I have a button in my WinForms application with the following Click event:
private void Button_Click(object sender, EventArgs e)
{
treasureFound = false;
refreshNumber = 0;
Label_StartDateTime.Text = DateTime.Now.ToString("dd-MM-yyyy HH:mm:ss");
while (!treasureFound)
{
Label_StatusData.Text = "Refreshed " + refreshNumber + " times.";
refreshNumber++;
using (WebClient client = new WebClient())
{
string htmlCode = client.DownloadString(webUrl);
if (htmlCode.Contains("Treasure"))
{
treasureFound = true;
Label_StatusData.Text = "Found.";
// etc etc
}
}
}
}
When the button is clicked, the UI thread locks up (not responding, labels don't update) until the while loop ends.
What can I do to keep the UI responsive? There should only be one WebClient instance at any one time.
you should execute the time-consuming tasks in a separate thread, so it will not block the main thread (aka your UI thread). One way is to use the BackgroundWorker.
public Form1()
{
InitializeComponent();
backgroundWorker1.DoWork += backgroundWorker1_DoWork;
backgroundWorker1.ProgressChanged += backgroundWorker1_ProgressChanged;
backgroundWorker1.WorkerReportsProgress = true;
}
private void button1_Click(object sender, EventArgs e)
{
backgroundWorker1.RunWorkerAsync();
}
private void backgroundWorker1_DoWork(object sender, System.ComponentModel.DoWorkEventArgs e)
{
for (int i = 0; i < 100; i++)
{
Thread.Sleep(1000);
backgroundWorker1.ReportProgress(i);
}
}
private void backgroundWorker1_ProgressChanged(object sender, System.ComponentModel.ProgressChangedEventArgs e)
{
progressBar1.Value = e.ProgressPercentage;
}
Taken from: How to use a BackgroundWorker?
Related
background worker in asp.net does not write the content to the web UI when background worker completed. please tell me the reasons why. and how to recover.???
static BackgroundWorker bwProcess;
[WebMethod()]
public static int GetProgress()
{
return Percentage;
}
background worker starts when click event happen
protected void btnClick_Click(object sender, EventArgs e)
{
bwProcess = new BackgroundWorker
{
WorkerReportsProgress = true,
WorkerSupportsCancellation = true
};
bwProcess.DoWork += new DoWorkEventHandler(bwProcess_DoWork);
bwProcess.ProgressChanged += new ProgressChangedEventHandler(bwProcess_ProgressChanged);
bwProcess.RunWorkerCompleted += new RunWorkerCompletedEventHandler(bwProcess_RunWorkerCompleted);
bwProcess.RunWorkerAsync("AsyncWorker");
}
do work event for the backgroundworker
void bwProcess_DoWork(object sender, DoWorkEventArgs e)
{
bwProcess.ReportProgress(1);
for (int i = 0; i <= 100; i++)
{
if (bwProcess.CancellationPending)
{
e.Cancel = true;
return;
}
bwProcess.ReportProgress(i);
Thread.Sleep(20);
}
e.Result = "100 %";
}
this part is not working. it run nut there is no response
void bwProcess_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
Response.WriteFile("D:\\Samples.xlsx");
}
You've passed something to e.Result in DoWork, but you don't anything with it in RunWorkerCompleted.
void bwProcess_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
var text = e.Result as string;
Response.Write(text);
Response.WriteFile("D:\\Samples.xlsx");
}
I want to know how to show image loading progress in progress-bar in win form.
my code is
private void Form2_Load(object sender, EventArgs e)//load form and get profile and avatar
{
backgroundWorker1.ProgressChanged += new ProgressChangedEventHandler(backgroundWorker1_ProgressChanged);
backgroundWorker1.RunWorkerCompleted += new RunWorkerCompletedEventHandler(backgroundWorker1_RunWorkerCompleted);
backgroundWorker1.RunWorkerAsync();
}
private void backgroundWorker1_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
label2.Text = "Avatar Loaded";
}
private void backgroundWorker1_ProgressChanged(object sender, System.ComponentModel.ProgressChangedEventArgs e)//showing progress
{
if (InvokeRequired)
{
BeginInvoke(new Action(() => backgroundWorker1_ProgressChanged(sender, e)));
}
else
{
if (progressBarX1.Value != e.ProgressPercentage)
{
progressBarX1.Value = e.ProgressPercentage;
progressBarX1.Refresh();
}
}
}
private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)//loading avatar
{
WebClient wc = new WebClient();
Stream stream = wc.OpenRead("http://avatar.nimbuzz.com/getAvatar?jid=" + textBox1.Text);
pictureBox1.Image = (Image.FromStream(stream));
}
The image loads successfully but do not show any progress in progress-bar
Well, i would use the ProgressChanged Event from a WebClient to get the result of how far the download progress actually is. Then you can't save it from the thread of the backgroundworker, so you gotta do this when you have the file.
