FlexibleGridLayout 2

//Tweaked the code to add more functionality
//Added a minimum to some variables so they don't go under 0 or 1
//Added all child alignments
using UnityEngine;
using UnityEngine.UI;

public class FlexibleGridLayout : LayoutGroup {
    public enum Alignment {
        Horizontal,
        Vertical
    }
    public enum FitType {
        Uniform,
        Width,
        Height,
        FixedRows,
        FixedColumns,
        FixedBoth
    }

    public Alignment alignment;
    [Space]
    public FitType fitType;
    [Min(1)]
    public int columns;
    [Min(1)]
    public int rows;
    [Space]
    [Min(0)]
    public Vector2 spacing;
    public Vector2 cellSize;

    public bool fitX;
    public bool fitY;

    public bool NudgeLastItemsOver;

    public override void CalculateLayoutInputVertical() {
        base.CalculateLayoutInputHorizontal();
        float sqrRt;

        switch (fitType) {
            case FitType.Uniform:
            default:
                fitX = fitY = true;
                sqrRt = Mathf.Sqrt(transform.childCount);
                rows = Mathf.CeilToInt(sqrRt);
                columns = Mathf.CeilToInt(sqrRt);
                rows = Mathf.CeilToInt(transform.childCount / (float)columns);
                columns = Mathf.CeilToInt(transform.childCount / (float)rows);
                break;
            case FitType.Width:
                fitX = fitY = true;
                sqrRt = Mathf.Sqrt(transform.childCount);
                rows = Mathf.CeilToInt(sqrRt);
                columns = Mathf.CeilToInt(sqrRt);
                rows = Mathf.CeilToInt(transform.childCount / (float)columns);
                break;
            case FitType.Height:
                fitX = fitY = true;
                sqrRt = Mathf.Sqrt(transform.childCount);
                rows = Mathf.CeilToInt(sqrRt);
                columns = Mathf.CeilToInt(sqrRt);
                columns = Mathf.CeilToInt(transform.childCount / (float)rows);
                break;
            case FitType.FixedRows:
                fitX = fitY = false;
                columns = Mathf.CeilToInt(transform.childCount / (float)rows);
                break;
            case FitType.FixedColumns:
                fitX = fitY = false;
                rows = Mathf.CeilToInt(transform.childCount / (float)columns);
                break;
            case FitType.FixedBoth:
                fitX = fitY = false;
                break;
        }

        float cellWidth;
        float cellHeight;

        switch (alignment) {
            case Alignment.Horizontal:
                cellWidth = (this.rectTransform.rect.width / (float)columns) - ((spacing.x / (float)columns) * (columns - 1)) - (padding.left / (float)columns) - (padding.right / (float)columns);
                cellHeight = (this.rectTransform.rect.height / (float)rows) - ((spacing.y / (float)rows) * (rows - 1)) - (padding.top / (float)rows) - (padding.bottom / (float)rows);
                break;
            case Alignment.Vertical:
            default:
                cellHeight = (this.rectTransform.rect.width / (float)columns) - ((spacing.x / (float)columns) * (columns - 1)) - (padding.left / (float)columns) - (padding.right / (float)columns);
                cellWidth = (this.rectTransform.rect.height / (float)rows) - ((spacing.y / (float)rows) * (rows - 1)) - (padding.top / (float)rows) - (padding.bottom / (float)rows);
                break;
        }

        cellSize.x = fitX ? (cellWidth <= 0 ? cellSize.x : cellWidth) : cellSize.x;
        cellSize.y = fitY ? (cellHeight <= 0 ? cellSize.y : cellHeight) : cellSize.y;

        int columnCount = 0;
        int rowCount = 0;

        for (int i = 0; i < rectChildren.Count; i++) {
            var item = rectChildren[i];
            float xPos;
            float yPos;
            float xLastItemOffset = 0;

