When I click the login button, my background worker starts processing and a loading dialog window shows up.
However, how can I close it after my task has been completed?
private void LoginButton_Click(object sender, RoutedEventArgs e)
{
AdjustControls(false);
if (Username == null)
{
Error("Username required");
return;
}
loading.ShowDialog();
backgroundWorker = new BackgroundWorker();
backgroundWorker.DoWork += login_backgroundWorker_DoWork;
backgroundWorker.ProgressChanged += login_backgroundWorker_ProgressChanged;
backgroundWorker.RunWorkerCompleted += login_backgroundWorker_RunWorkerCompleted;
backgroundWorker.WorkerReportsProgress = true;
backgroundWorker.RunWorkerAsync();
}
private void login_backgroundWorker_DoWork(object sender, System.ComponentModel.DoWorkEventArgs e)
{
var backgroundWorker = sender as BackgroundWorker;
try
{
this.Dispatcher.Invoke(new MethodInvoker(delegate ()
{
loading.ShowDialog();
Action closeAction = () => loading.Close();
loading.Dispatcher.Invoke(closeAction);
this.Close();
}));
}
catch (Exception InputChangedException)
{
Console.WriteLine(InputChangedException);
if (InputChangedException != null)
{
Error(InputChangedException.Message);
}
}
}
private void login_backgroundWorker_ProgressChanged(object sender, System.ComponentModel.ProgressChangedEventArgs e)
{
}
private void login_backgroundWorker_RunWorkerCompleted(object sender, System.ComponentModel.RunWorkerCompletedEventArgs e)
{
this.Dispatcher.Invoke(new MethodInvoker(delegate ()
{
loading.Close();
}));
}
I found the answer and it seems quite simple. I just needed to set an Action:
this.Dispatcher.BeginInvoke(new Action(() => loading.ShowDialog()));
This is to start it, then another time to close it
Related
I'm doing a simple login form that will show the login process after they click button. It will verify the user access rights and give true or false.
I got an error on this.Hide();
System.InvalidOperationException: 'Cross-thread operation not valid: Control 'formLogin' accessed from a thread other than the thread it was created on.'
Any help would be greatly appreciated. Thanks!!
private void btnLogin_Click(object sender, EventArgs e)
{
BackgroundWorker bgw = new BackgroundWorker();
bgw.DoWork += bgw_DoWork;
bgw.RunWorkerCompleted += bgw_RunWorkerCompleted;
PBLogin.Style = ProgressBarStyle.Marquee;
PBLogin.MarqueeAnimationSpeed = 50;
bgw.RunWorkerAsync();
}
void bgw_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
PBLogin.Style = ProgressBarStyle.Blocks;
PBLogin.MarqueeAnimationSpeed = 0;
}
void bgw_DoWork(object sender, DoWorkEventArgs e)
{
if (CheckAuthorization())
{
MessageBox.Show("Login Successfully");
TestScript next = new TestScript();
next.Show();
this.Hide();
}
else
{
MessageBox.Show("Login Failed");
}
From a background thread you can't reach the UI, that's what the exception is trying to tell you. In your background thread you should try to focus only on the Authorization logic itself. Try to avoid UI component manipulation.
In the RunWorkerCompleted event you can indeed modify the UI components. So, do the calculation on a dedicated background thread and do the UI manipulation inside the completion event.
void bgw_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
//TODO: Check against e.Error and e.Cancelled before you try to access e.Result
if((bool)e.Result)
{
//UI modification
}
else
{
//UI modification
}
}
void bgw_DoWork(object sender, DoWorkEventArgs e)
{
var isAuthorized = CheckAuthorization();
e.Result = isAuthorized;
}
I've implemented a background worker onLoad of my window. The code in the Progress_Load is reached but after that the DoWork function is not called. The function excel.Read() reads a quite big excel tabel into a list, this takes about 1.5 min and that's why i want to do it a-syn.
public List<Part> partList = new List<Part>() { };
//boolean that will be set when the backgroundworker is done
public bool listRead = false;
private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
{
_Excel excel = new _Excel();
partList = excel.Read();
backgroundWorker1.ReportProgress(100);
}
private void backgroundWorker1_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
Message m;
if (e.Cancelled == true)
{
m = new Message("The operation has been canceld!", "Canceled");
this.Close();
}
else if (e.Error != null)
{
Error er = new Error("Error: " + e.Error.Message, "Error!");
this.Close();
}
else
{
listRead = true;
}
}
private void backgroundWorker1_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
//Change the value of the ProgressBar to the BackgroundWorker progress.
