title: PNG in Firemonkey : how to specify Compression and 8-bit
body: <p>VCL allows me to specify a PNG's Compression level (not referring to Quality level).</p>
  <p>How do I specify the Compression level of a PNG in FireMonkey?  Is there a way to save the PNG as 8-bit instead of 32-bit?</p>
  <p>I'm using <code>TBitmapCodecManager</code>.  I only need 8-bit because the colors are only black/white (with some anti-aliasing).</p>
  <p>Note: I cannot use an external PNG library as this has to be integrated in my code.</p>
  <pre><code>begin
    var oStream := TMemoryStream.Create;
    var Surface := TBitmapSurface.Create;
    try
      BitmapCodecSaveParams.Quality := 100;  // PNG is 100% loss-less, how can we specify the Compression level?
      Surface.Assign(aBitmap);
      TBitmapCodecManager.SaveToStream(oStream, Surface, '.png', @BitmapCodecSaveParams);
    finally
      oMemoryStream.Free;
      Surf.Free;
    end;
  end;
  </code></pre>