Sleep windows forms c

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Introduction

I am just starting out with Windows Forms and .NET programming in general and I am learning my trade all over again. My background is as a C++/Win32 GUI and DCOM programmer with a strong MFC and Win32 Functions emphasis.

I relented and now do Windows Forms and ASP.NET programming, and I have discovered how effortless .NET development is when using Microsoft’s excellent tool, Visual Studio 2005 and up. Truth is, I am never going back. My personal preference is to use .NET and the visual tools provided by Microsoft to do my development from now on. Unmanaged C/C++ and MFC is not worth the extra time I see myself spending using those languages.

About This Series

However, now that I am coming to my trade all over again in some sense, I am having to learn where my old familiar Windows API functions are in the .NET world. I am sure I am not alone as there are other .NET beginners out there.

Audience

This series, «The ____ in .NET,» is something I am going to publish on The Code Project from time to time in an effort to provide beginners and newbies with quick, piecemeal tutorials on your favorite functionality. This is not a re-hash of the VS «How Do I?…» docs, since they provide more comprehensive help. These are «tutorials to go,» that focus very narrowly on one or other individual functionality items.

Language Used

Because my employer is having me do things in C#, the sample code provided with the articles in this series will all be in C#. I take it Visual Basic, etc., developers are smart, intelligent, capable people who can translate between languages as necessary.

Background

In Windows, APIs are provided to suspend threads and processes for a programmer-specified time period, usually given in milleseconds. In the old, Visual Studio-6.0-and-below-esque, unmanaged C++ and MFC, one could suspend the current thread (i.e., make your window stop responding) as such:

void CMyDialog::OnClickedSleep()
{
    
    ::Sleep(500);
    
}

Listing 1. A MFC message handler calling the Win32 function, ::Sleep()

Question is, where does this Sleep() function sit in the new .NET Framework?

To suspend an application, you must call the System.Threading.Thread.Sleep() static method. It takes one parameter, an int specifying the delay, in milliseconds.

This concludes this article. If you are a beginner and want help implementing this in your application, I invite you to follow the tutorial below to build the sample application distributed with this article.

Tutorial: Sleep.NET

This article presents a small sample Windows Forms application, Sleep.NET, demonstrating the use of the System.Threading.Thread.Sleep() static method.

Step 1: Open your copy of Visual Studio.NET

Step 2: Click the File menu, point to New, and then click Project

• Visual Studio opens the New Project window.

Step 3: In the Project Types box on the left, click Visual C#, and then click Windows

• If it is your personal preference, you may also choose your .NET language of choice to implement this tutorial in. It must be Windows Forms-compatible.

Step 4: In the Templates box on the right, under Visual Studio installed templates, click Windows Application

Step 5: In the Name box, type Sleep.NET

• You may use whichever name you choose if you’re following along; here, we shall use Sleep.NET.

Step 6: Using the Visual Studio Forms Designer — which I am going to leave the use of for you to learn — create a main form to match Figure 1 above.

• In my form, the Sleep for: text box was given the Name property txtSleep
• I assigned the value btnSleep for the Sleep button’s Name property
• I assigned the value btnQuitfor the Quit button’s Name property
• I set the form’s AcceptButton property to btnSleep and the form’s CancelButton property I set to have the value btnQuit

Step 7: Once your form has been created, press CTRL+F5 to build and run the project, so as to test. In order to kill the app, you will have to press the ALT+F4 keys on your keyboard.

Step 8: Purely for aesthetics, we’re going to program the form window to center itself on the screen before it’s shown. Double-click anywhere in a blank area of the form.

• The code window opens, with the insertion point on the Form1_Load event handler
• For help on this event handler, lookup Form.Load (Windows Forms) in the docs

Step 9: Implement the Form1_Load event handler as follows:

private void Form1_Load(object sender, EventArgs e)
{
    CenterToScreen(); Show();
    titleOld = this.Text;        
}

• This listing saves the window’s default title — since we update the title when we’re sleeping to indicate so to the user, shown below.

Step 10: Add a field to the Form1 class to store the window’s default title. Open the Form1.cs file and add the code shown below:

namespace Sleep.NET
{
    public partial class Form1 : Form
    {
        String titleOld;

        ...
    }
}

Step 11: Double-click the Quit button in the Designer, which brings you to code for the btnQuit_Click event handler. Implement the handler as shown below:

private void btnQuit_Click(object sender, EventArgs e)
{
    Hide(); Application.Exit();
}

Step 12: Double-click the Sleep button in the Designer, and add the following code:

private void btnSleep_Click(object sender, EventArgs e)
{
    
    

    
    
    EnableUI(false);

    
    Int32 SleepTime = 0;
    if (Int32.TryParse(txtSleep.Text, out SleepTime)) {
    System.Threading.Thread.Sleep(SleepTime);
    }

    
    
    EnableUI(true;)
}

Step 13: Add the EnableUI() method to the Form1 class, implemented as shown below.

