I wanted to write a program that opened a certain form based on certain criteria. In this particular case, if the shift key is down it will call Form1. If the key is not down, it will check the registry for a key. If the key is not there, it will load Form1. If the key IS there, it will do some checking, load the value and load form2.
The odd behavior I am seeing is that if Form1 gets loaded - either thru the shift key being held down, or by the reg key not being there, if the user clicks on the X in the upper right, it returns BACK to the Program.cs code from whence it came and does not exit the appliaction.
here is part of the code from Program.cs. I wanted to do the checking in Program.cs so I didn;t have to load and hide forms.
if (Control.ModifierKeys == Keys.Shift)
{
//MessageBox.Show("Shift key held down");
Application.Run(new Form1());
}
using (var hkcu = RegistryKey.OpenBaseKey(RegistryHive.CurrentUser, RegistryView.Registry64))
using (var key = hkcu.OpenSubKey(#"SOFTWARE\clpCopy"))
{
if (key == null)
{
hkcu.Close();
//MessageBox.Show("Key not found.");
Application.Run(new Form1());
//MessageBox.Show("Returning from Form 1.");
}
}
On Form1 I have added Form1_FormClosing to Form1.cs to catch the form close:
private void Form1_FormClosing(Object sender, FormClosingEventArgs e)
{
Application.Exit();
}
But when you click the X on Form1, it doesn't exit the app, it returns BACK to Program.cs and continues on with the rest of the code.
I have a Cancel button on Form1 which works and closes the app.
How can I force the form to close if I click on X? Why does it go back to the code in Program.cs?
You're seeing the expected behaviour.
Try this code:
var f = new Form();
f.Click += (s, e) => Application.Exit();
Application.Run(f);
Console.WriteLine("Hello");
The word Hello is not displayed to the console until the form is clicked on or it is closed.
Application.Run holds execution until an Application.Exit() call, or the main form closes, then execution continues. Application.Exit() doesn't abort threads or close the process - it just closes all forms and cleans up the message pump and allows the calling code to continue.
Related
I have some code meant to open a new windows form when one is closed, and yet I get nothing, no error.
I've tried a few different methods for opening a new form on a Form.FormClosed event.
This is the code I have right now:
private void Form1_FormClosed(object sender, FormClosedEventArgs e)
{
Form1 myForm = new Form1();
myForm.Show();
}
But yet I get no error, nothing.
I'm expecting for a new windows form to be opened when I close another one.
Any help would be appreciated, thanks!
The problem is that as soon as the first Form1 instance closes, your application shuts down and exits because the application message loop is defined with the initial Form instance, and it is just waiting for events on that form until it closes. On closing, the application will exit, opening a new form doesn't stop this process.
You need to adjust the Main() method in Program.cs to look something like this:
[STAThread]
static void Main()
{
// ... Application configuration as required here
new Form1().Show(); // The first form instance is now no longer bound to the Application message loop. Start it before we begin the run loop
Application.Run(); // Don't pass in Form1
}
Your original code should now work. I might add however, this is not a great user experience. Carefully consider what you're trying to achieve, and perhaps consider alternatives - do you just need a "reset form" button? Or is the primary goal to prevent a user from closing the application? If the latter, you can remove the Close icon altogether.
Perhaps something simple to get your going forward.
private Form1 myForm = new Form1(); //Declare the form as a private member variable
private void Form1_FormClosed(object sender, FormClosedEventArgs e)
{
e.Cancel = true; //Cancel the closing so this object stays alive
this.Visible = false; //Hide this form
myForm.Show(); //Show the next form
}
Please note #pcdevs comment. You'll need a way to indicate the form is being closed/application quiting vs progressing to the next step/form. You might want to look at some CodeProject articles about "C# Winform Wizards", those sequential dialog prompt apps...
I have 2 forms, form1 is the menu, with the buttons start, settings, quit, and form2 is where the program will run.
The problem I face is that if the user uses Alt+F4 on form2, it closes form2, but form1 runs in the background. I know I can use the form2 Closing event, so it can run an Environment.Exit(0), but that closing event also "activates" if I use the form2 "Back to Menu" button, which closes form2. I also tried just hiding form2 with the Menu button, but then when I need to call another form2, it opens up a new instance of it.
So, in summary: ALT+F4 should close the whole application, not just the current form, but can't use form2 Closing event, because I want to close form2 some other way too.
You can use KeyDownevent for that. Basically, you catch that key combination, tell the system that you are going to process it so it does not get passed to it and finally close the application. To close it, is always better to use Application.Exit() instead of Environment.Exit. You can see why here for example:
private void Form2_KeyDown(object sender, KeyEventArgs e)
{
if (e.Alt && e.KeyCode == Keys.F4)
{
e.Handled = true;
//Close your app
Application.Exit();
}
}
I am making a Windows form app in c# and the process is never killed after I close the main form. The process sits in the background, taking up memory. I have tried many methods, such as Application.exit and Environment.exit, none of which have worked.
