Render XAML with remote images

I'm working on a tool that renders pieces of XAML to images.The XAML is used as a template to design the images. Due to the way the rendering works it is not possible to use a codebehind. Rendering just xaml is no problem.

In one of my templates I want to give the renderer a lat/long and include an image from google maps, among other images stored on the web. The XAML is rendered, but the images are not included. I assume this has to do something with the delay of downloading the images.

A template would look something like:

 <UserControl
  xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
  xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
  <Border CornerRadius="10" Background ="#FF123456" >
    <Image Source="{0}" Width="250" Height="15开发者_JS百科0"/>
  </Border> 
</UserControl>

I use a string.Format to add the URL to the template.

Does anyone know how I can render XAML with remote images?

I've come up with a workaround. Since local images do work in the rendering I decided to use temporary images. Before rendering the piece of XAML I download the image, save it to disk and use that path as the source of the image.

This method looks something like:

public string GetGoogleMapsImage(string lat, string lng, string path)
{
    string googleMapsImage =
        string.Format(
            "http://maps.google.com/maps/api/staticmap?center={0},{1}&zoom=8&size=250x150&sensor=false" , lat, lng);
    string returnpath;
    using (var w = new WebClient())
    {
        var gm = w.DownloadData(googleMapsImage);
        returnpath = path + "\\~googletemp" + DateTime.Now.Ticks + ".png";
        File.WriteAllBytes(returnpath, gm);
        return returnpath;
    }
}