Control.Invoke must be used to interact with controls created on a seperate thread

[benjamin yap]

Hi, I get this error despite create a delegate..

    private delegate void ResumeChart();
    ResumeChart ChartResume;

    private void ResumeChartLayout()
    {
        this.m\_ChartControl.ResumeChartLayout();
    }

    void ResetChart()
    {
        this.Invoke(ChartResume);
    }

Inside my constructor I have this.

    public frmGraph(String stockQuote,String\[\] args)
    {
        InitializeComponent();
        newArgs = new String\[args.Length\];
        Array.Copy(args, newArgs, args.Length);
        token = newArgs\[0\];
        
        this.stockQuote = stockQuote;
        //this.stockQuote = "MGM";
        label1.Text = stockQuote;
        this.Text = stockQuote + " Graph";
        **ChartResume = ResumeChartLayout;**
    }

Inside my form load, i create a new thread to call another function

    private void frmGraph\_Load(object sender, EventArgs e)
    {   
        FillDataTable();

        //SetFilter(DateTime.Now.AddDays(-9), DateTime.Now);
        m\_ChartControl.Charts\[0\].Data = this.GenareteDataForCandle();
        m\_ChartControl.SuspendChartLayout();
        m\_ChartControl.LoadTheme("Manco.Chart.CF.Theme.xml");
        m\_ChartControl.Charts\[0\].ChartType = ChartType.Line;

        m\_ChartControl.Charts\[0\].ValueAxisList\[0\].Min = this.m\_dStokMin;
        m\_ChartControl.Charts\[0\].ValueAxisList\[0\].Max = this.m\_dStokMax;

        **workerThread2 = new Thread(new ThreadStart(AddAnnotations));
        workerThread2.Start();**

        m\_ChartControl.ResumeChartLayout();
    }

This is my AddAnnotation function that will invoke the ResetChart() method

    public void AddAnnotations()
    {
        string toa = "calls";
        Annotation\[\] anno = null;
        int countA = 0;
        int arrayIndex = 0;
        while (true)
        {

            XmlDocument xmlPlogs = getAllPlogs(toa);
            XmlNodeList plogs = xmlPlogs.SelectNodes("/PlogList/Plog");

            foreach (XmlNode plog in plogs)
            {
                XmlNodeList receivers = plog.SelectNodes("PlogUnique/Message/Receiver");
                
                foreach (DateTime dt in dateArray)
                {
                    DateTime newDT = Convert.ToDateTime(plog.SelectSingleNode("PlogCommon/T

[vivasaayi]

Try after changing the ResetChart function like this. void ResetChart() { this.m_ChartControl.Invoke(ChartResume); }

[benjamin yap]

hmm.. i still get the same error :( could this be the error? under the AddAnnotations method. anno[countA] = m_ChartControl.Charts[0].AnnotationList.CreateAnnotation();

[vivasaayi]

Yes. Previously I did not went through the AddAnnotation() function. Since you ChartControl is in the UI Thread, you can only access/modify the ChartControl properties by using a delegate. Just like you used a delegate to call the ChartResume method, use another Delegate to add annotation. This will surely solve the problem.

[benjamin yap]

i have create another Delegate

    private delegate void AddAnnotation();
    AddAnnotation addNewAnnotation;

    private void CreateAnnotation()
    {
        m\_ChartControl.Charts\[0\].AnnotationList.CreateAnnotation(); 
    }
    void cAnnotation()
    {
        this.Invoke(addNewAnnotation);
    }

and under the AddAnnoations method i change it to

anno[countA] = cAnnotation();

and i get this error Error 4 Cannot implicitly convert type 'void' to 'Manco.Chart.CF.Layout.Annotation' i tried change all the void to Annotation but still get error

modified on Friday, December 11, 2009 12:00 PM