如何在Google Maps，Winforms C＃

Question

我一直在用Winforms c＃开发一个项目，我想使用来自CSV文件的实时输入数据来移动GMap控件上的标记。

我尝试了一些，代码如下：

        cnn.Open();
        SqlCommand cmd = new SqlCommand("Select 
        baro_altitude,longitude,latitude from HzTBB", cnn);
        SqlDataReader reader = cmd.ExecuteReader();
        double lat=0, lon=0;
        while (reader.Read())
        {
            lat = Convert.ToDouble(reader.GetValue(2).ToString());
            lon = Convert.ToDouble(reader.GetValue(1).ToString());
            label3.Text = "Altitude : " + reader.GetValue(0).ToString();
        }

        gMapControl1.DragButton = MouseButtons.Left;
        gMapControl1.MapProvider = GMapProviders.GoogleMap;
        //double lat = Convert.ToDouble(textBox1.Text);
        //double lon = Convert.ToDouble(textBox2.Text);
        gMapControl1.Position = new PointLatLng(lat, lon);
        gMapControl1.MinZoom = 1;
        gMapControl1.MaxZoom = 100;
        gMapControl1.Zoom = 10;
        PointLatLng point = new PointLatLng(lat, lon);
        GMapMarker marker = new GMarkerGoogle(point, 
        GMarkerGoogleType.red_dot);

        GMapOverlay markers = new GMapOverlay("markers");
        markers.Markers.Add(marker);
        gMapControl1.Overlays.Add(markers);
        cnn.Close();

标记没有移动，但显示了带有两个标记点的第一个和最后一个地址。