I have created a Windows Forms Console Application in which I am reading a file which has been written by another console application.
The other console application will write about the status of some process and the Windows Forms application will read the status and accordingly update the status text box.
I wrote the following code for above scenario.
while (true)
{
if ((new FileInfo(filename)).Length > 0)
{
Status = File.ReadAllText(filename, Encoding.ASCII);
System.IO.File.WriteAllText(filename, string.Empty);
Statustb.Text = Status;
Statustb.Refresh();
if (Status.Equals("Data Got Loaded"))
{
Environment.Exit(0);
}
}
}
When I am running the Windows Forms application it shows "Form Not Responding" but when I comment out these lines then it will run smoothly. But for me it is important to update the status.
You have to understand the architecture of a GUI application.
All interactions with the user happen on one thread.
This includes reacting to things like mouse and keyboard events etc.
If one of these events happens you can handle that event and do something in response to it.
But, until you return from the handler, the application will not be able to receive any further notifications (Windows Messages aka events).
I suspect you have the above code in either the constructor or in one or other event handler. Since you never exit (infinite loop, due to while(true) without a return or break, the operating system cannot send any further events to the application. They get put in a queue to be sent, but never get picked up.
Windows will detect this situation and give you the Not Responding dialog message.
I suggest, that, instead of having the code inside the while(true) loop, you create a Timer with a suitable Interval, and put the body of the while statement (ie the bit between the { and }, but not the while(true) itself ) in the Tick handler.
It is better to use the code inside a timer.
Still, you need to make sure that no two different threads at the same time accessing a file. You should have used lock while reading and writing it.
I have a pattern that I use for getting long running tasks off of the UI thread. To see it, create a Winforms project and open the code-behind for Form1.cs. Delete the content and copy the following into that file. It should run and it has comments describing what it is doing.
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using System.Windows.Forms;
namespace POC_DoEvents_alternate
{
public partial class Form1 : Form
{
private Button button1;
private Button button2;
private TextBox textbox1;
public Form1()
{
InitializeComponent();
// programmatically create the controls so that the
// entire source code is contained in this file.
// normally you wouldn't do this.
button1 = new Button();
button1.Name = "button1";
button1.Enabled = true;
button1.Location = new Point(12, 12);
button1.Size = new Size(144, 35);
button1.Text = "button1";
button1.Click += button1_Click;
this.Controls.Add(button1);
button2 = new Button();
button2.Name = "button2";
button2.Enabled = false;
button2.Location = new Point(12, 53);
button2.Size = new Size(144, 35);
button2.Text = "button2";
button2.Click += button2_Click;
this.Controls.Add(button2);
textbox1 = new TextBox();
textbox1.Name = "textbox1";
textbox1.Location = new Point(12, 94);
textbox1.ReadOnly = true;
textbox1.Size = new Size(258, 22);
this.Controls.Add(textbox1);
this.Load += new System.EventHandler(this.Form1_Load);
}
private void Form1_Load(object sender, EventArgs e)
{
textbox1.Text = "You can't press button 2 yet...";
button1.Enabled = true;
button2.Enabled = false;
this.Cursor = Cursors.AppStarting;
// start the long running task in a separate background thread
ThreadPool.QueueUserWorkItem(Async_LongRunningTask, "Form1_Load");
// calling the QueueUserWorkItem will not block. Execution will
// contiune immediately with the lines below it.
textbox1.BackColor = Color.LightPink;
// this event handler finishes quickly so the form will paint and
// be responsive to the user.
}
private void button1_Click(object sender, EventArgs e)
{
textbox1.Text = "Button 1 pressed";
}
private void button2_Click(object sender, EventArgs e)
{
textbox1.Text = "Button 2 pressed";
}
private void Async_LongRunningTask(object state)
{
// put all your long running code here, just don't put any
// UI work on this thread
Thread.Sleep(5000); // simulates a long running task
// put any UI control work back on the UI thread
this.Invoke((MethodInvoker)delegate
{
button2.Enabled = true;
textbox1.Text = "End of long running task: " + state.ToString();
textbox1.BackColor = SystemColors.Control;
this.Cursor = Cursors.Default;
// as with anything on the UI thread, this delegate
// should end quickly
});
// once the delegate is submitted to the UI thread
// this thread can still do more work, but being a
// background thread, it will stop when the application
// stops.
