Error:The calling thread cannot access this object because a different thread owns it

[Don22Trader1]

Hello
I am working with a custom drawing tool. I am encountering this error and I think I have narrowed it down to the SolidColorBrush I am using to fill the anchor points. I have read on various forum threads and also on the help guide that the .Freeze() method works to fix this problem. The examples in the help guide work well with brushes created in Strategies and Indicators, however I am writing a Drawing Tool that uses SharpDX objects for rendering. Also, the SolidColorBrush is adjustable in the UI if the user wishes to change the look of the anchors. I will provide a snippet of how the SolidColorBrush is created and used and I would greatly appreciate another set of eye to see why this error is occurring and where the .Freeze() method would fit in.

public class MyDrawingTool: DrawingTool
{
  private SolidColorBrush anchorFillColor = new SolidColorBrush();

  //Set Anchor Fill Color
  [NinjaScriptProperty]
  [XmlIgnore]
  [Display(ResourceType = typeof(Custom.Resource), Name = "Anchor Fill", GroupName = "Anchors", Order = 13)]
  public SolidColorBrush anchorFill
  {
    get { return anchorFillColor; }
    set { anchorFillColor = value; }
  }

  //Serialize the anchorFill Color
  [Browsable(false)]
  public string anchorFillColorSerializable
  {
    get { return anchorFill.ToString(); }
    set { anchorFill = new SolidColorBrush((Color)ColorConverter.ConvertFromString(value)); }
  }

  if (State.Defaults)
  {
    anchorFillColor = Brushes.White;
  }

  OnRender()
  {
    var mediaColor = anchorFill.Color;
    var dxColor = new SharpDX.Color4(mediaColor.ScR, mediaColor.ScG, mediaColor.ScB, mediaColor.ScA);
  
    SharpDX.Direct2D1.SolidColorBrush customDXBrush = new SharpDX.Direct2D1.SolidColorBrush(RenderTarget, dxColor);

    RenderTarget.... //Render Anchor Points​
  }
}

[NinjaTrader_ChelseaB]

Hello Don22Trader1,

Thank you for your note.

With SolidColorBrushes you need to .Freeze() these.
Below are links to the help guide.
Help guide: NinjaScript > Educational Resources > Working with Brushes > Understanding custom brushes
Help guide: NinjaScript > NinjaScript Best Practices > Error handling practices > Using WPF brushes

The new SolidColorBrush() will need to be instantiated in OnStateChange() during State.SetDefaults.

private SolidColorBrush myBrush;

protected override void OnStateChange()
{
if (State == State.SetDefaults)
{
myBrush = new SolidColorBrush(Brushes.Green.Color);
}
}

public SolidColorBrush MyBrush
{
get { return myBrush; }
set
{
myBrush = value;
if (myBrush != null)
{
if (myBrush.IsFrozen)
myBrush = myBrush.Clone();
myBrush.Freeze();
}
}
}

[Browsable(false)]
public string MyBrushSerialize
{
get { return Serialize.BrushToString(myBrush); }
set { myBrush = (SolidColorBrush)Serialize.StringToBrush(value); }
}​​

Also, these examples show using brushes from UI properties and converting these to SharpDX brushes.
https://forum.ninjatrader.com/forum/ninjatrader-8/indicator-development/98639-performance-optimization?p=789606#post789606

[Don22Trader1]

Chelsea B,

I implemented the logic you provided and the tool did not work properly. However, after tinkering with it I changed this logic:

//~Chelsea B.
[Browsable(false)]
public string MyBrushSerialize
{
get { return Serialize.BrushToString(myBrush); }
set { myBrush = (SolidColorBrush)Serialize.StringToBrush(value); }
}

I reverted back to what I had originally:

//~Don22Trader1
[Browsable(false)]
public string anchorFillColorSerializable
{
get { return anchorFill.ToString(); }
set { anchorFill = new SolidColorBrush((Color)ColorConverter.ConvertFromString(value)); }
}

This reversion, paired with the other .Freeze() logic you provided did the trick and now I am able to have my tool used on separate windows without having that error occur. Thank you!