Getting the actual height of content size fitter parent

Question

I have a parent gameobject (Empty) with a content size fitter with horizontal and vertical fit set to preferred size which is also a Horizontal Layout Group with Control Child size width and height enabled:

It has got a TextMeshPro text as child, and now, as the text expands the parent also expands. The problem is, I want to get the height of this parent. And if I use this:

var rect = parent.gameObject.GetComponent<RectTransform>.rect
Debug.Log($"Width: {rect.width}, height: {rect.height}");

or even,

var mValue = parent.gameObject.GetComponent<RectTransform>.sizeDelta;
Debug.Log($"sizeDeltax: {mValue.x}, sizeDeltaY: {mValue.y}");

they both give 0.

I require some way to extract the expanded width and height. How can I do that?

NOTE: The content of the child i.e. text is being assigned dynamically, also the parent/text is a prefab being instantiated dynamically i.e. via Instantiate, and this is not done in the start method.

Okay, here's more detail about the hierarchy and stuff:
The hierarchy

Parent:

Interface

MessageField

OutputSection

Viewport

ChatPanel

So, eventually chat bubbles are supposed to stack on top of one another, they get parented to ChatPanel, and each child is a prefab instantiated as mentioned above, the prefab detail are:

hierarchy

stackItem

ItemParent

Tag

TextItem (Note the MessageTextItem is basically not used, it's there for some old code reasons)

ChatTextBubble

These are expanded below:

When I send message, I log the width and height of the white part of the chat bubble which is basically the **chatTextBubble above, using the code: **

   var expRect = chatTextBubble.GetComponent<RectTransform>();
            Debug.Log($"dvz:: expRect width is: {expRect.rect.width} and height is: {expRect.rect.height}");
  

and it logs 0. Please tell me what am I doing wrong. It looks similar to below example but, not working.

This is what it looks like during gameplay:

EDIT: I just noticed, the chatTextBubble has this during gameplay:

but, logs 0 when I log with the above mentioned code.

Answer 1

Something is amiss with your setup, because RectTransform.rect will contain correct updated values as ContentSizeFitter manipulates its dimensions.

Here is a minimum verifiable example. Project hierarchy:

Code, attached to Test Controller GameObject:

using UnityEngine;
using UnityEngine.UI;

public class GetParentSize : MonoBehaviour
{

    public RectTransform parent;
    public GameObject childPrefab;
    public Text readout;
    float timer = 0;

    void Update()
    {
        timer += Time.deltaTime;
        if(timer >= .5f)
        {
            var child = Instantiate(childPrefab);
            child.transform.SetParent(parent.transform);

            timer = 0;
        }
        readout.text = string.Format("Parent Width: {0} units",parent.rect.width.ToString());
    }
}

Code instantiates a UI prefab every .5s and sets the parent of the instanced gameobject to the gameobject with the ContentSizeFitter and HorizontalLayout components. Every frame it updates the UI readout text with the width of the gameobject with the ContentSizeFitter.

This is how the parent gameobject is configured in the inspector:

This is how the Test Controller is wired up:

And here it is in action:

Answer 2

I just had the same problem and I found the solution was to use ForceRebuildLayoutImmediate (2018 version):

LayoutRebuilder.ForceRebuildLayoutImmediate(go.GetComponent<RectTransform>());

I can then get the dimensions with: go.GetComponent<RectTransform>().sizeDelta.x (Width) or .y (Height)