Develop Reference

Checking for a non typing interval

This question is a bit obscure, however I cannot find an answer for it anywhere. I am writing a program in C# (Visual Studio Pro 2013) and I need to perform an action after the user has stopped typing for 2 seconds (setting the interval at 2000). I would need a standard timer for this however I need to detect when the user has stopped typing for 2 seconds. How would I go about doing this?

Here's the complete code:
public partial class Form1 : Form
{
System.Timers.Timer timer;
public Form1()
{
InitializeComponent();
// Initialize the timer.
timer = new System.Timers.Timer();
timer.Interval = 2000; // = 2 seconds; 1 second = 1000 miliseconds
timer.Elapsed += OnElapsed;
}
// Handles the TextBox.KeyUp event.
// The event handler was added in the designer via the Properties > Events > KeyUp
private void textBox1_KeyUp(object sender, System.Windows.Forms.KeyEventArgs e)
{
// Reset the timer on each KeyUp.
timer.Stop();
timer.Start();
}
private void OnElapsed(object source, ElapsedEventArgs e)
{
// When time's up...
// - stop the timer first...
timer.Stop();
// - do something more...
MessageBox.Show("Time out!");
}
}

king.code's answer would be correct if you just reset the timer in the first line of textBox1_KeyUp event and initialize the timer in constructor or main method depending on usage.
System.Timers.Timer timer;
private void textBox1_KeyUp(object sender, System.Windows.Forms.KeyEventArgs e)
{
timer.Stop();
timer.Start();
timer.Elapsed += new ElapsedEventHandler(OnTimedEvent);
}
private static void OnTimedEvent(object source, ElapsedEventArgs e)
{
// Do something
}
I would recommend you go for class that inherits text box and pass timer into it if you are going to use it at multiple places

Try this:
System.Timers.Timer timer = new System.Timers.Timer(2000);;
timer.Elapsed += new ElapsedEventHandler(OnTimedEvent);
timer.Enabled = false;
private void textBox1_KeyUp(object sender, System.Windows.Forms.KeyEventArgs e)
{
timer.Enabled = false;
timer.Enabled = true;
}
private static void OnTimedEvent(object source, ElapsedEventArgs e)
{
// Do something
timer.Enabled = false;
}

That is easy just create a timer that sets to 2000 Ms and handle
It by the text change interveral .
Ex:
Set an integer that count from 0 to 2000 then increase it by the
Timer if user starts typing then reset the number else keep
Counting till reach 2000 an ping do the rusty homeboy helped;)

I have just found a valid answer that is simple and compact. I will explain it first and then show a code example. You need to start the timer disabled, and then you need to enable it as soon as the the user presses a key. Then, while still in the method for the user pressing the button you would need to reset the timer interval back to 2000. Whenever the timer expires, you do the action that needs to happen when the keyboard has been inactive for 2 seconds. Code example:
private void textBox_KeyPress(object sender, KeyPressEventArgs e)
{
this.timer.Enabled = true;
this.timer.Interval = 2000;
}
Now the method for the timer_Tick:
private void timer_Tick(object sender, EventArgs e)
{
//Do something when the keyboard has been inactive in 2 seconds
}

Timer interval not working as expected

private void btnProveri_Click(object sender, EventArgs e)
{
lblRezultat.Text = DateTime.Now.ToString();
timer1.Interval = 1800;
timer1.Start();
MessageBox.Show(DateTime.Now.ToString());
}
private void timer1_Tick(object sender, EventArgs e)
{
timer1.Enabled = true;
timer1.Interval = 1800;
}
I am a newbie trying to learn timers and this is my code above. I want to make a Timer which last 1,8 seconds. Then I call it inside the button when it's clicked and the first time the label is set to specific date and then i set interval to the timer and start it, but the messagebox outputs the same time (no delay at all).

That's because you're displaying the message box from within the same code that creates the timer. Effectively:
buttonClick:
Populate some text field.
Start timer so that it calls timerTick in 1.8 seconds
Display message box
timerTick:
Restart timer so it calls this function in 1.8 seconds.
As you can see, the message box is displayed at the time you press the button, not when the timer fires. When the timer fires, all you do is set it to fire again in another 1.8 seconds, but you don't actually do anything else at that point.
If you want it to display after the timer fires, it will have to be done in the timer function timer1_Tick. But you may want to be careful with that, it's possible you may end up with a rather large number of dialog boxes.

