title: Need help to find FireMonkey equivalent of the VCL TpaintBox.Canvas.Handle in the context of building graph
body: <p><strong>Preambule:</strong>
  I'm working with Black Magic Design (BMD) Decklink input card to acquire HD video signal. They provide C++ Sample with their SDK. I've successfully translated the c++ sample into Delphi (VCL). I've also isolated the API call in a TDecklink witch I want it to be available to the Delphi community. It work very well in VCL (I can provide the TDecklnk with a demo app to use it if requested). </p>
  
  <p>Now I need to acquire the signal in a FMX form (but not crosscompile to other platform than Windows). I've tried to modify the TDecklink to be usable in FMX without success.</p>
  
  <p><strong>Core Question:</strong><br>
  In my VCL version, I pass a TPaintBox refference to my TDecklink. The TPaintBox is used by the GraphBuilder as area to display the live video.</p>
  
  <p>Here is some line of code I use in the VCL version to assign the TPaintBox to the GraphBuilder:</p>
  
  <pre><code>      pWnd := WindowFromDC(FpboxPreview.Canvas.Handle);   //WindowFromDC  retreive HWND from HDC
        hr:= pIVMRWindowlessCtrl.SetVideoClippingWindow(pWnd);   // set the bounds of the video to the preview window
        if hr = S_OK then
        begin
          previewRect.Left   := FpboxPreview.Left;
          previewRect.Right  := FpboxPreview.Width;
          previewRect.Top    := FpboxPreview.Top;
          previewRect.Bottom := FpboxPreview.Height;
          hr:= pIVMRWindowlessCtrl.SetVideoPosition(nil, @previewRect);   // show the whole of the source frame in the whole of the client area of the control
          hr:= pIVMRWindowlessCtrl.SetAspectRatioMode(VMR_ARMODE_LETTER_BOX); // maintain the aspect ratio of the video
          hr:= pIVMRWindowlessCtrl.SetBorderColor(GetSysColor(COLOR_BTNFACE));    // set the colour of the letter or pillar boxed area 
  </code></pre>
  
  <p>Where PWnd is a HWND</p>
  
  <p>In FMX, what is the best component and parameter to use to provide what the GraphBuilder expect to receive ?</p>