How to correctly implement a BackgroundWorker with ProgressBar updates?
As you haven't shown your full BackgroundWorker
code, I can't tell if you have implemented it correctly. As such, all I can do is to show you a simple working example of updating a ProgressBar
control:
UserControl
XAML:
<UserControl x:Class="WpfApplication1.Views.TestView"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
mc:Ignorable="d"
d:DesignHeight="300" d:DesignWidth="300" Loaded="UserControl_Loaded">
<ProgressBar x:Name="progressBar" Height="25" Margin="20" Minimum="0"
Maximum="50" />
</UserControl>
MainWindow
XAML:
<Window x:Class="WpfApplication1.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:Views="clr-namespace:WpfApplication1.Views"
Title="MainWindow" Height="350" Width="525">
<Views:TestView />
</Window>
UserControl
code behind:
using System.ComponentModel;
using System.Threading;
using System.Windows;
using System.Windows.Controls;
namespace WpfApplication1.Views
{
public partial class TestView : UserControl
{
private BackgroundWorker backgroundWorker = new BackgroundWorker();
public TestView()
{
InitializeComponent();
backgroundWorker.WorkerReportsProgress = true;
backgroundWorker.ProgressChanged += ProgressChanged;
backgroundWorker.DoWork += DoWork;
// not required for this question, but is a helpful event to handle
backgroundWorker.RunWorkerCompleted += BackgroundWorker_RunWorkerCompleted;
}
private void UserControl_Loaded(object sender, RoutedEventArgs e)
{
backgroundWorker.RunWorkerAsync();
}
private void DoWork(object sender, DoWorkEventArgs e)
{
for (int i = 0; i <= 100; i++)
{
// Simulate long running work
Thread.Sleep(100);
backgroundWorker.ReportProgress(i);
}
}
private void ProgressChanged(object sender, ProgressChangedEventArgs e)
{
// This is called on the UI thread when ReportProgress method is called
progressBar.Value = e.ProgressPercentage;
}
private void BackgroundWorker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
// This is called on the UI thread when the DoWork method completes
// so it's a good place to hide busy indicators, or put clean up code
}
}
}
Ian W
Trained engineer who self taught sql and vba and now has gone a training course on C# and is trying to convert
Updated on May 12, 2020Comments
-
Ian W about 4 years
-Updated--14/10 also asked this question
To give some clear idea of what is going on and taking into account the comments and from this article here
What I really want to do now is invoke a new form with a progress bar on it and have that run and animate whilst my back ground thread runs my long process to the database and then invoke a close form event
The background worker is set up here
public partial class MainWindow : Window { //Declare background workers BackgroundWorker bw = new BackgroundWorker(); BackgroundWorker bwLoadCSV = new BackgroundWorker(); BackgroundWorker bwProgressBar = new BackgroundWorker();
Then delegates added here
public MainWindow() { bwLoadCSV.WorkerReportsProgress = true; bwLoadCSV.WorkerSupportsCancellation = true; bwLoadCSV.DoWork += new DoWorkEventHandler(bwLoadCSV_DoWork); bwLoadCSV.ProgressChanged += new ProgressChangedEventHandler(bwLoadCSV_ProgressChanged); bwLoadCSV.RunWorkerCompleted += new RunWorkerCompletedEventHandler(bwLoadCSV_RunWorkerCompleted);
The call is made here from the main window class
private void CSV_Load_Click(object sender, RoutedEventArgs e) ///Function to read csv into datagrid /// { //Turn Cursor to wait System.Windows.Forms.Cursor.Current = System.Windows.Forms.Cursors.WaitCursor; //Test connection to sql server if (CHHoursDataProvider.IsDatabaseOnline() == false) { System.Windows.Forms.MessageBox.Show("Can not establish contact with sql server" + "\n" + "Contact IT", "Connection Error"); //Set UI picture return; } //Set a control to update the user here tbLoadDgStat.Visibility = Visibility.Visible; tbLoadDgStat.Text = "Getting data templete from Database..."; string FilePath = txFilePath.Text; if (bwLoadCSV.IsBusy != true) { //load the context object with parameters for Background worker bwCSVLoadContext Context = new bwCSVLoadContext(); Context.Site = cBChSite.Text; Context.FilePath = txFilePath.Text; Context.FileName = fileTest; Context.Wageyear = cbWageYear.Text; Context.Startdate = ((DateTime)dpStartDate.SelectedDate); Context.Enddate = ((DateTime)dpEndDate.SelectedDate); bwLoadCSV.RunWorkerAsync(Context); }
The background worker do work is
private void bwLoadCSV_DoWork(object sender, DoWorkEventArgs e) { BackgroundWorker worker = sender as BackgroundWorker; bwCSVLoadContext Context = e.Argument as bwCSVLoadContext; worker.ReportProgress((10)); if ((worker.CancellationPending == true)) { e.Cancel = true; } else { // Perform a time consuming operation and report progress load csv into datagrid.