• This method enables/disables the text box specifying the time to sleep for, enables/disables the Sleep button, and updates the form’s title to reflect its status.

private void EnableUI()
{
     txtSleep.Enabled = Enabled;
     this.Text = Enabled ? titleOld : "Sleep.NET - Sleeping";
     btnSleep.Enabled = Enabled;
     Refresh();
}

Step 14: Press CTRL+S on your keyboard to save your changes, and then CTRL+F5 in order to build and test the sample code.

• To test the sample code, enter a number of milliseconds (1 second = 1000 milliseconds) in the Sleep for: box, and then click Sleep. The title bar changes to say Sleeping, and the text box is grayed out for the duration of the sleep
• Experiment and try some other lengths of time and see the resulting behavior.
• When finished, close the sample application by clicking Quit or pressing ESC.

Points of Interest

In this section, we shall review interesting facts and .NET features learned while implementing the sample. Among these are:

• Message-pumping — in order to update the user-interface (UI) — with Control.Refresh()
• You can also refresh the form by calling its Refresh() method
• Using Refresh() is more thread-safe than, e.g., Application.DoEvents()
• Converting a String value to a 32-bit int value (to pass to the Sleep function) with Int32.TryParse()

I want to take a moment and acknowledge message board posters dubbele onzin and norm .net below for their comments about avoiding the use of Application.DoEvents() in favor of Refresh().

Refresh()

Notice the setting of properties of controls to, say, enable or disable them, or change the text. Note that when using Sleep(), the application’s Windows messages must be pumped (i.e., collected and distributed to all message handlers) or else the controls will not visibly change their state.

In the days of yore, or for those unlucky enough to still be maintaining legacy Win32 code, the way to pump messages is to run a message loop:

void MessageLoop()
{
    MSG msg;
    while(GetMessage(&Msg, NULL, 0, 0) > 0)
    {
        TranslateMessage(&Msg);
        DispatchMessage(&Msg);
    }
}

Listing 2. A legacy Win32 message pump

or some variant thereof, as appropriate to one’s application. With .NET, things are simpler, and in particular only one line of code accomplishes the same. Note that the function shown below can be called either for the whole form, or the control whose UI you want to refresh. This is shown in ‘Listing 3’ below:

Refresh();

Listing 3. A message pump run in .NET (C#)

Whenever you change a UI-visible property of a control, such as Enabled, you want to make sure and force the UI to update with a call to Control.Refresh() before you implement other functionality.

Int32.TryParse()

The int type — as well as the other types — appears to implement the TryParse() method, which takes as parameters a string and an out parameter which is the type into which to convert the string. The useful aspect of this method is that it returns false if there is garbage in the string and you can simply avoid processing the result if this occurs, as is shown in ‘Listing 1’.

Int32.TryParse(string s, out Int32 result)

Notice how an out parameter is used. You first declare an instance of the variable to which the parsed value should be assigned. Next, supply the variable to the out parameter, with the out keyword in front of the variable name. Finally, test the method’s return value for true before using the result.

Where To Go for Help

Feel free to email me with specific questions about this article, and I will be happy to explain. I also want to invite you to make use of the Forums at the bottom of this article. I wish you well.

History

In this section, I will keep a running history of the changes and updates I’ve made to this article.

• 16 Oct 2007 9:08 AM Pacific
  Article updated to reflect the use of Refresh() in lieu of Application.DoEvents() to update the UI, and the use of Int32.TryParse() in lieu of Convert.ToInt32() as per reader feedback and tips (see below)
• 11 Oct 2007 12:46 PM Pacific
  Article written

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Last Updated :
01 Feb, 2019

In C#, a Sleep() method temporarily suspends the current execution of the thread for specified milliseconds, so that other threads can get the chance to start the execution, or may get the CPU for execution. There are two methods in the overload list of Thread.Sleep Method as follows:

• Sleep(Int32)
• Sleep(TimeSpan)

Sleep(Int32)

This method suspends the current thread for the descriptor number of milliseconds. This method will throw an ArgumentOutOfRangeException if the time-out value is negative and is not equal to infinite.

Syntax:

public static void Sleep (int millisecondsTimeout);

Here, millisecondsTimeout is a number of milliseconds for which the thread is suspended. If the value of the millisecondsTimeout argument is zero, then the thread renounces the remainder of its time slice to any thread of equal priority that is ready to run. If there are no other threads of equal priority that are ready to run, then execution of the current thread is not suspended.

