Windows forms событие закрытия формы

Form.Closing Event

People also askHow do I cancel a formclosing event?How do I cancel a
formclosing event?The FormClosingevent 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 Cancelproperty of the FormClosingEventArgspassed to
your event handler to true.Form.FormClosing Event (System.Windows.Forms)
Microsoft Docs

public:
 event System::ComponentModel::CancelEventHandler ^ Closing;


public event System.ComponentModel.CancelEventHandler Closing;


[System.ComponentModel.Browsable(false)]
public event System.ComponentModel.CancelEventHandler Closing;


[System.ComponentModel.Browsable(false)]
public event System.ComponentModel.CancelEventHandler? Closing;


member this.Closing : System.ComponentModel.CancelEventHandler 


[<System.ComponentModel.Browsable(false)>]
member this.Closing : System.ComponentModel.CancelEventHandler 


Public Custom Event Closing As CancelEventHandler 


private:
   void Form1_Closing( Object^ /*sender*/, System::ComponentModel::CancelEventArgs^ e )
   {
      // Determine if text has changed in the textbox by comparing to original text.
      if ( textBox1->Text != strMyOriginalText )
      {
         // Display a MsgBox asking the user to save changes or abort.
         if ( MessageBox::Show( "Do you want to save changes to your text?", "My Application", MessageBoxButtons::YesNo ) == ::DialogResult::Yes )
         {
            // Cancel the Closing event from closing the form.
            e->Cancel = true;

            // Call method to save file...
         }
      }
   }



private void Form1_Closing(object sender, System.ComponentModel.CancelEventArgs e)
{
   // Determine if text has changed in the textbox by comparing to original text.
   if (textBox1.Text != strMyOriginalText)
   {
      // Display a MsgBox asking the user to save changes or abort.
      if(MessageBox.Show("Do you want to save changes to your text?", "My Application",
         MessageBoxButtons.YesNo) ==  DialogResult.Yes)
      {
         // Cancel the Closing event from closing the form.
         e.Cancel = true;
         // Call method to save file...
      }
   }
}



   Private Sub Form1_Closing(sender As Object, e As System.ComponentModel.CancelEventArgs) Handles MyBase.Closing
      ' Determine if text has changed in the textbox by comparing to original text.
      If textBox1.Text <> strMyOriginalText Then
         ' Display a MsgBox asking the user to save changes or abort.
         If MessageBox.Show("Do you want to save changes to your text?", "My Application", MessageBoxButtons.YesNo) = DialogResult.Yes Then
            ' Cancel the Closing event from closing the form.
            e.Cancel = True
         End If ' Call method to save file...
      End If
   End Sub
End Class

Windows Forms in C# cancel event

By making e.Cancel = true;, you are telling the grid to not let the cell lose
focus, but the MessageBox makes the cursor leave the control. Things go a
little haywire. Things go a little haywire. The coloring part should be
working, but because the cell is highlighted, you probably aren’t seeing the
result.

        private void dataInventory_CellValidating(object sender, DataGridViewCellValidatingEventArgs e)
    {

        switch (e.ColumnIndex)
        {
            case 0:
                if (!Utilities.validName(e.FormattedValue))
                {
                    dataInventory.Rows[e.RowIndex].Cells[e.ColumnIndex].Style.BackColor = Color.Red;
                    MessageBox.Show("The value entered is not valid.");
                    e.Cancel = true;
                }
                else
                {
                    dataInventory.Rows[e.RowIndex].Cells[e.ColumnIndex].Style.BackColor = Color.White;
                }
                break;



dataGridView1.Rows[e.RowIndex].ErrorText = "Fix this";
e.Cancel = true;



void dataGridView1_CellEndEdit(object sender, DataGridViewCellEventArgs e)
{
  dataGridView1.Rows[e.RowIndex].ErrorText = String.Empty;
}



DataGridViewCellStyle CellStyle = new DataGridViewCellStyle();
CellStyle.BackColor = Color.Red;
dataInventory.Rows[e.RowIndex].Cells[e.ColumnIndex].Style = CellStyle;

