internal class PolarPoint
    {
        public double Angle { get; private set; }
        public double Y { get; private set; }
        public PolarPoint(double angle, double y)
        {
            this.Angle = angle;
            this.Y = y;
        }
    }

    internal class RectangleInPolarPoints
    {
        public PolarPoint TopLeft { get; private set; }
        public PolarPoint TopRight { get; private set; }
        public PolarPoint BottomLeft { get; private set; }
        public PolarPoint BottonRight { get; private set; }
        public RectangleInPolarPoints(PolarPoint topLeft, PolarPoint bottomLeft, PolarPoint topRight, PolarPoint bottomRight)
        {
            this.TopLeft = topLeft;
            this.TopRight = topRight;
            this.BottomLeft = bottomLeft;
            this.BottonRight = bottomRight;
        }
    }

    internal struct PointD
    {
        public double X { get; private set; }
        public double Y { get; private set; }
        public PointD(double x, double y)
            : this()
        {
            this.X = x;
            this.Y = y;
        }
    }

    #endregion

    #region Designer code

    private System.Windows.Forms.DataVisualization.Charting.Chart chart1;
    private System.Windows.Forms.TextBox textBox1;
    private System.Windows.Forms.SplitContainer splitContainer1;

    private void InitializeComponent()
    {
        System.Windows.Forms.DataVisualization.Charting.ChartArea chartArea1 = new System.Windows.Forms.DataVisualization.Charting.ChartArea();
        System.Windows.Forms.DataVisualization.Charting.Legend legend1 = new System.Windows.Forms.DataVisualization.Charting.Legend();
        System.Windows.Forms.DataVisualization.Charting.Series series1 = new System.Windows.Forms.DataVisualization.Charting.Series();
        this.chart1 = new System.Windows.Forms.DataVisualization.Charting.Chart();
        this.textBox1 = new System.Windows.Forms.TextBox();
        this.splitContainer1 = new System.Windows.Forms.SplitContainer();
        ((System.ComponentModel.ISupportInitialize)(this.chart1)).BeginInit();
        this.splitContainer1.Panel1.SuspendLayout();
        this.splitContainer1.Panel2.SuspendLayout();
        this.splitContainer1.SuspendLayout();
        this.SuspendLayout();
        //
        // chart1
        //
        chartArea1.Name = "ChartArea1";
        this.chart1.ChartAreas.Add(chartArea1);
        this.chart1.Dock = System.Windows.Forms.DockStyle.Fill;
        legend1.Name = "Legend1";
        this.chart1.Legends.Add(legend1);
        this.chart1.Location = new System.Drawing.Point(0, 0);
        this.chart1.Name = "chart1";
        series1.ChartArea = "ChartArea1";
        series1.Legend = "Legend1";
        series1.Name = "Series1";
        this.chart1.Series.Add(series1);
        this.chart1.Size = new System.Drawing.Size(644, 339);
        this.chart1.TabIndex = 0;
        this.chart1.Text = "chart1";
        //
        // textBox1
        //
        this.textBox1.Dock = System.Windows.Forms.DockStyle.Fill;
        this.textBox1.Font = new System.Drawing.Font("Courier New", 9.75F, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, ((byte)(0)));
        this.textBox1.Location = new System.Drawing.Point(0, 0);
        this.textBox1.Multiline = true;
        this.textBox1.Name = "textBox1";
        this.textBox1.ScrollBars = System.Windows.Forms.ScrollBars.Vertical;
        this.textBox1.Size = new System.Drawing.Size(644, 79);
        this.textBox1.TabIndex = 1;
        //
        // splitContainer1
        //
        this.splitContainer1.Dock = System.Windows.Forms.DockStyle.Fill;
        this.splitContainer1.Location = new System.Drawing.Point(0, 0);
        this.splitContainer1.Name = "splitContainer1";
        this.splitContainer1.Orientation = System.Windows.Forms.Orientation.Horizontal;
        //
        // splitContainer1.Panel1
        //
        this.splitContainer1.Panel1.Controls.Add(this.chart1);
        //
        // splitContainer1.Panel2
        //
        this.splitContainer1.Panel2.Controls.Add(this.textBox1);
        this.splitContainer1.Size = new System.Drawing.Size(644, 422);
        this.splitContainer1.SplitterDistance = 339;
        this.splitContainer1.TabIndex = 2;
        //
        // Form1
        //
        this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 13F);
        this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
        this.ClientSize = new System.Drawing.Size(644, 422);
        this.Controls.Add(this.splitContainer1);
        this.Name = "MyForm";
        this.Text = "Polar chart with selection";
        ((System.ComponentModel.ISupportInitialize)(this.chart1)).EndInit();
        this.splitContainer1.Panel1.ResumeLayout(false);
        this.splitContainer1.Panel2.ResumeLayout(false);
        this.splitContainer1.Panel2.PerformLayout();
        this.splitContainer1.ResumeLayout(false);
        this.ResumeLayout(false);

