// Place clip points, maximum 4 private void ImagePanel_MouseClick(object sender, MouseEventArgs e) { if (ClipPoints.Count < 4) { Point p = ImagePanel.PanelToImage(e.Location); if (p.X < 0 || p.Y < 0 || p.X > ImagePanel.img.Width || p.Y > ImagePanel.img.Height) { return; } ClipPoints.Add(p); if (ClipPoints.Count == 4) { ImageClipButton.Enabled = true; } } }