Question

I have a function that is intended to allow my user to move a set of objects (an airport) to a new location.

On the dialog that for this I have four controls – two textboxes that represent coordinates and two numeric up downs one for distance and one for bearing. The user can choose to enter either a distance and bearing or a set of coordinates. This is done via a checkbox and the non used set is disabled. So that the user has feedback I would like to update the disabled pair values as the user enters the enabled pair. If they are entering coordinates then the distance and bearing updates and vice versa.

My method for doing this is to respond to the TextChanged event of each object to update the others. Of course this creates one event firing another and back again as the other control updates. It does not create an infinite loop as far as I can tell but it does mess up the caret position in the active boxes.

I have tried some approaches including including trying to disable events based on which boxes are active or using some bool flags. I also tried using a timer rather than events. It is all very messy and no approach seems to work. I would like to know if there is a better way.

Thanks

Answer 1

Assuming you are using Windows Forms:

// this.ckPosition.CheckedChanged += new System.EventHandler(this.ckPosition_CheckedChanged);
private void ckPosition_CheckedChanged(object sender, EventArgs e)
{
  txtX.Enabled = txtY.Enabled = ckPosition.Checked;
  numBearing.Enabled = numDistance.Enabled = !ckPosition.Checked;
}

// this.txtX.TextChanged += new System.EventHandler(this.Position_TextChanged);
// this.txtY.TextChanged += new System.EventHandler(this.Position_TextChanged);
private void Position_TextChanged(object sender, EventArgs e)
{
  if (ckPosition.Checked)
  {
    // Replace with your calculations
    numBearing.Value = Convert.ToInt32(txtX.Text);
    numDistance.Value = Convert.ToInt32(txtY.Text);
  }
}

// this.numBearing.ValueChanged += new System.EventHandler(this.BearingDistance_ValueChanged);
// this.numDistance.ValueChanged += new System.EventHandler(this.BearingDistance_ValueChanged);
private void BearingDistance_ValueChanged(object sender, EventArgs e)
{
  if (ckPosition.Checked == false)
  {
    // Replace with your calculations
    txtX.Text = numBearing.Value.ToString();
    txtY.Text = numDistance.Value.ToString();
  }
}

As long as you don’t change the position in the position event handler or the bearing/distance in it’s handler, there should not be any ‘looping’ of events.