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C# simple stopwatch - Total beginner

I come from embedded C programming and I don't absolutely know anything about oop, task, threads, ecc..
I'm figuring out the basics concepts of C# and oop and wanted to try coding a simple stopwatch.
Goal: Toggle the stopwatch state with a button and show the value inside the button itself.
So far I've come to this:
namespace Cronometro
{
public partial class MainWindow : Window
{
public MainWindow()
{
InitializeComponent();
}
}
public class MyTimerClass
{
private DateTime TimeValue;
private System.Timers.Timer TimerObj;
private const int TimeInterval = 1;
public MyTimerClass()
{
TimeValue new DateTime(0, 0, 0, 0, 0, 0, 0, DateTimeKind.Local);
TimerObj = new System.Timers.Timer(TimeInterval);
TimerObj.AutoReset = true;
TimerObj.Elapsed += TimerObj_Elapsed;
}
private void TimerObj_Elapsed(object sender, System.Timers.ElapsedEventArgs e)
{
TimeValue = TimeValue.AddMilliseconds((double)TimeInterval);
}
public void Start()
{
TimerObj.Start();
}
public void Stop()
{
TimerObj.Stop();
}
}
}
Come to this point, I just wanted to print the value with Button.Content but seems like I cannot use it outside of the MainWindow class.
What should I do? I started thinking about creating a task inside the main class and wait for the timer event to print the value but I know nothing about threads and tasks.

It's unclear exactly what you mean, as at the moment you can't use it in the MainWindow class at all. Just expose the value via a public function, and you can fetch the instance's value anywhere you want.
namespace Cronometro
{
public partial class MainWindow : Window
{
public MainWindow()
{
InitializeComponent();
var x = new MyTimerClass(); // <<<
x.Start(); // <<<
var timeValue = x.GetTimeValue(); // <<<
}
}
public class MyTimerClass
{
private DateTime TimeValue;
private System.Timers.Timer TimerObj;
private const int TimeInterval = 1;
public MyTimerClass()
{
TimeValue new DateTime(0, 0, 0, 0, 0, 0, 0, DateTimeKind.Local);
TimerObj = new System.Timers.Timer(TimeInterval);
TimerObj.AutoReset = true;
TimerObj.Elapsed += TimerObj_Elapsed;
}
private void TimerObj_Elapsed(object sender, System.Timers.ElapsedEventArgs e)
{
TimeValue = TimeValue.AddMilliseconds((double)TimeInterval);
}
public DateTime GetTimeValue() // <<<
{ // <<<
return TimeValue; // <<<
} // <<<
public void Start()
{
TimerObj.Start();
}
public void Stop()
{
TimerObj.Stop();
}
}

First, you don't have to write your own Stopwatch class. DotNet has its own:
https://learn.microsoft.com/en-us/dotnet/api/system.diagnostics.stopwatch?view=netframework-4.8
Second, try to understand async/await pattern:
https://learn.microsoft.com/en-us/dotnet/csharp/programming-guide/concepts/async/
So, you can do something like this:
https://wouterdekort.com/2013/10/01/async-and-await-and-the-ui-thread/

One way you could populate the button text is you create an event in the MyTimerClass class, and attach a listener delegate to it from inside the MainWindow class.
Then, fire the event in TimerObj_Elapsed in MyTimerClass, so that the event handler in MainWindow will be called, and you will have a chance to populate the button.
However, there is something other than "practicing class" you have to deal with. Because you are using a thread pool timer, so the Elapsed event handler of the timer is invoked from a worker thread. In a GUI app, only the main / UI thread can interactive with controls. So chances are, you will get an exception when trying to set Button.Text. You will need to marshal the set action to the UI thread.
Frankly, if you are practicing writing classes in C#, I'd recommend you using a Console App to start with rather than a GUI app. It is probably not a good idea if people throwing out too many concepts on the table that you don't know at the same time.

