Question

I’m trying to create a graph that draws some edges between specific vertices. The idea is that I am creating random vertices, and specifying a “transmit power” integer. The way it works is that if the distance between two nodes is less than or equal to the transmit power, a line will get drawn between them.

I’m using the MSDN chart control to do this. Having problems getting lines drawn though. I keep getting the following error message:

Error   2   Argument 2: cannot convert from 'System.Windows.Forms.DataVisualization.Charting.DataPoint' to 'System.Drawing.Point'   

Been trying to crack this one so figured I’d log on to here and see if anyone else might know what to do here. I can’t find anything regarding how to convert this.

Here is some code example:

public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();
    }

    public void createNodes(int x, int y, int Nodes, int dgNodes)
    {
        Random rdn = new Random();

        for (int i = 0; i < (Nodes - dgNodes); i++)
        {
            chtGraph.Series["NoDG"].Points.AddXY
                        (rdn.Next(x), rdn.Next(y));
        }

        for (int i = 0; i <= dgNodes - 1; i++)
        {
            chtGraph.Series["DG"].Points.AddXY
                        (rdn.Next(x), rdn.Next(y));
        }
    }

    public void buildGraph(int x, int y, int Nodes, int dgNodes)
    {
        //set the min/max axis on the chart
        chtGraph.ChartAreas["ChartArea1"].AxisX.Maximum = x;
        chtGraph.ChartAreas["ChartArea1"].AxisX.Minimum = 0;
        chtGraph.ChartAreas["ChartArea1"].AxisY.Maximum = y;
        chtGraph.ChartAreas["ChartArea1"].AxisY.Minimum = 0;
        chtGraph.ChartAreas["ChartArea1"].AxisX.Interval = x / 10;
        chtGraph.ChartAreas["ChartArea1"].AxisY.Interval = y / 10;

        chtGraph.ChartAreas["ChartArea1"].AxisX.MajorGrid.Enabled = false;
        chtGraph.ChartAreas["ChartArea1"].AxisY.MajorGrid.Enabled = false;

        //build all the nodes
        createNodes(x, y, Nodes, dgNodes);
    }

    public void drawEdges(int intNumNodes, int intTransPower)
    {
        ChartGraphics gr = new ChartGraphics();
        Pen pen = new Pen(Color.Black, 1);
        //System.Drawing.Point[] pts = new Point[4];
        //pts[0] = new Point(20, 20);
        //pts[1] = new Point(20, 140);
        //pts[2] = new Point(60, 60);
        //pts[3] = new Point(180, 80);
        //gr.DrawLine(pen, pts[1], pts[2]);

        DataPoint[] pts = new DataPoint[intNumNodes];
        int i = 0;

        //Gather all the data points into an array
        foreach (DataPoint p in chtGraph.Series[0].Points)
        {
            pts[i] = p;
            i++;
        }

        i = 0;

        //loop through all the data points
        foreach (DataPoint p in pts)
        {
            //examine all the other data points for each data point visited
            for (int j = 0; j < pts.Length; j++)
            {
                //convert the y values
                int yval = Convert.ToInt32(p.YValues[0]);
                int yValNeighbors = Convert.ToInt32(pts[j].YValues[0]);

                //if the distance from the parent node (p) to the neighbor node is less than the transmit power, then draw a line
                if (Math.Sqrt(Math.Pow((p.XValue - pts[j].XValue), 2) + Math.Pow((yval - yValNeighbors), 2)) <= intTransPower)
                {
                    gr.Graphics.DrawLine(pen, p, pts[j);
                }
            }
        }
    }

    private void btnExecute_Click(object sender, EventArgs e)
    {
        if (txtDG.Text == "" || txtNodes.Text == "" || txtStorage.Text == "" || txtTransPower.Text == ""
            || txtXAxis.Text == "" || txtXAxis.Text == "")
        {
            lblError.Text = "Please enter in all inputs!";
            lblError.Visible = true;
            return;
        }
        //create variables for use through program

        int intTransPower = Convert.ToInt32(txtTransPower.Text);
        int intXAxis = Convert.ToInt32(txtXAxis.Text);
        int intYAxis = Convert.ToInt32(txtYAxis.Text);
        int intNum_DG = Convert.ToInt32(txtDG.Text);
        int intNumNodes = Convert.ToInt32(txtNodes.Text);
        int intStorage = Convert.ToInt32(txtStorage.Text);

        lblError.Visible = false;
        lblError.Text = "";

        if (txtDG.Text == "" || txtNodes.Text == "" || txtStorage.Text == "" || txtTransPower.Text == "" 
            || txtXAxis.Text == "" || txtXAxis.Text == "")
        {
            lblError.Text = "Please enter in all inputs!";
            lblError.Visible = true;}

            chtGraph.Series["NoDG"].Points.Clear();
            chtGraph.Series["DG"].Points.Clear();
            buildGraph(intXAxis, intYAxis, intNumNodes, intNum_DG);
            drawEdges(intNumNodes, intTransPower);
        }
    }
}

Answer 1

Forgive me if I got this wrong, but DataPoint does not subclass Point. They cant be converted to System.Drawing.Point automatically. Why not create new Points?

//if the distance from the parent node (p) to the neighbor node is less than the transmit power, then draw 
if (Math.Sqrt(Math.Pow((p.XValue - pts[j].XValue), 2) + Math.Pow((yval - yValNeighbors), 2)) <= intTransPower)
{
    var point = new System.Drawing.Point((int)p.XValue, (int)p.YValue); 
    gr.Graphics.DrawLine(pen, point, pts[j);
}