动态 LiveTile - 添加背景图像？

在我的 Windows Phone 7 应用程序中使用动态磁贴，效果非常好。

我现在正在尝试创建动态动态图块，但无法显示背景图像。当使用下面的代码时，我只得到一个黑色的瓷砖。显示我添加的文本，但不显示背景图像。图像“构建操作”设置为“内容”。

有任何想法吗？

StackPanel sp = new StackPanel();
sp.Height = 173;
sp.Width = 173;

string fileName = "tile.jpg";
BitmapImage image = new BitmapImage(new Uri(fileName, UriKind.Relative));
ImageBrush brush = new ImageBrush();
brush.ImageSource = image;
sp.Background = brush;

sp.Measure(new Size(173, 173));
sp.Arrange(new Rect(0, 0, 173, 173));
sp.UpdateLayout();
WriteableBitmap wbm = new WriteableBitmap(173, 173);
wbm.Render(sp, null);
wbm.Invalidate();

我在使用时也遇到了问题BitmapImage并且仍然不知道如何解决。但我找到了一个解决方法WriteableBitmap:

        // grid is container for image and text
        Grid grid = new Grid();

        // load your image
        StreamResourceInfo info = Application.GetResourceStream(new Uri(filename, UriKind.Relative));
        // create source bitmap for Image control (image is assumed to be alread 173x173)
        WriteableBitmap wbmp2 = new WriteableBitmap(1,1);
        wbmp2.SetSource(info.Stream);
        Image img = new Image();
        img.Source = wbmp2;
        // add Image to Grid
        grid.Children.Add(img);

        TextBlock text = new TextBlock() { FontSize = (double)Resources["PhoneFontSizeExtraLarge"], Foreground = new SolidColorBrush(Colors.White) };
        // your text goes here:
        text.Text = "Hello\nWorld";
        grid.Children.Add(text);

        // this is our final image containing custom text and image
        WriteableBitmap wbmp = new WriteableBitmap(173, 173);

        // now render everything - this image can be used as background for tile
        wbmp.Render(grid, null);
        wbmp.Invalidate();