UPDATED
private BackgroundWorker bgw;
private void Form1_Load(object sender, EventArgs e)
{
bgw = new BackgroundWorker();
bgw.DoWork += bgw_DoWork;
bgw.WorkerReportsProgress = true;
bgw.RunWorkerCompleted += bgw_RunWorkerCompleted;
bgw.ProgressChanged += bgw_ProgressChanged;
bgw.RunWorkerAsync();
}
void bgw_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
progressBar1.Value = e.ProgressPercentage;
}
void bgw_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
pictureBox1.Image = (Image)e.Result;
}
void bgw_DoWork(object sender, DoWorkEventArgs e)
{
WebClient wc = new WebClient();
wc.DownloadProgressChanged += wc_DownloadProgressChanged;
Stream stream = wc.OpenRead("" + textBox1.Text);
e.Result = (Image.FromStream(stream));
}
void wc_DownloadProgressChanged(object sender, DownloadProgressChangedEventArgs e)
{
bgw.ReportProgress(e.ProgressPercentage);
}
The problem with your code is that backgroundWorker1_ProgressChanged() is called in the context of the worker thread but UI updates can only be done within the UI thread (main thread). In your scenario you must call:
progressBarX1.Value = e.ProgressPercentage;
within the UI thread. There are many ways how to do this but a simple one is to use InvokeReqzired() to check if you are in the UI thread and you are not then call BeginInvoke() to send the execution of that command to the UI-/main-thread. The following should do the trick:
private void backgroundWorker1_ProgressChanged(object sender, System.ComponentModel.ProgressChangedEventArgs e)
{
if (InvokeRequired)
{
BeginInvoke(new Action(() => backgroundWorker1_ProgressChanged(sender, e)));
}
else
{
progressBarX1.Value = e.ProgressPercentage;
}
}
Update:
I would also change:
backgroundWorker1.RunWorkerAsync();
backgroundWorker1.ProgressChanged += new ProgressChangedEventHandler(backgroundWorker1_ProgressChanged);
to:
backgroundWorker1.ProgressChanged += new ProgressChangedEventHandler(backgroundWorker1_ProgressChanged);
backgroundWorker1.RunWorkerAsync();
so the progress event is assigned (and therefore in place) before starting the asynchronous work. Otherwise you may miss a progress call.
Update 2:
You also need the following line to execute in the UI thread:
pictureBox1.Image = (Image.FromStream(stream));
To do so use the Completed event of BackgroundWorker and bass the image data using the result parameter. Then in the eventhandler use InvokeRequired() and BeginInvoke() just like in the Progress event).
Uodate 3:
Remeins unchanged is good as you don't get a crash because of not calling UI stuff in the UI thread ;-)
Try to force a repaint on the control by calling:
progressBarX1.Refresh();
(just after you assigned a new value to it).
So the code in the progress event looks like this:
private void backgroundWorker1_ProgressChanged(object sender, System.ComponentModel.ProgressChangedEventArgs e)
{
if (InvokeRequired)
{
BeginInvoke(new Action(() => backgroundWorker1_ProgressChanged(sender, e)));
}
else
{
if (progressBarX1.Value != e.ProgressPercentage)
{
progressBarX1.Value = e.ProgressPercentage;
progressBarX1.Refresh();
}
}
}
If that still doesn't work check that your main/UI thread is not blocked or totally busy.
Update 4:
Just to make sure: you need to enable progress-reporting on the background worker and call its ReportProgress() method from time to time within the backgroundWorker1_DoWork(). See the following MS-Tutorial for more information on usage of the BackgroundWorker: http://msdn.microsoft.com/en-us/library/cc221403(v=vs.95).aspx
Enabling progress reporting on a backgroundworker:
backgroundWorker1.WorkerReportsProgress = true;
or use the form-designer and set the property WorkerReportsProgress to True. Then you still need to call the backgroundWorker1.ReportProgress() from time to time.
