How do I get the actual size of ReferenceRect in container

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:information_source: Attention Topic was automatically imported from the old Question2Answer platform.
:bust_in_silhouette: Asked By SimonTC

I’m working on a tool for my game where I can visualize charts.

To visualize the charts I use a Line2D in a container so that I can control the layout better.
My current layout looks like this:

PanelContainer (scene root)
  HBoxContainer
    ReferenceRect
      Line2D

To ensure all points in Line2D fit inside the width of the ReferenceRect I calculate the x position for the points as follows:

for (int i = 0; i < points.Length; i++)
{
  var x = i * (chartWidth / points.Length)
}

I had hoped that I could get chartWidth by accessing the size of the parent ReferenceRect: chartWidth = parentReferenceRect.RectSize.x.
This works fine in the scene itself.

However, when I create an instance of the chart editor in a container in another scene it no longer works:

enter image description here

Layout in other scene:

Node2d (scene root)
  VBoxContainer
    ChartEditor scene instance

Even though the size of the ReferenceRect is increased, the RectSize property has not been changed. Is there a way for me to get the actual size at runtime instead of relying on whatever size is set in the editor?