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  1. using System;
  2. using System.Collections.Generic;
  3. using System.ComponentModel;
  4. using System.Data;
  5. using System.Drawing;
  6. using System.Linq;
  7. using System.Text;
  8. using System.Windows.Forms;
  9.  
  10. namespace CircleGesture
  11. {
  12.     public partial class Form1 : Form
  13.     {
  14.         private List<Point> points;
  15.         private bool capturing;
  16.         private bool isCircle;
  17.         private Point centroid;
  18.         private double radius;
  19.  
  20.         private double Distance( Point a, Point b ) {
  21.             return Math.Sqrt((b.X - a.X) * (b.X - a.X) + (b.Y - a.Y) * (b.Y - a.Y));
  22.         }
  23.         private bool isApproxCircle() {
  24.             int k = points.Count;
  25.             radius = 0;
  26.             foreach (Point p in points)
  27.                 radius += Distance(centroid, p);
  28.             radius /= k;
  29.  
  30.             const double eps = 0.35; // 35% difference to average is still ok.
  31.  
  32.             foreach (Point p in points)
  33.             {
  34.                 double r = Distance(centroid, p);
  35.                 if (Math.Abs((radius-r)/radius)>eps)
  36.                     return false;
  37.             }
  38.             return true;
  39.         }
  40.  
  41.         public Form1()
  42.         {
  43.             InitializeComponent();
  44.             points = new List<Point>();
  45.         }
  46.  
  47.         private void Form1_MouseDown(object sender, MouseEventArgs e)
  48.         {
  49.             points.Clear();
  50.             capturing = true;
  51.             points.Add(e.Location);
  52.             centroid.X = e.Location.X; centroid.Y = e.Location.Y;
  53.         }
  54.  
  55.         private void Form1_MouseMove(object sender, MouseEventArgs e)
  56.         {
  57.             if (capturing) {
  58.                 points.Add(e.Location);
  59.                 centroid.X += e.Location.X; centroid.Y += e.Location.Y;
  60.             }
  61.         }
  62.  
  63.         private void Form1_MouseUp(object sender, MouseEventArgs e)
  64.         {
  65.             if (capturing) {
  66.                 points.Add(e.Location);
  67.                 centroid.X += e.Location.X; centroid.Y += e.Location.Y;
  68.                 centroid.X /= points.Count; centroid.Y /= points.Count;
  69.                 capturing = false;
  70.                 isCircle = isApproxCircle();
  71.                 Invalidate();
  72.             }
  73.         }
  74.  
  75.         private void Form1_Paint(object sender, PaintEventArgs e)
  76.         {
  77.             System.Drawing.Graphics graphicsObj = this.CreateGraphics();
  78.             Pen myPen = new Pen(System.Drawing.Color.Black, 2);
  79.             int cnt = points.Count;
  80.             if (cnt > 0)
  81.             {
  82.                 Point[] pts = new Point[cnt];
  83.                 for (int i = 0; i < cnt; ++i)
  84.                 {
  85.                     pts[i] = points[i];
  86.                     graphicsObj.DrawLine(myPen, centroid, pts[i]);
  87.                 }
  88.                 graphicsObj.DrawPolygon(myPen, pts);
  89.                 if (isCircle)
  90.                 {
  91.                     Int32 r = Convert.ToInt32(radius);
  92.                     Rectangle myRectangle = new Rectangle(centroid.X - r, centroid.Y - r, 2*r, 2*r);
  93.                     graphicsObj.DrawEllipse(myPen, myRectangle);
  94.                 }
  95.             }
  96.         }
  97.     }
  98. }
  99.  
Compilation error #stdin compilation error #stdout 0s 0KB
comments (?)
stdin 
Standard input is empty
compilation info 
prog.cs(4,14): error CS0234: The type or namespace name `Data' does not exist in the namespace `System'. Are you missing an assembly reference?
prog.cs(5,14): error CS0234: The type or namespace name `Drawing' does not exist in the namespace `System'. Are you missing an assembly reference?
prog.cs(8,14): error CS0234: The type or namespace name `Windows' does not exist in the namespace `System'. Are you missing an assembly reference?
Compilation failed: 3 error(s), 0 warnings
stdout 
Standard output is empty
https://ideone.com/DOjnd
language:
C# (gmcs 5.20.1)
created:
12 years ago
visibility:
public

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