Form.Closing Event

public:
 event System::ComponentModel::CancelEventHandler ^ Closing;


public event System.ComponentModel.CancelEventHandler Closing;


[System.ComponentModel.Browsable(false)]
public event System.ComponentModel.CancelEventHandler Closing;


[System.ComponentModel.Browsable(false)]
public event System.ComponentModel.CancelEventHandler? Closing;


member this.Closing : System.ComponentModel.CancelEventHandler 


[<System.ComponentModel.Browsable(false)>]
member this.Closing : System.ComponentModel.CancelEventHandler 


Public Custom Event Closing As CancelEventHandler 


private:
   void Form1_Closing( Object^ /*sender*/, System::ComponentModel::CancelEventArgs^ e )
   {
      // Determine if text has changed in the textbox by comparing to original text.
      if ( textBox1->Text != strMyOriginalText )
      {
         // Display a MsgBox asking the user to save changes or abort.
         if ( MessageBox::Show( "Do you want to save changes to your text?", "My Application", MessageBoxButtons::YesNo ) == ::DialogResult::Yes )
         {
            // Cancel the Closing event from closing the form.
            e->Cancel = true;

            // Call method to save file...
         }
      }
   }



private void Form1_Closing(object sender, System.ComponentModel.CancelEventArgs e)
{
   // Determine if text has changed in the textbox by comparing to original text.
   if (textBox1.Text != strMyOriginalText)
   {
      // Display a MsgBox asking the user to save changes or abort.
      if(MessageBox.Show("Do you want to save changes to your text?", "My Application",
         MessageBoxButtons.YesNo) ==  DialogResult.Yes)
      {
         // Cancel the Closing event from closing the form.
         e.Cancel = true;
         // Call method to save file...
      }
   }
}



   Private Sub Form1_Closing(sender As Object, e As System.ComponentModel.CancelEventArgs) Handles MyBase.Closing
      ' Determine if text has changed in the textbox by comparing to original text.
      If textBox1.Text <> strMyOriginalText Then
         ' Display a MsgBox asking the user to save changes or abort.
         If MessageBox.Show("Do you want to save changes to your text?", "My Application", MessageBoxButtons.YesNo) = DialogResult.Yes Then
            ' Cancel the Closing event from closing the form.
            e.Cancel = True
         End If ' Call method to save file...
      End If
   End Sub
End Class

Form.FormClosing Event

To cancel the closure of a form, set the Cancel property of the
FormClosingEventArgs passed to your event handler to true. When a form is
displayed as a modal dialog box, clicking the Close button (the button with an
X at the upper-right corner of the form) causes the form to be hidden and the
DialogResult property to be set to DialogResult.Cancel .

public:
 event System::Windows::Forms::FormClosingEventHandler ^ FormClosing;


public event System.Windows.Forms.FormClosingEventHandler FormClosing;


public event System.Windows.Forms.FormClosingEventHandler? FormClosing;


member this.FormClosing : System.Windows.Forms.FormClosingEventHandler 


Public Custom Event FormClosing As FormClosingEventHandler 


private void Form1_FormClosing(Object sender, FormClosingEventArgs e) {

System.Text.StringBuilder messageBoxCS = new System.Text.StringBuilder();
messageBoxCS.AppendFormat("{0} = {1}", "CloseReason", e.CloseReason );
messageBoxCS.AppendLine();
messageBoxCS.AppendFormat("{0} = {1}", "Cancel", e.Cancel );
messageBoxCS.AppendLine();
MessageBox.Show(messageBoxCS.ToString(), "FormClosing Event" );
}



Private Sub Form1_FormClosing(sender as Object, e as FormClosingEventArgs) _ 
     Handles Form1.FormClosing

    Dim messageBoxVB as New System.Text.StringBuilder()
    messageBoxVB.AppendFormat("{0} = {1}", "CloseReason", e.CloseReason)
    messageBoxVB.AppendLine()
    messageBoxVB.AppendFormat("{0} = {1}", "Cancel", e.Cancel)
    messageBoxVB.AppendLine()
    MessageBox.Show(messageBoxVB.ToString(),"FormClosing Event")

