c# - Timer event to increase the value of a variable

Question

I'm working on a very basic program where I want a ball to follow a parabolic curve. My idea is to set a timer to tick with a certain interval and set the time as an variable which I use in my equation which will also be my x-value.

I've created an event timer_Tick. How can I increase the value of X each time the timer ticks?

Answer 1

You need to create class field (e.g. elapsedTime) to store value between event handler calls:

private int elapsedTime; // initialized with zero
private Timer timer = new System.Windows.Forms.Timer();

public static int Main() 
{
    timer.Interval = 1000; // interval is 1 second
    timer.Tick += timer_Tick;
    timer.Start();
}

private void timer_Tick(Object source, EventArgs e) {
    elapsedTime++; // increase elapsed time 
    DrawBall();
}

Answer 2

This isn't a direct answer to your question - but you might find it helpful.

It's a completely different way to go that uses Reactive Extensions (create a console app and add Nuget package "Rx-Testing") and also demonstrates how you can virtualize time which can be helpful for testing purposes. You can control time as you please!

using System;
using System.Reactive.Concurrency;
using System.Reactive.Linq;

namespace BallFlight
{
    class Program
    {
        static void Main()
        {
            var scheduler = new HistoricalScheduler();
            // use this line instead if you need real time
            // var scheduler = Scheduler.Default;

            var interval = TimeSpan.FromSeconds(0.75);

            var subscription =
                Observable.Interval(interval, scheduler)
                          .TimeInterval(scheduler)
                          .Scan(TimeSpan.Zero, (acc, cur) => acc + cur.Interval)
                          .Subscribe(DrawBall);

            // comment out the next line of code if you are using real time
            // - you can't manipulate real time!
            scheduler.AdvanceBy(TimeSpan.FromSeconds(5));

            Console.WriteLine("Press any key...");
            Console.ReadKey(true);

            subscription.Dispose();
        }

        private static void DrawBall(TimeSpan t)
        {
            Console.WriteLine("Drawing ball at T=" + t.TotalSeconds);
        }
    }
}

Which gives the output:

Drawing ball at T=0.75
Drawing ball at T=1.5
Drawing ball at T=2.25
Drawing ball at T=3
Drawing ball at T=3.75
Drawing ball at T=4.5
Press any key...

Answer 3

private int myVar= 0;//private field which will be incremented

void timer_Tick(object sender, EventArgs e)//event on timer.Tick
{
            myVar += 1;//1 or anything you want to increment on each tick.
}

Answer 4

First the variable needs to be declared outside of any method, which is 'class scope'

In the tick event method, you can then just x = x + value, or x += value. Note that the tick event doesn't tell you how many ticks! So you're likely to need a second variable to keep track of this too.