饼图的绘制

        private Color selectcolor=Color.Green;
        private ArrayList duixiang=new ArrayList();

        private void button3_Click(object sender, System.EventArgs e)
        {
            float data=0;
            try
            {
                data=float.Parse(this.textBox1.Text);
            }
            catch{}
            Class1 cl1=new Class1(data,selectcolor);  
            duixiang.Add(cl1);  //将新对象添加进duixiang.
            this.draw(); //绘制

            Random rand = new Random();

            this.selectcolor = Color.FromArgb(rand.Next(255), rand.Next(255), rand.Next(255));
            this.label1.BackColor = this.selectcolor;
            this.label1.Text=selectcolor.Name.ToString();

        
        }

        private void draw()
        {
            float startangle=0.0f;   //开始角度
            float total=0.0f;        //总体数据。
            Graphics gs=this.panel1.CreateGraphics();
            Rectangle rect = new Rectangle(10,10,150,150); //定义矩形位置大小
            foreach(Class1 cl1 in duixiang)
            {
                total+=cl1.share;      //计算总体的数据
            }
            gs.Clear(this.panel1.BackColor);
            for (int i=0;i<duixiang.Count;i++)
            {
                Class1 cls=(Class1)duixiang[i];
                float endangle=cls.share/total *360;   //结束绘制的角度.
                Pen pen = new Pen(this.panel1.BackColor);
                SolidBrush sBrush = new SolidBrush(cls.color);
                gs.DrawArc(pen,rect,startangle,endangle);  //绘制弧线
                gs.FillPie(sBrush,rect,startangle,endangle); //填充扇形
                startangle += endangle;     //重新计算开始绘制的角度
            }
        }





    public class Class1
    {
        public float share; 
        public Color color;
        public Class1(float share,Color color)
        {
            this.share=share;
            this.color=color;
        }
    }