Silverlight 4 WriteableBitmap ScaleTransform Exception but was working in v3 - silverlight

Question

I am getting the following exception for code that used to work in silverlight 3 but has stopped working since upgrading to silverlight 4:
System.AccessViolationException was unhandled
Message=Attempted to read or write protected memory. This is often an indication that other memory is corrupt.
namespace SilverlightApplication1
{
public partial class MainPage : UserControl
{
public MainPage()
{
InitializeComponent();
}
private void button1_Click(object sender, RoutedEventArgs e)
{
var OpenFileDialog = new OpenFileDialog();
OpenFileDialog.Filter = "*.jpg|*.jpg";
if (OpenFileDialog.ShowDialog() == true)
{
var file = OpenFileDialog.Files.ToArray()[0];
ScaleStreamAsBitmap(file.OpenRead(), 200);
}
}
public static WriteableBitmap ScaleStreamAsBitmap(Stream file, int maxEdgeLength)
{
file.Position = 0;
var src = new BitmapImage();
var uiElement = new System.Windows.Controls.Image();
WriteableBitmap b = null;
var t = new ScaleTransform();
src.SetSource(file);
uiElement.Source = src;
//force render
uiElement.Effect = new DropShadowEffect() { ShadowDepth = 0, BlurRadius = 0 }; ;
//calc scale
double scaleX = 1;
double scaleY = 1;
if (src.PixelWidth > maxEdgeLength)
scaleX = ((double)maxEdgeLength) / src.PixelWidth;
if (src.PixelHeight > maxEdgeLength)
scaleY = ((double)maxEdgeLength) / src.PixelHeight;
double scale = Math.Min(scaleX, scaleY);
t.ScaleX = scale;
t.ScaleY = scale;
b = new WriteableBitmap(uiElement, t);
return b;
}
}
}
Thanks

Answer 1

I had the same problem and I succeeded to resolve it!
b=new new WriteableBitmap(0, 0);
b.SetSource(file);
b.Render( new Image() { Source = src, Effect = new DropShadowEffect() { ShadowDepth = 0, BlurRadius = 0 } }, new ScaleTransform() { ScaleX = scaleX , ScaleY = scaleY });
And you can remove :uiElement and file.Position!