Develop Reference

Why does an event handler output all of its actions at the same time? [duplicate]

This question already has answers here:
How to put delay before doing an operation in WPF
(2 answers)
Closed 1 year ago.
I want that when the button is pressed, two numbers one are displayed with an interval of half a second in textbox
But if you do everything as in my example, both numbers are displayed simultaneously in half a second
private void Button_Click(object sender, RoutedEventArgs e)
{
Checker.Text += "1";
System.Threading.Thread.Sleep(500);
Checker.Text += "1";
}
The same will happen with any loop inside any event handler

The Thread.Sleep() call will block the Dispatcher thread. Its that thread that updates your UI, in order to do what you want you will need to either run a background worker thread, or more simply use the Async/Await syntax
private async void Button_Click(object sender, RoutedEventArgs e)
{
Checker.Text += "1";
await Task.Delay(500);
Checker.Text += "1";
}

Trying to change output for a timer in a form in c#

I need to make a form in C# have a timer and have a label that will have be the display of the timer. The label will need to be a generic label at first saying it is a counter, but when the timer starts it needs to display the count. Currently I have the display as a number up down but, it needs to be the control that can tweak the count, which it does. It just can't be the sole counter.
Here is my assignment:
Create a Windows Application. In the main form, create a label named “lTickCount”.
Create a timer named “tPeriodic”, and a numerical control of your own choosing.
Each time the timer “ticks” increment an integer, display the integer value as a string in
lTickCount. Use the numerical control to change the update rate of the timer
interactively.
I think I have done everything correctly except for the bold part. To finish I tried to make a string in both the label and the counter. I know I shouldn't have in both, I just wanted to show you the two things I've tried to help get better feedback:
namespace WindowsFormsApplication3
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
this.Text = "AAAAAAAA AAAAAAAA ########";
}
private void checkBox1_CheckedChanged(object sender, EventArgs e)
{
if (checkBox1.Checked)
{
TickCounter.Text = "The timer has started";
tPeriodic.Enabled = true;
}
else
{
TickCounter.Text = "The timer has ended";
tPeriodic.Enabled = false;
}
}
private void TickCounter_ValueChanged(object sender, EventArgs e)
{
TickCounter.Text = TickCounter.Value.ToString();
}
private void tPeriodic_Tick(object sender, EventArgs e)
{
TickCounter.Value += 1;
}
private void label1_Click(object sender, EventArgs e)
{
TickCounter.Text = TickCounter.Value.ToString();
}
private void Form1_Load(object sender, EventArgs e)
{
}
}
}
Can someone help me figure out what I'm doing wrong and point me in the right way?

If you are going to try to add to a string (A label value) you need to convert it to an Integer first.
A couple ways to do this:
TextCount.Text = (Convert.ToInt32(TextCount.Text) + 1).ToString();
is one way, of course you could still use your += or any other math syntax for basic addition of +1.
You can also use tryParse, and in fact this should probably be used to verify you have an integer in the first place:
int count;
if (int.TryParse(TextCount.Text, out count))
{
count++;
TextCount.Text = count.ToString();
}

int count;
int tmrInterval = 1000; //1 sec
private void tPeriodic_Tick(object sender, EventArgs e)
{
count++;
lTickCount.Text = count.ToString();
}
private void TickCounter_ValueChanged(object sender, EventArgs e)
{
if (TickCounter.Value == 0)
{
return; // or stop the timer
}
tPeriodic.Interval = TickCounter.Value * tmrInterval;
}
tPeriodic.Interval is the time till next tick in milliseconds.
You are updating the timer interval according to tmrInterval and the value of the numeric control. You can change the interval or the formula i wrote to your own.
valter

Ok I found that:
tPeriodic.Interval = 1000 / Convert.ToInt32(TickCounter.Value * TickCounter.Value);
seemed to work in the numericupdown class.
Thanks for the help.

