C # Rotating Oval

This are used to show how to generate an oval.

The moon ' s orbit around the sun is an oval.

Nobelium controlling sing system;using system.windows.forms;using system.drawing;using system.collections.generic;class haha:form{Haha        () {WindowState = formwindowstate.maximized;        Paint + = draw;        Timer T = new timer ();        T.tick + = delegate {Invalidate ();        };        Init ();         T.interval = 200;        T.start ();        Activated + = delegate {T.start ();        };        SizeChanged + = delegate {if (WindowState = = formwindowstate.minimized) t.stop ();    };     } const int period=100;    int now=0;    Bitmap[] Bit=new Bitmap[period];        void init () {double the=math.pi*2/period;        linkedlist<point> mark = new Linkedlist<point> ();        var p = new Pen (new SolidBrush (Color.tomato), 1); for (int i = 0; i < bit. Length;            i++) {Bit[i] = new Bitmap (200,200);            var g = Graphics.fromimage (Bit[i]); int R = Math.min (Bit[i]. Width, Bit[i].            Height) >> 1; int x = Bit[i].            Width >> 1; int y = bit[i].            Height >> 1;            G.drawellipse (P, X-r, Y-r, R << 1, r << 1);            int RR = R >> 1;            Double xx = x + RR * MATH.COS (the * i);            Double yy = y + RR * Math.sin (the * i);            G.drawellipse (P, (float) (XX-RR), (float) (YY-RR), RR << 1, RR << 1);            Double r = RR * 0.5;            Double xxx = xx + R * Math.Cos (-the * i);            Double yyy = yy + R * Math.sin (-the * i); Mark.            AddLast (new Point ((int) xxx, (int) yyy));            G.drawellipse (P, (float) (xxx-r), (float) (yyy-r), (float) R * 2, (float) R * 2); foreach (Var point in Mark) {G.fillellipse (new SolidBrush (Color.tomato), point. X, point.            Y, 2, 2);            } g.drawline (P, (float) xxx, (float) yyy, (float) xx, (float) yy);         G.drawline (P, (float) xx, (float) yy, (float) x, (float) y);   } } void Draw (Object O,painteventargs e) {now = (now + 1)% period;        int w = math.min (Clientsize.width, clientsize.height);     E.graphics.drawimage (BIT[NOW],0,0,W,W);    } static void Main () {Application.Run (New Haha ()); }}

The oval rotates around its own corner.

1 usingSystem;2 usingSystem.Windows.Forms;3 usingSystem.Drawing;4 classHaha:form5 {6 Haha ()7     {8Text ="Elliptical Focus Polar coordinate equation: clockwise rotation minus rotation angle, counterclockwise rotation plus rotation angle";9Paint + =Draw;TenWindowState =formwindowstate.maximized; One     } A     DoubleA, B, W, H; -     DoubleC, E, K; -     DoubleFxDoubleThe,DoublePhi) the     { -         returnK/(1+ E * Math.Cos (the-phi)) *Math.Cos (the); -     } -     DoubleFyDoubleThe,DoublePhi) +     { -         returnK/(1+ E * Math.Cos (the-phi)) *Math.sin (the); +     } A Point Mix, Miy, corner; at     DoubleMinX (DoublePhi) -     { -         DoubleL = Math.PI/2, r = Math.PI/2*3; -          while(R-l > 1e-8) -         { -             DoubleD = (r-l)/3; in             DoubleLM = L +D; -             DoubleRM = R-D; to             if(FX (LM, PHI) > FX (rm, phi)) L =LM; +             ElseR =RM; -         } theMix. X = (int) FX (L, PHI); *Miy. Y = (int) FY (l, phi); $         returnFX (L, PHI);Panax Notoginseng     } -     DoubleMiny (DoublePhi) the     { +         DoubleL =-math.pi, r =0; A          while(R-l > 1e-8) the         { +             DoubleD = (r-l)/3; -             DoubleLM = L +D; $             DoubleRM = R-D; $             if(FY (LM, phi) > FY (rm, phi)) L =LM; -             ElseR =RM; -         } theMiy. X = (int) FX (L, PHI); -Miy. Y = (int) FY (l, phi);Wuyi         returnfy (L, phi); the     } -     voidDrawObjecto, PaintEventArgs pe) Wu     {  -         DoublePhi = math.pi* -/ the; AboutText =""+ Phi/math.pi * the; $ PE. Graphics.clear (color.wheat); -         varPen =NewPen (NewSolidBrush (Color.aqua),3); -         DoubleThe =2* Math.PI/ the; -A=math.min (clientsize.width,clientsize.height) >>2; Ab=0.618*A; +k=b*b/A; theC=MATH.SQRT (a*a-b*b); -e=c/A; $         intCenterX = Clientsize.width >>1; the         intCenterY = Clientsize.height >>1; the          for(Doublei =0; i<2* MATH.PI; i + =The ) the         { the             Doublex=k/(1+e*math.cos (I-phi)) *Math.Cos (i); -             Doubley = k/(1+ E * Math.Cos (i-phi)) *Math.sin (i); inPe. Graphics.FillEllipse (NewSolidBrush (Color.tomato), (int) (X+centerx), (int) (Y+centery),2,2); the         } thePe. Graphics.FillEllipse (NewSolidBrush (Color.tomato), CenterX, CenterY,8,8); About MinX (PHI); the Miny (PHI); theCorner. x=mix. X; theCorner. y=Miy. Y; +Mix. X + =CenterX; -Mix. Y + =CenterY; theMiy. X + =CenterX;BayiMiy. Y + =CenterY; theCorner. X + =CenterX; theCorner. Y + =CenterY; -Pen. Color =Color.Black; - PE. Graphics.drawline (pen, mix, corner); thePen. Color =Color.Blue; the PE. Graphics.drawline (pen, Miy, corner); thePe. Graphics.FillEllipse (NewSolidBrush (Color.Blue), Miy. X, Miy. Y8,8); the     } -     Static voidMain () the     { theApplication.Run (NewHaha ()); the     }94}

C # Rotating Oval