Update 5:
Ok, lets give it a complete try. I've checked some reference docs from MS so in case of the backgroundworker ProgressChanged and Completed events you don't need to BeginInvoke() them as MS does this already for you.
private void Form2_Load(object sender, EventArgs e)
{
getto();
backgroundWorker1.WorkerReportsProgress = true;
backgroundWorker1.ProgressChanged -= backgroundWorker1_ProgressChanged;
backgroundWorker1.ProgressChanged += backgroundWorker1_ProgressChanged;
backgroundWorker1.RunWorkerCompleted -= backgroundWorker1_Completed;
backgroundWorker1.RunWorkerCompleted += backgroundWorker1_Completed;
backgroundWorker1.RunWorkerAsync();
}
private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
{
using (var wc = new WebClient())
{
wc.DownloadProgressChanged += (sender, e) => backgroundWorker1.ReportProgress(sender, e);
using (var stream = wc.OpenRead("http://avatar.nimbuzz.com/getAvatar?jid=" + textBox1.Text))
{
e.Result = (Image.FromStream(stream));
}
}
}
private void backgroundWorker1_ProgressChanged(object sender, System.ComponentModel.ProgressChangedEventArgs e)
{
progressBarX1.Value = e.ProgressPercentage;
progressBarX1.Refresh();
}
private void backgroundWorker1_Completed(object sender, DoWorkEventArgs e)
{
pictureBox1.Image = e.Result;
}
I have a backgroundworker in the designer. Set the option WorkerReportsProgress and WorkerSupportsCancellations to true.
Also added all the three events of the backgroundworker.
Now i have timer1 tick event:
private void timer1_Tick(object sender, EventArgs e)
{
counter += 1;
label9.Text = counter.ToString();
label9.Visible = true;
}
I havea method called it NewsUpdate:
private void NewsUpdate()
{
if (counter == 10)
{
scrollLabel1.Reset();
scrollLabel1.Text = " ";
scrollLabel1.Invalidate();
client.Encoding = System.Text.Encoding.GetEncoding(1255);
page = client.DownloadString("http://rotter.net/scoopscache.html");
TextExtractor.ExtractDateTime(page, newText, dateTime);
StreamWriter w = new StreamWriter(#"d:\rotterhtml\rotterscoops.html");
w.Write(page);
w.Close();
TextExtractor.ExtractText(#"d:\rotterhtml\rotterscoops.html", newText, dateTime);
combindedString = string.Join(Environment.NewLine, newText);
this.scrollLabel1.Text = combindedString;
scrollLabel1.Invalidate();
counter = 0;
}
}
And all the backgroundworker events:
private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
{
NewsUpdate();
}
Progress:
private void backgroundWorker1_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
}
Completed:
private void backgroundWorker1_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
}
What i want to do is to call each 10 seconds to the method NewsUpdate through the backgroundworker so it will not freeze the application for 1-2 seconds each time it's making an update. But now it's calling the NewsUpdate method only once.
How do i use the backgroundworker with the NewsUpdate method ?
What should i add if at all in each of the events of the backgroundworker ?
Are there any methods or files in the NewsUpdate method that the backgroundworker will throw exception on them since it's ui or something ?
How can I stop my application from not displaying until the form_load code is completed?
public partial class updater : Form
{
public updater()
{
InitializeComponent();
timer1.Interval = (10000) * (1);
progressBar1.Value = 0;
progressBar1.Maximum = 100;
progressBar1.Update();
timer1.Start();
}
private void updater_Load(object sender, EventArgs e)
{
WebClient webClient = new WebClient();
webClient.DownloadProgressChanged += webClient_DownloadProgressChanged;
webClient.DownloadFile("http://download827.mediafire.com/jl9c098fnedg/ncqun56uddq0y1d/Stephen+Swartz+-+Survivor+%28Feat+Chloe+Angelides%29.wav", Application.StartupPath + "\\Stephen Swartz - Survivor (Feat Chloe Angelides).wav");
// System.Diagnostics.Process.Start("\\Test.exe");
this.Close();
}
void webClient_DownloadProgressChanged(object sender, DownloadProgressChangedEventArgs e)
{
progressBar1.Value = e.ProgressPercentage;
progressBar1.Update();
}
}
If you use DownloadFileAsync it wont block the UI thread and will allow the Form to load and show the progress in the Progressbar, then you can use the DownloadFileCompleted event to close the Form
Example:
public Form1()
{
InitializeComponent();
progressBar1.Value = 0;
progressBar1.Maximum = 100;
progressBar1.Update();
}
private void updater_Load(object sender, EventArgs e)
{
WebClient webClient = new WebClient();
webClient.DownloadProgressChanged += webClient_DownloadProgressChanged;
webClient.DownloadFileCompleted += new AsyncCompletedEventHandler(webClient_DownloadFileCompleted);
webClient.DownloadFileAsync(new Uri("http://download827.mediafire.com/jl9c098fnedg/ncqun56uddq0y1d/Stephen+Swartz+-+Survivor+%28Feat+Chloe+Angelides%29.wav"), Application.StartupPath + "\\Stephen Swartz - Survivor (Feat Chloe Angelides).wav");
}
private void webClient_DownloadFileCompleted(object sender, AsyncCompletedEventArgs e)
{
Close();
}
private void webClient_DownloadProgressChanged(object sender, DownloadProgressChangedEventArgs e)
{
progressBar1.Value = e.ProgressPercentage;
progressBar1.Update();
}
One way is to move your code from Load Shown Event. So the code will start runing after the form is shown.
