Question

I would like to use the following code in C# but I just can’t seem to get out of it. I would like to terminate the application if the user presses a key or moves the rodent (aka mouse). Here is my code (no laughing!).

private void frmDots_KeyDown(object sender, KeyEventArgs e)
{
  bgNotClicked = false;
  Close();
}   

private void frmDots_Click(object sender, EventArgs e)
{
  bgNotClicked = false;
  Close();
}   



  while (bgNotClicked)
  {

    // Clear the first element in our XY position. This is the reverse of the way I   normally create the dots application
    System.Drawing.Rectangle clearDots = new System.Drawing.Rectangle(Dots.PositionX[iCounter], Dots.PositionY[iCounter], 8, 8);

    // Create the black color and brush to clear dots
    Color clearDotsColor = Color.Black;
    SolidBrush clearDotsBrush = new SolidBrush(clearDotsColor);

    // Finally clear the dot
    e.Graphics.FillEllipse(clearDotsBrush, clearDots);


    GetRandomPosition(iCounter);

    // Fill the elements to display colors on the displays canvas
    System.Drawing.Rectangle colorDots = new System.Drawing.Rectangle(Dots.PositionX[iCounter], Dots.PositionY[iCounter], 8, 8);

    // Create the color and brush to show dots
    Color colorRandom = GetRandomColor();
    SolidBrush colorBrush = new SolidBrush(colorRandom);

    // Finally show the dot
    e.Graphics.FillEllipse(colorBrush, colorDots);

    Thread.Sleep(5);

    iCounter++;
    if (iCounter == 399)
    {
      iCounter = 0;
    }

  }
}

Answer 1

Edit:

After seeing your edit, this is definitely your problem. The issue is that your while loop blocks the main UI thread, so it never handles the Windows Messages which trigger your key press/mouse/etc handlers.

You have a couple of options – you can either move some of this onto a separate thread, do what I suggested below, or add a call to Application.DoEvents in your while loop. This would allow your event handlers to run, which would in turn set bgNotClicked = false;. Right now, that’s never occurring because your UI is blocked entirely.

---

Original Post:

If you’re doing this loop in your UI thread, you’re going to need to rethink the design a bit.

Setting bgNotClicked = false; somewhere in an event handler will work, but only if your event handler is able to run. If you’re doing the above code in the UI thread, it will block your UI thread indefinitely, preventing the event handler from firing.

I would recommend reworking this to be based off a timer (so it runs repeatedly on regular intervals), instead of locked into a while loop. This would allow your other UI events to fire between runs, and instead of setting bgNotClicked = false;, your event handler could just set the timer to be not enabled.