Develop Reference

C# why cant i exit this while loop?

I'm tryig to make a program that can auto press space.
but i can only enable it. after the program crashes.
so i cant turn it off. pleace help
here is my code:
using System.Windows.Forms;
namespace Auto_Abillty
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
public bool startFlag = false;
public bool stopFlag = false;
private void Preiststop_Click(object sender, EventArgs e)
{
stopFlag = true;
}
private void Preist_Click(object sender, EventArgs e)
{
startFlag = true;
while (startFlag)
{
SendKeys.Send(" ");
Thread.Sleep(5000);
if (stopFlag)
startFlag = false;
}
}
}
}

I would suggest using System.Windows.Forms.Timer with 5000 ms interval instead of your approach. Then by clicking on the button on a form you may start or stop it.
Another approach is to move your while loop into another thread that will make UI thread still be responsive

You must abort the thread as well.
public bool x = false;
public bool j = false;
private void Preiststop_Click(object sender, EventArgs e)
{
j = true;
}
private void Preist_Click(object sender, EventArgs e)
{
x = true;
Thread newThread = new Thread(delegate ()
{
DoPriestWork();
});
newThread.Start();
//loop to wait for the response from DoPriestWork thread
while (x)
{
Thread.Sleep(5000);
if (j)
x = false;
}
newThread.Abort();
}
public void DoPriestWork()
{
//x = true;
//while (x == true)
//{
SendKeys.Send(" ");
//Thread.Sleep(5000);
// if (j == true)
// x = false;
//}
}

Seems like all you need is a thread so another button can be pushed to change the condition of "j". If there is only one thread, the UI will not be updated until that thread is stopped hence the need to make another thread, like below example.
public Form1()
{
InitializeComponent();
}
public bool x = false;
public bool j = false;
private void Preiststop_Click(object sender, EventArgs e)
{
j = true;
}
private void Preist_Click(object sender, EventArgs e)
{
Thread newThread = new Thread(DoPriestWork);
newThread.Start();
}
public void DoPriestWork()
{
x = true;
while (x == true)
{
SendKeys.Send(" ");
Thread.Sleep(5000);
if (j == true)
x = false;
}
}

Your Preist_Click call blocks the UI: it executes in the same thread, instead of starting its own.
Try this:
private bool keepRunning = true;
private void Preiststop_Click(object sender, EventArgs e)
{
keepRunning = false;
}
private async void Preist_Click(object sender, EventArgs e)
{
keepRunning = true;
await Task.Run(() => {
while (keepRunning)
{
SendKeys.Send(" ");
Thread.Sleep(5000);
}
});
}

wpf not refresh code if not focused

I have this situation: a class that contains a background worker that do some thing in a while cycle:
public class CControls
{
public delegate void ControlChangedEventHandler();
public event ControlChangedEventHandler ControlChangedEvent;
private readonly BackgroundWorker worker;
bool bClose = false;
public CControls(IntPtr hwnd)
{
worker = new BackgroundWorker();
worker.DoWork += worker_DoWork;
worker.RunWorkerCompleted += worker_RunWorkerCompleted;
}
void worker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
bClose = true;
}
public void enable(bool bEnable)
{
if (bEnable && !worker.IsBusy)
{
worker.RunWorkerAsync();
}
else
{
bClose = true;
}
}
void worker_DoWork(object sender, DoWorkEventArgs e)
{
while (!bClose)
{
// my job
// ..............................................
//
if (ControlChangedEvent != null)
{
ControlChangedEvent();
}
}
}
}
I have my form that create an instance of this class and set the listener of ControlChangedEvent:
CControls ct = new CControls();
ct.ControlChangedEvent += ct_ControlChangedEvent;
int changes = 0;
void ct_ControlChangedEvent()
{
Dispatcher.Invoke(DispatcherPriority.Background, (Action)delegate
{
changes ++;
infoLabel.Content = string.Format("changes: {0}", changes);
});
}
but the infoLabel changes only if my program have the focus, otherwise is not fired...
any ideas?
thanks ;)

Why is the backgroundworker not pausing when I click the button?

