C# NumericUpDown.OnValueChanged, how it was changed?

Question

I would like to ask how to make custom EventArgs for existing event handler.

Lets say, that I have NumericUpDown numericUpDown control and I want handler for its OnValueChanged event. Double clicking to ValueChanged in visual studio makes snippet like this

private void numericUpDown_ValueChanged(object sender, EventArgs e)
{

}

However, I'd like to know how it was changed (like +5, -4.7), but plain EventArgs does not have this information. Maybe Decimal change = Value - Decimal.Parse(Text) would do the trick (because of delayed text change), but that's ugly way and may not work every single time.

I guess I should make my own EventArgs like this

class ValueChangedEventArgs : EventArgs
{
    public Decimal Change { get; set; }
}

and then somehow override NumericUpDown.OnValueChanged event to generate my EventArgs with proper information.

Answer 1

It may be much easier to just tag the last value.

    private void numericUpDown1_ValueChanged(object sender, EventArgs e) {
        NumericUpDown o = (NumericUpDown)sender;
        int thisValue = (int) o.Value;
        int lastValue = (o.Tag == null) ? 0 : (int) o.Tag;
        o.Tag = thisValue;
        MessageBox.Show("delta = " + (thisValue - lastValue));
    }