I am pretty new to C# and have a problem with a Windows Form project. I am
not sure if I am doing this correctly?
I have a 'Help button' on a windows form which shows a 'Modeless dialog box'.
I want this to be Modeless so the user can carry on working in the main form
and leave open the Help form and if required minimise it.
I am requiring the user to be able to press the 'Help button' again which will
simply bring the Modeless dialog box back to the front even if it is minimized.
I do not want to create a new 'Modeless Help dialog box' and end up with many
of them I just want the single one.
I have a global variable for the main form
FormHelp goHelpDialog = null;
and the handler for the 'Help button' is
private void buttonHelp_Click(object sender, EventArgs e)
{
// If we havent already created a HelpDialog create it and Show() it
// Else just bring it to the front
if (goHelpDialog == null)
{
goHelpDialog = new FormHelp();
// Show goHelpDialog as a modless dialog so dont dispose of a modeless as we want that to stay alive
// Note Dispose() is automatically called when user closes dialog.
goHelpDialog.Show();
}
else
{
if (goHelpDialog.WindowState == FormWindowState.Minimized)
goHelpDialog.WindowState = FormWindowState.Normal;
goHelpDialog.BringToFront();
}
return;
}
This works fine if the user keeps hitting the 'Help button'. The problem I have is when
the user closes the 'Modeless Help dialog box' and presses the 'Help button' again I
get an assertion because
if (goHelpDialog == null)
is not null. Therefore a new 'Modeless Help dialog box' is not created.
I assume that goHelpDialog is not being Dispose() correctly?
Your advice is appreciated thank you.
Related
I am showing some database records in a Dialog. When I click any particular record that record fills to Active Form. But I want to focus to a button when my dialog close. So I have written the following code on form closing evennt.
private void frmDG_RecordSelection_FormClosing(object sender, FormClosingEventArgs e)
{
RecordSelectionStatus.Text = "False";
Form TargetForm = Home.ActiveMdiChild;
Button SelectRefConsultant = (Button)TargetForm.Controls.Find("btnSelectRefConsultant_NI", true).SingleOrDefault();
SelectRefConsultant.Focus();
TargetForm.ActiveControl = SelectRefConsultant;
}
But it's not working. Focus still remain to it's previous place. What am I missing ?
I am assuming that the dialog is modal... Instead of doing this in FormClosing do it, after calling ShowDialog(). If not, try using the FormClosed event instead.
I think your code is not working because, while the Form is closing, it still has modal focus.
If frmDG_RecordSelection is also MDIChild, then Home.ActiveMDIChild is this form. That is being closed.
But if frmDG is just a Dialog, the problem is different.
This dialog is Closing. But it's still visible. You cannot set focus to control that is not visible.
So you will have to set focus after this frmDG is completely closed, and invisible... To be more specific, when your MDI form is visible.
It's far more easier to do this from your MDI Form. I don't know how you have programmmed it, but I suppose it's something like that:
//this is in your MDI form
void OnRecordSelected(...)
{
frmDG yourDialog = new frmDG();
frmDG.ShowModal();
frmDG.Dispose();
}
In this case, you will have to set focus after frmDG is disposed.
I'm working on a C# project. I need to do the following but I'm not really experienced and I can't find it on the Internet.
I want to do an action when the user clicks on the cross button (for closing one form). I mean, if the user clicks on the "X" button on the top right of the form I want to use a method that deletes one file.
I just want to know the code for noticing that the user clicked on the "X" (close) button. I hope you guys understand my question. Thank you so much!!
I don't think it's user friendly to delete something on closing a form (especially as the 'X' button is understood as the close button by everybody who uses a computer), but you can override the OnFormClosing method of a form. Something like this:
// this will also close the form
protected override void OnFormClosing(FormClosingEventArgs e)
{
base.OnFormClosing(e);
if (e.CloseReason == CloseReason.WindowsShutDown) return;
// Do some stuff here (delete the file or whatever)
}
If you want to alter the behavior so bad that the form won't close on pressing 'X', you could do sth like
protected override void OnFormClosing(FormClosingEventArgs e)
{
e.Cancel = true;
// some stuff here...
}
Which is very nasty IMO
You have to handle FormClosing event:
The FormClosing event occurs as the form is being closed. When a form
is closed, it is disposed, releasing all resources associated with the
form. If you cancel this event, the form remains opened. To cancel the
closure of a form, set the Cancel property of the FormClosingEventArgs
passed to your event handler to true.
