OnRenderTargetChanged() returns null value

[asmmbillah]

Hi,
I have simply copied and pasted the codes from NT8 help guide for testing like below, but it returns null exception for OnRenderTargetChanged(). Can you advise?

private SharpDX.Direct2D1.Brush dxBrush = null; // the SharpDX brush used for rendering      
private System.Windows.Media.SolidColorBrush brush Color; // used to determine the color of the brush conditionally

protected override void OnStateChange()
{
  if (State == State.SetDefaults)
  {
    Name = "OnRenderTargetChanged Example";
    IsOverlay = false;
  }
}

protected override void OnBarUpdate()
{
  if (Close[0] > Open[0])
  {
    brushColor = Brushes.Green;
  }

  else if (Close[0] < Open[0])
  {
    brushColor = Brushes.Red;
  }

  else brushColor = Brushes.Blue;
}

public override void OnRenderTargetChanged()
{
  // if dxBrush exists on first render target change, dispose of it
  if (dxBrush != null)
  {
    dxBrush.Dispose();
  }

  // recalculate dxBrush from value calculated in OnBarUpdated when RenderTarget is recreated
  if (RenderTarget != null)
    dxBrush = brushColor.ToDxBrush(RenderTarget);
}

protected override void OnRender(ChartControl char tControl, ChartScale chartScale)
{
  // fill a custom SharpDX rectangle using the dx brush
  RenderTarget.FillRectangle(new SharpDX.Rectangle F(ChartPanel.X, ChartPanel.Y, ChartPanel.W, ChartP anel.H), dxBrush);
}

[NinjaTrader_BrandonH]

Hello asmmbillah,

Thanks for your post.

It seems that the brushColor variable is returning a null value when applying the script to a chart. You could resolve this error message by setting brushColor to an initial value in State.SetDefaults. For example, see below.

private SharpDX.Direct2D1.Brush dxBrush = null; // the SharpDX brush used for rendering
private System.Windows.Media.SolidColorBrush brushColor; // used to determine the color of the brush conditionally

protected override void OnStateChange()
{
  if (State == State.SetDefaults)
  { 
    Name = "OnRenderTargetChanged Example";
    IsOverlay = false;
    brushColor = Brushes.Blue;
  }
}

Let us know if we may assist further.

[asmmbillah]

thanks for that. But I can see, it does not change the color of the render based on the logics within onbarupdate. Can you please check and advise?

[NinjaTrader_BrandonH]

Hello asmmbillah,

Thanks for your note.

Upon initially adding the OnRenderTargetChanged example script to a chart, a blue rectangle will appear. Then, the next time the RenderTarget is recreated, the rectangle color will reflect the brush color set in OnBarUpdate(). Note that the color of the rectangle will only change colors once a RenderTarget is recreated.

See this demonstration video to see the OnRenderTargetChanged example in action: https://brandonh-ninjatrader.tinytak...Nl8xNzM4MzkxOQ

I have also attached the OnRenderTargetChanged script that I am testing with.

Let us know if we may assist further.

[asmmbillah]

thanks, I missed pressing the click.