Subscribing to an event of a class that holds the override method of the class you reference

I am working with background workers to update a progress bar in a WPF UI I am working on. This background worker is getting its progress updates from multiple events that I am subscribed to, because the progress bar goes through several loading stages, and the percentages for those come from several places. here is some example/pseudo code explaining what I mean
The DoWork method of my background worker and the methods I am using to currently get some progress updates
// These are working fine
private void BwOnDoWork(object sender, DoWorkEventArgs doWorkEventArgs)
{
orderProcessing.OnOrderProgress += OrderStatus;
orderProcessing.OnStandardOrderProgress += StandardOrderStatus;
orderProcessing.CreateOrders(orders);
}
private void OrderStatus(int currentCount, int totalItems, string Message)
{
if (totalItems > 0)
bw.ReportProgress(Convert.ToInt32(((double)currentCount / (double)totalItems) * 100),
Message);
}
private void StandardOrderStatus(int currentCount, int totalItems, string Message)
{
if (totalItems > 0)
bw.ReportProgress(Convert.ToInt32(((double)currentCount / (double)totalItems) * 100),
Message);
}
Some code from my order processing class
public abstract class OrderProcessing
{
public delegate void OrderProgress(int CurrentItems, int TotalItems, string Message);
public event MasterSalesOrder.StandardOrderProgress OnStandardOrderProgress;
public event OrderProgress OnOrderProgress;
public abstract List<MasterSalesOrder> CreateOrders(List<Order> orders);
}
Some code from the class that holds the override method for CreateOrders()
public abstract class OrderProcessingFile : OrderProcessing
{
public event OrderProgress OnOrderProgress;
public override List<MasterSalesOrder> CreateOrders(List<Order> orders)
{
//Does Some Stuff
foreach(var stuff in stuffs)
{
OnOrderProgress(currentCount, totalCount, "Message");
}
}
}
Since I am clearly not explaining this well, I need to get info from the OrderProcessingFiles OnOrderProgress event via the OrderProcessing class that I create in the DoWork method.I am unsure on how to subscribe to an event when my code never directly instantiates an instance of the OrderProcessingFile class and it is never directly referred to.
I have tried looking for answers but as my title will show I am having a hard time even wording this in a way to get useful results, and I am genuinely stuck on this one. Let me know if more detail is needed, I tried to strip down my code to only the relevant parts but I feel like I'm explaining this strangely.

I would recommend that you create a thread safe singleton progress manager. Then have each of the background workers contact it with updates. The progress manager will use a DispatcherTimer (which runs on the GUI thread) to update the GUI appropriately.
Raw example:
public static class StatusReportManager
{
// Standard singleton code to create the manager and access it.
// Start/create the dispatch time as well.
private static DispatcherTimer Timer { get; set; }
private static object _syncObject = new object();
public static void ReportStatus(...)
{
lock (_syncObject)
{
// Process any states and set instance properties for reading
// by the timer operation.
}
}
private void ShowStatus() // Used by the dispatch timer
{
lock (_syncObject)
{
// Do any updates to the GUI in here from current state.
}
}
}

I have realized what it is I was really trying to do and have thus found an answer. Using the method found in this MSDN article I have implemented the follow code:
This is my UI
private void BwOnDoWork(object sender, DoWorkEventArgs doWorkEventArgs)
{
orderProcessing.OnOrderProgress += OrderStatus;
orderProcessing.CreateOrders(FanGlobal.BrandItems, FanGlobal.BrandItemMasterCustomers);
}
private void OrderStatus(object obj, OrderProcessing.OrderProgressEventArgs e)
{
if (e.totalCount > 0)
bw.ReportProgress(Convert.ToInt32(((double)e.currentCount / (double)e.totalCount) * 100),e.message);
}
This in my OrderProcessing class
public event EventHandler<OrderProgressEventArgs> OnOrderProgress;
public class OrderProgressEventArgs : EventArgs
{
public int currentCount;
public int totalCount;
public string message;
public OrderProgressEventArgs(int c, int t, string m)
{
currentCount = c;
totalCount = t;
message = m;
}
}
protected virtual void OnOrderProgressChanged(OrderProgressEventArgs e)
{
EventHandler<OrderProgressEventArgs> handler = OnOrderProgress;
if (handler != null)
{
handler(this, e);
}
}
public abstract List<MasterSalesOrder> CreateOrders(List<BrandItem> BrandItems = null, List<BrandItemMasterCustomer> BrandItemMasterCustomers = null);
and then I can use it in my child class OrderProcessingFile like so
public override List<MasterSalesOrder> CreateOrders(List<BrandItem> BrandItems = null, List<BrandItemMasterCustomer> BrandItemMasterCustomers = null)
{
//Do some Stuff
OnOrderProgressChanged(new OrderProgressEventArgs(count, totalItems, "Extracting"));
}
and everything is working like a charm. Sorry for the utterly confusing question and the apparent huge gap of knowledge I have/had, but hopefully this will help someone else in the future.

