WPF: How to rotate a BitmapSource by any angle

Question

Ok, I tried this:

TransformedBitmap tbm = new TransformedBitmap(myBitmapSource, new RotateTransform(angle));
return tbm;

But this does not work with angles other than multiples of 90degrees.

New I tried to use a RenderTargetBitmap:

  var image = new Canvas();
  image.Width = myBitmapSource.PixelWidth;
  image.Height = myBitmapSource.PixelHeight;
  image.Background = new ImageBrush(myBitmapSource);
  image.RenderTransform = new RotateTransform(angle);
  RenderTargetBitmap rtb = new RenderTargetBitmap(myBitmapSource.PixelWidth, myBitmapSource.PixelHeight, myBitmapSource.DpiX, myBitmapSource.DpiY, myBitmapSource.Format);
  rtb.Render(image);
  return rtb;

But this gives me:

"The calling thread must be STA, because many UI components require this."

This runs in a service without a GUI.

Can somebody give me a working code sample on how to rotate a BitmapSource in WPF (without a GUI) by any angle?

update:

Vote for feature request: http://visualstudio.uservoice.com/forums/121579-visual-studio-2015/suggestions/10870098-allow-rotation-of-bitmapsource-by-any-angle

Answer 1

Well you can run that code in a separate thread. Just set the single-threaded apartment (STA).

Thread thread = new Thread(DoTheRotation);
thread.SetApartmentState(ApartmentState.STA);
thread.Start();
thread.Join();

Code for rotation in a method called by the thread:

public void DoTheRotation()
{
    var image = new Canvas();
    image.Width = myBitmapSource.PixelWidth;
    image.Height = myBitmapSource.PixelHeight;
    image.Background = new ImageBrush(myBitmapSource);
    image.RenderTransform = new RotateTransform(angle);
    RenderTargetBitmap rtb = new RenderTargetBitmap(myBitmapSource.PixelWidth, myBitmapSource.PixelHeight, myBitmapSource.DpiX, myBitmapSource.DpiY, myBitmapSource.Format);
    rtb.Render(image);
}

Then you just need to change the code to pass the object.