Thread.Sleep(2000); // simulates a long running task
}
}
}
You can add using System.Windows.Forms;
Application.DoEvents();
in the While
Related
I am interested in checking the content of a website, the content changes frequently and when I view the website on any browser, it refreshes itself every 30 seconds. I want to know when the content has changed.
I am using winforms and I want to just click a button to start a loop, every 30 seconds. I don't want to hit the website too frequently, in fact the web pages own refresh is more than enough for my needs.
My code works when I click a button (btnCheckWebsite), if I wait a minute and then click btnCheckWebsite again, my message box pops up because the web page has changed. This is great however I want to do this in a while loop. When I un-comment my while loop, the DocumentText never changes. I have debugged it and for some reason it's the same text every time, even when the web page has changed in the real world, it stays the same in my code.
So my question is why can't I use a loop and what can I do instead to run this repeatedly without any input from me?
As a bonus, I would like to remove the .Refresh() I added this because it won't work without it however as I understand it, this refreshes the whole page. When I use a browser I see the page updating even when I don't refresh the whole page.
Just for background info, I did start by having a WebBrowser control on my form, the page refreshes automatically. I used the same code and have the same problem, interestingly, the WebBrowser control on my windows form refreshes by itself no problem, until I click btnCheckWebsite and then it stops refreshing! Also I know about webrequest but I don't know how to use it for my purposes.
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Threading;
namespace Check_Website
{
public partial class Form1 : Form
{
public WebBrowser _memoryWebBrowser = new WebBrowser();
String _previousSource = "emptySource";
public Form1()
{
InitializeComponent();
_memoryWebBrowser.Navigate(new Uri("http://www.randomurl.com/"));
}
private void btnCheckWebsite_Click(object sender, EventArgs e)
{
//I want to un-comment this while loop and let my code run itself but it stops working
//when I introduce my while loop.
//while (1 < 2 )
//{
//Thread.Sleep(30000);
checkWebsite();
//}
}
private void checkWebsite()
{
//Why do I need this refresh? I would rather not have to hit the web page with a refresh.
//When I view the webpage it refreshed with new data however when I use a WebBrowser
//the refresh just doesn't happen unless I call Refresh.
_memoryWebBrowser.Refresh();
Thread.Sleep(500);
while (((_memoryWebBrowser.ReadyState != WebBrowserReadyState.Complete) || (_memoryWebBrowser.DocumentText.Length < 3000)))
{
Thread.Sleep(1000);
}
String source = _memoryWebBrowser.DocumentText;
if ((source != _previousSource) && (_previousSource != "emptySource"))
{
//Hey take a look at the interesting new stuff on this web page!!
MessageBox.Show("Great news, there's new stuff on this web page www.randomurl.co.uk!!" );
}
_previousSource = source;
}
}
}
You'd need to do your processing upon DocumentCompleted event. This event is asynchronous, so if you want to do this in a loop, the execution thread must pump messages for this event to fire. In a WinFroms app, your UI thread is already pumping messages in Applicaiton.Run, and the only other endorsed way to enter nested message loop on the same thread is via a modal form (here's how it can be done, see in the comments).
Another (IMO, better) way of doing such Navigate/DocumentCompleted logic without a nested message loop is by using async/await, here's how. In the classic sense, this is not exactly a loop, but conceptually and syntactically it might be exactly what you're looking for.
You can catch the WebBrowser.Navigated Event to get notified when the page was reloaded. So you wouldn't need a loop for that. (I meant the ready loop)
Just navigate every 30 seconds to the page in a loop and in the Navigated Event you can check whether the site has changed or not.
You'd better hook up DocumentCompleted event to check its DocumentText property!
