private void DisplayMap_Load(object sender, EventArgs e)
        {
            winformsMap1.MapUnit = GeographyUnit.DecimalDegree;
            GdiPlusRasterLayer gdiPlusRasterLayer=new GdiPlusRasterLayer();
            gdiPlusRasterLayer.StreamLoading += new EventHandler<StreamLoadingEventArgs>(a_StreamLoading);
            LayerOverlay ov=new LayerOverlay();
            ov.Layers.Add(gdiPlusRasterLayer);
            winformsMap1.Overlays.Add(ov);
            winformsMap1.Refresh();
        }

        void a_StreamLoading(object sender, StreamLoadingEventArgs e)
        {
            if (e.StreamType == "Image File")
            {
                Bitmap bitmap = new Bitmap(@"..\..\SampleData\Data\world.tif");
                bitmap.RotateFlip(RotateFlipType.Rotate90FlipNone);
                MemoryStream  memoryStream=new MemoryStream();
                bitmap.Save(memoryStream, System.Drawing.Imaging.ImageFormat.Tiff);
                e.AlternateStream = memoryStream;
            }

            if (e.StreamType == "World File")
            {
                Stream stream = new FileStream(@"..\..\SampleData\Data\world.tfw", FileMode.Open, FileAccess.Read);
                e.AlternateStream = stream;
            }
        }