如何在EnterKeyPress上阻止NumericUpDown播放“叮”声

Question

I have a few NumericUpDown controls on my form, and everytime I hit the enter key while it is active, it plays this horrible DING noise, right in my ears. It plays if I don't handle the KeyPress event, and it plays if I do handle the KeyPress event, with or without e.Handled = true :

myNumericUpDown.KeyPress += myNumericUpDown_KeyPress;

private void myNumericUpDown_KeyPress(object sender, EventArgs e)
{
    if (e.KeyChar == 13)
    {
        e.Handled = true; //adding / removing this has no effect
        myButton.PerformClick();
    }
}

And I don't think it is happening because I am handling it, as if I don't register the event (removing the first line above), it still plays the noise.

Answer 1

Use KeyDown() and SuppressKeyPress, but click the button in KeyUp():

    private void myNumericUpDown_KeyDown(object sender, KeyEventArgs e)
    {
        if (e.KeyCode == Keys.Enter)
        {
            e.Handled = e.SuppressKeyPress = true;
        }
    }

    private void myNumericUpDown_KeyUp(object sender, KeyEventArgs e)
    {
        if (e.KeyCode == Keys.Enter)
        {
            e.Handled = e.SuppressKeyPress = true;
            myButton.PerformClick();
        }
    }

*If you set the Forms AcceptButton Property to "myButton", then NO code is needed at all!

Answer 2

Well, you are not supposed to use the Enter key like that in a GUI app. It is reserved for another role. The DING! is an unsubtle reminder of that.

You can easily unding it by actually giving the Enter key the intended usage. Drop a button on the form, set its Visible property to False. Select the form and set the AcceptButton property to that button. No more dings.

Extrapolating somewhat from the odd usage of Enter, you probably want to make the Enter key behave like it does in a console mode app, taking the user to the next control. Normally done by using the Tab key instead. You can accomplish that, and unding you UI, by copy/pasting this code into your form class:

    protected override bool ProcessCmdKey(ref Message msg, Keys keyData) {
        if (keyData == Keys.Enter) {
            var ctl = this.ActiveControl;
            var box = ctl as TextBoxBase;
            // Make Enter behave like Tab, unless it is a multiline textbox
            if (ctl != null && (box == null || !box.Multiline)) {
                this.SelectNextControl(ctl, true, true, true, true);
                return true;
            }
        }
        return base.ProcessCmdKey(ref msg, keyData);
    }

Answer 3

NumericUpDown also checks if the key you pressed is a "number key" (1-9,-,.), which is obviously not the case for the enter key. After you did what you wanted to do, just set e.KeyChar to any number key. Setting e.Handled = true is still necessary, otherwise the system treats your input as if you actually pressed that key instead and inserts the number.

//Do something
e.Handled = true;
e.KeyChar = (char)Keys.D2;

For me, this worked perfectly.

Answer 4

I do this trick:

Inside the numericUpandDown KeyPress function, if e.KeyChar=13 (Enter key), you have to set e.Handled=true; (that will prevent your control from changing it's value in any way) and just after that set e.KeyChar=(char)46; (or any other numerical accepted value, it will not be written as e.Handled is already set to true).

This way, e.KeyChar has an accepted value by Visual Studio, and that "Ding" will not sound.