C# how to loop while mouse button is held down

Question

Can you point me in the right direction? I'm trying to get a loop to trigger while the form button is depressed.

//pseudocode
While (button1 is pressed)
value1 += 1

And then of course stop looping when the button is released

Answer 1

To avoid using threads you can add a Timer component on your form/control and simply enable it on mouse down and disable it on mouse up. Then put the code you would normally put inside the loop in the Timer_Tick event. If you want to use System.Timers.Timer you can use the Timer.Elapsed event instead.

Example (using System.Timers.Timer):

using Timer = System.Timers.Timer;
using System.Timers;
using System.Windows.Forms;//WinForms example
private static Timer loopTimer;
private Button formButton;
public YourForm()
{ 
    //loop timer
    loopTimer = new Timer();
    loopTimer.Interval = 500;/interval in milliseconds
    loopTimer.Enabled = false;
    loopTimer.Elapsed += loopTimerEvent;
    loopTimer.AutoReset = true;
    //form button
    formButton.MouseDown += mouseDownEvent;
    formButton.MouseUp += mouseUpEvent;
}
private static void loopTimerEvent(Object source, ElapsedEventArgs e)
{
    //this does whatever you want to happen while clicking on the button
}
private static void mouseDownEvent(object sender, MouseEventArgs e)
{
    loopTimer.Enabled = true;
}
private static void mouseUpEvent(object sender, MouseEventArgs e)
{
    loopTimer.Enabled = false;
}

Answer 2

You could use a thread to do the counting, and stop the thread when the mouse is released. The following has worked nicely for me:

var b = new Button { Text = "Press me" };

int counter = 0;
Thread countThread = null;
bool stop = false;

b.MouseDown += (s, e) =>
{
    stop = false;
    counter = 0;
    countThread = new Thread(() =>
    {
        while (!stop)
        {
            counter++;
            Thread.Sleep(100);
        }
    });
    countThread.Start();
};

b.MouseUp += (s, e) =>
{
    stop = true;
    countThread.Join();
    MessageBox.Show(counter.ToString());
};

Of course, if you want the event handlers to be methods rather than lambdas, you will have to turn all the variables into fields.

Answer 3

    private void button1_MouseDown(object sender, MouseEventArgs e)
    {
        timer1.Enabled = true;
        timer1.Start();

    }

    private void button1_MouseUp(object sender, MouseEventArgs e)
    {
        timer1.Stop();
    }



    private void timer1_Tick(object sender, EventArgs e)
    {
        numericUpDown1.Value++;

    }

Answer 4

I was inspired by what I read here and decided to write my own button class called a RepeatingButton. On first click it waits for 500ms, then repeats ever 300ms until 2s, then repeats every 100ms (i.e. it uses acceleration).

Here is the code;

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows.Forms;

/// <summary>
/// A repeating button class.
/// When the mouse is held down on the button it will first wait for FirstDelay milliseconds,
/// then press the button every LoSpeedWait milliseconds until LoHiChangeTime milliseconds,
/// then press the button every HiSpeedWait milliseconds
/// </summary>
public class RepeatingButton : Button
{
    /// <summary>
    /// Initializes a new instance of the <see cref="RepeatingButton"/> class.
    /// </summary>
    public RepeatingButton()
    {
        internalTimer = new Timer();
        internalTimer.Interval = FirstDelay;
        internalTimer.Tick += new EventHandler(internalTimer_Tick);
        this.MouseDown += new MouseEventHandler(RepeatingButton_MouseDown);
        this.MouseUp += new MouseEventHandler(RepeatingButton_MouseUp);
    }

    /// <summary>
    /// The delay before first repeat in milliseconds
    /// </summary>
    public int FirstDelay = 500;

    /// <summary>
    /// The delay in milliseconds between repeats before LoHiChangeTime
    /// </summary>
    public int LoSpeedWait = 300;

    /// <summary>
    /// The delay in milliseconds between repeats after LoHiChangeTime
    /// </summary>
    public int HiSpeedWait = 100;

    /// <summary>
    /// The changeover time between slow repeats and fast repeats in milliseconds
    /// </summary>
    public int LoHiChangeTime = 2000;

    private void RepeatingButton_MouseDown(object sender, MouseEventArgs e)
    {
        internalTimer.Tag = DateTime.Now;
        internalTimer.Start();
    }

    private void RepeatingButton_MouseUp(object sender, MouseEventArgs e)
    {
        internalTimer.Stop();
        internalTimer.Interval = FirstDelay;
    }

    private void internalTimer_Tick(object sender, EventArgs e)
    {
        this.OnClick(e);
        TimeSpan elapsed = DateTime.Now - ((DateTime)internalTimer.Tag);
        if (elapsed.TotalMilliseconds < LoHiChangeTime)
        {
            internalTimer.Interval = LoSpeedWait;
        }
        else
        {
            internalTimer.Interval = HiSpeedWait;
        }
    }

    private Timer internalTimer;
}

Anywhere you have a button, you can just replace it with a repeating button and it will just have all the new functionality built in.

Enjoy!

Sterren