using Invoke to handle cross threading

[mobeen89]

Hello. So I am making an application that sets up a serial port and creates a DataReceived event whenever there is data received on the serial port. Now, I want to update a listbox in my UI whenever the data received event occurs but a cross threading error occurs. I have no exposure to threads and the article on MSDN about invoke is too sparse. So I am attaching my code and can you please edit it to include invokes such that my listbox gets refreshed whenever there is a DataReceived event. Thanks!

using System;
    using System.Collections.Generic;
    using System.ComponentModel;
    using System.Data;
    using System.Drawing;
    using System.Linq;
    using System.Text;
    using System.Windows.Forms;
    using System.IO;
    using System.IO.Ports;
    using System.Collections;
    using System.Management;
    using System.Threading;
    using System.Runtime.InteropServices;
    using Microsoft.Win32;

    namespace testListBox
    {
     /*Class1 is used to automatically find and open a serial port, and has an event handler for whenever there is DataReceived*/   

        class Class1
        {
            /*just defining variables to automatically allocate a serial port, no need to follow*/
        public SerialPort ZigbeePort;
            public string[] available_ports = SerialPort.GetPortNames();
            RegistryKey myKey = Registry.LocalMachine.OpenSubKey("HARDWARE\\DEVICEMAP\\SERIALCOMM", false);
            public string[] valueNames;
            string name_of_module = "VCP0";
            public int number_ports;
            public string COM_port_name;

            List<byte> HandlerReceived = new List<byte>();
            public Form1 form;

            /*just opening a COM port, do not need to follow*/
            public void init()
            {
                valueNames = myKey.GetValueNames(); /*Store the value names of the keys in a string array*/
                number_ports = valueNames.Length;
                for (int i = 0; i < number_ports; i++)
                {
                    if (valueNames[i].EndsWith(name_of_module))
                    {
                        ZigbeePort = new SerialPort(available_ports[i], 9600, Parity.None, 8, StopBits.Two);
                        if (!ZigbeePort.IsOpen)
                        {
                            ZigbeePort.Open();
                        }
                        COM_port_name = available_ports[i];
                    }
                }
                ZigbeePort.DataReceived += new SerialDataReceivedEventHandler(DataReceivedHandler);
            }


            /*Data Received handler*/
            public void DataReceivedHandler(object sender, SerialDataReceivedEventArgs e)
            {
                byte[] TempRxData = new Byte[ZigbeePort.BytesToRead];
                ZigbeePort.Read(TempRxData, 0, TempRxData.Length);
                for (int i = 0; i < TempRxData.Length; i++)
                {
                    HandlerReceived.Add(Convert.ToByte(TempRxData[i]));
                }

                /*Just adding a name to the items list that the Listbox has*/
                form.a.Add("Handler Item");
                System.Console.WriteLine(HandlerReceived.Count);

            }
        }

        public partial class Form1 : Form
        {
            public BindingList <string> a = new BindingList <string>();
            Class1 clas = new Class1();

            public Form1()
            {
                InitializeComponent();
                listBox1.DataSource = null;
                a.Add("1st Item");
                a.Add("2nd Item");
                listBox1.DataSource = a;
                clas.init();
                clas.form = this;
                a.ListChanged += new ListChangedEventHandler(a_ListChanged);
            }
            private void button1_Click(object sender, EventArgs e)
            {
                a.Add("Button item");
            }

            void a_ListChanged(object sender, ListChangedEventArgs e)
            {
                /*cross threading occurs here*/
                listBox1.Refresh();
            }
        }
    }

[Philippe.Lahaie]

how is the msdn article about this too sparse? i find it pretty straight foward!

article

// This method demonstrates a pattern for making thread-safe
        // calls on a Windows Forms control. 
        //
        // If the calling thread is different from the thread that
        // created the TextBox control, this method creates a
        // SetTextCallback and calls itself asynchronously using the
        // Invoke method.
        //
        // If the calling thread is the same as the thread that created
        // the TextBox control, the Text property is set directly. 

        private void SetText(string text)
        {
            // InvokeRequired required compares the thread ID of the
            // calling thread to the thread ID of the creating thread.
            // If these threads are different, it returns true.
            if (this.textBox1.InvokeRequired)
            {   
                SetTextCallback d = new SetTextCallback(SetText);
                this.Invoke(d, new object[] { text });
            }
            else
            {
                this.textBox1.Text = text;
            }
        }