private void ScreenBody_MouseDown(object sender, MouseEventArgs e)
{
    if (e.Button == MouseButtons.Left)
    {
        isDowned = true;
       
        if (RectReady == false)
        {
            Rect.X = e.X;
            Rect.Y = e.Y;
            downPoint = new Point(e.X, e.Y);
        }
        if (RectReady == true)
        {
            tmpx = e.X;
            tmpy = e.Y;
        }
    }
    if (e.Button == MouseButtons.Right)
    {
        if (RectReady != true)
        {
            this.Close();
            return;
        }
        MainPainter.DrawImage(baseImage, 0, 0);
        RectReady = false;
    }

}

private void ScreenBody_MouseUp(object sender, MouseEventArgs e)
{
    if (e.Button == MouseButtons.Left)
    {
        isDowned = false;
        RectReady = true;
    }
}

private void ScreenBody_MouseMove(object sender, MouseEventArgs e)
{

    if (RectReady == false)
    {
        if (isDowned == true)
        {
            Image New = DrawScreen((Image)baseImage.Clone(), e.X, e.Y);
            MainPainter.DrawImage(New, 0, 0);
            New.Dispose();
        }
    }
    if (RectReady == true)
    {
        if (Rect.Contains(e.X, e.Y))
        {
            //this.Cursor = Cursors.Hand;
            if (isDowned == true)
            {
                //和上一次的位置比较获取偏移量
                Rect.X = Rect.X + e.X - tmpx;
                Rect.Y = Rect.Y + e.Y - tmpy;
                //记录现在的位置
                tmpx = e.X;
                tmpy = e.Y;
                MoveRect((Image)baseImage.Clone(), Rect);
            }
        }
    }
   
}