How to unit test a timer class (adapter pattern)?

I'm currently abstracting the concept of timers so that my classes that need one can use mock timers in tests or different implementations in operative mode (e.g. threadpool timers, thread-affine timers, etc.). Therefore, I created this interface:
public interface ITimer : IDisposable
{
bool IsEnabled { get; }
bool IsAutoResetting { get; set; }
TimeSpan Interval { get; set; }
void Start();
void Stop();
event EventHandler IntervalElapsed;
}
Now I want to create a wrapper that adapts the System.Threading.Timer class and implements that interface. I want to do it using test-driven development. My class currently looks somewhat like this:
public sealed class ThreadPoolTimer : ITimer
{
private readonly Timer _timer;
public bool IsEnabled { get; private set; }
public bool IsAutoResetting { get; set; }
public TimeSpan Interval { get; set; }
public ThreadPoolTimer()
{
Interval = this.GetDefaultInterval();
_timer = new Timer(OnTimerCallback);
}
public void Dispose()
{
_timer.Dispose();
}
public void Start()
{
}
public void Stop()
{
}
private void OnTimerCallback(object state)
{
OnIntervalElapsed();
}
public event EventHandler IntervalElapsed;
private void OnIntervalElapsed()
{
var handler = IntervalElapsed;
if (handler != null)
handler(this, EventArgs.Empty);
}
}
My actual question is: how would you write unit tests that describe the (soft real-time) requirements for the behavior of Start, Stop and IntervalElapsed?
In my opinion, i should use e.g. an AutoResetEvent and check if the event is raised within a certain timespan (maybe +/- 3ms). But writing that code somewhat violates the DAMP (descriptive and meaningful phrases) principle, I think. Is there an easier way to do this?
Should I make the dependency to System.Threading.Timer external and then maybe use a shim for testing purposes? Unfortunately, the .NET timers do not have a common interface (which would make my work obsolete...)
What are your thoughts on that topic? Is there any documentation that I have not found yet and that I should read?
Sorry for having actually more than one question in this post, but this testing of soft real-time requirements is quite interesting, I think.

As no one answered this question yet, I'll tell you how I approached the problem: I used the spy pattern to actually implement the code that observes the behavior of the timer. The class looks like this:
public class ThreadPoolTimerSpy : IDisposable
{
private readonly ThreadPoolTimer _threadPoolTimer;
private int _intervalElapsedCallCount;
private readonly ManualResetEvent _resetEvent = new ManualResetEvent(false);
public int NumberOfIntervals { get; set; }
public DateTime StartTime { get; private set; }
public DateTime EndTime { get; private set; }
public ThreadPoolTimerSpy(ThreadPoolTimer threadPoolTimer)
{
if (threadPoolTimer == null) throw new ArgumentNullException("threadPoolTimer");
_threadPoolTimer = threadPoolTimer;
_threadPoolTimer.IntervalElapsed += OnIntervalElapsed;
NumberOfIntervals = 1;
}
public void Measure()
{
_intervalElapsedCallCount = 0;
_resetEvent.Reset();
StartTime = DateTime.Now;
_threadPoolTimer.Start();
_resetEvent.WaitOne();
}
private void OnIntervalElapsed(object sender, EventArgs arguments)
{
_intervalElapsedCallCount++;
if (_intervalElapsedCallCount < NumberOfIntervals)
return;
_threadPoolTimer.Stop();
EndTime = DateTime.Now;
_resetEvent.Set();
}
public void Dispose()
{
_threadPoolTimer.Dispose();
_resetEvent.Dispose();
}
}
This class takes a ThreadPoolTimer and registers to its IntervalElapsed event. One can specify how much intervals the spy should wait until it stops measuring. As I'm using a ManualResetEvent to block the thread that starts the timer in the Measure method, all calls to that method are synchronous, which results in DAMP code in the actual test class, in my opinion.
A test method that uses the spy would look like this:
[TestInitialize]
public void InitializeTestEnvironment()
{
_testTarget = new ThreadPoolTimerBuilder().WithAutoResetOption(true)
.WithInterval(100)
.Build() as ThreadPoolTimer;
Assert.IsNotNull(_testTarget);
_spy = new ThreadPoolTimerSpy(_testTarget);
}
[TestMethod]
public void IntervalElapsedMustBeRaisedExactlyTenTimesAfter1000Milliseconds()
{
CheckIntervalElapsed(10, TimeSpan.FromMilliseconds(1000), TimeSpan.FromMilliseconds(100));
}
private void CheckIntervalElapsed(int numberOfIntervals, TimeSpan expectedTime, TimeSpan toleranceInterval)
{
_spy.NumberOfIntervals = numberOfIntervals;
_spy.Measure();
var passedTime = _spy.EndTime - _spy.StartTime;
var timingDifference = Math.Abs(expectedTime.Milliseconds - passedTime.Milliseconds);
Assert.IsTrue(timingDifference <= toleranceInterval.Milliseconds, string.Format("Timing difference: {0}", timingDifference));
}
If you have any questions or recommendations, please feel free to leave a comment.
Besides: the tolerance interval I have to choose to make the tests pass are relatively high. I thought that maybe 3 to 5 milliseconds might suffice, but in the end for ten intervals I figured out that the actual measured time span is up to 72ms different than the expected time of 1000ms in this case. Well, never use a managed runtime for real time applications, I guess...

