private void Device_MouseMove(object sender, MouseEventArgs e)
{
if (is_drag)
{
int delta_x = e.X - previous_point.X;
int delta_y = e.Y - previous_point.Y;
device.Left += delta_x;
device.Top += delta_y;
if (DeviceMove != null)
{
DeviceMove.Invoke(new Point(device.Left, device.Top), device);
}
}
}