The WebBrowser Element is very buggy and has much overhead for your needs. Instead of that you should use WebRequest. Because you said you don't know how to use, here's an (working) example for you.
using System;
using System.Windows.Forms;
using System.Net;
using System.IO;
namespace Check_Website
{
public partial class Form1 : Form
{
String _previousSource = string.Empty;
System.Windows.Forms.Timer timer;
private System.Windows.Forms.CheckBox cbCheckWebsite;
private System.Windows.Forms.TextBox tbOutput;
public Form1()
{
InitializeComponent();
this.cbCheckWebsite = new System.Windows.Forms.CheckBox();
this.tbOutput = new System.Windows.Forms.TextBox();
this.SuspendLayout();
//
// cbCheckWebsite
//
this.cbCheckWebsite.AutoSize = true;
this.cbCheckWebsite.Location = new System.Drawing.Point(12, 12);
this.cbCheckWebsite.Name = "cbCheckWebsite";
this.cbCheckWebsite.Size = new System.Drawing.Size(80, 17);
this.cbCheckWebsite.TabIndex = 0;
this.cbCheckWebsite.Text = "checkBox1";
this.cbCheckWebsite.UseVisualStyleBackColor = true;
//
// tbOutput
//
this.tbOutput.Location = new System.Drawing.Point(12, 35);
this.tbOutput.Multiline = true;
this.tbOutput.Name = "tbOutput";
this.tbOutput.Size = new System.Drawing.Size(260, 215);
this.tbOutput.TabIndex = 1;
//
// Form1
//
this.ClientSize = new System.Drawing.Size(284, 262);
this.Controls.Add(this.tbOutput);
this.Controls.Add(this.cbCheckWebsite);
this.Name = "Form1";
this.Load += new System.EventHandler(this.Form1_Load);
this.ResumeLayout(false);
this.PerformLayout();
timer = new System.Windows.Forms.Timer();
timer.Interval = 30000;
timer.Tick += timer_Tick;
}
private void Form1_Load(object sender, EventArgs e)
{
timer.Start();
}
void timer_Tick(object sender, EventArgs e)
{
if (!cbCheckWebsite.Checked) return;
WebRequest request = WebRequest.Create("http://localhost/check_website.html");
request.Method = "GET";
WebResponse response = request.GetResponse();
string newContent;
using (var sr = new StreamReader(response.GetResponseStream()))
{
newContent = sr.ReadToEnd();
}
tbOutput.Text += newContent + "\r\n";
if (_previousSource == string.Empty)
{
tbOutput.Text += "Nah. It's empty";
}
else if (_previousSource == newContent)
{
tbOutput.Text += "Nah. Equals the old content";
}
else
{
tbOutput.Text += "Oh great. Something happened";
}
_previousSource = newContent;
}
}
}
This is in Win forms
On button click I want to change the color of the button temporarily say only for 1 second and then the button color should get back to the previous color. I used lambda expression and timer for this.
private void btn_Read_Click(object sender, EventArgs e)
{
System.Windows.Forms.Timer t1 = new System.Windows.Forms.Timer();
t1.Interval = 1000;
t1.Tick += (src, ee) =>
{
btn_Read.BackColor = Color.Transparent; t1.Stop();
};
t1.Start();
btn_Read.BackColor = Color.YellowGreen;
lvwMessages.Items.Clear();
string strcommand = "AT+CMGL=\"ALL\"";
objShortMessageCollection = ReadSMS(strcommand); // Line wher I am reading messages from the port
foreach (ShortMessage msg in objShortMessageCollection)
{
ListViewItem item = new ListViewItem(new string[] { msg.Sender, msg.Message, msg.Sent, msg.Index });
item.Tag = msg;
lvwMessages.Items.Insert(0, item);
}
if (lvwMessages.Items.Count == 0)
{
status_other.Visible = true;
status_other.Text = "No messages";
lbl_total.Text = "Total: 0";
System.Windows.Forms.Timer timer1 = new System.Windows.Forms.Timer();
timer1.Interval = 2000;
timer1.Tick += (source, ex) => { status_other.Visible = false; timer1.Stop(); };
timer1.Start();
}
else
{
status_other.Visible = false;
chk_selectmsg.Visible = true;
btn_delete.Visible = true;
lbl_total.Text = "Total: " + lvwMessages.Items.Count.ToString(); ;
}
}
Later in this code I am reading the data from serial port, displaying it, etc. The problem is that the button color doesnot change as I click the button. It takes some time and does not give the desired feel I want. Some times doesn't even change the color. What could be the reason?
