在窗体中显示字符，字体每隔一秒变大些，变到一定寸尺后，每隔一秒字体又变小些，增加一个按钮，可以启动和停止字符串字体的大小，是怎样做的呢？？？？？？？

我做的：
 int a = 9;
        int b = 9;
        public Form1()
        {
            InitializeComponent();
        }
        private void Form1_Load(object sender, EventArgs e)
        {
            timer1.Interval = 1000;
            timer1.Enabled = false;
            toolTip1.SetToolTip(button1, "启动定时控件");
            toolTip1.SetToolTip(button2, "停止定时控件");
        }
        private void button1_Click(object sender, EventArgs e)
        {
            timer1.Enabled = true;
                     
        }
        private void button2_Click(object sender, EventArgs e)
        {
            timer1.Enabled = false;
        }
        private void timer1_Tick(object sender, EventArgs e)
        {
            if(a<30&&b==9)
            {
               a++;
               label1.Font = new Font("",a);
               if (a == 30)
                   b = 30;
            
            }
            if (b <30&&a == 30)
            {
                b--;
                label1.Font = new Font("",b);
                if (b == 9)
                    a = 9;
            }

            label1.ForeColor = Color.Red;
        }