第20回 アナログ時計の作成

namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();

            timer1.Start();
        }

        private void timer1_Tick(object sender, EventArgs e)
        {
            DateTime d = DateTime.Now;
            label1.Text = d.ToLongTimeString();

            //画面を消す
            Graphics g = this.CreateGraphics();
            g.Clear(Color.Black);
            g.Dispose();

            //針を描く
            draw(6, Pens.Aqua, d.Second, 100); //秒
            draw(6, Pens.Yellow, d.Minute, 80);  //分
            draw(30, Pens.Pink, d.Hour, 50);    //時
        }

        private void draw(int 倍率, Pen pen, int time, int 針の長さ) {

            int cx = 150;
            int cy = 150;

            //原点
            int x1 = cx;
            int y1 = cy;

            //針
            double 角度1度あたり = Math.PI / 180;
            double 角度 = 角度1度あたり * 倍率 * time - Math.PI / 2;

            
            int x2 = cx + (int)(Math.Cos(角度) * 針の長さ);
            int y2 = cy + (int)(Math.Sin(角度) * 針の長さ);

            Graphics g = this.CreateGraphics();
            g.DrawLine(pen, x1, y1, x2, y2);
            g.Dispose();
        }

        private void button2_Click(object sender, EventArgs e)
        {
            Graphics g = this.CreateGraphics();
            //g.Clear(Color.Black);
            g.DrawLine(Pens.Black, 0, 0, 100, 200);
            g.Dispose();
        }
    }
}