How can I clear the Panel of what I've drawn without erasing the background image?

Question

C++ / C#

Panel.Invalidate();Does not help. Because I'm redrawing multiple times per second and it's redrawing when the key is released.
Panel.Clear(Color.Teal);Does not help. Draws the entire screen . Doesn't help. Same as the point above. Draws the screen, and the background image. Helps, but also redraws the background image. What should I do?
Panel.Clear(Color.FromArgb(255));
Panel.Refresh();

Answer 1

You place the background image in a bitmap and, when redrawing from it, draw it on the control canvas. Draw only what you need:

protected override void OnPaint(PaintEventArgs e)
{
     base.OnPaint(e);
     var g = e.Graphics;
     var clipRect = e.ClipRectangle;
     ...
}

It is also better to draw first on a separate bitmap from which everything is transferred to the control canvas. (double buffering)
Try and erase only that part of the control that has really changed.
Invalidate(Rectangle.Round(rect));