It looks like you want to do something like this:
private void btnProveri_Click(object sender, EventArgs e)
{
lblRezultat.Text = DateTime.Now.ToString();
var timer = new System.Timers.Timer(1800);
timer.Start();
timer.Elapsed += timer1_Tick;
}
private void timer1_Tick(object sender, System.Timers.ElapsedEventArgs e)
{
MessageBox.Show(DateTime.Now.ToString());
}
Here is working console example:
class Program
{
static void Main(string[] args)
{
Console.WriteLine("App started");
var timer = new System.Timers.Timer(1800);
timer.Start();
timer.Elapsed += timerHandler;
Console.ReadLine();
}
private static void timerHandler(object sender, System.Timers.ElapsedEventArgs e)
{
Messenger(DateTime.UtcNow.ToString());
}
private static void Messenger(string time)
{
Console.WriteLine(time);
}
}

Making a control to be visible only for a particular amount of time in c#

I am developing an application where i need the following requirement:
Suppose i have a button and a label (initially visibility set to false) in my form, and user clicks on the button, then the label should be displayed with some text that i assign to the label in the button click. But this label should be displayed only for some time, say some 3 secs and then it should automatically go invisible. For this if i gave:
private void button1_Click(object sender, EventArgs e)
{
label1.Visible=true;
label1.Text= "Magic";
Thread.Sleep(3000);
label1.Visible=false;
}
This code does not help the purpose. What is the approach to do it?

Try replacing the last two lines of your method with this:
System.Windows.Forms.Timer timer = new System.Windows.Forms.Timer();
timer.Interval = 3000;
timer.Tick += (source, e) => {label1.Visible = false; timer.Stop();};
timer.Start();
Using Thread.Sleep() is never a good idea in WinForms; use timers instead.

Create a timer with 3s as Interval, start it, and set Visible to false in your timer Tick event. Also don't forget to stop the timer.
Never call Thread.Sleep in your UI thread: the application will be blocked as the UI thread won't accept messages (user click...) while sleeping.

// create a global _timer object
static Timer _timer; // From System.Timers
private void button1_Click(object sender, EventArgs e)
{
label1.Text = "Magic";
// Thread.Sleep(3000); // don't do Thread.Sleep()!
label1.Visible = false;
Start();
}
static void Start()
{
label1.Visible = true;
_timer = new Timer(3000); // Set up the timer for 3 seconds
_timer.Elapsed += new ElapsedEventHandler(_timer_Elapsed);
_timer.Enabled = true; // Enable it
}
static void _timer_Elapsed(object sender, ElapsedEventArgs e)
{
label1.Visible = false;
_timer.Stop();
}

Use Timer, perhaps Windows.Forms.Timer. You may have to play with enabling and disabling it when needed and not needed. Your current way does not help, coz your making the main UI thread to sleep. No use.

c# loop every minute - where to put the code?

Currently I'm moving from java to c# and I'm full of crazy questions.
I'm trying new things on a windows form application and now,I would like to create a loop wich is executing a code every 1 minute,the problem is that I have no idea where to put this code.
For example,the form structure is like:
using System;
namespace Tray_Icon
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void Form1_Load(object sender, EventArgs e)
{
}
private void button1_Click(object sender, EventArgs e)
{
notifyIcon1.ShowBalloonTip(5000);
}
private void notifyIcon1_BalloonTipClicked(object sender, EventArgs e)
{
label1.Text = "Baloon clicked!";
}
private void notifyIcon1_BalloonTipClosed(object sender, EventArgs e)
{
label1.Text = "baloon closed!";
}
private void contextMenuStrip1_Opening(object sender, CancelEventArgs e)
{
}
private void option1ToolStripMenuItem_Click(object sender, EventArgs e)
{
//some code here
}
private void option2ToolStripMenuItem_Click(object sender, EventArgs e)
{
//some code here
}
private void option3ToolStripMenuItem_Click(object sender, EventArgs e)
{
label1.Text = "Option 3 clicked!";
}
private void notifyIcon1_MouseDoubleClick(object sender, MouseEventArgs e)
{
option1ToolStripMenuItem_Click(this, null);
}
private void closeToolStripMenuItem_Click(object sender, EventArgs e)
{
this.Close();
}
private void btnWrite_Click(object sender, EventArgs e)
{
//code here
}
}
}
Where should I put the loop code? :(
Thanks in advance for ANY replay!!!