A simple solution would be using mouse hover event and mouse leave event
Use it this way:
private void btn_Read_MouseHover(object sender, EventArgs e)
{
btn_Read.BackColor = Color.AliceBlue;
}
private void btn_Read_MouseLeave(object sender, EventArgs e)
{
btn_Read.BackColor = Color.AntiqueWhite;
}
This does'nt require any change in your code and definitely will give you the functionality. See if it helps!
you should avoid having work-intensive code on the UI thread
to get the desired effect, sepperate the code for the UI from the code that does the work ...
when the button is clicked, change its appearence and start some background task (threadpool,backgroundworker,etc) that does the work
be aware that you can interact with a control only from the thread it was created on, so to display your data or interact with the UI, you will have to invoke the UI thread (see Control.Invoke(...))
if you have a lot of UI reseting stuff like that, you should think about a timer on the form, to check every let's say 200ms if there is something to be reset/done
you could use a sorted list with tuples (Datetime,delegate) that are executed and removed once the time has come ...
Write the rest of code in thread and fire that thread. this will make your UI responsive and will give you the desired output you want for button. Or use btnedit.Refresh() just after changing color to force button to redraw itself
In the designer i put backgroundworker and i have two events: Do Work and Progress Changed.
I used breakpoint and its getting inside the Do Work event but it never get into the Progress Changed event. Its never stop there like the event isnt working. Why the progrss changed event isnt working ?
This is the code:
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using Google.GData.Client;
using Google.GData.Extensions;
using Google.GData.Extensions.MediaRss;
using Google.GData.YouTube;
using Google.YouTube;
using System.Threading;
namespace YoutubeTesting
{
public partial class Form1 : Form
{
YouTubeRequestSettings settings;
YouTubeRequest request;
string devkey = "AI39si6xhSQXx95FTYIACWPfq-lLIphblgaReuz9z6VEjR1Q6YjrV6FRN2U6FN6P6-lGF2OYaUZhCVOKJ_MCk4o6kPeUszvf5A";
string username = "chocolade13091972#gmail.com";
string password = "password";
public Form1()
{
InitializeComponent();
worker.RunWorkerAsync();
}
private void Form1_Load(object sender, EventArgs e)
{
}
private void upload()
{
try
{
settings = new YouTubeRequestSettings("You Manager", devkey, username, password);
settings.Timeout = -1;
request = new YouTubeRequest(settings);
Video video = new Video();
video.Title = "test";
video.Tags.Add(new MediaCategory("Comedy", YouTubeNameTable.CategorySchema));
video.Keywords = "Comedy";
video.Private = false;
video.MediaSource = new MediaFileSource("d:\\VIDEO0037.3gp", "video/3gp");
request.Upload(video);
MessageBox.Show("Successfully Uploaded");
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}
}
private void worker_DoWork(object sender, DoWorkEventArgs e)
{
upload();
}
private void worker_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
textBox1.Text = e.ProgressPercentage.ToString();
}
}
}
You need to report the progress using worker.ReportProgress()
From MSDN:
If you need the background operation to report on its progress, you
can call the ReportProgress method to raise the ProgressChanged event.
The WorkerReportsProgress property value must be true, or
ReportProgress will throw an InvalidOperationException.
It is up to you to implement a meaningful way of measuring your
background operation's progress as a percentage of the total task
completed.
The call to the ReportProgress method is asynchronous and returns
immediately. The ProgressChanged event handler executes on the thread
that created the BackgroundWorker.
