UWP 显示图片到Image控件

<Image  x:Name="imageHidden"/>

　　　　　　　FileOpenPicker picker = new FileOpenPicker();
            picker.FileTypeFilter.Add(".jpg");
            picker.FileTypeFilter.Add(".jpeg");
            picker.FileTypeFilter.Add(".png");
            picker.FileTypeFilter.Add(".bmp");
            picker.SuggestedStartLocation = PickerLocationId.PicturesLibrary;

            var file = await picker.PickSingleFileAsync();
            if (file != null)
            {
                    IRandomAccessStream ir = await file.OpenAsync(FileAccessMode.Read);
                    BitmapImage bi = new BitmapImage();
                    await bi.SetSourceAsync(ir);
                    imageHidden.Source = bi;
            }