ScreenToGif.Webcam.DirectX.CaptureWebcam.RenderGraph C# (CSharp) Method

        protected void RenderGraph()
        {
            Guid cat;
            Guid med;
            int hr;
            bool didSomething = false;
            const int WS_CHILD = 0x40000000;
            const int WS_CLIPCHILDREN = 0x02000000;
            const int WS_CLIPSIBLINGS = 0x04000000;

            // Stop the graph
            if (MediaControl != null)
                MediaControl.Stop();

            // Create the graph if needed (group should already be created)
            CreateGraph();

            // Derender the graph if we have a capture or preview stream
            // that we no longer want. We can't derender the capture and 
            // preview streams seperately. 
            // Notice the second case will leave a capture stream intact
            // even if we no longer want it. This allows the user that is
            // not using the preview to Stop() and Start() without
            // rerendering the graph.
            if (!WantPreviewRendered && IsPreviewRendered)
                DerenderGraph();

            // Render preview stream (only if necessary)
            if (WantPreviewRendered && !IsPreviewRendered)
            {
                // Render preview (video -> renderer)
                cat = Uuid.PinCategory.Preview;
                med = Uuid.MediaType.Video;
                hr = CaptureGraphBuilder.RenderStream(ref cat, ref med, VideoDeviceFilter, _baseGrabFlt, null);
                if (hr < 0) Marshal.ThrowExceptionForHR(hr);

                // Get the IVideoWindow interface
                VideoWindow = (ControlStreaming.IVideoWindow)GraphBuilder;

                // Set the video window to be a child of the main window
                var source = PresentationSource.FromVisual(PreviewWindow) as HwndSource;
                hr = VideoWindow.put_Owner(source.Handle);
                if (hr < 0) Marshal.ThrowExceptionForHR(hr);

                // Set video window style
                hr = VideoWindow.put_WindowStyle(WS_CHILD | WS_CLIPCHILDREN | WS_CLIPSIBLINGS);
                if (hr < 0) Marshal.ThrowExceptionForHR(hr);

                // Position video window in client rect of owner window
                PreviewWindow.SizeChanged += OnPreviewWindowResize;
                OnPreviewWindowResize(this, null);

                // Make the video window visible, now that it is properly positioned
                hr = VideoWindow.put_Visible(CoreStreaming.DsHlp.OATRUE);
                if (hr < 0) Marshal.ThrowExceptionForHR(hr);

                IsPreviewRendered = true;
                didSomething = true;

                var media = new CoreStreaming.AMMediaType();
                hr = SampGrabber.GetConnectedMediaType(media);

                if (hr < 0)
                    Marshal.ThrowExceptionForHR(hr);
                if ((media.formatType != Uuid.FormatType.VideoInfo) || (media.formatPtr == IntPtr.Zero))
                    throw new NotSupportedException("Unknown Grabber Media Format");

                _videoInfoHeader = (EditStreaming.VideoInfoHeader)Marshal.PtrToStructure(media.formatPtr, typeof(EditStreaming.VideoInfoHeader));
                Marshal.FreeCoTaskMem(media.formatPtr); media.formatPtr = IntPtr.Zero;
            }

            if (didSomething)
                ActualGraphState = GraphState.Rendered;
        }