You have to set this.
backgroundWorker.WorkerReportsProgress = true;
Gets or sets a value indicating whether the BackgroundWorker can
report progress updates.
EDIT
If still not working checks whether you have bind the event properly in the designer code. Or just add something like below in your class.
backgroundWorker1.ProgressChanged += new System.ComponentModel.ProgressChangedEventHandler(this.worker_ProgressChanged);
In your Upload method you have to report progress. Otherwise above event won't fire. Keep in mind that, it's not easy to report actual progress always.
Below is an example code for a DoWork method. Look at here if you want to see a complete example.
static void bw_DoWork (object sender, DoWorkEventArgs e)
{
for (int i = 0; i <= 100; i += 20)
{
if (_bw.CancellationPending) { e.Cancel = true; return; }
_bw.ReportProgress (i);
Thread.Sleep (1000); // Just for the demo... don't go sleeping
} // for real in pooled threads!
e.Result = 123; // This gets passed to RunWorkerCompleted
}
i can run timer but it is hanging , when i run background i need timer to be run in background.
can anyone say me how to run timer in background.
My timer code is
btnIntraday.Enabled = false;
btnStartBackfill.Enabled = false;
btnStop.Enabled = true;
if (btnIntraday.Text == "Intraday")
{
timerIntraday.Interval = 5000;
timerIntraday.Enabled = true;
btnIntraday.Text = "Updating..";
}
else if (btnIntraday.Text == "Updating..")
{
timerIntraday.Enabled = false;
btnIntraday.Text = "Intraday";
}
and my background code is
btnIntraday.Enabled = false;
btnStartBackfill.Enabled = false;
btnStop.Enabled = true;
txtInterval.Text = ddTimeInterval.Value.ToString();
int inter = (int.Parse(txtInterval.Text)) * multiplyingFactorBackfill;
try
{
bgBackfillDCX.RunWorkerAsync();
}
catch (Exception ex)
{
}
can anyone please say me how to run timer in background.
Thanks in advance.
You may use a BackgroundWorker.
Handle the BackgroundWorker.DoWork to run your timer.
Handle the BackgroundWorker.ProgressChanged to handle timing events.
Handle the BackgroundWorker.RunWorkerCompleted to stop the timer.
I think what you are saying is that you want to set off the background code then have IT periodically do some work. If so you need a timer in the background code not the front end. Which means using a different timer class - in System.Timers, IIRC. System.Timers.Timer
If You insist on having the timer working at the front end (though I don't recommend it, I can understand it is easier in some scenarios), there is a way (note: I presume Windows Forms are used):
In the following code, there is:
a timer referring to an instance of System.Windows.Forms.Timer object
a notifyIcon referring to an instance System.Windows.Forms.NotifyIcon object
MainWindow_Resize method associated with Resize event of the form
notifyIcon_Click method associated with Click event of the notifyIcon
The resize method if-block is executed when user minimizes form (form is not visible anywhere in desktop and setting ShowInTaskBar to false hides it from task bar as well, so it is effectively hidden).
private void MainWindow_Resize(object sender, EventArgs e)
{
if (WindowState == FormWindowState.Minimized)
{
this.ShowInTaskbar = false;
notifyIcon.Visible = true;
}
}
When user clicks notification icon, the form's window is restored to its former size and position and the form is brought to user
private void notifyIcon_Click(object sender, EventArgs e)
{
notifyIcon.Visible = false;
this.WindowState = FormWindowState.Normal;
this.ShowInTaskbar = true;
this.BringToFront();
this.Activate();
}
I have a form (Developed in C# using VS2010) with a Progress Bar.
It's kind of stopwatch form where I fill the progress bar in say 10secs.... As Time elapses, Progress bar fills accordingly.... Means after 5secs, Progress Bar will be filled 50% and so on....
I used a for loop to perform this operation:-
for(int count=0;count<200;count++)
{
progbar.performstep();
progbar.update();
update();
Thread.Sleep(50);
}
I have used Thread.Sleep of 50msec so that progress bar updates smoothly.
