Image control gets stuck after internet disconnection - wpf

Question

I have a image control in WPF window and its xmls is as follows:
<Image Source="{Binding Path=ImageUrl,Converter={StaticResource ImageSourceConverter}}"
Height="150" HorizontalAlignment="Left" Margin="100,15,0,0" Name="image1" Stretch="Fill" VerticalAlignment="Top" Width="200" />
At run time I change the source of Image by changing the value of bounded property. This code works fine in normal scenario. Issue appears only after internet is disconnected. If there is disconnection while downloading the image then image is not shown. Thats fine. But when internet comes back and image source is changed to another image url, image doesn't get downloaded. ImageConverter is not even called. After this point there is no way to display image in the control. Image control gets stuck.
public class ImageSourceConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
string url;
try
{
if (value is string)
url = (string)value;
else
url = ((Uri)value).AbsolutePath;
}
catch (Exception)
{
url = string.Empty;
return value;
}
BitmapImage src = new BitmapImage();
if (targetType == typeof(ImageSource))
{
if (value is string)
{
string str = (string)value;
src.BeginInit();
src.CacheOption = BitmapCacheOption.OnLoad;
src.CreateOptions = BitmapCreateOptions.IgnoreImageCache;
src.UriSource = new Uri(str, UriKind.RelativeOrAbsolute);
src.EndInit();
return src;
}
else if (value is Uri)
{
Uri uri = (Uri)value;
return new BitmapImage(uri);
}
}
return value;
}
public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
throw new NotImplementedException();
}
}
Any help will be highly appreciated.

Answer 1

In article about memory leaks discusses leak caused by use of downloaded BitmapImage as Image Source[7]:
Quote: "This leak is triggered because WPF does not remove internal reference to certain objects (such as LateBoundBitmapDecoder, BitmapFrameDecode, etc) which are used during web download and causes the leak.
This leak only happens when you download an image from the internet. (E.g. it does not appear when you load images from your local machine)"
...
The Fix/Workaround
The workaround is to consider downloading the BitmapImage first in other means to a temporary folder or to memory and then use the local BitmapImage . (See WebClient.DownloadFile & WebClient.DownloadData APIs)
Maybe it you will approach.

Answer 2

I fixed issue by downloading the image first and if it succeeds then only assign it to Image control. Posting it here in case anyone needs it.
private bool ValidImage(string url, out BitmapImage image)
{
try
{
System.Net.WebRequest request = System.Net.WebRequest.Create(url);
System.Net.WebResponse response = request.GetResponse();
System.IO.Stream responseStream = response.GetResponseStream();
Bitmap bitmap = new Bitmap();
using (MemoryStream stream = new MemoryStream())
{
bitmap.Save(stream, ImageFormat.Png);
stream.Position = 0;
BitmapImage result = new BitmapImage();
result.BeginInit();
// According to MSDN, "The default OnDemand cache option retains access to the stream until the image is needed."
// Force the bitmap to load right now so we can dispose the stream.
result.CacheOption = BitmapCacheOption.OnLoad;
result.StreamSource = stream;
result.EndInit();
result.Freeze();
image = result;
}
}
catch (Exception ex)
{
logger.Error(ex, "error downlading image");
image = null;
return false;
}
return true;
}