In Form1 I removed/deleted the _busy variable. In Form1 top I did:
BackgroundWebCrawling bgwc;
Then in the button4 pause click event I did:
private void button4_Click(object sender, EventArgs e)
{
bgwc.PauseWorker();
label6.Text = "Process Paused";
button5.Enabled = true;
button4.Enabled = false;
}
In the button5 click event button I did:
private void button5_Click(object sender, EventArgs e)
{
bgwc.ContinueWorker();
label6.Text = "Process Resumed";
button4.Enabled = true;
button5.Enabled = false;
}
And the cancel button click event:
private void button3_Click(object sender, EventArgs e)
{
bgwc.CancelWorker();
cancel = true;
}
Then I'm checking in Form1 completed event if cancel is true or not:
if (cancel == true)
{
label6.Text = "Process Cancelled";
}
else
{
label6.Text = "Process Completed";
}
And this is how the BackgroundWebCrawling class look like now:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using HtmlAgilityPack;
using System.Net;
using System.Windows.Forms;
using System.ComponentModel;
using System.Threading;
namespace GatherLinks
{
class BackgroundWebCrawling
{
public string f;
int counter = 0;
List<string> WebSitesToCrawl;
int MaxSimultaneousThreads;
public BackgroundWorker mainBackGroundWorker;
BackgroundWorker secondryBackGroundWorker;
WebcrawlerConfiguration webcrawlerCFG;
List<WebCrawler> webcrawlers;
int maxlevels;
public event EventHandler<BackgroundWebCrawlingProgressEventHandler> ProgressEvent;
ManualResetEvent _busy = new ManualResetEvent(true);
public BackgroundWebCrawling()
{
webcrawlers = new List<WebCrawler>();
mainBackGroundWorker = new BackgroundWorker();
mainBackGroundWorker.WorkerSupportsCancellation = true;
mainBackGroundWorker.DoWork += mainBackGroundWorker_DoWork;
}
private void mainBackGroundWorker_DoWork(object sender, DoWorkEventArgs e)
{
BackgroundWorker worker = sender as BackgroundWorker;
for (int i = 0; i < WebSitesToCrawl.Count; i++)
{
_busy.WaitOne();
if ((worker.CancellationPending == true))
{
e.Cancel = true;
break;
}
while (counter >= MaxSimultaneousThreads)
{
Thread.Sleep(10);
}
WebCrawler wc = new WebCrawler(webcrawlerCFG);
webcrawlers.Add(wc);
counter++;
secondryBackGroundWorker = new BackgroundWorker();
secondryBackGroundWorker.DoWork += secondryBackGroundWorker_DoWork;
object[] args = new object[] { wc, WebSitesToCrawl[i] };
secondryBackGroundWorker.RunWorkerAsync(args);
}
while (counter > 0)
{
Thread.Sleep(10);
}
}
private void secondryBackGroundWorker_DoWork(object sender, DoWorkEventArgs e)
{
object[] args = (object[])e.Argument;
WebCrawler wc = (WebCrawler)args[0];
string mainUrl = (string)args[1];
wc.ProgressEvent += new EventHandler<WebCrawler.WebCrawlerProgressEventHandler>(x_ProgressEvent);
wc.webCrawler(mainUrl, maxlevels);
counter--;
}
public void Start(List<string> sitestocrawl, int threadsNumber, int maxlevels, WebcrawlerConfiguration wccfg)
{
this.maxlevels = maxlevels;
webcrawlerCFG = wccfg;
WebSitesToCrawl = sitestocrawl;
MaxSimultaneousThreads = threadsNumber;
mainBackGroundWorker.RunWorkerAsync();
}
private void x_ProgressEvent(object sender, WebCrawler.WebCrawlerProgressEventHandler e)
{
// OK .. so now you get the data here in e
// and here you should call the event to form1
Object[] temp_arr = new Object[8];
temp_arr[0] = e.csFiles;
temp_arr[1] = e.mainUrl;
temp_arr[2] = e.levels;
temp_arr[3] = e.currentCrawlingSite;
temp_arr[4] = e.sitesToCrawl;
temp_arr[5] = e.done;
temp_arr[6] = e.failedUrls;
temp_arr[7] = e.failed;
OnProgressEvent(temp_arr); /// Send the data + additional data from this class to Form1..
///
/*
* temp_arr[0] = csFiles;
temp_arr[1] = mainUrl;
temp_arr[2] = levels;
temp_arr[3] = currentCrawlingSite;
temp_arr[4] = sitesToCrawl;*/
}
private void GetLists(List<string> allWebSites)
{
}
public class BackgroundWebCrawlingProgressEventHandler : EventArgs
{
public List<string> csFiles { get; set; }
public string mainUrl { get; set; }
public int levels { get; set; }
public List<string> currentCrawlingSite { get; set; }
public List<string> sitesToCrawl { get; set; }
public bool done { get; set; }
public int failedUrls { get; set; }
public bool failed { get; set; }
}
protected void OnProgressEvent(Object[] some_params) // Probably you need to some vars here to...
{
// some_params to put in evenetArgs..
if (ProgressEvent != null)
ProgressEvent(this,
new BackgroundWebCrawlingProgressEventHandler()
{
csFiles = (List<string>)some_params[0],
mainUrl = (string)some_params[1],
levels = (int)some_params[2],
currentCrawlingSite = (List<string>)some_params[3],
sitesToCrawl = (List<string>)some_params[4],
done = (bool)some_params[5],
failedUrls = (int)some_params[6],
failed = (bool)some_params[7]
});
}
public void PauseWorker()
{
if (mainBackGroundWorker.IsBusy)
{
_busy.Reset();
}
}
public void ContinueWorker()
{
_busy.Set();
}
public void CancelWorker()
{
ContinueWorker();
mainBackGroundWorker.CancelAsync();
}
}
}
So I added the methods the pause the continue the cancel. In the dowork event, I changed all the things and added things.
But when I click the buttons there is no effect. Not pausing, not continue and not cancel. Nothing.

