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

namespace アフィン変換サンプル___
{
    public partial class Form1 : Form
    {
        static PointF[] Arrow = new PointF[] { new PointF(0, 2), new PointF(1.5f, 1), new PointF(1, 1), new PointF(1, -1), new PointF(-1, -1), new PointF(-1, 1), new PointF(-1.5f, 1) };
        PointF[] ArrowD = new PointF[Arrow.Count()];

        double Direction = 0;
        float Sc = 32;//Scale. コントロールに同名の何かが会ったから短くした。

        uint Mode = 3;

        public Form1()
        {
            InitializeComponent();
            Application.Idle += new EventHandler(OnIdle);
        }

        void OnIdle(object sender, EventArgs e)
        {  
            PointF Move= new PointF(this.ClientSize.Width/2.0f,this.ClientSize.Height/2.0f);
            
            for (int i = 0; i < Arrow.Count(); i++)
            {
                ArrowD[i] = TransForm(Arrow[i], Direction, new SizeF(Sc, Sc), Move);//大変換！！
            }
            this.Invalidate(false);
            System.Threading.Thread.Sleep(15);
        }

        private void Form1_Paint(object sender, PaintEventArgs e)//event
        {
            Graphics g = e.Graphics;
            g.FillPolygon(Brushes.Green, ArrowD);//多角形塗りつぶし。

            float X = this.ClientSize.Width / 2;
            float Y = this.ClientSize.Height / 2;
            float L = 8;

            g.DrawLine(Pens.Black, X - L, Y, X + L, Y);
            g.DrawLine(Pens.Black, X, Y - L, X, Y + L);
        }
        
        private void Form1_MouseMove(object sender, MouseEventArgs e)//event
        {                
            float X = this.ClientSize.Width/2.0f-e.X;
            float Y = this.ClientSize.Height/2.0f-e.Y;

            if ((Mode&1) !=0) Direction = Math.Atan2(Y, X) + ToRadian(90);
            if ((Mode&2) !=0) Sc = (float)Math.Sqrt(X * X + Y * Y);

        }

        private void Form1_MouseDown(object sender, MouseEventArgs e)//event
        {            
            Mode %= 3;
            Mode++;
        }
       
        double SingleRadian = Math.PI / 180.0; 

        public double ToRadian(double Degree)
        {
            return SingleRadian * (Degree % 360.0);
        }
        public double ToDegree(double Radian)
        {
            return (Radian / SingleRadian) % 360.0;
        }
        public PointF TransForm(PointF Pos, double RotRadian, SizeF Scale, PointF Move)
        {
            PointF Ret = new PointF();
            double Sin = Math.Sin(RotRadian);
            double Cos = Math.Cos(RotRadian);

            Ret.X = (float)(((Pos.X * Scale.Width) * Cos) - ((Pos.Y * Scale.Height) * Sin) + Move.X);
            Ret.Y = (float)(((Pos.X * Scale.Width) * Sin) + ((Pos.Y * Scale.Height) * Cos) + Move.Y);

            return Ret;
        }

    }
}