c# 自定义控件使其填充方格且自动变换大小

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Drawing;
using System.Data;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace 方格练习
{
    public partial class FillBtn : UserControl
    {
        public FillBtn()
        {
            InitializeComponent();
        }
               /// <summary>
/// 填充按钮
/// </summary>
/// <param name="btnNum">按钮数量</param>
        public void FillButton(int btnNum)
        {
            //填充btnNum*btnNum个方格,现在放置的是罗列着的
            for (int i = 0; i < btnNum * btnNum; i++)
            {
                Button btn = new Button();
                this.Controls.Add(btn);
            }
            //定义方法,因为需要改变大小,所以单独
            this.LayoutBtns();
        }
        /// <summary>
/// 布局按钮
/// </summary>
/// <returns></returns>
        private void LayoutBtns()
        {
            //去除启动状态,以免开启的时候FillBtn_SizeChanged会报错
            if (this.Controls.Count==0)
            {
                return;
            }
            //循环多少次?计算出来
            int btnLineNum = (int)Math.Sqrt(this.Controls.Count);
            //计算按钮的宽度
            int btnWidth = this.Width / btnLineNum;
            int btnHeight = this.Height / btnLineNum;

            int btnIndex = 0;
            int btnX = 0, btnY = 0;
            //竖向的循环嵌套横着的循环
            for (int verticalIndex = 0; verticalIndex < btnLineNum; verticalIndex++)
            {
                btnY = verticalIndex * btnHeight;
                //水平向的循环
                for (int horizontalIndex = 0; horizontalIndex < btnLineNum; horizontalIndex++)
                {
                    btnX = horizontalIndex * btnWidth;
                    //获取要放置的方格
                    Button btn = this.Controls[btnIndex] as Button;
                    //设置当前方格的大小
                    btn.Size = new Size(btnWidth, btnHeight);
                    //设置当前方格的位置
                    btn.Location = new Point(btnX, btnY);
                    //下一个方格
                    btnIndex++;
                }
            }
        }

        private void FillBtn_SizeChanged(object sender, EventArgs e)
        {
            //设置当控件大小改变时的事件
            this.LayoutBtns();
        }
    }
}