You never check the _busy status in mainBackGroundWorker_DoWork method;
for (int i = 0; i < WebSitesToCrawl.Count; i++)
{
_busy.WaitOne();
//...
}
also you should have your ManualResetEvent _busy in class with BackgroundWorker
ManualResetEvent _busy = new ManualResetEvent(true);
public BackgroundWorker mainBackGroundWorker;
public void PauseWorker()
{
if(mainBackGroundWorker.IsBusy)
{
_busy.Reset();
}
}
public void ContinueWorker()
{
_busy.Set();
}
and in Form1:
private void button4_Click(object sender, EventArgs e)
{
bgwc.PauseWorker();
//...
}
private void button5_Click(object sender, EventArgs e)
{
bgwc.ContinueWorker();
//...
}
to cancel the BackgroundWorker you can use CancellationPending property and CancelAsync method. Note: you should first unpause the worker.
public void CancelWorker()
{
ContinueWorker();
mainBackGroundWorker.CancelAsync();
}
private void mainBackGroundWorker_DoWork(object sender, DoWorkEventArgs e)
{
BackgroundWorker worker = sender as BackgroundWorker;
for (int i = 0; i < WebSitesToCrawl.Count; i++)
{
_busy.WaitOne();
if ((worker.CancellationPending == true))
{
e.Cancel = true;
break;
}
//...
}
}
If this doesn't help you, then you have problems with mainBackGroundWorker code and secondryBackGroundWorker.
This code only pauses mainBackGroundWorker, but not secondryBackGroundWorkers. The same with cancelation. If main worker is canceled? it will wait for all the secondary workers to finish their jobs. Also if you pause main worker? you can still have new results arriving from secondary workers.
You do not handle errors. If you have an exception in second worker, than you do not get any notification about that and also your main worker will never stop, because counter will never be 0.
There can be another problems, witch cause this behaviour.

Update ProgressBar UI object from Task Parallel Library

Basically i would like to update ProgressBar UI object on the FormMain (WindowsForm). I am using .NET 4.0
Here are the code in the Form1.Designer.cs
namespace ProgressBarApp
{
public partial class Form1 : Form
{
private System.Windows.Forms.ProgressBar curProgressBar;
public Form1()
{
InitializeComponent();
}
private void Form1_Load(object sender, EventArgs e)
{
CustomProcess theProcess = new CustomProcess();
theProcess.Process();
}
}
}
Here is the definition of CustomProcess.cs
namespace ProgressBarApp
{
class CustomProcess
{
public void Process()
{
for (int i = 0; i < 10; i++)
{
Task ProcessATask = Task.Factory.StartNew(() =>
{
Thread.Sleep(1000); // simulating a process
}
);
Task UpdateProgressBar = ProcessATask.ContinueWith((antecedent) =>
{
// how do i update the progress bar object at UI here ?
}
);
}
}
}
}

You can use SynchronizationContext to do this. To use it for a Task, you need to create a TaskScheduler, which you can do by calling TaskScheduler.FromCurrentSynchronizationContext:
Task UpdateProgressBar = ProcessATask.ContinueWith(antecedent =>
{
// you can update the progress bar object here
}, TaskScheduler.FromCurrentSynchronizationContext());
This will work only if you call Process() directly from the UI thread.