            switch (alignment) {
                case Alignment.Horizontal:
                    rowCount = i / columns;
                    columnCount = i % columns;
                    if (NudgeLastItemsOver && rowCount == (rectChildren.Count / columns)) { xLastItemOffset = (cellSize.x + padding.left) / 2; }
                    break;
                case Alignment.Vertical:
                default:
                    rowCount = i / rows;
                    columnCount = i % rows;
                    if (NudgeLastItemsOver && rowCount == (rectChildren.Count / rows)) { xLastItemOffset = (cellSize.x + padding.left) / 2; }
                    break;
            }

            xPos = (cellSize.x * columnCount) + (spacing.x * columnCount) + padding.left + xLastItemOffset;
            yPos = (cellSize.y * rowCount) + (spacing.y * rowCount) + padding.top;

            switch (m_ChildAlignment) {
                case TextAnchor.UpperLeft:
                default:
                    //No need to change xPos;
                    //No need to change yPos;
                    break;
                case TextAnchor.UpperCenter:
                    xPos += (0.5f * (this.gameObject.GetComponent<RectTransform>().sizeDelta.x + (spacing.x + padding.left + padding.left) - (columns * (cellSize.x + spacing.x + padding.left)))); //Center xPos
                    //No need to change yPos;
                    break;
                case TextAnchor.UpperRight:
                    xPos = -xPos + this.gameObject.GetComponent<RectTransform>().sizeDelta.x - cellSize.x; //Flip xPos to go bottom-up
                    //No need to change yPos;
                    break;
                case TextAnchor.MiddleLeft:
                    //No need to change xPos;
                    yPos += (0.5f * (this.gameObject.GetComponent<RectTransform>().sizeDelta.y + (spacing.y + padding.top + padding.top) - (rows * (cellSize.y + spacing.y + padding.top)))); //Center yPos
                    break;
                case TextAnchor.MiddleCenter:
                    xPos += (0.5f * (this.gameObject.GetComponent<RectTransform>().sizeDelta.x + (spacing.x + padding.left + padding.left) - (columns * (cellSize.x + spacing.x + padding.left)))); //Center xPos
                    yPos += (0.5f * (this.gameObject.GetComponent<RectTransform>().sizeDelta.y + (spacing.y + padding.top + padding.top) - (rows * (cellSize.y + spacing.y + padding.top)))); //Center yPos
                    break;
                case TextAnchor.MiddleRight:
                    xPos = -xPos + this.gameObject.GetComponent<RectTransform>().sizeDelta.x - cellSize.x; //Flip xPos to go bottom-up
                    yPos += (0.5f * (this.gameObject.GetComponent<RectTransform>().sizeDelta.y + (spacing.y + padding.top + padding.top) - (rows * (cellSize.y + spacing.y + padding.top)))); //Center yPos
                    break;
                case TextAnchor.LowerLeft:
                    //No need to change xPos;
                    yPos = -yPos + this.gameObject.GetComponent<RectTransform>().sizeDelta.y - cellSize.y; //Flip yPos to go Right to Left
                    break;
                case TextAnchor.LowerCenter:
                    xPos += (0.5f * (this.gameObject.GetComponent<RectTransform>().sizeDelta.x + (spacing.x + padding.left + padding.left) - (columns * (cellSize.x + spacing.x + padding.left)))); //Center xPos
                    yPos = -yPos + this.gameObject.GetComponent<RectTransform>().sizeDelta.y - cellSize.y; //Flip yPos to go Right to Left
                    break;
                case TextAnchor.LowerRight:
                    xPos = -xPos + this.gameObject.GetComponent<RectTransform>().sizeDelta.x - cellSize.x; //Flip xPos to go bottom-up
                    yPos = -yPos + this.gameObject.GetComponent<RectTransform>().sizeDelta.y - cellSize.y; //Flip yPos to go Right to Left
                    break;
            }

            SetChildAlongAxis(item, 0, xPos, cellSize.x);
            SetChildAlongAxis(item, 1, yPos, cellSize.y);
        }

    }

    public override void SetLayoutHorizontal() {

    }

    public override void SetLayoutVertical() {

    }
}