Dynamically modify the size of the container of a vertical layout group.

Vertical Layout Group Dynamic Content.md

Vertical Layout Group Dynamic Content

Dynamically modifies the size of the RectTransform of a VerticalLayoutGroup in Uniy. This component has to be attached to, for example, the Content GameObject of a ScrollView. If an new item is added to the container you must call the Adjust method to resize the RectTransform.

VerticalLayoutGroupDynamicContent.cs

using UnityEngine;
using UnityEngine.UI;
using UnityEngine.EventSystems;

/// <summary>
/// Vertical Layout Group Dynamic Content.
/// 
/// <para>
/// Allows you to dynamically modify the size of the container of a vertical
/// layout group. Can be easily adapted to an horizontal layout group.
/// </para>
/// 
/// <para> By Javier García | @jvrgms | 2019 </para>
/// 
/// </summary>
[ExecuteInEditMode]
[RequireComponent (typeof (VerticalLayoutGroup))]
public class VerticalLayoutGroupDynamicContent: UIBehaviour {



    #region Class Members

    VerticalLayoutGroup layoutGroup;    //  Layout group reference.
    RectTransform rectTransform;  //  RectTransform of this GO.

    #endregion



    #region Accessors

    /// <summary> Gets the layout group. </summary>
    /// <value> The layout group. </value>
    public VerticalLayoutGroup LayoutGroup {
        get {
            if (layoutGroup != null)
                return layoutGroup;

            layoutGroup = GetComponent<VerticalLayoutGroup> ();
            return layoutGroup;
        }
    }

    /// <summary> Gets the rect transform. </summary>
    /// <value> The rect transform. </value>
    public RectTransform RectTransform {
        get {
            if (rectTransform != null)
                return rectTransform;

            rectTransform = GetComponent<RectTransform> ();
            return rectTransform;
        }
    }

    #endregion



    #region UI Behaviour Overrides

    /// <summary> Called when the transform parent changed. </summary>
    protected override void OnTransformParentChanged () {
        Adjust ();
    }

    /// <summary> Called when the rect transform dimensions chenged. </summary>
    protected override void OnRectTransformDimensionsChange () {
        Adjust ();
    }

    #endregion



    #region Class Implementation

    /// <summary> Adjust the size of the rect transform. </summary>
    public void Adjust () {

        //  Set to zero if this instance does not have any child.
        if (transform.childCount == 0) {
            RectTransform.sizeDelta = new Vector2 (RectTransform.sizeDelta.x, 0);
            return;
        }

        float height;
        int childCount = transform.childCount;

        //  Obtaning height size.
        height = LayoutGroup.spacing * (childCount - 1);
        height += LayoutGroup.padding.bottom;
        height += LayoutGroup.padding.top;

        foreach (RectTransform child in transform)
            height += child.sizeDelta.y;

        //  Applying height size.
        RectTransform.sizeDelta = new Vector2 (RectTransform.sizeDelta.x, height);
    }

    #endregion
}