How about using System.Reactive.Linq:
[UPDATE]
using System.Reactive.Linq;
namespace WindowsFormsApplication6
{
public partial class Form1 : Form
{
//private System.Windows.Forms.ProgressBar curProgressBar;
public Form1()
{
InitializeComponent();
}
private void Form1_Load(object sender, EventArgs e)
{
CustomProcess theProcess = new CustomProcess();
var x = Observable.FromEventPattern(theProcess, "TaskCompleted");
curProgressBar.Maximum = 4;
x.Subscribe((a) =>
{
curProgressBar.Value = ((CustomProcess)a.Sender).Counter;
});
theProcess.Process();
}
}
class CustomProcess
{
public int Counter { get; set; }
public event EventHandler TaskCompleted = OnTaskCompleted;
private static void OnTaskCompleted(object sender, EventArgs e)
{
((CustomProcess)sender).Counter++;
}
public void Process()
{
for (int i = 0; i <= 3; i++)
{
Task ProcessATask = Task.Factory.StartNew(() =>
{
Thread.Sleep(1000); // simulating a process
}
);
var awaiter = ProcessATask.GetAwaiter();
awaiter.OnCompleted(() =>
{
TaskCompleted(this, null);
});
}
}
}
}

Close Form when Thread has finished

Everybody.
I've two form as follow by
From1 has a button, when click this Form2 will appear.
From2 has a Progressbar, It's counting and update Progressbar from Maximun value until It has finished, Form2 will close.
This below code of Form2
public delegate void ProgressbarHandler(int value);
public partial class Form2 : Form
{
public event WaitCallback CloseThreadEvent;
private Thread t;
public void OnCloseEvent(ThreadState state)
{
if (CloseThreadEvent != null)
CloseThreadEvent(state);
}
public Form2()
{
InitializeComponent();
progressBar1.Minimum = 0;
progressBar1.Maximum = 20000;
}
private void Form2_Load(object sender, EventArgs e)
{
InitThread();
}
private void InitThread()
{
t = new Thread(new ThreadStart(RunThread));
t.Start();
CloseThreadEvent += new WaitCallback(CloseForm);
Thread tt = new Thread(ThreadObserver);
tt.IsBackground = true;
tt.Start();
}
private void RunThread()
{
for (int i = 0; i < progressBar1.Maximum; i++)
{
progressBar1.Invoke(new ProgressbarHandler(UpdateProgressbar), i);
}
}
private void UpdateProgressbar(int value)
{
progressBar1.Value = value + 1;
}
private void ThreadObserver()
{
while (t.IsAlive)
{
OnCloseEvent(t.ThreadState);
}
}
private void CloseForm(Object state)
{
if ((ThreadState)state == ThreadState.Stopped)
this.Close();
}
}
From my code, It has a "Cross-thread operation not valid" error on
this.Close();
Please give suggestion, How to coding follow by my purpose.
Thank you.

You can only access controls from the thread they were created on. A form is also a control.
Have a look at Control.Invoke.
I use a class similar to this to handle these scenarios:
public static class ControlExtensions
{
public static void Invoke(this Control control, Action action)
{
if (control.InvokeRequired)
{
control.Invoke(new MethodInvoker(action), null);
}
else
{
action.Invoke();
}
}
}
Then you would be able to call this.Invoke(() => Close()); to close your form.

Pretty simple fix.
this.Invoke(new MethodInvoker(delegate { this.Close(); }));
I don't know why you didn't think of it? Isn't it obvious? :P

Thank you, Everybody
It works!!
public partial class Form2 : Form
{
private Thread tstart, trun;
public Form2()
{
InitializeComponent();
progressBar1.Minimum = 0;
progressBar1.Maximum = 100;
}
private void Form2_Load(object sender, EventArgs e)
{
tstart = new Thread(InitThread);
tstart.Start();
}
private void InitThread()
{
trun = new Thread(new ThreadStart(RunThread));
trun.Start();
trun.Join();
CloseForm(trun.ThreadState);
}
private void RunThread()
{
for (int i = 0; i < progressBar1.Maximum; i++)
{
Thread.Sleep(10);
progressBar1.Invoke(new MethodInvoker(delegate { progressBar1.Increment(1); }));
}
}
private void CloseForm(Object state)
{
if ((ThreadState)state != ThreadState.Stopped)
return;
else
{
if (this.InvokeRequired)
this.Invoke(new MethodInvoker(delegate { this.Close(); }), null);
}
}
private void Form2_FormClosing(object sender, FormClosingEventArgs e)
{
if (tstart.IsAlive)
tstart.Abort();
if (trun.IsAlive)
trun.Abort();
}
}