End Sub

Form.Closed Event

To prevent a form from closing, handle the Closing event and set the Cancel
property of the CancelEventArgs passed to your event handler to true. You can
use this event to perform tasks such as freeing resources used by the form and
to save information entered in the form or to update its parent form.

public:
 event EventHandler ^ Closed;


public event EventHandler Closed;


[System.ComponentModel.Browsable(false)]
public event EventHandler Closed;


[System.ComponentModel.Browsable(false)]
public event EventHandler? Closed;


member this.Closed : EventHandler 


[<System.ComponentModel.Browsable(false)>]
member this.Closed : EventHandler 


Public Custom Event Closed As EventHandler 


static int x = 200;
static int y = 200;
void Button1_Click( System::Object^ sender, System::EventArgs^ e )
{

   // Create a new Form1 and set its Visible property to true.
   Form1^ form2 = gcnew Form1;
   form2->Visible = true;

   // Set the new form's desktop location so it  
   // appears below and to the right of the current form.
   form2->SetDesktopLocation( x, y );
   x += 30;
   y += 30;

   // Keep the current form active by calling the Activate
   // method.
   this->Activate();
   this->Button1->Enabled = false;
}


// Updates the label text to reflect the current values of x 
// and y, which was were incremented in the Button1 control's 
// click event.
void Form1_Activated( Object^ sender, System::EventArgs^ e )
{
   Label1->Text = String::Format( "x: {0} y: {1}", x, y );
   Label2->Text = String::Format( "Number of forms currently open: {0}", count );
}

static int count = 0;
void Form1_Closed( Object^ sender, System::EventArgs^ e )
{
   count -= 1;
}

void Form1_Load( Object^ sender, System::EventArgs^ e )
{
   count += 1;
}



static int x = 200;
static int y = 200;

private void Button1_Click(System.Object sender, 
    System.EventArgs e)
{
    // Create a new Form1 and set its Visible property to true.
    Form1 form2 = new Form1();
    form2.Visible = true;

    // Set the new form's desktop location so it  
    // appears below and to the right of the current form.
    form2.SetDesktopLocation(x, y);
    x += 30;
    y += 30;

    // Keep the current form active by calling the Activate
    // method.
    this.Activate();
    this.Button1.Enabled = false;
}

// Updates the label text to reflect the current values of x 
// and y, which was were incremented in the Button1 control's 
// click event.
private void Form1_Activated(object sender, System.EventArgs e)
{
    Label1.Text = "x: "+x+" y: "+y;
    Label2.Text = "Number of forms currently open: "+count;
}

static int count = 0;

private void Form1_Closed(object sender, System.EventArgs e)
{
    count -= 1;
}

private void Form1_Load(object sender, System.EventArgs e)
{
    count += 1;
}



Shared x As Integer = 200
Shared y As Integer = 200

Private Sub Button1_Click(ByVal sender As System.Object, _
    ByVal e As System.EventArgs) Handles Button1.Click

    ' Create a new Form1 and set its Visible property to true.
    Dim form2 As New Form1
    form2.Visible = True

    ' Set the new form's desktop location so it appears below and 
    ' to the right of the current form.
    form2.SetDesktopLocation(x, y)
    x += 30
    y += 30

    ' Keep the current form active by calling the Activate method.
    Me.Activate()
    Me.Button1.Enabled = False
End Sub



' Updates the label text to reflect the current values of x and y, 
' which was were incremented in the Button1 control's click event.
Private Sub Form1_Activated(ByVal sender As Object, _
    ByVal e As System.EventArgs) Handles MyBase.Activated
    Label1.Text = "x: " & x & " y: " & y
    Label2.Text = "Number of forms currently open: " & count
End Sub

Shared count As Integer = 0

Private Sub Form1_Closed(ByVal sender As Object, _
    ByVal e As System.EventArgs) Handles MyBase.Closed
    count -= 1
End Sub

Private Sub Form1_Load(ByVal sender As Object, _
    ByVal e As System.EventArgs) Handles MyBase.Load
    count += 1
End Sub