Progress bar c# - loading like process [duplicate]

This question already has answers here:
How to use a BackgroundWorker?
(2 answers)
Closed 1 year ago.
Hello I have a function which takes time to load. that's why i'm planning to put a progress bar on my winform so that the user would know that my program is still running. however, I do not know how I'm gonna solve it. is there someone here who could help guide me.
Here's what I'm planning to do:
private void btnProcess_Click(object sender, EventArgs e)
{
//function which takes time because it contacts to a server
}
I want to have a progressbar which increments and ends after my process has finished. Should I use a backgroundworker for this?
***I've followed this tutorial http://www.codeproject.com/Tips/83317/BackgroundWorker-and-ProgressBar-demo but it does not wait for a specific function or event to finish like a loading screen.
***My progressbar does not end after my buttonclick event has finished executing all its functions.
I've created:
private void myBackgroundWorker_DoWork(object sender, DoWorkEventArgs e)
{
for (int i = 0; i <= 100; i++)
{
myBackgroundWorker.ReportProgress(i);
System.Threading.Thread.Sleep(100);
}
}
private void myBackgroundWorker_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
myProgressBar.Value = e.ProgressPercentage;
}
private void btnProcess_Click(object sender, EventArgs e)
{
myBackgroundWorker.RunWorkerAsync();
//function which takes time because it contacts to a server
}
How Would I know when will my buttonclick event gonna end? so that my progress bar will end also?

These are the two really good examples
http://www.dreamincode.net/forums/topic/112547-using-the-backgroundworker-in-c%23/
http://www.dreamincode.net/forums/topic/246911-c%23-multi-threading-in-a-gui-environment/
Hope that helps
EDIT:
public partial class Form1 : Form
{
//--------------------------------------------------------------------------
public Form1()
{
InitializeComponent();
//Initialize backgroundworker
Shown += new EventHandler(Form1_Shown);
backgroundWorker1.WorkerReportsProgress = true;
backgroundWorker1.DoWork += new DoWorkEventHandler(backgroundWorker1_DoWork);
backgroundWorker1.ProgressChanged +=
new ProgressChangedEventHandler(backgroundWorker1_ProgressChanged);
//counter
YourObject.Counter = 100;
}
//--------------------------------------------------------------------------
void btnClick_Clicked(object sender, EventArgs e)
{
//Trigger the background process
backgroundWorker1.RunWorkerAsync();
}
//--------------------------------------------------------------------------
void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
{
//Your freakishly long process,
//which needs to be run in the background
//to make it simple, I'll just do a for loop
for (int i = 0; i < 100; i++)
{
//The counter will keep track of your process
//In your case, it might not be a for loop
//So you will have to decide how to keep track of this counter
//My suggestion is to decrease/increase this counter
//right after importants action of your process
backgroundWorker1.ReportProgress(YourObject.Counter--);
}
}
void backgroundWorker1_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
//The counter is updated and displayed with a progress bar
YourObject.Counter = e.ProgressPercentage;
}
}

Yeah, you should. It's pretty straightforward.
Make a background worker that executes whatever work btnProcess_Click does.
Have it report progress:
worker.WorkerReportsProgress = true;
And now you can have this progress report be triggered by an event you subscribe to.
worker.ProgressChanged += new ProgressChangedEventHandler(worker_ProgressChanged);
In doing so, you can create a progress bar than can update itself based on this worker_ProgressChanged event, triggered by your computation.
You can find plenty of implementations of this just by Googling. Good luck, hope this helps.

how can I use BackGroundWorker to make continuous execution for a method which is depends on user input to stop? [duplicate]

This question already has answers here:
Closed 10 years ago.
Possible Duplicate:
How To Start And Stop A Continuously Running Background Worker Using A Button
I have 2 buttons the first one it's name "Continuous" .. the second one "Stop"
I want to call a method when press the continuous button :
private void continuous_Click(object sender ,EvantArgs e)
{
// continuous taking pictures ...
}
my question is : how can I stop the execution by pressing the stop button ??
I've written a code to take a picture and I've succeeded to take pictures ...
now I want the camera to take continuous snapshots ... but if I press stop button the camera should stop taking pictures ...
I've used BackGroundWorker but the code does not work !!!
this is the code :
private void ContinousSnaps_Click(object sender, EventArgs e)
{
Contiguous.DoWork += Contiguous_DoWork;
Contiguous.RunWorkerCompleted += Contiguous_RunWorkerCompleted;
Contiguous.RunWorkerAsync();
}
private void Contiguous_DoWork(object sender, DoWorkEventArgs e)
{
for (int i = 0; ; i++) TakeSnapShotCommand();
}
private void Contiguous_RunWorkerCompleted(object sender,
RunWorkerCompletedEventArgs e)
{
MessageBox.Show("complete");
}
//------------------------------------------------------------------//
private void Stop_Click(object sender, EventArgs e)
{
Contiguous.CancelAsync();
}
//--------------------------------------------------------------------//
how can I achieve the result that I want ?!