I have tried:
private void Form1_FormClosing(Object sender, FormClosingEventArgs e)
{
Environment.Exit(0);
}
And
static void Main()
{
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
Application.Run(new Form1());
Environment.Exit(0);
}
}
I have tried both methods using both Application.Exit and Environment.Exit
I just want a solution that kills the process upon closing the main form
EDIT:
Upon closer inspection, this error only occurs when a button is pressed that switches to my project's second form using:
Form2 f = new Form2();
f.Show();
this.Hide();
I have used:
Environment.Exit(0);
Application.Exit();
and it was working for me on a project of mine.
If it isn't already, you need to mark your main method with [STAThread] attribute (see https://stackoverflow.com/a/1361048/1497128), like so --
[STAThread]
private static void Main()
{
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
Application.Run(new Form1());
}
If it is, then make sure that...
... all foreground threads are being terminated before the form closes
... if you subscribe to FormClosing event then ensure you are not setting Cancel = true
Neither of your solutions are necessary, WinForm applications terminate the process when the main form is closed (assuming nothing else is blocking, such as another foreground thread). You can test this by creating a new WinForm project in Visual Studio, running it and closing the form.
Unless you are using specific logic to control when the application should exit, you definitely shouldn't need Environment.Exit(0) (mainly used for console apps) nor Application.Exit() (used with WinForm apps). Closing the form should do it, which can be done programmatically by calling form.Close().
when using a button click to open a new form use USING
using (Form1 frm = new Form())
{
frm.ShowDialog();
}
I have program that opens subwindows inside of it (mdi.parent). I have made component that is in one window under it, however, i want that that window never actually disposed after its created because i want to keep only one instance of it.
This can be made with code:
// This prevents this window disposing from window close button, we want always show one and only
// one instance of this window.
FormClosing += (o, e) =>
{
Hide();
e.Cancel = true;
};
However, after this there is problem, closing program requires pressing close button press twice. First press closes subwindow and second terminates program. How this can be get around?
I am working with Winforms.
As Habib said, you can call Application.Exit, but:
The Form.Closed and Form.Closing events are not raised when the
Application.Exit method is called to exit your application
If this is important to you, you can do something like this (MDI parent code):
private Boolean terminating;
protected override void OnClosing(CancelEventArgs e)
{
if (!terminating)
{
terminating = true;
Close();
}
base.OnClosing(e);
}
Call Application.Exit() in the form close event.
Application.Exit - MSDN
Informs all message pumps that they must terminate, and then closes
all application windows after the messages have been processed.
The code inside of your FormClosing event handler method is a bit too terse. It does its job of preventing the user from closing the form, but as you've also noticed, it prevents you from closing the form programmatically as well.
This is easily solved by testing the value of the CloseReason property of the FormClosingEventArgs that are passed in each time the event is raised.
These will tell you the reason why the form is attempting to close. If the value is CloseReason.UserClosing, then you want to set e.Cancel to true and hide the form. If the value is something else, then you want to allow the form to continue closing.
// This prevents this window disposing when its close button is clicked by the
// user; we want always show one and only one instance of this window.
// But we still want to be able to close the form programmatically.
FormClosing += (o, e) =>
{
if (e.CloseReason == CloseReason.UserClosing)
{
Hide();
e.Cancel = true;
}
};
Use This
Form[] ch = this.MdiChildren;
foreach (Form chfrm in ch)
chfrm.Close();
You can use Application.Exit if there is no processing happening when the application is closed. Otherwise, you can check Application.OpenForms collection in MDI parent's closing event and close all the other forms that are open.
I have 2 forms: signin and control_panel. After signin done I'm hiding this form by this.Hide() function and same time I am making new object of control_panel form and showing it by newobj.Show();. But when I am closing directly control_panel form, I am seeing first form thread are still running. I am closing it by stop_debugging button. How will I close every threads or whole program exit simultaneously.
The thread for your first form is still running because you're only calling this.Hide. All that does is hide the form; it doesn't close it. Instead, you need to use this.Close, which will close your original form.
If you want to make sure that your entire application exits, and in the process close any forms that may still be open, you can use the Application.Exit method anywhere in your form's code.
EDIT: To expand on my last comment, you might want something like this in your Program.cs file:
static class Program
{
/// <summary>
/// The main entry point for the application.
/// </summary>
[STAThread]
static void Main()
{
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
SignInForm frmSignIn = new SignInForm();
if (frmSignIn.ShowDialog() == DialogResult.Yes)
{
//If the sign-in completed successfully, show the main form
//(otherwise, the application will quit because the sign-in failed)
Application.Run(new ControlPanelForm());
}
}
}
Create a FormClosed event in control_panel form property window of control_panel and write the following line as
private void control_panel_FormClosed(object sender, FormClosedEventArgs e)
{
Application.Exit();
}