Form.OnClosing(CancelEventArgs) Method

The following example uses Closing to test if the text in a TextBox has
changed. If it has, the user is asked whether to save the changes to a file.
C#. Copy. private void Form1_Closing(object sender,
System.ComponentModel.CancelEventArgs e) { // Determine if text has changed in
the textbox by comparing to original text. if (textBox1.Text !=
strMyOriginalText) { // Display a …

protected:
 virtual void OnClosing(System::ComponentModel::CancelEventArgs ^ e);


protected virtual void OnClosing (System.ComponentModel.CancelEventArgs e);


abstract member OnClosing : System.ComponentModel.CancelEventArgs -> unit
override this.OnClosing : System.ComponentModel.CancelEventArgs -> unit


Protected Overridable Sub OnClosing (e As CancelEventArgs)


private:
   void Form1_Closing( Object^ /*sender*/, System::ComponentModel::CancelEventArgs^ e )
   {
      // Determine if text has changed in the textbox by comparing to original text.
      if ( textBox1->Text != strMyOriginalText )
      {
         // Display a MsgBox asking the user to save changes or abort.
         if ( MessageBox::Show( "Do you want to save changes to your text?", "My Application", MessageBoxButtons::YesNo ) == ::DialogResult::Yes )
         {
            // Cancel the Closing event from closing the form.
            e->Cancel = true;

            // Call method to save file...
         }
      }
   }



private void Form1_Closing(object sender, System.ComponentModel.CancelEventArgs e)
{
   // Determine if text has changed in the textbox by comparing to original text.
   if (textBox1.Text != strMyOriginalText)
   {
      // Display a MsgBox asking the user to save changes or abort.
      if(MessageBox.Show("Do you want to save changes to your text?", "My Application",
         MessageBoxButtons.YesNo) ==  DialogResult.Yes)
      {
         // Cancel the Closing event from closing the form.
         e.Cancel = true;
         // Call method to save file...
      }
   }
}



   Private Sub Form1_Closing(sender As Object, e As System.ComponentModel.CancelEventArgs) Handles MyBase.Closing
      ' Determine if text has changed in the textbox by comparing to original text.
      If textBox1.Text <> strMyOriginalText Then
         ' Display a MsgBox asking the user to save changes or abort.
         If MessageBox.Show("Do you want to save changes to your text?", "My Application", MessageBoxButtons.YesNo) = DialogResult.Yes Then
            ' Cancel the Closing event from closing the form.
            e.Cancel = True
         End If ' Call method to save file...
      End If
   End Sub
End Class

How to suspend events when setting a property of a WinForms control

b) Use a custom flag indicating whether or not to execute event handlers. This
must be checked within every involved handler manually. By the framework
supported solution as with (b) or a method pair aka SuspendLayout (),
ResumeLayout (bool) designed to suspend all custom events would be what I’m
looking for.

        private void button1_Click(object sender, EventArgs e)
        {
            EventSuppressor oES = new EventSuppressor(checkBox1);
            oES.Suppress();
            checkedListBox1.SetItemChecked(0, checkedListBox1.CheckedItems.Count == 0);
            oES.Resume();
        }

        private void checkedListBox1_ItemCheck(object sender, ItemCheckEventArgs e)
        {
            MessageBox.Show("checkedListBox1_ItemCheck");
        }



public class MyForm: Form
{
    private bool disableField;

    public partial class MyForm()
    {
        // assume it contains a numericUpDown
        NumericUpDown numericUpDownField;
        numericUpDownField.ValueChanged += new System.EventHandler(this.numericUpDownField_ValueChanged);

        disableField = false;
    }

    public void SetInitialValues()
    {
        // disable event
        disableField = true;

        // set value
        numericUpDownField.Value = 100;

        // enable event
        disableField = false;
    }

    void numericUpDownField_ValueChanged(object sender, EventArgs e)
    {
        // jump out when disabled
        if (disableField) return

