CODEWITHSUNDEEP
c#stringformstimerlabel
RebeccaWhiteflower22
RebeccaWhiteflower22

Reputation: 33

How to update label text from a timer event handler in a different class?

I have a form with a label in it called labelTime. In another class called TimeCalculate I have a Timer with Timer_tick event handler. In this class I also have a function GetTime() that returns the time in string format. I want this string to appear in labelTime for every Timer_tick. Is there a way to achieve that?

public void MyTimer(Label o_TimeLabel) 
{
  Timer Clock = new Timer(); 
  Clock.Tag = o_TimeLabel.Text; 
  Clock.Interval = 1000; Clock.Start(); 
  Clock.Tick += new EventHandler(Timer_Tick); 
} 

private void Timer_Tick(object sender, EventArgs eArgs) 
{ 
  if (sender == Clock) 
  { 
    //LabelTime.Text = GetTime(); <-- I want this to work! 
  } 
}

Upvotes: 3

Views: 19393

Answers (3)

user1548266
user1548266

Reputation:

The Timer and Timer_Tick event do not need to be in the same class as your Label, you can create a simple custom event to publish/subscribe to your Timer_Tick event.

Your TimeCalculate class:

namespace StackOverflow.WinForms
{
    using System;
    using System.Windows.Forms;

    public class TimeCalculate
    {
        private Timer timer;

        private string theTime;
        public string TheTime
        {
            get
            {
                return theTime;
            }
            set
            {
                theTime = value;
                OnTheTimeChanged(this.theTime);
            }
        }

        public TimeCalculate()
        {
            timer = new Timer();
            timer.Tick += new EventHandler(Timer_Tick);
            timer.Interval = 1000;
            timer.Start();
        }

        private void Timer_Tick(object sender, EventArgs e)
        {
            TheTime = DateTime.UtcNow.ToString("dd/mm/yyyy HH:mm:ss");
        }

        public delegate void TimerTickHandler(string newTime);
        public event TimerTickHandler TheTimeChanged;

        protected void OnTheTimeChanged(string newTime)
        {
            if (TheTimeChanged != null)
            {
                TheTimeChanged(newTime);
            }
        }
    }
}

The extremely simplified example above shows how you can use a delegate and event to publish a notification when the Timer_Tick Timer object event fires.

Any objects that require notification when the Timer_Tick event fires (I.E. your time is updated) need only to subscribe to your custom event publisher:

namespace StackOverflow.WinForms
{
    using System.Windows.Forms;

    public partial class Form1 : Form
    {
        private TimeCalculate timeCalculate;

        public Form1()
        {
            InitializeComponent();
            this.timeCalculate = new TimeCalculate();
            this.timeCalculate.TheTimeChanged += new TimeCalculate.TimerTickHandler(TimeHasChanged);

        }

        protected void TimeHasChanged(string newTime)
        {
            this.txtTheTime.Text = newTime;
        }
    }
}

We create an instance of the TimeCalcualte class before subscribing to the TimerTickHandler event specifying a method (TimeHasChanged) to handle the notification. Note that txtTheTime is the name I gave a TextBox on my form.

Upvotes: 1

Colin Steel
Colin Steel

Reputation: 1055

You need the Timer and its event in the same form as the Label

EDIT

Since you have done it that way, you need to;

Declare the Timer object as an instance variable, outside of the constructor, initialise it in the constructor.
Don't have to worry about testing 'sender == Clock'.
And have a Label instance object in this class as well, setting it to the Label you pass as a parameter in the constructor.

    Timer Clock;
    Label LabelTime;
    public void MyTimer(Label o_TimeLabel) 
    {
      LabelTime = o_TimeLabel;
      Clock = new Timer(); 
      Clock.Tag = o_TimeLabel.Text; 
      Clock.Interval = 1000;
      Clock.Start(); 
      Clock.Tick += new EventHandler(Timer_Tick); 
    } 

    private void Timer_Tick(object sender, EventArgs eArgs) 
    { 
      LabelTime.Text = GetTime(); // For your custom time
    }

Upvotes: 1

MethodMan
MethodMan

Reputation: 18843

Rebecca in your Time_Tick Event you could do the following 

private void Timer_Tick(object sender, EventArgs e)
{      
  lblTime.Text = DateTime.Now.ToString("hh:mm:ss");
}

Upvotes: 1

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