I have a WPF application with a GUI on the MainWindow. I want to dispose this window after a while based on some user actions. But I want the application continue to run in background. I know that Window can be set to hidden, but it still uses the memory.How to destroy the MainWindow without quitting the WPF application? Also I would like to know if it is possible to relaunch the MainWindow after it was disposed.
this.Close(); //Will close the window but keep the application running.
var mw = new MainWindow();
mw.Show(); //Will open a new MainWindow and show it.
mw.Close(); //Close this one too.
That said hiding it is the best choice, the amount of memory it uses should really be irrelevant. That's what memory is there for.
Related
I've a WPF App. Windows Start-up, run it. after 'OnStartup' ,the MainWindow appears,then It's very slow to open A window. Opening B Window is fast. Open B before A, Opening B window is slow.
Why is there such a situation and how to solve it?
It's slow because Window Show Method,It takes about 5s,second, 0.5s.
This only happens when Windows is first started.
If i don't restart Windows, just restart the App, just 1s+ .
I had the same problem using a Method from another class inside my Start-Up.
My Solution was just to change the method to a static one.
This works, cause the StartUp wasnt forced to create a new Object of the Class( there was a lot of Stuff going on in the ctor).
I'm working WPF application, Currently it has one window and at specific time (As per my requirement). It's displayed on top most priority.
this.Visibility = Visibility.Visible;
this.Topmost = true;
Now, I want like user should close first this windows(WPF application window), till cannot access any other thing from system.(user cannot able access even other application also) Seems like to force close first this window
I've been searched, but not getting anything.
How Can i do that?
You can't.
Imagine another application tried to do the same thing at the same time - you can't close window A before window B, but you can't close window B before window A, but...
Edit: the short version above can be misunderstood, so in more detail:
Let's say, your application has this very important message for the user, so it opens a special window. The special property of this window is that as long as it exists, the user can't access any other window. This also means, the user cannot close any other window.
Now while the user reads the message, another application has an important message, so it opens a window, using the same method as you to block access to other windows until it is closed.
The user cannot close the second window, because the first window is special and must be closed first. The user cannot close the first window, because the second window is special and must be closed first => the UI is completely locked. The poor user must use Task Manager to kill one of the two applications or reboot the system.
See also Raymond Chen's more detailed discussion of this principle.
Is there some way to watch for / intercept a window opening in Windows and then to block said window from opening? This would be for an application that's already running and I wouldn't want to stop the process, just close the popup window it spawns.
Update:
A process is already running (e.g. it's in Task Manager) but has no visible windows.
At some random time, that process will popup a window
I manually close the window (click "OK").
The process continues to run at this point and will, again, popup a window a bit later (repeating these steps).
I want to automate step #3, where I have to manually close the popup, by intercepting that window opening and closing it or hiding it or never letting it open in the first place. I don't want to do this by polling the open windows. I want to receive some event that a window is about to open.
I do not control this other application, so I can't otherwise change it. And I don't want to kill the process, itself.
If you're trying to do what I asked (allow only one instance of a program to run at a time), here is an elegant solution using a Mutex. You can probably copy and paste most of that code to achieve what you want.
I am asking this, because i want to know if when we are running an app, for start if we have an window to authenticate like a Log In window, after validating the user, can we open the Main Window in the same Thread without creating a new one?
I am trying to do this in WPF, but i think that is same thing in WPF or in Windows Forms.
Yes, you can.
Just do it.
When you generate a Windows Forms application via the IDE, it will generate the code for one form, as well as a Main function that displays the form at runtime. You can rewrite the Main method so it displays one form modally then displays the next form.
But there's a simpler way to achieve your objectives:
Have two windows: your Main window, where most of the work is done, and the login screen.
In the OnLoad event of your main window, create an instance of your login window and call ShowModal() on this instance.
If the login fails, then exit the application.
This question does not offer enough context to tell you how to do this in your specific case. In general you can just Close() a window, construct a new one and call Show() on it.
You should make sure the Application.ShutdownMode does not kill off your application when the window is closed though.
I'm writting an WPF application using the mvvm toolkint.
In the main windows I have a command in a button that open another window using:
catView.ShowDialog();
Well, I close that window (using a close button or the X) and when I close the main window, the app is still running and I have to kill it.
If I don't open the second window, the app shutdown normally.
Why if I open another window I can't close the app normally?
I have this in the close button of the second window:
this.DialogResult = true;
this.Close();
On the other hand, I start the app in this way (mvvm toolkit way):
Views.MainView view = new Views.MainView();
view.DataContext = new ViewModels.MainViewModel();
view.Show();
Thank you very much.
The problem is probably unrelated to opening and closing the window but is somthing inside that window.
This usually happens when you have another thread still running when you close the application, check for anything that might be creating a new thread inside the window's code (including System.Threading.Thread, ThreadPool, BackgroundWorker and 3rd party components), make sure all background threads shut down before closing the application (or if you can't shut them down at least mark them as background threads).
Also look for anything that can open another (invisible) window, it's common to use window messages to an invisible window as an inter-process communication mechanism, again look for 3rd party code that might be doing that.
Nir is correct, a thread is probably still running in your other window.
You can fix this by terminating the application's thread dispatcher when the window closes.
public Window1()
{
InitializeComponent();
// This line should fix it:
this.Closed += (sender, e) => this.Dispatcher.InvokeShutdown();
}
I'm happy to be corrected if this is not the right way to do things. Worked well for me though.
PS.
If your other window is designed to run in a different thread, then read this by Eugene Prystupa:
running-wpf-application-with-multiple-ui-threads
I don't know if this is causing your issue or not, but you don't need the call to Close() in your second window. Setting the DialogResult automatically closes the window.