Moving dot on picturebox in vb.net

Question

I have a picturebox, and would need to draw a single red pixel at a given coordinate. This pixel will move, and when i assign a new position the old position is removed, so that only a single pixel is red at any given time. If possible it would be nice that this pixel is 50% transparent.

The most crucial thing is that it has to be fast. It is just used to display the current position that is beeing processed on the image, so it is imperative that it does not slow down the main program.

Can this be done? Thanks

Answer 1

In addition to Hans's comment:

Dim currentPoint As Point = Point.Empty 
Private Sub button1_Click(ByVal sender As Object, ByVal e As EventArgs) Handles button1.Click
    ' Clear previous pixel
    Dim invalidRect As Rectangle = New Rectangle(currentPoInteger.X,currentPoInteger.Y, 1, 1) 
    pictureBox1.Invalidate(invalidRect)

    ' Move to next point some how
    currentPoint.X = currentPoint.X + 1

    ' Invalidate to draw new pixel
    invalidRect = New Rectangle(currentPoInteger.X, currentPoInteger.Y, 1, 1)
    pictureBox1.Invalidate(invalidRect)
End Sub

Private  Sub pictureBox1_Paint(ByVal sender As Object, ByVal e As PaintEventArgs) Handles pictureBox1.Click
    If e.ClipRectangle.Contains(currentPoint) Then
        e.Graphics.FillRectangle(Brushes.Red, currentPoInteger.X, currentPoInteger.Y, 1, 1)
    End If
End Sub