Example:

CSharp

// C# program to illustrate the
// concept of Sleep(Int32) method
using System;
using System.Threading;

class ExampleofThread {

    // Non-Static method
    public void thread1()
    {
        for (int x = 0; x < 2; x++) {

            Console.WriteLine("Thread1 is working");

            // Sleep for 4 seconds
            // Using Sleep() method
            Thread.Sleep(4000);
        }
    }

    // Non-Static method
    public void thread2()
    {
        for (int x = 0; x < 2; x++) {

            Console.WriteLine("Thread2 is working");
        }
    }
}

// Driver Class
public class ThreadExample {

    // Main method
    public static void Main()
    {

        // Creating instance for mythread() method
        ExampleofThread obj = new ExampleofThread();

        // Creating and initializing threads
        Thread thr1 = new Thread(new ThreadStart(obj.thread1));
        Thread thr2 = new Thread(new ThreadStart(obj.thread2));

        thr1.Start();
        thr2.Start();
    }
}

Output:

Thread1 is working
Thread2 is working
Thread2 is working
Thread1 is working

Explanation: By using Thread.Sleep(4000); in the thread1 method, we make the thr1 thread sleep for 4 seconds, so in between 4 seconds the thr2 thread gets the chance to execute after 4 seconds the thr1 thread resume its working.

Sleep(TimeSpan)

This method suspends the current thread for the described amount of time. This method will throw an ArgumentOutOfRangeException if the value of timeout is negative and is not equal to the infinite in milliseconds, or is greater than MaxValue milliseconds.

Syntax :

public static void Sleep (TimeSpan timeout);

Here, the timeout is the amount of time for which the thread is suspended. If the value of the millisecondsTimeout argument is Zero, then the thread renounces the remainder of its time slice to any thread of equal priority that is ready to run. If there are no other threads of equal priority that are ready to run, then execution of the current thread is not suspended.

Example:

CSharp

// C# program to illustrate the
// concept of Sleep(TimeSpan)
using System;
using System.Threading;

class GFG {

    // Main method
    static void Main()
    {

        // Set the timeout value, i.e. 3 seconds
        TimeSpan timeout = new TimeSpan(0, 0, 3);

        for (int k = 0; k < 3; k++) {

            Console.WriteLine("Thread is" + 
                 " sleeping for 3 seconds.");

            // Using Sleep(TimeSpan) method
            Thread.Sleep(timeout);
        }

        Console.WriteLine("Main thread exits");
    }
}

Output:

Thread is sleeping for 3 seconds.
Thread is sleeping for 3 seconds.
Thread is sleeping for 3 seconds.
Main thread exits

Reference:

• https://docs.microsoft.com/en-us/dotnet/api/system.threading.thread.sleep?view=netframework-4.7.2

An example. Sleep is found on the Thread class. It is a static method that receives one parameter. You must either include System.Threading or call System.Threading.Thread.Sleep.

Tip: You do not need to create a new Thread to use the Sleep method as it is static.

Static

Here: We call Sleep() 3 times. The surrounding code takes the system’s time and uses Stopwatch to time the Thread.Sleep calls.

Stopwatch

C# program that sleeps

using System;
using System.Diagnostics;
using System.Threading;

class Program
{
static void Main()
{
//
// Demonstrates 3 different ways of calling Sleep.
//
var stopwatch = Stopwatch.StartNew();

Thread.Sleep

(0);
stopwatch.Stop();
Console.WriteLine(stopwatch.ElapsedMilliseconds);
Console.WriteLine(DateTime.Now.ToLongTimeString());

stopwatch = Stopwatch.StartNew();

Thread.Sleep

(5000);
stopwatch.Stop();
Console.WriteLine(stopwatch.ElapsedMilliseconds);
Console.WriteLine(DateTime.Now.ToLongTimeString());

stopwatch = Stopwatch.StartNew();

System.Threading.Thread.Sleep

(1000);
stopwatch.Stop();
Console.WriteLine(stopwatch.ElapsedMilliseconds);

//
// Bonus: shows SpinWait method.
//
stopwatch = Stopwatch.StartNew();

Thread.SpinWait

(100000 * 10000);
stopwatch.Stop();
Console.WriteLine(stopwatch.ElapsedMilliseconds);
}
}

Output

0 ElapsedMilliseconds after Sleep(0)
8:14:43 AM Time after Sleep(0)
4999 ElapsedMilliseconds after Sleep(5000)
8:14:48 AM Time after Sleep(5000)
999 ElapsedMilliseconds after Sleep(1000)
3144 ElapsedMilliseconds after SpinWait(Int32)