    }
    #endregion

    #region Constructor

    public Form1()
    {
        InitializeComponent();

        this.chart1.MouseDown += new MouseEventHandler(chart1_MouseDown);
        this.chart1.MouseMove += new MouseEventHandler(chart1_MouseMove);
        this.chart1.MouseUp += new MouseEventHandler(chart1_MouseUp);
        this.chart1.PostPaint += new EventHandler<ChartPaintEventArgs>(chart1_PostPaint);
    }
    #endregion

    #region Chart Data Initialization

    protected override void OnLoad(EventArgs e)
    {
        this.FillChart();
    }

    private void FillChart()
    {
        var items = new[] { new PolarPoint(0, 10), new PolarPoint(30, 4), new PolarPoint(120, 2), new PolarPoint(185, 9), new PolarPoint(240, 7) };

        this.chart1.Series.Clear();
        var seriesLines = this.chart1.Series.Add("Values");
        seriesLines.XValueMember = "Angle";
        seriesLines.YValueMembers = "Y";
        seriesLines.ChartType = SeriesChartType.Polar;

        this.chart1.DataSource = items;
    }
    #endregion

    #region Selection Management

    Point? clickPoint;
    RectangleF? highlightRectAbs;
    RectangleInPolarPoints highlightRect;

    void chart1_MouseDown(object sender, MouseEventArgs e)
    {
        this.highlightRectAbs = null;
        this.highlightRect = null;

        // deselect all points
        var s = this.chart1.Series[0];
        for (int i = 0; i < s.Points.Count; i++)
            s.Points[i].Tag = false;

        this.clickPoint = e.Location;
    }

    void chart1_MouseMove(object sender, MouseEventArgs e)
    {
        if (this.clickPoint.HasValue && this.clickPoint != e.Location)
        {
            int width = Math.Abs(e.X - this.clickPoint.Value.X);
            int height = Math.Abs(e.Y - this.clickPoint.Value.Y);
            int x = Math.Min(e.X, this.clickPoint.Value.X);
            int y = Math.Min(e.Y, this.clickPoint.Value.Y);

            this.highlightRectAbs = new RectangleF(x, y, width, height);
            this.highlightRect = null;
            if (this.highlightRectAbs.Value.Width != 0 && this.highlightRectAbs.Value.Height != 0)
            {
                this.chart1.Invalidate();
            }
        }
    }

    void chart1_MouseUp(object sender, MouseEventArgs e)
    {
        this.clickPoint = null;
        this.chart1.Invalidate();

        // here we have finished our selection
        this.SelectionFinished();
    }

    void chart1_PostPaint(object sender, ChartPaintEventArgs e)
    {
        var area = e.ChartElement as ChartArea;
        if (area == null)
            return;

        if (!this.highlightRectAbs.HasValue)
            return;

        // get center and radius
        var minY = area.AxisY.ValueToPixelPosition(area.AxisY.Minimum);
        var maxX = area.AxisX.ValueToPixelPosition(area.AxisX.Maximum);
        var maxY = area.AxisY.ValueToPixelPosition(area.AxisY.Maximum);
        var radius = Math.Abs(maxY - minY);
        var centerX = maxX;
        var centerY = minY;

        if (this.highlightRect == null)
            this.highlightRect = GetRectangleInPolarPoints(this.highlightRectAbs.Value, area, centerX, centerY, radius);
        this.highlightRectAbs = GetRectangleF(this.highlightRect, area, centerX, centerY, radius);

        using (var brush = new SolidBrush(Color.FromArgb(15, Color.Black)))
        {
            var cg = e.ChartGraphics;
            cg.Graphics.FillRectangle(brush, this.highlightRectAbs.Value);
            cg.Graphics.DrawRectangle(Pens.Red, this.highlightRectAbs.Value.X, this.highlightRectAbs.Value.Y,
                                      this.highlightRectAbs.Value.Width, this.highlightRectAbs.Value.Height);

            var s = e.Chart.Series[0];
            for (int i = 0; i < s.Points.Count; i++)
            {
                var point = s.Points[i];

                var pt = GetCoordsOfPoint(point.XValue, point.YValues[0], area, centerX, centerY, radius);

