Develop Reference

Global error handling doesn't work in WPF

I want to handle all unexpected errors in a WPF application. When I look at, there are different events for different situation to capture and control error. Also I added these in application constructor method
public App()
{
AppDomain.CurrentDomain.FirstChanceException += OnFirstChanceException;
AppDomain.CurrentDomain.UnhandledException += OnUnhandledException;
Dispatcher.UnhandledException += OnDispatcherUnhandledException;
TaskScheduler.UnobservedTaskException += OnUnobservedTaskException;
}
However, I try that for checking handling but they didn't work. What is the reason?
private void btnStart_Click(object sender, RoutedEventArgs e) //2021112242
{
throw new StackOverflowException();
}

Every exception event has his own callback method & event object
// Dispatcher.UnhandledException
private static void OnDispatcherUnhandledException(object sender, DispatcherUnhandledExceptionEventArgs e)
{
}
// TaskScheduler.UnobservedTaskException
private static void OnTaskSchedulerUnobservedTaskException(object sender, UnobservedTaskExceptionEventArgs e)
{
}
// AppDomain.CurrentDomain.UnhandledException
private static void OnCurrentDomainUnhandledException(object sender, UnhandledExceptionEventArgs e)
{
}
// AppDomain.CurrentDomain.FirstChanceException
private static void OnCurrentDomainUnhandledException(object sender, FirstChanceExceptionEventArgs e)
{
}

App has an event for this called DispatcherUnhandledException. This works in most cases but when the exception is thrown from a separate thread it gets a little hairy.
public partial class App
{
public App()
{
// Globally handle errors/exceptions for a friendly close.
DispatcherUnhandledException += DispatcherOnUnhandledException;
}
private void DispatcherOnUnhandledException(object sender, DispatcherUnhandledExceptionEventArgs e)
{
try
{
e.Handled = true;
e.Exception.Display("An unhandled exception occurred, the application will now close.");
e.Exception.Log(); // log the problem.
Shutdown(-1); // assume not recoverable.
}
catch
{
Shutdown(-1);
}
}
}

why Window.Current.CoreWindow.PointerMoved event handled property won't work in uwp?

what i have tried is?
Window.Current.CoreWindow.PointerMoved += OnCorePointerMoved1;
Window.Current.CoreWindow.PointerMoved += OnCorePointerMoved2;
private void OnCorePointerMoved1(CoreWindow sender, PointerEventArgs args)
{
args.Handled = true;
}
private void OnCorePointerMoved2(CoreWindow sender, PointerEventArgs args)
{
}
when i run the code,the PointreMoved1 Event is triggered first.In that ,I had handled e.Handled=true .And then why PointerMoved2 Event also triggered.I don't know why this is happening?

FiddlerCore C# HTTPS events not firing

Right I have the following code:
public partial class Form1 : Form
{
delegate void UpdateUI();
public Form1()
{
InitializeComponent();
}
private void Form1_Load(object sender, EventArgs e)
{
if (!Fiddler.CertMaker.rootCertExists())
{
if (!Fiddler.CertMaker.createRootCert())
{
throw new Exception("Unable to create cert for FiddlerCore.");
}
}
if (!Fiddler.CertMaker.rootCertIsTrusted())
{
if (!Fiddler.CertMaker.trustRootCert())
{
throw new Exception("Unable to install FiddlerCore's cert.");
}
}
Fiddler.FiddlerApplication.OnNotification += delegate (object snder, NotificationEventArgs oNEA) { MessageBox.Show("** NotifyUser: " + oNEA.NotifyString); };
Fiddler.FiddlerApplication.Log.OnLogString += delegate (object snder, LogEventArgs oLEA) { MessageBox.Show("** LogString: " + oLEA.LogString); };
Fiddler.FiddlerApplication.AfterSessionComplete += FiddlerApplication_OnAfterSessionComplete;
Fiddler.FiddlerApplication.Startup(0, FiddlerCoreStartupFlags.Default & FiddlerCoreStartupFlags.DecryptSSL);
}
void FiddlerApplication_OnAfterSessionComplete(Session oSession)
{
if(oSession.fullUrl.Contains("google.com"))
richTextBox1.Invoke(new UpdateUI(() =>
{
richTextBox1.AppendText(oSession.GetResponseBodyAsString());
}));
}
private void Form1_FormClosing(object sender, FormClosingEventArgs e)
{
Fiddler.FiddlerApplication.Shutdown();
}
}
The thing is with DecryptSSL flag set on startup the on aftersesssion complete never fires, I also never get any messages from either the notification or logs callbacks.
Any ideas?

