private void rotationToolStripMenuItem_Click(object sender, EventArgs e)
{
if (img == null) // verify if the image is already opened
{
return;
}
Cursor = Cursors.WaitCursor; // clock cursor
InputBox form = new InputBox("Input angle (Deg)");
form.ShowDialog();
float angle = (float)ImageClass.ConvertDegreesToRadians(double.Parse(form.ValueTextBox.Text));
//copy Undo Image
imgUndo = img.Copy();
ImageClass.Rotation(img, imgUndo, angle);
ImageViewer.Image = img.Bitmap;
ImageViewer.Refresh(); // refresh image on the screen
Cursor = Cursors.Default; // normal cursor
}