VC# Form Flickers

这就是我要做的。我正在制作一款只使用swf和sd命名空间的游戏。当我使用间隔为1000/30(30帧)的计时器时，在它的tick事件中，我调用了InvokeGraphics()。所有的渲染或多或少都很好，除了椭圆是闪烁的。我尝试使用双缓冲，和this.SetStyle()，但都失败了。下面是代码:

public partial class MainForm : Form
{
    int x = 0;
    public MainForm()
    {
        InitializeComponent();
        var sz = SystemInformation.PrimaryMonitorSize;
        this.FormBorderStyle = FormBorderStyle.None;
        this.Size = sz;
        this.SetStyle(ControlStyles.OptimizedDoubleBuffer,true);
        Timer tmr = new Timer();
        tmr.Enabled = true;
        tmr.Interval = 1000/30;
        tmr.Tick += delegate(object sender, EventArgs e)
        { 
            x++;
            this.InvokePaint(this,new PaintEventArgs(this.CreateGraphics(),this.Bounds));
        };
    }
    protected override void OnKeyPress(KeyPressEventArgs e)
    {
        if((int)e.KeyChar == 27) Application.Exit();
        base.OnKeyPress(e);
    }
    protected override void OnPaint(PaintEventArgs e)
    {
        var g = e.Graphics;
        g.Clear(Color.Firebrick);
        // this ellipse flickrs
        g.FillEllipse(Brushes.Green,x,64,64,64);
        base.OnPaint(e);
    }
    protected override void OnMouseClick(MouseEventArgs e)
    {
        base.OnMouseClick(e);
    }
}