Refresh Progressbar UI using Thread

I have a FTP proccess that run without UI. and have a winform that use this ftp control. in that window I have a progressbar that show the ftp upload progress. The progress arrives to the window via interfase that is updated on the underliying presenter (I'm using MVP pattern).
My problem is when try to update the progress, it allways throw me this exception.
Through threads illegal operation: control 'prgProgresoSubido' is accessed from a thread other than that in which you created it.
That problem persists even if I use a BackGroundWorker in the Form.
// This is a delegated on presenter when a File finish to upload
void client_FileUploadCompletedHandler(object sender, FileUploadCompletedEventArgs e)
{
string log = string.Format("{0} Upload from {1} to {2} is completed. Length: {3}. ",
DateTime.Now, e.LocalFile.FullName, e.ServerPath, e.LocalFile.Length);
archivosSubidos += 1;
_Publicacion.ProgresoSubida = (int)((archivosSubidos / archivosXSubir) * 100);
//this.lstLog.Items.Add(log);
//this.lstLog.SelectedIndex = this.lstLog.Items.Count - 1;
}
// This is My interfase
public interface IPublicacion
{
...
int ProgresoSubida { set; }
}
/// And Here is the implementartion of the interfase on the form
public partial class PublicarForm : Form ,IPublicacion
{
//Credenciales para conectarse al servicio FTP
public FTPClientManager client = null;
public XmlDocument conf = new XmlDocument();
public string workingDir = null;
public webTalk wt = new webTalk();
private readonly PublicacionesWebBL _Publicador;
public PublicarForm()
{
InitializeComponent();
String[] laPath = { System.AppDomain.CurrentDomain.BaseDirectory};
String lcPath = System.IO.Path.Combine(laPath);
_Publicador = new PublicacionesWebBL(this, lcPath);
}
public int ProgresoSubida
{
set
{
// This is my prograss bar, here it throw the exception.
prgProgresoSubido.Value = value;
}
}
}
How can I do to avoid this problem ?

In general, all updates to the User Interface and Controls has to be done from the main thread (event dispatcher). If you attempt to modify the properties of a control from a different thread you will get an exception.
You must call Control.Invoke to invoke on the event dispatcher the method that updates your UI
Control.Invoke
Here, place a button and a label on a form, then try this
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void button1_Click(object sender, EventArgs e)
{
Thread t = new Thread(new ThreadStart(TestThread));
t.Start();
}
private void TestThread()
{
for (int i = 0; i < 10; i++)
{
UpdateCounter(i);
Thread.Sleep(1000);
}
}
private void UpdateCounter(int i)
{
if (label1.InvokeRequired)
{
label1.Invoke(new ThreadStart(delegate { UpdateCounter(i); }));
}
else
{
label1.Text = i.ToString();
}
}
}
Realize, that if you are firing an event from a thread, that the event will be on the same Thread. Therefore, if that thread is not the event dispatcher, you'll need to invoke.
Also, there may be mechanisms that BackgroundWorker gives you (As the commentator said) that simplify this for you, but I've never used it before so I'll leave that up to you to investigate.