I'm encountering strange behaviour from my WinForms app in VS 2010. I launch a new form using straight-forward code:
MainDisplayForm.cs:
using (MyForm myForm = new MyForm())
{
var result = myForm.ShowDialog();
if (result == DialogResult.OK)
{
// do stuff
}
}
I added a Cancel button to MyForm that displayed a confirmation MessageBox to the user and then called this.Close(). I later removed the this.Close() line because I added a dedicated Close button. However, whenever I press Cancel the instance of MyForm still closes!
MyForm.cs:
private void cmdCancel_Click(object sender, EventArgs e)
{
DialogResult result = MessageBox.Show( ... )
// clear the form if user really wants to quit
// this.Close()
// even after removing the above line, program still jumps to FormClosing
}
When I debug line-by-line after clicking on the Cancel button, the program flow just jumps to MyForm_FormClosing after it hits the end of cmdCancel_Click. I created a new button and set its click event to cmdCancel_Click and it did not close the form - so the problem is solved, but I am still wondering if this is just a bug, or something else? I also made sure to reset the DialogResult property of my Cancel button back to None (after changing it to Cancel before I introduced the dedicated Close button).
When exiting the scope of 'using' statement, it calls 'myForm.Dispose()' (that's the whole point of 'using' - to make sure Dispose()is called). This in turn destroys 'myForm' instance, including closing the window.
I have another issue in converting my Winforms program to a WPF program. In my first program, I had a smaller window open to allow the user to adjust some data, and then when it closed, the other form was activated again with the new data.
I used form2.ShowDialog(); to open the form, which automatically makes the parent form deactivated in Winforms. This way when I closed form2, the parent form was activated, and I was able to use an event handler form1_Activated to reload and re-initialize some of the settings successfully.
However, now when I attempt to do the same thing with WPF, I am still able to open form2 using form2.ShowDialog();, but then when I close the form, it does not register the form1_Activated event handler. Instead, in order to reload the settings, I must click on another window, and then come back into my program to register the form1_Activated event handler.
Am I just doing something wrong, or is there another event handler that I should be using in WPF to achieve the same thing I was able to do in Winforms?
Calling ShowDialog() causes the dialog box top appear in modal mode so I don't understand why you would need an event handler to process the results after the dialog box is closed. Keep in mind that you can access public variables in the DialogBox, as well. If I understand your question, this should do what you are asking:
MainWindow:
My_DialogBox dlg = new My_DialogBox();
dlg.Owner = this;
dlg.MyPublicVariable = ''; //some value that you might need to pass to the dialog
dlg.ShowDialog(); //exection of MainWindow is suspended until dialog box is closed
if (dlg.DialogResult == true)
{
//dlg.MyPublicVariable is still accessible
//call whatever routines you need in order to refresh the main form's data
}
DialogBox:
private void OK_Button_Click(object sender, RoutedEventArgs e)
{
MyPublic variable = something; //accessible after the dialog has closed.
this.DialogResult = true;
}
private void Cancel_Button_Click(object sender, RoutedEventArgs e)
{
this.DialogResult = false;
}
The MSDN write-up on dialog boxes is pretty good. There may be some tips that might help you even more:
http://msdn.microsoft.com/en-us/library/aa969773.aspx
Good luck!
I have a form, wherein I prohibit the user from closing it when the user clicks the Close (X) button. Is it possible to show a tooltip on the Close (X) button whenever it is clicked? I want to do it to notify the user why the form would not close.
I thought of a messagebox but then I thought it would be too annoying to close the messagebox every time you click the Close (X) button.
Is there a better way to notify the user, than what I'm trying to do?
EDIT:
This is my code for the FormClosing event
private void InputForm_FormClosing(object sender, FormClosingEventArgs e)
{
if (e.CloseReason == CloseReason.UserClosing)
{
e.Cancel = true;
if (!mCloseReason)
{
e.Cancel = false;
}
}
}
I have a method that will save the inputs in the form. Once that method is finished, I need to automatically close the form. The if-statement will be true once I call this.Close(), this means I can't close the form. That's why I used a variable called mCloseReason to be able to close the form automatically. Now, that's why I was asking if I can notify the user through a tooltip once the Close (X) button is clicked.
I believe the default tooltip for the close(X) button is not editable without some hacking (and it is not practical).
Maybe what you could do is have a status field below your form, so when the user clicks the close button, it says in the status field "cannot close form (...)"
Or another idea is to have a message pop up somewhere on the form and go away after a little, indicating the form cannot be closed.
Another good idea was mentioned by Roger... just have a Close button somewhere on the form with a tooltip coded to it, and hide the forms' title bar?