moving the panel inside a form (like photoshop hand tool)

Code:

        int x;
        int y;
        private void panel1_MouseMove(object sender, MouseEventArgs e)
        {
                if (e.Button == MouseButtons.Left) 
                {
                       panel1.Top += (e.Y - y); 
                       panel1.Left += (e.X - x);
                     } 
        }

        private void panel1_MouseDown(object sender, MouseEventArgs e)
        {
                 if (e.Button == MouseButtons.Left)
                {
                       x = e.X;
                       y = e.Y;
                }
        }

I have added a picture in the panel and now its like google maps the panel is moving but the problem is it isn't smooth !

when I move vertically no problem panel moves smoothly, horizontally also ok
but wen it comes 2 angle wise move I mean 45 degree move the panel flikers it vibrates

pls advice me on how to make this ryt i mean how to move smoothly ?

 

i din get u ?
do u mean I hav to drag only the border of the pictue ?