As Alan has just pointed out, you must do all operations with UI controls in UI thread.
Just modify your property like this:
public int ProgresoSubida
{
set
{
MethodInvoker invoker = delegate
{
prgProgresoSubido.Value = value;
}
if (this.InvokeRequired)
{
Invoke(invoker);
}
else
{
invoker();
}
}
}

Alarm clock application in .Net

I'm not really writing an alarm clock application, but it will help to illustrate my question.
Let's say that I have a method in my application, and I want this method to be called every hour on the hour (e.g. at 7:00 PM, 8:00 PM, 9:00 PM etc.). I could create a Timer and set its Interval to 3600000, but eventually this would drift out of sync with the system clock. Or I could use a while() loop with Thread.Sleep(n) to periodically check the system time and call the method when the desired time is reached, but I don't like this either (Thread.Sleep(n) is a big code smell for me).
What I'm looking for is some method in .Net that lets me pass in a future DateTime object and a method delegate or event handler, but I haven't been able to find any such thing. I suspect there's a method in the Win32 API that does this, but I haven't been able to find that, either.

Or, you could create a timer with an interval of 1 second and check the current time every second until the event time is reached, if so, you raise your event.
You can make a simple wrapper for that :
public class AlarmClock
{
public AlarmClock(DateTime alarmTime)
{
this.alarmTime = alarmTime;
timer = new Timer();
timer.Elapsed += timer_Elapsed;
timer.Interval = 1000;
timer.Start();
enabled = true;
}
void timer_Elapsed(object sender, ElapsedEventArgs e)
{
if(enabled && DateTime.Now > alarmTime)
{
enabled = false;
OnAlarm();
timer.Stop();
}
}
protected virtual void OnAlarm()
{
if(alarmEvent != null)
alarmEvent(this, EventArgs.Empty);
}
public event EventHandler Alarm
{
add { alarmEvent += value; }
remove { alarmEvent -= value; }
}
private EventHandler alarmEvent;
private Timer timer;
private DateTime alarmTime;
private bool enabled;
}
Usage:
AlarmClock clock = new AlarmClock(someFutureTime);
clock.Alarm += (sender, e) => MessageBox.Show("Wake up!");
Please note the code above is very sketchy and not thread safe.

Interesting, I've actually come across a very similar issue and went looking for a method in the .Net framework that would handle this scenario. In the end, we ended up implementing our own solution that was a variation on a while loop w/ Thread.Sleep(n) where n gets smaller the closer you get to the desired target time (logarithmically actually, but with some reasonable thresholds so you're not maxing the cpu when you get close to the target time.) Here's a really simple implementation that just sleeps half the time between now and the target time.
class Program
{
static void Main(string[] args)
{
SleepToTarget Temp = new SleepToTarget(DateTime.Now.AddSeconds(30),Done);
Temp.Start();
Console.ReadLine();
}
static void Done()
{
Console.WriteLine("Done");
}
}
class SleepToTarget
{
private DateTime TargetTime;
private Action MyAction;
private const int MinSleepMilliseconds = 250;
public SleepToTarget(DateTime TargetTime,Action MyAction)
{
this.TargetTime = TargetTime;
this.MyAction = MyAction;
}
public void Start()
{
new Thread(new ThreadStart(ProcessTimer)).Start();
}
private void ProcessTimer()
{
DateTime Now = DateTime.Now;
while (Now < TargetTime)
{
int SleepMilliseconds = (int) Math.Round((TargetTime - Now).TotalMilliseconds / 2);
Console.WriteLine(SleepMilliseconds);
Thread.Sleep(SleepMilliseconds > MinSleepMilliseconds ? SleepMilliseconds : MinSleepMilliseconds);
Now = DateTime.Now;
}
MyAction();
}
}

