CODEWITHSUNDEEP
c#winformsprogress-baruilabel
Sandy
Sandy

Reputation: 11707

Progress bar working but label is not updating

I have a library with an Interface.

Public Interface Progress
{
    int ProgressValue{get;set;},
    string ProgressText{get;set;},
}

Library has a method Create (dummy code):

Public Class TestLibrary
{

    Progress _progress;

    Public void Create()
    {
        foreach(var n in TestList)
        {
            // Do Something
            _progress.ProgressValue = GetIndex(n);
            _progress.ProgressText = "Updating..." + n;
        }
    }
}

I have a project that references this library and calls Create method. It even Implements Interface Progress.

Public Class TestProject : Progress
{
    public int ProgressValue
    {
        get{return progressBar1.Value;}
        set{progressBar1.Value = value;}
    }

    public int ProgressText
    {
        get{return label1.Text;}
        set{label1.Text = value;}
    }
}

Now when I run the application, Progress Bar behaves properly and shows the progress correctly, but the Text of label1 does not change at all. But it do change in the end of for loop and shows the last item in loop. Can anyone help me out in this?

Note: All these codes are written directly without testing as I don't have my application now with me. Sorry for any syntax errors.

Upvotes: 4

Views: 4652

Answers (3)

abhiroop mukherjee
abhiroop mukherjee

Reputation: 69

The code you posted uses one thread. That means every operation is excuted in sequence right after the previous one finished. Since you can update GUI elements right away, I suppose the code to be run from main thread (a.k.a "GUI thread"). Blocking the GUI thread results in the GUI ("Graphical User Interface") not updating until there is some idle time for it.

Use following example to refresh your label every iteration so that it updates your UI.

label1.Text = i.ToString();
label1.Refresh();

Upvotes: 1

Angshuman Agarwal
Angshuman Agarwal

Reputation: 4866

Used a Label instead of ProgressBar. You can try this code [using BackGroundWorker] -

using System.ComponentModel;
using System.Windows.Forms;

namespace WindowsFormsApplication1
{
    public partial class Form3 : Form
    {
        private BackgroundWorker _worker;
        BusinessClass _biz = new BusinessClass();
        public Form3()
        {
            InitializeComponent();
            InitWorker();
        }

        private void InitWorker()
        {
            if (_worker != null)
            {
                _worker.Dispose();
            }

            _worker = new BackgroundWorker
            {
                WorkerReportsProgress = true,
                WorkerSupportsCancellation = true
            };
            _worker.DoWork += DoWork;
            _worker.RunWorkerCompleted += RunWorkerCompleted;
            _worker.ProgressChanged += ProgressChanged;
            _worker.RunWorkerAsync();
        }


        void DoWork(object sender, DoWorkEventArgs e)
        {
            int highestPercentageReached = 0;
            if (_worker.CancellationPending)
            {
                e.Cancel = true;
            }
            else
            {
                double i = 0.0d;
                int junk = 0;
                for (i = 0; i <= 199990000; i++)
                {
                    int result = _biz.MyFunction(junk);
                    junk++;

                    // Report progress as a percentage of the total task.
                    var percentComplete = (int)(i / 199990000 * 100);
                    if (percentComplete > highestPercentageReached)
                    {
                        highestPercentageReached = percentComplete;
                        // note I can pass the business class result also and display the same in the LABEL  
                        _worker.ReportProgress(percentComplete, result);
                        _worker.CancelAsync();
                    }
                }

            }
        }

        void RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
        {
            if (e.Cancelled)
            {
                // Display some message to the user that task has been
                // cancelled
            }
            else if (e.Error != null)
            {
                // Do something with the error
            }
        }

        void ProgressChanged(object sender, ProgressChangedEventArgs e)
        {
            label1.Text =  string.Format("Result {0}: Percent {1}",e.UserState, e.ProgressPercentage);
        }
    }

    public class BusinessClass
    {
        public int MyFunction(int input)
        {
            return input+10;
        }
    }
}

Posted the same a few days ago here

Upvotes: 5

Jon Skeet
Jon Skeet

Reputation: 1502935

It sounds like all your work is being done on the UI thread. Don't do that.

Instead, run the loop itself in a background thread, and use Control.Invoke or Control.BeginInvoke (probably in the Progress implementation) to marshal a call across to the UI thread just to update the UI. This will leave your UI responsive (and able to update labels etc) while it's still processing.

Upvotes: 9

Related Questions