        // write to database
        write();
    }
}


public class MyForm: Form
{
    private List<object> disabledFields;

    public partial class MyForm()
    {
        // assume it contains a numericUpDown
        NumericUpDown numericUpDownField;
        numericUpDownField.ValueChanged += new System.EventHandler(this.numericUpDownField_ValueChanged);

        disabledFields = new List<object>();
    }

    public void SetInitialValues()
    {
        // Add to list to disable ONCE
        disabledFields.Add(numericUpDownField);

        // set value
        numericUpDownField.Value = 100;

    }

    void numericUpDownField_ValueChanged(object sender, EventArgs e)
    {
        // jump out when disabled, but remove entry before exiting
        if (disabledFields.contains(sender))
        {
            disabledFields.remove(sender);
            return
        }

        // write to database
        write();
    }
}


public class EventSuspender
    {
        private List<object> disabledControls;

        public EventSuspender()
        {
            disabledControls = new List<object>();
        }

        public bool CheckIfDisabled(object sender)
        {
            if (disabledControls.Contains(sender))
            {
                disabledControls.Remove(sender);
                return true;
            }
            else
            {
                return false;
            }
        }

        public void SetTextValue(TextBox box, string value)
        {
            if (box.Text != value)
            {
                disabledControls.Add(box);
                box.Text = value;
            }
        }

        public void SetNumericValue(NumericUpDown num, decimal value)
        {
            if (num.Value != value)
            {
                disabledControls.Add(num);

                if (value > num.Maximum) num.Value = num.Maximum;
                else if (value < num.Minimum) num.Value = num.Minimum;
                else num.Value = value;
            }
        }

        public void SetCheckBox(CheckBox box, bool value)
        {
            if (box.Checked != value)
            {
                disabledControls.Add(box);
                box.Checked = value;
            }
        }

        public void SetRadioButton(RadioButton button, bool value)
        {
            if (button.Checked != value)
            {
                if (value)
                {
                    disabledControls.Add(button);
                }
                button.Checked = value;
            }
        }
    }

// one-liner in event handlers:
// if (suspender.CheckIfDisabled(sender)) return;

How to handle a control event (Windows Forms .NET)

Use the Properties pane to remove the handler of an event: Open the Visual
Designer of the form containing the control to change. Select the control.
Change the Properties pane mode to Events by pressing the events button ().
Find the event containing the handler you want to remove, for example, the
Click event: Right-click on the event and choose Reset.

private void button1_Click(object sender, EventArgs e)
{
    // Create and add the button
    Button myNewButton = new()
    {
        Location = new Point(10, 10),
        Size = new Size(120, 25),
        Text = "Do work"
    };

    // Handle the Click event for the new button
    myNewButton.Click += MyNewButton_Click;
    this.Controls.Add(myNewButton);

    // Remove this button handler so the user cannot do this twice
    button1.Click -= button1_Click;
}

private void MyNewButton_Click(object sender, EventArgs e)
{

}



Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
    'Create and add the button
    Dim myNewButton As New Button() With {.Location = New Point(10, 10),
                                          .Size = New Size(120, 25),
                                          .Text = "Do work"}

    'Handle the Click event for the new button
    AddHandler myNewButton.Click, AddressOf MyNewButton_Click
    Me.Controls.Add(myNewButton)

    'Remove this button handler so the user cannot do this twice
    RemoveHandler Button1.Click, AddressOf Button1_Click
End Sub

Private Sub MyNewButton_Click(sender As Object, e As EventArgs)

End Sub



button1.Click -= button1_Click;



RemoveHandler Button1.Click, AddressOf Button1_Click



Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click, Button2.Click
    'Do some work to handle the events
End Sub

C# windows forms cancel event

c# windows forms cancel event. private void form1_FormClosing (object sender,
FormClosingEventArgs e) { MessageBox.Show («Form Closing»); e.Cancel = true;
MessageBox.Show («Form Closing Canceled.»); }

 private void form1_FormClosing(object sender, FormClosingEventArgs e)
 {
    MessageBox.Show("Form Closing...");
    e.Cancel = true;
    MessageBox.Show("Form Closing Canceled.");
}