                // highlights the points if they're into the selection
                if (this.highlightRectAbs.Value.Contains(pt))
                {
                    cg.Graphics.FillEllipse(Brushes.GreenYellow, pt.X - 5, pt.Y - 5, 10, 10);
                    point.Tag = true;
                }
                else
                {
                    point.Tag = false;
                }
            }
        }

    }

    private void SelectionFinished()
    {
        this.textBox1.Text = "Selection:" + Environment.NewLine;
        var s = this.chart1.Series[0];
        for (int i = 0; i < s.Points.Count; i++)
        {
            var point = s.Points[i];
            if (point.Tag is bool && (bool)point.Tag == true)
                this.textBox1.AppendText(string.Format("Angle = {0,6:N2}, Y = {1,6:N2}rn", point.XValue, point.YValues[0]));
        }
    }

    #endregion

    #region Helper Methods

    static PointF GetCoordsOfPoint(PolarPoint polPt, ChartArea area, double centerX, double centerY, double radius)
    {
        return GetCoordsOfPoint(polPt.Angle, polPt.Y, area, centerX, centerY, radius);
    }

    static PointF GetCoordsOfPoint(double angle, double yVal, ChartArea area, double centerX, double centerY, double radius)
    {
        double xRatio = 360.0 / Math.Abs(area.AxisX.Maximum - area.AxisX.Minimum);
        double radAngle = (-(angle * xRatio + area.AxisX.Crossing) - 270) * Math.PI / 180;
        double yRadius = Scale(yVal, area.AxisY.Minimum, area.AxisY.Maximum, 0, radius);

        double h = Math.Sin(radAngle);
        double w = Math.Cos(radAngle);

        return new PointF((float)(centerX + w * yRadius), (float)(centerY - h * yRadius));
    }

    static PolarPoint GetPolarPointFromCoords(double x, double y, ChartArea area, double centerX, double centerY, double radius)
    {
        double xRatio = 360.0 / Math.Abs(area.AxisX.Maximum - area.AxisX.Minimum);

        var xComp = x - centerX;
        var yComp = centerY - y;

        var hypotenuseLength = Math.Sqrt(xComp * xComp + yComp * yComp);
        var angle = GetZero360Angle(-(Math.Atan2(yComp, xComp) * 180 / Math.PI) - 270);

        //angle = Scale(angle, 0, 360, area.AxisX.Minimum, area.AxisX.Maximum);
        angle = (angle - area.AxisX.Crossing) / xRatio;

        return new PolarPoint(angle , Scale(hypotenuseLength, 0, radius, area.AxisY.Minimum, area.AxisY.Maximum));
    }

    static RectangleInPolarPoints GetRectangleInPolarPoints(RectangleF rect, ChartArea area, double centerX, double centerY, double radius)
    {
        var topLeft = GetPolarPointFromCoords(rect.Left, rect.Top, area, centerX, centerY, radius);
        var bottomLeft = GetPolarPointFromCoords(rect.Left, rect.Bottom, area, centerX, centerY, radius);
        var topRight = GetPolarPointFromCoords(rect.Right, rect.Top, area, centerX, centerY, radius);
        var bottomRight = GetPolarPointFromCoords(rect.Right, rect.Bottom, area, centerX, centerY, radius);
        return new RectangleInPolarPoints(topLeft, bottomLeft, topRight, bottomRight);
    }

    static RectangleF GetRectangleF(RectangleInPolarPoints recPolar, ChartArea area, double centerX, double centerY, double radius)
    {
        var topLeftPt = GetCoordsOfPoint(recPolar.TopLeft, area, centerX, centerY, radius);
        var bottomLeftPt = GetCoordsOfPoint(recPolar.BottomLeft, area, centerX, centerY, radius);
        var topRightPt = GetCoordsOfPoint(recPolar.TopRight, area, centerX, centerY, radius);

        var width = (float)(topRightPt.X - topLeftPt.X);
        var height = (float)(bottomLeftPt.Y - topLeftPt.Y);

        return new RectangleF(topLeftPt, new SizeF(width, height));
    }

    static double GetZero360Angle(double angle)
    {
        while (angle < 0)
            angle += 360;
        while (angle > 360)
            angle -= 360;
        return angle;
    }


    static double Scale(double oldScaleVal, double oldScaleMin, double oldScaleMax, double newScaleMin, double newScaleMax)
    {
        return newScaleMin + (oldScaleVal - oldScaleMin) / (oldScaleMax - oldScaleMin) * (newScaleMax - newScaleMin);
    }

    #endregion
}