如何将自定义控件上的图片转换成bitmap格式？
控件类型：ImageTools.ExtendedImage

代码是：
protected override void OnNavigatedTo(System.Windows.Navigation.NavigationEventArgs e)
{
ImageTools.IO.Decoders.AddDecoder<GifDecoder>();

//自定义控件：imageMine
ImageTools.ExtendedImage imageMine = new ImageTools.ExtendedImage();

var store = IsolatedStorageFile.GetUserStoreForApplication();
IsolatedStorageFileStream fs = new IsolatedStorageFileStream("combined.gif", FileMode.OpenOrCreate, store);
if (fs.Length != 0)
{
imageMine.SetSource(fs);
}
else
{
imageMine.UriSource = new Uri(default_gif, UriKind.RelativeOrAbsolute);
}
imgeSend2.Source = imageMine;
}

现在需要做一个上传的操作，可是上传接口参数是BitmapImage..
public void Publish(BitmapImage photo,string status = null)
{
string bmpStr = ReadImageToString(photo);
PublisRequest.CreateUploadPhotoRequest(bmpStr,-1,status);
PublisRequest.SendRequest();

}

string ReadImageToString(BitmapImage img)
{
string imgString;
WriteableBitmap btmMap = new WriteableBitmap(img);
imgString = ReadWriteableBmpToString(btmMap);
return imgString;
}

求大神解救。。。
最好有代码。。

[解决办法]
wp7 不支持.bmp吧？