Add a Timer to your form:
set its Interval property to 60000 (one minute in milliseconds) and Enabled to True:
and attach an event handler to the Timer.Tick event, e.g. by double-clicking the timer in the Forms designer:
private void timer1_Tick(object sender, EventArgs e)
{
// do something here. It will be executed every 60 seconds
}

You would have to add a timer, and set the interval to 1000 miliseconds, and in the OnTick event you add the code with your loop
Timer tmr = null;
private void StartTimer()
{
tmr = new Timer();
tmr.Interval = 1000;
tmr.Tick += new EventHandler<EventArgs>(tmr_Tick);
tmr.Enabled = true;
}
void tmr_Tick(object sender, EventArgs e)
{
// Code with your loop here
}

You can't put any loop code in here.
In your designer look for the Timer control. When you have that, configure it to run every minute and place your code in the Timer_Tick event.
Or create a timer manually in code and respond to the event :) But for starters, doing it by the designer is easier!

Drag a Timer component on the Form and doubleclick it. There you go with the code.
The Timer component runs in the main thread so you can modify UI components without worrying.
Alternatively You could create a System.Timers.Timer, which has it's own thread and has some advantages, but possible caveats when modifying UI components. See http://msdn.microsoft.com/en-us/library/system.timers.timer.aspx

Try to use Background Worker and put the code in the backgroundWorker.DoWork or use a Timer

Use System.Timers.Timer:
System.Timers.Timer aTimer;
{
aTimer = new System.Timers.Timer();
aTimer.Elapsed += new ElapsedEventHandler(OnTimedEvent);
aTimer.Interval = 60000;
aTimer.Enabled = true;
}
private static void OnTimedEvent(object source, ElapsedEventArgs e)
{
Console.WriteLine("The Elapsed event was raised at {0}", e.SignalTime);
}
for using Timer see this tutorial: C# Timer

How you do it in Java platform?
I think Java should be the same with .net.
In fact, a form program is just normal program which contains a event dispatcher. The event dispatcher listen to the UI events and dispatch them to the event handlers. I think all the UI mode should like this, no matter Java or .net platform.
So generally speaking, you have 2 options:
Start the loop at beginning. In this case, you should insert your
code in the constructor of the Form.
Start the loop when user
click the button. In this case, you should insert your code in the
event handler function.
Yes, as others mentioned, you should use the timer. But this should after you know where your code should locate. You also can use a endless loop with a sleep call. But timer is a better solution.

Idea of timer is more better. But If you want to use threads. Then Follow this
Let me assume that You want to do it right from the start of program
You can write in body of function (event in fact) named Form1_Load as
Your actual code is just within while loop other code only to guide
I can guide if you don't know the use of threads in C#
bool button2Clicked = false;
private void Form1_Load(object sender, EventArgs e)
{
// A good Way to call Thread
System.Threading.Thread t1 = new System.Threading.Thread(delegate()
{
while (!button2Clicked)
{
// Do Any Stuff;
System.Threading.Thread.Sleep(60000); //60000 Millieconds=1M
}
});
t1.IsBackground = true; // With above statement Thread Will automatically
// be Aborted on Application Exit
t1.Start();
}

Does .NET webbrowser.stop() function fire DocumentCompleted event?

I use the webbrowser control of .NET to open piles of urls,and the loop is called in the DocumentCompleted event.
Now I want to control the timeout.So I use a timer,and when timeout it will stop the webbrowser using the stop() function.
The question is: it seems that the stop function fires the DocumentCompleted event sometimes.So if the timer calls the next loop after stop the webbrowser,error happens.And if it doesn't call the next loop,sometimes the loop will be stopped in the middle.
The procedure like this(codes not related are deleted):
private string[] urls;//urls are stored here
private int index = 0;//next url index
private void loopFunc()
{
timer.Enabled = true;
wb.navigate(urls[index]);
index++;
return;
}
private void wb_DocumentCompleted(object sender, WebBrowserDocumentCompletedEventArgs e)
{
loopFunc();
}
private void timer1_Tick(object sender, EventArgs e)
{
wb.stop();
//loopFunc() or not?
}
I don't know for sure whether it fires the event or not,and I found nothing via google.

If I have understood your situation clearly this could solve your problem:
Timer On ---> loopFunc() --> goto url --> oncomplete -> start timer again -->
|
|---> Stop timer so it doesn't call loopFunc again
So stop the timer after loopFunc, when the download completes, loopFunc is called again:
private void loopFunc()
{
timer.Enabled = true;
wb.navigate(urls[index]);
index++;
timer.stop(); //<<<<<
return;
}
And your tick should be:
private void timer1_Tick(object sender, EventArgs e)
{
loopFunc();
}
Then start your timer again on document complete:
private void wb_DocumentCompleted(object sender,
WebBrowserDocumentCompletedEventArgs e)
{
wb.Stop();
timer.Start();
}