Stop the Bell on CTRL-A (WinForms)

问题

Any ideas how to stop the system bell from sounding when CTRL-A is used to select text in a Winforms application?

Here's the problem. Create a Winforms project. Place a text box on the form and add the following event handler on the form to allow CTRL-A to select all the text in the textbox (no matter which control has the focus).

void Form1_KeyDown(object sender, KeyEventArgs e)
{
    if (e.KeyCode == Keys.A && e.Modifiers == Keys.Control)
    {
        System.Diagnostics.Debug.WriteLine("Control and A were pressed.");
        txtContent.SelectionStart = 0;
        txtContent.SelectionLength = txtContent.Text.Length;
        txtContent.Focus();
        e.Handled = true;
    }
}

It works, but despite e.Handled = true, the system bell will sound every time CTRL-A is pressed.

Thanks for the reply.

KeyPreview on the Form is set to true - but that doesn't stop the system bell from sounding - which is the problem I'm trying to solve - annoying.

回答1:

    private void textBox1_KeyDown(object sender, KeyEventArgs e)
    {
        if (e.Control && e.KeyCode == Keys.A)
        {
            this.textBox1.SelectAll();
            e.SuppressKeyPress = true;
        }
    }

hope this helps

回答2:

Thanks to an MSDN Forum post - this problem only occurs when textboxes are in multiline mode and you'd like to implement Ctrl+A for select all.

Here's the solution

protected override bool ProcessCmdKey(ref Message msg, Keys keyData) 
{
  if (keyData == (Keys.A | Keys.Control)) {
    txtContent.SelectionStart = 0;
    txtContent.SelectionLength = txtContent.Text.Length;
    txtContent.Focus();
    return true;
  }
  return base.ProcessCmdKey(ref msg, keyData);
}

回答3:

This worked for me:

Set the KeyPreview on the Form to True.

Hope that helps.

回答4:

@H7O solution is good, but I improved it a bit for multiply TextBox components on the form.

private void textBox_KeyDown(object sender, KeyEventArgs e)
{
  if (e.Control && e.KeyCode == Keys.A)
  {
    ((TextBox)sender).SelectAll();
    e.SuppressKeyPress = true;
  }
}

来源：https://stackoverflow.com/questions/225711/stop-the-bell-on-ctrl-a-winforms

标签

winforms

keyeventargs