The other is create a thread, where you will download a file.
For this purpose you can use BackgroundWorker
private void updater_Load(object sender, EventArgs e)
{
BackgroundWorker worker = new BackgroundWorker();
worker.DoWork += (s, eArgs) =>
{
WebClient webClient = new WebClient();
webClient.DownloadFile("someUrl", "somePath");
};
worker.RunWorkerAsync();
}
Also there exists webClient.DownloadFileAsync method witch suits better in this situation. You can find description in sa_ddam213 answer.
This is how I create a thread that does domething reps times:
protected virtual void RedButtonClicked(object sender, System.EventArgs e)
{
Nuker n = new Nuker(target, reps);
bombThread = new Thread(new ThreadStart(n.nuke));
bombThread.Start();
}
The thread class:
public class Nuker
{
private string target;
private int reps;
//...
public void nuke()
{
for(int i=0; i<reps; ++i)
{
ICBM.nuke(target);
Thread.Sleep(5500);
}
System.Console.WriteLine("Done.");
}
}
(I create a new class to store some variables since I can't pass these in ThreadStart().)
Now I would like to have a simple visualisation of the process, let's say printing the current repetition in a text field on a form. How would I use the i from the loop to do that?
In the simplest form you proved a callback in the Nuker class
public Nuker(string target, int reps, Action reportCallback){..}
In the loop you just call reportCallback(i);
Nuker n = new Nuker(target, reps, ReportMethod);
with
private void ReportMethod(int currentIdx)
{
if (InvokeRequired) // Invoke if UI update
...
}
But, probably you want to use the BackgroundWorker that has build in methods for reporting progress on the UI thread. Just check the examples on MSDN.
you can do it with a backgroundworker, it´s one of the easiest threads :-)
below i have post you a sample that i have createt to teach some friends the use of the backgroundworker ;-)
private BackgroundWorker bw = new BackgroundWorker();
public Form1()
{
InitializeComponent();
bw.WorkerReportsProgress = true;
bw.WorkerSupportsCancellation = true;
bw.ProgressChanged += new ProgressChangedEventHandler(bw_ProgressChanged);
bw.DoWork += new DoWorkEventHandler(bw_DoWork);
bw.RunWorkerCompleted += new RunWorkerCompletedEventHandler(bw_RunWorkerCompleted);
}
public void buttonStart_Click(object sender, EventArgs e)
{
if (bw.IsBusy != true)
bw.RunWorkerAsync(12); //Start
}
public int Pils(int i)
{
Thread.Sleep(2000);
bw.ReportProgress(70, "In the middle of the work..");
Thread.Sleep(2000);
bw.ReportProgress(90, "Returning the result..");
Thread.Sleep(2000);
return (2 * i);
}
private void bw_DoWork(object sender, DoWorkEventArgs e)
{
bw.ReportProgress(20, "Waiting for cancel..");
Thread.Sleep(2000);
if ((bw.CancellationPending == true))
e.Cancel = true;
else
{
bw.ReportProgress(50, "Starting process..");
e.Result = Pils((int)e.Argument);
}
}
private void bw_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
bw.ReportProgress(100, "Work done..");
if ((e.Cancelled == true))
textBox1.Text = "Canceled!";
else if (e.Error != null)
textBox1.Text = ("Error: " + e.Error.Message);
else textBox1.Text = e.Result.ToString();
}
private void buttonCancel_Click(object sender, EventArgs e)
{
if (bw.WorkerSupportsCancellation == true)
bw.CancelAsync();
}
private void bw_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
listBox1.Items.Add((e.ProgressPercentage.ToString() + "%") + " - " + e.UserState as String);
}
url to the blogpost: link