I think port 0 might be a problem in the Startup(), I tried with port 8888:
Fiddler.FiddlerApplication.Startup(8888, FiddlerCoreStartupFlags.Default & FiddlerCoreStartupFlags.DecryptSSL);
I tried with these before response and before request handlers instead of OnAfterSessionComplete. In your Form1_Load():
Fiddler.FiddlerApplication.BeforeRequest += new SessionStateHandler(HandleBeforeRequest);
Fiddler.FiddlerApplication.BeforeResponse += new SessionStateHandler(HandleBeforeResponse);
And the handlers:
private void HandleBeforeRequest(Session oSession)
{
oSession.bBufferResponse = true;
}
private void HandleBeforeResponse(Session oSession)
{
if(oSession.fullUrl.Contains("google.com"))
{
richTextBox1.Invoke(new UpdateUI(() =>
{
richTextBox1.AppendText(oSession.GetResponseBodyAsString());
}));
}
}
By the way, don't know if you omitted them from your sample but I needed to add these in the constructor:
Load += Form1_Load;
FormClosing += Form1_FormClosing;
Might also be good to add this before Shutdown():
FiddlerApplication.oProxy.Detach();

c# request FormClosing

I have a form to ask for some data. At leaving of an input field (TextBox, DGV) the appropriate _Validating methode or _CellValueChanged methode is called.
If I want to end the program this methode is called, too - before the _FormClosing methode is called.
How can I fin out whether the program branches into the _FormClosing methode or not?
private void txb_Validating(object sender, CancelEventArgs e)
{
doLog("Text 1");
}
private void dgv_CellValueChanged(object sender, DataGridViewCellEventArgs e)
{
doLog("Text 2");
}
private void doLog(string txt)
{
// this is first called at closing...
if( [FormClosing is active] )
{
// Do something
}
else
{
// Do someting different
}
}
private void MyForm_FormClosing(object sender, FormClosingEventArgs e)
{
// ... and this but later
// Write the Logfile
}
How have I to replace [FormClosing is active] to get to the right result?
I tried so
if ( this.FormClosing== true )
and so
this.FormClosing +=new FormClosingEventHandler(MyForm_FormClosing);
and so
FormClosingEventHandler cl = new FormClosingEventHandler(MyForm_FormClosing);
but I always was in a dead end.

This would do the trick:
public class YourForm : Form
{
private bool bIsClosing = false;
public YourClass()
{
InitializeComponent();
this.FormClosing +=
new FormClosingEventHandler(MyForm_FormClosing);
}
private void txb_Validating(object sender, CancelEventArgs e)
{
doLog("Text 1");
}
private void dgv_CellValueChanged(object sender,
DataGridViewCellEventArgs e)
{
doLog("Text 2");
}
private void doLog(string txt)
{
// this is first called at closing...
if( bIsClosing )
{
// Do something
}
else
{
// Do someting different
}
}
private void MyForm_FormClosing(object sender, FormClosingEventArgs e)
{
bIsClosing = true;
// Write the Logfile
doLog("whatever");
}
}

this.FormClosing is an event that gets triggered once your form starts closing (like clicking the close button), hence the name. You need your application to register that event like so:
this.FormClosing +=new FormClosingEventHandler(MyForm_FormClosing);
This insures that once the FormClosing event gets triggered, your MyForm_FormClosing will be called.
You can create a flag like bool bIsFormClosing and set that flag once your closing function get called.
Edit:
As I understand now by reviewing your answer and your comments, you want to know in your doLog function if the form is closing.
Here is another approach
`
public class YourForm : Form
{
private bool bIsClosing = false;
Private bool bClosingHandled = false;
public YourClass()
{
InitializeComponent();
this.FormClosing +=
new FormClosingEventHandler(MyForm_FormClosing);
}
private void txb_Validating(object sender, CancelEventArgs e)
{
doLog("Text 1");
}
private void dgv_CellValueChanged(object sender,
DataGridViewCellEventArgs e)
{
doLog("Text 2");
}
private void doLog(string txt)
{
// this is first called at closing...
if( bIsClosing )
{
// Do something
bClosingHandled = true;
this.close();
}
else
{
// Do someting different
}
}
private void MyForm_FormClosing(object sender, FormClosingEventArgs e)
{
If(!bClosingHandled)
{
bIsClosing = true;
e.Cancel = true;
return;
}
// Write the Logfile
doLog("whatever");
}
}`
This approach uses two flags... When you first receive a close event, you set the bIsClosing flag to true, cancels the event and return. Then once your dolog function get called, you force the close operation.

How to call event before Environment.Exit()?

I have a console application in C#. If something goes wrong, I call Environment.Exit() to close my application. I need to disconnect from the server and close some files before the application ends.
In Java, I can implement a shutdown hook and register it via Runtime.getRuntime().addShutdownHook(). How can I achieve the same in C#?

You can attach an event handler to the current application domain's ProcessExit event:
using System;
class Program
{
static void Main(string[] args)
{
AppDomain.CurrentDomain.ProcessExit += (s, e) => Console.WriteLine("Process exiting");
Environment.Exit(0);
}
}

Hook AppDomain events:
private static void Main(string[] args)
{
var domain = AppDomain.CurrentDomain;
domain.UnhandledException += new UnhandledExceptionEventHandler(MyHandler);
domain.ProcessExit += new EventHandler(domain_ProcessExit);
domain.DomainUnload += new EventHandler(domain_DomainUnload);
}
static void MyHandler(object sender, UnhandledExceptionEventArgs args)
{
Exception e = (Exception)args.ExceptionObject;
Console.WriteLine("MyHandler caught: " + e.Message);
}
static void domain_ProcessExit(object sender, EventArgs e)
{
}
static void domain_DomainUnload(object sender, EventArgs e)
{
}

I'd recommend wrapping the call to Environment.Exit() in your own method and using that throughout. Something like this:
internal static void MyExit(int exitCode){
// disconnect from network streams
// ensure file connections are disposed
// etc.
Environment.Exit(exitCode);
}