To report the background work I do this. This is where I am trying to load a new form call ProgressDialog which has a progress bar on it, which I am try set to Indeterminable so it just "swishes" across my ProgressDialoge form to show the user something is still going on. I have used the reporter part of the background work because I believe it has access to the main window thread and I am hoping that the invoke method is then called from the main window thread, but I am not really sure
Here is the reporter
private void bwLoadCSV_ProgressChanged(object sender, ProgressChangedEventArgs e) { this.Dispatcher.Invoke((MethodInvoker)delegate { tbLoadDgStat.Visibility = Visibility.Visible; }); //tbLoadDgStat.Visibility = Visibility.Visible; //this.progressBar1.Value = e.ProgressPercentage;//This works but pauses on long steps if (e.ProgressPercentage == 10) { //Try to open a new form with a class ProgressDialog and set the progressbar // on the frm to IsIndeterminate=true //THIS IS NOT WORKING this.Dispatcher.BeginInvoke (new Action(() => { ProgressDialog progressDialog = new ProgressDialog(); progressDialog.SetIndeterminate(true); })); //this updates the main form OK this.Dispatcher.Invoke((MethodInvoker)delegate { tbLoadDgStat.Text = "Getting data templete from Database..."; }); } else if (e.ProgressPercentage == 20) { this.Dispatcher.Invoke((MethodInvoker)delegate { tbLoadDgStat.Text = "Data template retrieved..."; }); } else { if (e.ProgressPercentage % 10 == 0) { this.Dispatcher.Invoke((MethodInvoker)delegate { tbLoadDgStat.Text = "Adding Data..." + e.ProgressPercentage.ToString() + "%"; }); } }
Lastly the xaml for the ProgressDialog Form and it's class
<Window x:Class="Test_Read_CSV.ProgressDialog" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" Title="Progress Dialog" Height="115" Width="306" Name="ProgressPopup"> <Grid> <ProgressBar Height="31" HorizontalAlignment="Left" Margin="12,33,0,0" Name="progressBar1" VerticalAlignment="Top" Width="250" /> <TextBox Height="23" HorizontalAlignment="Left" Margin="7,4,0,0" Name="tbEvent" VerticalAlignment="Top" Width="254" IsReadOnly="True" IsEnabled="False" /> </Grid>
class
/// <summary> /// Interaction logic for ProgressDialog.xaml /// </summary> public partial class ProgressDialog : Window { public ProgressDialog() { WindowStartupLocation = WindowStartupLocation.CenterScreen; InitializeComponent(); } public ProgressDialog(String Purpose) { InitializeComponent(); tbEvent.Text = Purpose; WindowStartupLocation = WindowStartupLocation.CenterScreen; } public void UpdateProgress(int progress) { progressBar1.Dispatcher.BeginInvoke( new Action(() => { progressBar1.Value = progress; } )); } public void SetIndeterminate(bool isIndeterminate) { progressBar1.Dispatcher.BeginInvoke( new Action(() => { if (isIndeterminate) { progressBar1.IsIndeterminate = true; } else { progressBar1.IsIndeterminate = false; } } )); } } }
I have read and done a number of tutorial on background worker and even some on threads but can not seem to get the result I want
The idea is I have two long processes where I am either getting a datatable clone from my remote bd or I am updating the db from my wpf application (.net 4). While the process is running I want a progress bar control and to update it, for the obivous reason of making it clear that some work is going on. So I did the usual report progress routines in the background worker and it works....However, in my dowork thread I have this command
CHHoursDataProvider CH = new CHHoursDataProvider(); oTable = CH.CloneCHHours();
this where the communication with db is and this command takes a good 60 - 90 secs on a vpn remote connection so even if I do this
CHHoursDataProvider CH = new CHHoursDataProvider(); worker.ReportProgress((10)); oTable = CH.CloneCHHours(); worker.ReportProgress((20));
The main window still looks frozen and like it has crashed!
So all I want to do is at the start of the call to the background work is set a progressbar running and leave it running till the end of the task. This is all I need to do to finish my first ever project and after three days I still can not get my head around it!
So I have tried the follow
In the bw progress changed and in the main window class
this.progressBar2.IsIndeterminate = true;
However the animation does not start till the Dowork thread has finished.
I then created another background worker to do update the progressbar2, which linked to a button on the main window was ok, but as soon as I tried to use it from the other background worker or from the main window class did not run till the dowork thread had completed on the first background worker
I then tried to follow a invoke method but REALLY got lost on that!
So can anyone help I can guess it is something to do with threading and working on the wrong thread etc but what I do about it I have no clue.
I can post more code as needed
Ian