Try and see if this is going to work:
In your _DoWork event:
private void Contiguous_DoWork(object sender, DoWorkEventArgs e)
{
for (int i = 0; ; i++)
{
if (Contiguous.CancellationPending)
{
e.Cancel = true;
return;
}
TakeSnapShotCommand();
}
}
And in the Stop_Click to the following:
private void Stop_Click(object sender, EventArgs e)
{
if (Contiguous.WorkerSupportsCancellation)
Contiguous.CancelAsync();
}
Also make sure you allow cancellation (and if you want to take my advice here - move these event registrations in a the form load, so they will be executed once, not every time the button is clicked - leave just the Continuous.RunWorkerAsync()):
// your form load <---
private void Form1_Load(object sender, EventArgs e)
{
Contiguous.DoWork += Contiguous_DoWork;
Contiguous.RunWorkerCompleted += Contiguous_RunWorkerCompleted;
Contiguous.WorkerSupportsCancellation = true; // allowing cancellation
}
private void ContinousSnaps_Click(object sender, EventArgs e)
{
// not a bad idea if you disable the button here at this point
Contiguous.RunWorkerAsync();
}

C# Creating a Timer that at a specific values changes a label

I am new to C#, and I have searched I but didn't find a simple solution to my problem.
I am creating a Windows form application.
After the start button is clicked, it counts every millisecond and when it reaches specific values from an array changes a label.
How can milliseconds be counted?
-------------------------
AlekZanDer Code:
namespace timer_simple3
{
public partial class Form1 : Form
{
long result = 0;
public Form1()
{
InitializeComponent();
this.timer1 = new System.Windows.Forms.Timer(this.components);
}
private void Form1_Load(object sender, EventArgs e)
{
this.timer1.Tick += new System.EventHandler(this.timer1_Tick);
}
private void timer1_Tick(object sender, EventArgs e)
{
result = result + 1;
label1.Text = Convert.ToString(result);
}
private void btstart_Click(object sender, EventArgs e)
{
timer1.Interval = 1; //you can also set this in the
//properties tab
timer1.Enabled = true;
timer1.Start();
// label1.Text = Convert.ToString(timer1);
}
private void btstop_Click(object sender, EventArgs e)
{
timer1.Stop();
}
}
}

How can milliseconds be counted?
You can't do that, because Windows Forms Timer component is single-threaded, and is limited to an accuracy of 55 milliseconds. If you require a multithreaded timer with greater accuracy, use the Timer class in the System.Timers namespace.
Also any other timer will not give you accuracy more than 16 milliseconds (actually 15.625 milliseconds, or 64Hz). So, you can't increment some counter to count elapsed milliseconds.
Option for you - instead of long result counter use difference between current time and time of timer start:
label1.Text = (DateTime.Now - startDateTime).Milliseconds.ToString();

First you have to create a method that tells the timer what to do every [put the needed number here] milliseconds.
private void randomTimer_Tick(object sender, EventArgs e)
{
if (conditions)
{
... //stuff to do
... //more stuff to do
... //even more stuff to do
}
}
Then you set the timer to call this method: you can do this by using the events tab of the properties of the timer or write:
this.randomTimer1.Tick += new System.EventHandler(this.randomTimer1_Tick);
in the ProjectName.Designer.cs file in the private void InitializeComponent(){} method after the line this.randomTimer = new System.Windows.Forms.Timer(this.components);.
And lastly you enable the timer:
private void startButton (object sender, EventArgs e)
{
randomTimer.Interval = timeInMilliseconds; //you can also set this in the
//properties tab
randomTimer.Enabled = true;
}
Of course, you will have to set the button to call this method too.
If you don't know where the Properties window is (I assume that you are using Visual C#): it's usually a tab located on the right side of the window. In order something to appear in the tab, you have to select the form you want to edit in the design view. If there is no such tab anywhere in the window of the compiler, go to "View" -> "Other Windows" and select "Properties Window".
If the answers you have found are long and complicated, that's mostly because they are explaining the whole process with details and examples. If you use the "drag and drop" option of Visual C#, the declaration code of the forms will happen automatically, afterwards it's up to you to write the code of the methods. There are also other features that are self explanatory and make programming more pleasant. Use them!