For 1sec, it increments in steps.
Problem is if I do anyother operation like Moving this form or even clicking on another icon on desktops makes this form "Not Responding".... But it perfoms the operation and at the end of 10 secs, It regains it's state and shows the pop up indicating 10secs are elapsed with Progress Bar Full.
Thanks for help and Sorry for using such complicated language.
Regards,
Swanand
Update: I solved this problem with the help of Answers below.... One common mistake I got to know is forgetting "Applications.DoEvents()" along with "update()".... If you enter this line, there are less chances of getting "hanged"!
You're performing a long-running operation on the UI thread, which means that the UI "message loop" (responsible for handling events such as user input and updating the screen) doesn't get a chance to run.
You should perform the long-running operation on a different thread (whether one you create yourself or a background thread) and either use BackgroundWorker to easily update your progress bar, or use Control.Invoke/BeginInvoke to marshall a delegate call back to the UI thread when you need to update the UI. (You mustn't update controls from the wrong thread.)
If your only UI interaction is filling in a progress bar, I suggest using BackgroundWorker.
If you're not really doing "real" work, just waiting for time to pass, you could use a System.Windows.Forms.Timer instead of all of this, however. That will "tick" on the UI thread, but won't block the UI thread between ticks. You should only use this if you don't have a lot of work to do though - if it really is just updating a progress bar, not (say) processing a file etc. Note that you shouldn't rely on the timer firing exactly "on time" - you should probably set the position of the progress bar based on the observed time, rather than the observed number of ticks.
You are blocking the UI thread, which means it isn't processing events such as "paint". To do this properly, you should be using something like BackgroundWorker, and just updating the UI from the progress event.
using System;
using System.Windows.Forms;
using System.ComponentModel;
using System.Threading;
static class Program
{
[STAThread]
static void Main()
{
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
Application.Run(new MyForm());
}
}
class MyForm : Form
{
Button btn;
BackgroundWorker worker;
ProgressBar bar;
public MyForm()
{
Controls.Add(btn = new Button { Text = "Click me" });
btn.Click += new EventHandler(btn_Click);
Controls.Add(bar = new ProgressBar { Dock = DockStyle.Bottom, Visible = false, Minimum = 0, Maximum = 100 });
worker = new BackgroundWorker { WorkerReportsProgress = true };
worker.ProgressChanged += new ProgressChangedEventHandler(worker_ProgressChanged);
worker.DoWork += new DoWorkEventHandler(worker_DoWork);
worker.RunWorkerCompleted += new RunWorkerCompletedEventHandler(worker_RunWorkerCompleted);
}
void worker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
bar.Visible = false;
if (e.Error != null)
{
Text = e.Error.Message;
}
else if (e.Cancelled)
{
Text = "cancelled";
}
else
{
Text = e.Result == null ? "complete" : e.Result.ToString();
}
btn.Enabled = true;
}
void worker_DoWork(object sender, DoWorkEventArgs e)
{
for (int count = 0; count < 100; count++)
{
worker.ReportProgress(count);
Thread.Sleep(50);
}
}
void worker_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
bar.Value = e.ProgressPercentage;
}
void btn_Click(object sender, EventArgs e)
{
bar.Value = 0;
bar.Visible = true;
btn.Enabled = false;
worker.RunWorkerAsync();
}
}
You are blocking the Main UI thread. You can use a background worker to do this. You can find more details in MSDN
If you want to run your code you should put this code in a function and call this function with one thread.
public static void fun1()
{
for (int i = 0; i <= 10; i++)
{
Console.Write("This is function1");
Console.Write("\n");
}
}
Thread firstthread = new Thread(new ThreadStart(fun1));
firstthread.Start();
firstthread.suspend();//whenever you want your current control to stop.
b'caz Thread.sleep(100) will stop the whole context not that particular you want..
Answer suggested by Marc will help. Lon running operations can make your application crash or not responsive. I have a blog post related to the usage of the background worker class.
http://midnightprogrammer.net/post/Using-Background-Worker-in-C.aspx