Using ShellExecute or CreateProcess caller lose its focus

Lost User

sdancer75 wrote:

As you can see ... What ever I tried I had no success.

We cannot see anything, you need to show your code and explain where it goes wrong.

Jochen Arndt

When the external update process should also update the executable of your main application, that must be terminated before the new exe file can be copyied. So there is no need to get the focus back. A typical sequence for such a process:

Ask the user if the update should be installed
Perform closing tasks that are time consuming or require user interaction like closing open documents
Start the update process
Terminate your application
The update process should check if there is a running instance of your application (after a short wait time) and terminate with an error if so
The update process might restart your application

In another post you mentioned that you are using WaitForSingleObject to wait for the update process to be terminated. If you call that from within your main thread, your application's message loop is blocked so that paint events are not processed. If you don't want to update the executable itself and must wait for the external process to be finished start the process from within a worker thread where you can call WaitForSingleObject without blocking the message loop. Use a global state variable indicating that the update is executing to disallow specific tasks of your application or just show a modal dialog that is closed automatically when the update has finished.

Victor Nijegorodov

> I need the parent window -which is the main app- to be disabled (like a modal dialog box behaviour) until the new app -update application- will finish its job. Did you try to hide or minimize the "parent window" instead?

sdancer75

Yes this way it works but I dont want to minimize the parent window. I need a modal like behaviour.

sdancer75

sdancer75

Quote:

When the external update process should also update the executable of your main application, that must be terminated before the new exe file can be copyied. So there is no need to get the focus back.

I have managed this kind of problems with success so, dont bother with that.

Quote:

In another post you mentioned that you are using WaitForSingleObject to wait for the update process to be terminated. If you call that from within your main thread, your application's message loop is blocked so that paint events are not processed.

Thats correct. Windows Vista/Win7/Win8 does not have problems with paint events but XP they have. For that reason I want to disable the parent to avoid such kind of problems.

Quote:

If you don't want to update the executable itself and must wait for the external process to be finished start the process from within a worker thread where you can call WaitForSingleObject without blocking the message loop. Use a global state variable indicating that the update is executing to disallow specific tasks of your application or just show a modal dialog that is closed automatically when the update has finished.

I update the executables too, but I dont have problems with that. If you download the sample code, you will understand the focus problem i currently have.

sdancer75

sdancer75

I posted a link in my 1st post with a sample MFC/SDI application that have all the code you need. http://www.filedropper.com/shellexecutecreateprocesstestapp[^]

sdancer75

Victor Nijegorodov

But what is a problem for you to attach a piece of code to your post?

sdancer75

Hi, No problem at all, I just gave all the code in the link. Anyway, I attach you the most important code from the sample app.

void CMainFrame::OnRunExternalApp() {

SHELLEXECUTEINFO	lpExecInfo;
PROCESS\_INFORMATION processInfo;
DWORD				dwExitCode;
HANDLE				hProcess = 0;
BOOL				bResult;
LPTSTR				strCmd;





strCmd = \_T("");

//bResult = StartupApplicationWithShell (\_T("LiveUpdate.exe"), (LPTSTR)strCmd,  GetSafeHwnd(), &hProcess);
bResult = StartupApplicationWithProcess (\_T("C:\\\\Windows\\\\notepad.exe"), (LPTSTR)strCmd,  &processInfo);

EnableWindow(FALSE);



if(bResult) { //(UINT)result > HINSTANCE\_ERROR)

	//ShowWindow( SW\_HIDE );
	//ShowWindow( SW\_SHOWNOACTIVATE );
	

    //WaitForSingleObject( hProcess, INFINITE );
	WaitForSingleObject(processInfo.hProcess, INFINITE);
	//WaitForMultipleObjects(1, &processInfo.hThread, TRUE, INFINITE );



	   
	//if (!GetExitCodeProcess(hProcess, &dwExitCode)) {
	//	   	AMLOGINFO(\_T("LiveUpdate is not terminated normally.")); 
	//}
	if (!GetExitCodeProcess(processInfo.hProcess, &dwExitCode)) {
		   	//failed
	}
	CloseHandle( processInfo.hProcess );
    CloseHandle( processInfo.hThread );
	//CloseHandle(hProcess);


} else {
	
	// failed
}

BringWindowToTop();
EnableWindow(TRUE);

//UpdateWindow();

//::SetWindowPos( GetSafeHwnd(), HWND\_TOP, 0, 0, 0, 0, SWP\_NOMOVE | SWP\_NOSIZE | SWP\_SHOWWINDOW );

}

sdancer75

Victor Nijegorodov

Maybe this will help you: windows forceforeground (bringWindowToTop) brings it to top but without being active (a forceForeGround that works with windows xp and windows 7) | Roger's woze[^]

sdancer75

I will give it a try but as you may already see, I am using the bringWindowToTop without success. Thanx

sdancer75

Jochen Arndt

My intention was to show you a solution that differs from your current implementation and pointing to the fact that you block the message loop. You must not call WaitForSingleObject from within your main thread to ensure that the window is repainted (e.g. when moving another window over the application window). That will solve the problem of paint corruption and might also solve your other problems. Overall I think I must shout: Don't use WaitForSingleObject from within your main GUI thread; especially with long wait times! I (like most others here) will not download a complete project and build it. Especially in this case where it must be tested with XP too.

Victor Nijegorodov

Yes, I see. But try it in the following order: EnableWindow SetForegroundWindow SetActiveWindow BringWindowToTop

sdancer75

Thanks for your time. Do you suggest to use WaitForMultipleObjects instead ?

sdancer75

Jochen Arndt

No. That is similar (it can just wait for more events). Don't use any blocking wait (or more general: any function that may block for long intervals) from within the main GUI thread. As already suggested you might use a worker thread.

sdancer75

Seems to work with one exception. I get a flicker since it instantly lose its focus and then regain it back....

sdancer75

sdancer75

The worker thread does not lock the main app as long as its active. I dont want this. I just want a modal like behaviour and not floating windows all around the desktop.

sdancer75

sdancer75

One last thing. The EnableWindow(xxxx) do the mess in my situation. If I dont use this function I have to process the paint messages from the child window. In this case I think that

WaitForMultipleObjects

will do the job in the XP case. Do you agree with this guess ? .... or better i will give it a try right now.

sdancer75

Jochen Arndt

You can disable your app window and/or show a modal dialog while the worker thread is active and re-enable when it finishes. So the message loop is not blocked and repainting is ensured while the app itself is blocked. What do you mean by floating windows? There is no additional window.

sdancer75

Quote:

You can disable your app window and/or show a modal dialog while the worker thread is active and re-enable when it finishes.

You mean a dummy dialog just to block to main app ?

Quote:

What do you mean by floating windows? There is no additional window.

I mean the two windows that will be active at the same time (main and child) and user will have the ability to work with the both of them.

sdancer75

Jochen Arndt

sdancer75 wrote:

You mean a dummy dialog just to block to main app ?

Yes. Or just disable the main window. The dialog can show something like "Please wait until the update is installed".

sdancer75 wrote:

I mean the two windows that will be active at the same time (main and child) and user will have the ability to work with the both of them.

When the app is blocked by disabling or a dialog it can't be moved by the user (the dialog may be moved). So when not using a dialog it is the same behaviour as with your current solution.