progressBar1.Value = e.ProgressPercentage;
//Set the text.
this.Text = e.ProgressPercentage.ToString();
}
private void Progress_Load(object sender, EventArgs e)
{
if (backgroundWorker1 == null)
{
backgroundWorker1 = new BackgroundWorker();
backgroundWorker1.DoWork += new DoWorkEventHandler(backgroundWorker1_DoWork);
backgroundWorker1.ProgressChanged += new ProgressChangedEventHandler(backgroundWorker1_ProgressChanged);
backgroundWorker1.RunWorkerCompleted += new RunWorkerCompletedEventHandler(backgroundWorker1_RunWorkerCompleted);
}
backgroundWorker1.WorkerReportsProgress = true;
backgroundWorker1.WorkerSupportsCancellation = true;
backgroundWorker1.RunWorkerAsync();
}
Probably it's not null when loading the form. You may have added the BackgroundWorker via the designer. If so it's never null, you can hook up the event handlers also from its Properties/Events.
Try this
private void Progress_Load(object sender, EventArgs e)
{
if (backgroundWorker1 == null)
{
backgroundWorker1 = new BackgroundWorker();
}
backgroundWorker1.DoWork += new DoWorkEventHandler(backgroundWorker1_DoWork);
backgroundWorker1.ProgressChanged += new ProgressChangedEventHandler(backgroundWorker1_ProgressChanged);
backgroundWorker1.RunWorkerCompleted += new RunWorkerCompletedEventHandler(backgroundWorker1_RunWorkerCompleted);
backgroundWorker1.WorkerReportsProgress = true;
backgroundWorker1.WorkerSupportsCancellation = true;
backgroundWorker1.RunWorkerAsync();
}
In WPF Dispatcher.BeginInvoke(DispatcherPriority.Background, workAction); is a another option because report progress is not much useful in your scenario. Here example for Dispatcher and Background worker comparison.
Is it possible to add a callback to a background worker while it is running ?
bw.DoWork += new DoWorkEventHandler( some callback );
bw.RunWorkerAsync();
bw.DoWork += new DoWorkEventHandler( some callback );
Thank you.
Yes you can as it's only a subscription to an event but you can't run bw until he has completed the execution of the first task
here an example to illustrate this the following code will show an InvalidOperationException telling This BackgroundWorker is currently busy and cannot run multiple tasks concurrently."
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
backgroundWorker1.DoWork += new DoWorkEventHandler(backgroundWorker1_DoWork);
backgroundWorker1.RunWorkerAsync();
backgroundWorker1.DoWork+=new DoWorkEventHandler(backgroundWorker2_DoWork);
//at this line you get an InvalidOperationException
backgroundWorker1.RunWorkerAsync();
}
void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
{
do
{
} while (true);
}
void backgroundWorker2_DoWork(object sender, DoWorkEventArgs e)
{
do
{
} while (true);
}
}
As an answer to your comment question
#SriramSakthivel Thanks. Is there a way to put tasks in a queue ?
yes you can if you are using .net 4.0 you can use task with ContinueWith and attach it to your UI
taskScheduler it will have the same behavior as if you are using BackgroundWorker
private void TestButton_Click(object sender, EventArgs e)
{
TestButton.Enabled = false;
var uiThreadScheduler = TaskScheduler.FromCurrentSynchronizationContext();
var backgroundTask = new Task(() =>
{
Thread.Sleep(5000);
});
var uiTask = backgroundTask.ContinueWith(t =>
{
TestButton.Enabled = true;
}, uiThreadScheduler);
backgroundTask.Start();
}
How to program wait Custom MessageBox OK,Cancel,Yes,No responses? i have been using custom messageBox because of my natural language because messagebox has only english ok,yes,no i have found this one: Customizing MessageBox on Windows Phone 7
private MessageBoxService CustomMsgBox= new MessageBoxService();
public async void Handle(RecordRequest message)
{
AutoResetEvent waitHandle = new AutoResetEvent(false);
Dispatcher.BeginInvoke(() =>
{
CustomMsgBox.Closed += CustomMsgBox_Closed;
CustomMsgBox.Closed += (s, e) => waitHandle.Set();
CustomMsgBox.Show(
"Login Please! ",
"Kayıt",
MessageBoxServiceButton.OKCancel);
});
waitHandle.WaitOne();
// Must Wait MessageBox Ok or Cancel like Normal MessageBox!!!
