Determine If Changed Event Occurred from User Input Or Not

Question

In C#, the Changed event for a control (say, a numericupdown) gets fired whether the value was change directly by the user or if it was changed programatically as the result

Answer 1

I have solved this problem before. Let's take the NumericUpDown control as an illustrative example.

First, create a new control (call it MyNumericUpDown) that inherits from the NumericUpDown. Create overrides for the UpButton, DownButton, and OnLostFocus methods. Also create a public method for setting the value of the control programmatically. Create an enum type called 'ValueChangedType' that has 4 different values called TextEdit, UpButton, DownButton, and Programmatic (or call them whatever you like). Also create a property called ChangedType of type ValueChangedType. Here is what the class looks like.

public partial class MyNumericUpDown : NumericUpDown
{
    public enum ValueChangedType
    {
        TextEdit,
        UpButton,
        DownButton,
        Programmatic
    }
    public ValueChangedType ChangedType = ValueChangedType.Programmatic;
    public MyNumericUpDown()
    {
        InitializeComponent();
    }
    public override void UpButton()
    {
        this.ChangedType = ValueChangedType.UpButton;
        base.UpButton();
    }
    public override void DownButton()
    {
        this.ChangedType = ValueChangedType.DownButton;
        base.DownButton();
    }
    protected override void OnLostFocus(EventArgs e)
    {
        this.ChangedType = ValueChangedType.TextEdit;
        base.OnLostFocus(e);
    }
    public void SetValue(decimal val)
    {
        this.ChangedType = ValueChangedType.Programmatic;
        this.Value = val;
    }
}

Now, in your form, create a MyNumericUpDown control (call it 'myNUD'). In the ValueChanged event handler for the control, you can get the value of the ChangedType property, and do something with it:

    private void myNUD_ValueChanged(object sender, EventArgs e)
    {
            MyNumericUpDown nud = sender as MyNumericUpDown;
            var myChangedType = nud.ChangedType;
            /* do something */
    }