namespace baitapc31

{

    public partial class Form1 : Form

    {

        Graphics g;

        Bitmap b;

        Pen pen;

        public struct point2D

        {

            public double x, y;

        }

        public Form1()

        {

            InitializeComponent();

            b = new Bitmap(this.ClientRectangle.Width, this.ClientRectangle.Height);

            g = Graphics.FromImage(b);

            pen=new Pen(Color.Black);

        }

        public void drawpolygon(point2D []p)

        {

            for (int i = 0; i < p.Length-1; i++)

            {

                myline(p[i], p[i + 1]);

            }

            myline(p[p.Length - 1], p[0]);

        }

        public void myline(point2D p1, point2D p2)

        {

            double y1 = b.Height - p1.y;

            double y2 = b.Height - p2.y;//chuyen ve toa do duoi goc trai

            g.DrawLine(pen ,(float)p1.x, (float)y1, (float)p2.x, (float)y2);

        }

        public void Tinhtiendiem(ref double x,ref double y, double tx, double ty)

        {

            x += tx;

            y += ty;

        }

        public void TinhtienDsdiem(point2D[]p, double tx, double ty)

        {//tu viet

            for(int i=0;i<p.Length;i++)

            {

                Tinhtiendiem(ref p[i].x, ref p[i].y, tx, ty);

            }

        }

        public void xoaydiem(ref double x, ref double y, double alpha)

        {

            alpha = Math.PI * alpha / 180;

            double x1 = Math.Cos(alpha) * x - Math.Sin(alpha) * y;//cong them 1 phan nua neu xoay theo tam c

            double y1 = Math.Sin(alpha) * x + Math.Cos(alpha) * y;

            x = x1; y = y1;

        }

        public void xoaydiemtoadobatky(ref double x, ref double y, double alpha,double incx,double incy)

        {

            alpha = Math.PI * alpha / 180;

            double x1 = Math.Cos(alpha) * x - Math.Sin(alpha) * y+(1-Math.Cos(alpha))*incx+Math.Sin(alpha)*incy;//cong them 1 phan nua neu xoay theo tam c

            double y1 = Math.Sin(alpha) * x + Math.Cos(alpha) * y - Math.Sin(alpha) * incx + (1 - Math.Cos(alpha)) * incy;

            x = x1; y = y1;

        }

        public void xoayDsdiem(point2D[] p, double al)

        {

            for (int i = 0; i < p.Length; i++)

            {

                xoaydiem(ref p[i].x, ref p[i].y,al);

            }

        }

        public void xoayDsdiemtoadobaky(point2D[] p, double al, double incx, double incy)

        {

            for (int i = 0; i < p.Length; i++)

            {

                xoaydiemtoadobatky(ref p[i].x, ref p[i].y, al,incx,incy);

            }

        }

        public void Phongto(ref double x, ref double y, double sx, double sy)

        {

            x *= sx;

            y *= sy;

        }

        public void PhongtoDsdiem(point2D[] p, double sx, double sy)

        {

            for (int i = 0; i < p.Length; i++)

            {

                Phongto(ref p[i].x, ref p[i].y, sx, sy);

            }

      }

        private void Form1_Load(object sender, EventArgs e)

        {

        }

        private void Form1_Paint(object sender, PaintEventArgs e)

        {

            point2D []vert;

            vert = new point2D[4];

            vert[0].x = 100; vert[0].y = 100;

            vert[1].x = 200; vert[1].y = 100;

            vert[2].x = 200; vert[2].y = 200;

            vert[3].x = 100; vert[3].y = 200;

            drawpolygon(vert);

            TinhtienDsdiem(vert, 100, 100);

            drawpolygon(vert);

            PhongtoDsdiem(vert, 1.5, 1.5);

            drawpolygon(vert);

            xoayDsdiemtoadobaky(vert, 45, 300, 300);

            drawpolygon(vert);

            Graphics gr = e.Graphics;

            gr.DrawImageUnscaled(b, 0, 0);

        }

    }

}