Login.IsOpen= true;
// do something ...
}
void CustomMsgBox_Closed(object sender, EventArgs e)
{
this.CustomMsgBox.Closed -= this.CustomMsgBox_Closed;
string rst = this.CustomMsgBox.Result.ToString();
}
Normally wp8 messagebox is locked while clicking OK-Cancel. But My Costom MessageBox is not waiting. How to lock my CustomMsgBox until clicking ok-Cancel.
SAMPLE USAGE:
private PixelLab.Common.MessageBoxService _service = new PixelLab.Common.MessageBoxService();
private void Button_Click(object sender, RoutedEventArgs e)
{
this._service.Closed += this.MessageBoxService_Closed;
this._service.Show(
"test",
"alo!",
MessageBoxServiceButton.OKCancel);
//if (_service.IsOpen == true)
//{
// MessageBoxResult rslt = _service.Result;
// if (rslt == MessageBoxResult.No)
// {
// MessageBox.Show("işlem iptal edildi");
// }
// else
// {
// MessageBox.Show("işlem onaylandı");
// }
//}
}
private void MessageBoxService_Closed(object sender, EventArgs e)
{
this._service.Closed -= this.MessageBoxService_Closed;
string rst = this._service.Result.ToString();
}
This case is using C# WPF. I want to instantly disable a button after clicking it to prevent clicking it twice in short succession. I disabled the button in OnClick_Event but still clickable.
Part of source is as below.
private void Button_Click_UpdateBurndownChart(object sender, RoutedEventArgs e)
{
if(threadNotWorking)
{
updateButton.IsEnabled = false;
startWorkThread();
}
}
private void startWorkThread()
{
... ...
//after finish required process
updateButton.IsEnabled = true;
}
Is there any way to accomplish this?
you may want to use a dispatcher, there is probably a threading problem (callback function running on seperate thread and trying to access ui which runs on another thread). try this . .
updateButton.Dispatcher.BeginInvoke(
new ThreadStart(() => updateButton.IsEnabled = false),
System.Windows.Threading.DispatcherPriority.Input, null);
instead of
updateButton.IsEnabled = false;
What happens if you were instead to change the order of your events from:
updateButton.IsEnabled = false;
startWorkThread();
To
startWorkThread();
updateButton.IsEnabled = false;
Let me know how this goes.
What it looks like is that you are starting your thread then immediatly enabling your button before your thread has finished. You would be better off using a BackgroundWorker and enable your Button in the RunWorkerCompleted Event. Though you can do something similar by enabling your button using a BeginInvoke at the end of your Process.
public void doWork()
{
System.Threading.Thread.Sleep(10000); //Simulating your Process
Dispatcher.BeginInvoke(new System.Threading.ThreadStart(delegate() { updateButton.IsEnabled = true; }), System.Windows.Threading.DispatcherPriority.Background);
}
Example with BackgroundWorker
using System.ComponentModel;
public partial class MainWindow : Window
{
BackgroundWorker bgw;
public MainWindow()
{
InitializeComponent();
bgw = new BackgroundWorker();
bgw.DoWork += new DoWorkEventHandler(bgw_DoWork);
bgw.RunWorkerCompleted += new RunWorkerCompletedEventHandler(bgw_RunWorkerCompleted);
}
void bgw_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
updateButton.IsEnabled = true;
}
void bgw_DoWork(object sender, DoWorkEventArgs e)
{
System.Threading.Thread.Sleep(10000); //Simulating your work
}
private void startWorkThread()
{
bgw.RunWorkerAsync();
}
private void updateButton_Click(object sender, RoutedEventArgs e)
{
if (bgw.IsBusy != true)
{
updateButton.IsEnabled = false;
startWorkThread();
}
}
}