Question

Hi have a ListView in the main forma called Dlist, i have a background worker to download a file, in the background worker how can i edit the subitem “Progress” in the main form listview ?

My Code:

BackgroundWorker worker = new BackgroundWorker();
worker.DoWork += (obj, e) => WorkerDoWork(link, savepath,Dlist);
worker.RunWorkerCompleted += new RunWorkerCompletedEventHandler(progress_complete);
worker.ProgressChanged += new ProgressChangedEventHandler(progress_changed);
worker.RunWorkerAsync();


rivate void WorkerDoWork(string link, string savepath, ListView Dlist)
    {
        // Start Download
        Uri url = new Uri(link);
        System.Net.HttpWebRequest request = (System.Net.HttpWebRequest)System.Net.WebRequest.Create(url);
        System.Net.HttpWebResponse response = (System.Net.HttpWebResponse)request.GetResponse();
        response.Close();
        Int64 iSize = response.ContentLength;
        Int64 iRunningByteTotal = 0;
        using (System.Net.WebClient client = new System.Net.WebClient())
        {
            using (System.IO.Stream streamRemote = client.OpenRead(new Uri(link)))
            {
                using (Stream streamLocal = new FileStream(savepath, FileMode.Create, FileAccess.Write, FileShare.None))
                {
                    int iByteSize = 0;
                    byte[] byteBuffer = new byte[256];
                    while ((iByteSize = streamRemote.Read(byteBuffer, 0, byteBuffer.Length)) > 0)
                    {
                        streamLocal.Write(byteBuffer, 0, iByteSize);
                        iRunningByteTotal += iByteSize;
                        double dIndex = (double)(iRunningByteTotal);
                        double dTotal = (double)byteBuffer.Length;
                        double dProgressPercentage = (dIndex / dTotal);
                        int iProgressPercentage = (int)(dProgressPercentage * 100);
                        //Dlist.Items[Dlist.Items.IndexOfKey(fileName)].SubItems[2].Text = iProgressPercentage.ToString();
                    }
                    streamLocal.Close();
                }
                streamRemote.Close();
            }
        }
    }

this line (//Dlist.Items[Dlist.Items.IndexOfKey(fileName)].SubItems[2].Text = iProgressPercentage.ToString();) it is to update the listview but i keep getting cross thread.

Answer 1

Why not use BackgroundWorker.ReportProgress method (see Examples section)?

http://msdn.microsoft.com/en-us/library/system.componentmodel.backgroundworker.aspx