window you can call GetWindowThreadProcessID to get the processID of the enumerated window. If the processID matches the processID you got from CreateProcess, you have a window of the newly created process. It's a pain to do it like that, but there is no other way (I know).

Regards, Madshi.
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by:Gwena
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Listening :-)
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by:DragonSlayer
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If you use ShellExecuteEx to execute it, you will need to pass in a PShellExecuteInfo. The function will return back the ShellExecuteInfo structure, which contains hProcess, a handle to the newly started application (of course, you need to set PShellExecuteInfo^.fMask to include SEE_MASK_NOCLOSEPROCESS). Using that handle, you can call stuff like what Madshi said.

(Hi, Madshi!)



DragonSlayer
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by:Madshi
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Hi DragonSlayer!  :-)

Unfortunately it's not fully correct, what you said. You can get a process *HANDLE* from ShellExecuteEx. But what we need for comparing enumerated windows is a process *ID*. That are two different beasts. And there is no official way to get the ID from the handle (though I'm having hacked functions that do that... :-).

Regards, Madshi.
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by:Slavak
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Thanks, Madshi.

I thinked about the way, but hoped for better way to do it.
This way has 2 major problems:
-- how much is "a bit" (time between calls to CreateProcess and EnumWindows)
-- it can be too slow

still hope for better solution :)

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by:Slavak
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I can compromise with the solution if I can GET EVENT  that started application ready
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Madshi earned 100 total points
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Well, you can call WaitForInputIdle(processHandle, INFINITE). That at least brings you nearer to the time point, where you can enumerate the windows. How about this logic?

(1) CreateProcess
(2) WaitForInputIdle
(3) Loop for 5 seconds
(4) In the loop check for a taskbar window (a window of that new process, which appears on the taskbar), if you don't find one, sleep for 100ms, then check again
(5) As soon as you find a taskbar window, break the loop
(6) If you don't find a taskbar in 5 seconds, either give back 0, or the first non-taskbar window

Is not nice, I know. But there is no real message/event, that an application has fully loaded.

It should not be slow, in case the application really will create a taskbar window. Then the logic from above should work very fine. But in case the application will never create taskbar window, you'll wait 5 seconds and nevertheless find no window...   :-(

Regards, Madshi.
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by:Slavak
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There is more elegant (but more difficult too) way:
(1) Create process
(2) Set hook on CreateWindow(ex) function in the process.

Demerit of this way is that hook function should be in dll.

I should minimize executable file(s) size.

May be you can suggest another way.

Thanks
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by:Madshi
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Well, but in your exe file you need the window handle, don't you? So you would in your exe file still need to wait for your dll to send the window handle to you, or am I wrong? So basically I see no advantage, the only advantage is that you don't need to poll, but get notified about the window creation. But polling in a loop with a sleep(100) in the loop is really no problem at all.

For what purpose do you need the window handle? What do you want to do with it? Maybe we can find a better way, if I know what you really want to do.
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by:Slavak
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I want set position and size of the window.

For this, no need return event from hook to application. I can pass required values when I set the hook, and after first top window, remove the hook.

I think about way to open file in my window, like com objects in TOLEContainer.
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by:Madshi
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Hmmm... Okay, in such a situation a hook could be solution, a bit work, but possible. However, if you look at how e.g. Delphi's windows look like (multiple top-level windows, main window, edit window, object inspector, project manager, etc) you'll run into problems with what you want to do...   :-(

Regards, Madshi.
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