You could simply reset the timer duration each time it fires, like this:
// using System.Timers;
private void myMethod()
{
var timer = new Timer {
AutoReset = false, Interval = getMillisecondsToNextAlarm() };
timer.Elapsed += (src, args) =>
{
// Do timer handling here.
timer.Interval = getMillisecondsToNextAlarm();
timer.Start();
};
timer.Start();
}
private double getMillisecondsToNextAlarm()
{
// This is an example of making the alarm go off at every "o'clock"
var now = DateTime.Now;
var inOneHour = now.AddHours(1.0);
var roundedNextHour = new DateTime(
inOneHour.Year, inOneHour.Month, inOneHour.Day, inOneHour.Hour, 0, 0);
return (roundedNextHour - now).TotalMilliseconds;
}

You could create an Alarm class which has a dedicated thread which goes to sleep until the specified time, but this will use the Thread.Sleep method. Something like:
/// <summary>
/// Alarm Class
/// </summary>
public class Alarm
{
private TimeSpan wakeupTime;
public Alarm(TimeSpan WakeUpTime)
{
this.wakeupTime = WakeUpTime;
System.Threading.Thread t = new System.Threading.Thread(TimerThread) { IsBackground = true, Name = "Alarm" };
t.Start();
}
/// <summary>
/// Alarm Event
/// </summary>
public event EventHandler AlarmEvent = delegate { };
private void TimerThread()
{
DateTime nextWakeUp = DateTime.Today + wakeupTime;
if (nextWakeUp < DateTime.Now) nextWakeUp = nextWakeUp.AddDays(1.0);
while (true)
{
TimeSpan ts = nextWakeUp.Subtract(DateTime.Now);
System.Threading.Thread.Sleep((int)ts.TotalMilliseconds);
try { AlarmEvent(this, EventArgs.Empty); }
catch { }
nextWakeUp = nextWakeUp.AddDays(1.0);
}
}
}

I know it's a bit of an old question, but I came across this when I was looking for an answer to something else. I thought I'd throw my two cents in here, since I recently had this particular issue.
Another thing you can do is schedule the method like so:
/// Schedule the given action for the given time.
public async void ScheduleAction ( Action action , DateTime ExecutionTime )
{
try
{
await Task.Delay ( ( int ) ExecutionTime.Subtract ( DateTime.Now ).TotalMilliseconds );
action ( );
}
catch ( Exception )
{
// Something went wrong
}
}
Bearing in mind it can only wait up to the maximum value of int 32 (somewhere around a month), it should work for your purposes. Usage:
void MethodToRun ( )
{
Console.WriteLine ("Hello, World!");
}
void CallingMethod ( )
{
var NextRunTime = DateTime.Now.AddHours(1);
ScheduleAction ( MethodToRun, NextRunTime );
}
And you should have a console message in an hour.

What about System.Timers.Timer class ? See http://msdn.microsoft.com/en-us/library/system.timers.timer.aspx

I have used this before with great success:
Vb.net:
Imports System.Threading
Public Class AlarmClock
Public startTime As Integer = TimeOfDay.Hour
Public interval As Integer = 1
Public Event SoundAlarm()
Public Sub CheckTime()
While TimeOfDay.Hour < startTime + interval
Application.DoEvents()
End While
RaiseEvent SoundAlarm()
End Sub
Public Sub StartClock()
Dim clockthread As Thread = New Thread(AddressOf CheckTime)
clockthread.Start()
End Sub
End Class
C#:
using System.Threading;
public class AlarmClock
{
public int startTime = TimeOfDay.Hour;
public int interval = 1;
public event SoundAlarmEventHandler SoundAlarm;
public delegate void SoundAlarmEventHandler();
public void CheckTime()
{
while (TimeOfDay.Hour < startTime + interval) {
Application.DoEvents();
}
if (SoundAlarm != null) {
SoundAlarm();
}
}
public void StartClock()
{
Thread clockthread = new Thread(CheckTime);
clockthread.Start();
}
}
I don't know if the c# works, but the vb works just fine.
Usage in VB:
Dim clock As New AlarmClock
clock.interval = 1 'Interval is in hours, could easily convert to anything else
clock.StartClock()
Then, just add an event handler for the SoundAlarm event.