How to make an exe file in C# that locks the screen and starts screensaver immediately?

Question

1.00/5 (1 vote)

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I want to assign it to one of my additional keyboard keys, I know how to assign an exe to one of my additional keyboard keys.

What I have tried:

With the code below it starts the screensaver and when I move the mouse the screensaver stops but the screen is shown as my work in the desktop for 1 second then the screen locks, moving

LockWorkStation();

up 1 or 2 lines didn't help much as the screen locks but no screensaver runs.

using System;
using System.Diagnostics;
using System.IO;
using System.Runtime.InteropServices;
using Microsoft.Win32;


namespace LockAndStartScreenSaver
{
    static class Program
    {
        /// <summary>
        /// The main entry point for the application.
        /// </summary>
        [STAThread]
        static void Main()
        {
            if (screenSaverKey != null)
            {
                string screenSaverFilePath = screenSaverKey.GetValue("SCRNSAVE.EXE", string.Empty).ToString();
                if (!string.IsNullOrEmpty(screenSaverFilePath) && File.Exists(screenSaverFilePath))
                {
                    Process screenSaverProcess = Process.Start(new ProcessStartInfo(screenSaverFilePath, "/s"));  // "/s" for full-screen mode
                    screenSaverProcess.WaitForExit();  // Wait for the screensaver to be dismissed by the user
                    LockWorkStation();
                }
            }
        }


        [DllImport("user32")]
        static public extern void LockWorkStation();


        static RegistryKey screenSaverKey = Registry.CurrentUser.OpenSubKey(@"Control Panel\Desktop");
    }
}

Posted 6-Apr-23 0:50am

John Smith 27

Updated 6-Apr-23 5:33am

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Comments

0x01AA 6-Apr-23 6:55am

Maybe this helps with some ideas: Programmatically Turning on the Screen Saver[^]

John Smith 27 6-Apr-23 7:03am

It didn't help, sorry.

0x01AA 6-Apr-23 7:45am

Did you try it? If yes what is the problem?

John Smith 27 6-Apr-23 7:50am

Actually it works like magic I'm sorry I didn't understand it first, submit as an answer plz.

John Smith 27 6-Apr-23 7:54am

But the application keeps running and doesn't exit after login, how to fix that?

0x01AA 6-Apr-23 7:56am

I would say this is a subject for a new question ;)
[Edit]
I'm not clear about what the problem is. But it sounds like you need to use PostMessage() instead of SendMessage()

John Smith 27 6-Apr-23 8:12am

And what would be its parameters that to be sent then?

[DllImport("user32.dll")]
static extern bool PostMessage(HandleRef hWnd, uint Msg, IntPtr wParam, IntPtr lParam);

0x01AA 6-Apr-23 8:16am

Same as for SendMessage:

PostMessage(new IntPtr((int)SpecialHandles.HWND_BROADCAST),
        WM_SYSCOMMAND,
        SC_SCREENSAVE,
        0);

I'm something confused. Above you wrote it works and I should submit it as an answer.
Now it looks for me, nothing works?

John Smith 27 6-Apr-23 8:22am

The first should be a HandleRef.

John Smith 27 6-Apr-23 8:23am

It works but it keeps open in the system even after the screen is unlocked.

0x01AA 6-Apr-23 8:26am

I don't understand what you mean with this (keep in mind I'm not native English speaker ;) )
What keeps open? Your app?

John Smith 27 6-Apr-23 8:29am

In Visual Studio, when I run the app it shows the screensaver, and when I exit the screensaver and log into Windows, I still see the program open as it doesn't exit when it finished its job, it keeps showing me that it's running and its RAM usage statistics while it's still running instead of having exited after I logged in to Windows and the exe's job is finished.

0x01AA 6-Apr-23 8:37am

I'm groping in the dark, most probably my lack in English :(
Also I'm not shure what code you are using now. The one in your question or the one of the article.
But maybe simply remove screenSaverProcess.WaitForExit(); will help?
Another thing: Running that kind of code from VS can also have some side effects.

John Smith 27 6-Apr-23 8:47am

I have 2 programs, 2 Visual Studio solutions each in a separate File Explorer folder, one I made and one entirely from your code, but the exe that is entirely from your code keeps open after it has finished its job there's still an open thread in it that keeps running in the background in Windows after I log in to Windows and it should exit and not keep running in the background eating up RAM from the computer without doing a job as it has ran the screensaver and locked the screen and when I log in Windows it should exit.

0x01AA 6-Apr-23 8:56am

Can you please post the code of the app based on the CPs article code?

Btw. I will delete my answer, because it does not looks like it helped ;)
Think also about to delete what you posted as answer to prevent you from downvotes.

John Smith 27 6-Apr-23 9:06am

See the code in the new answer I submitted plz.

0x01AA 6-Apr-23 9:20am

Thanks, but for this somebody downvoted you :(
Use 'Improve Question' on you original question to add such information.
... and it looks like you did not try to replace SendMessage by PostMessage :(

John Smith 27 6-Apr-23 9:30am

The arguments you provided for PostMessage aren't correct, please provide correct arguments for this:

[DllImport("user32.dll")]
static extern bool PostMessage(HandleRef hWnd, uint Msg, IntPtr wParam, IntPtr lParam);

0x01AA 6-Apr-23 9:41am

The arguments are exactly the same as for SendMessage. Or where I'm wrong, where is the problem?

John Smith 27 6-Apr-23 9:44am

[DllImport("User32.dll")]
public static extern int SendMessage (IntPtr hWnd, uint Msg, uint wParam, uint lParam);

[DllImport("User32.dll")]
static extern bool PostMessage(HandleRef hWnd, uint Msg, IntPtr wParam, IntPtr lParam);

0x01AA 6-Apr-23 9:54am

Send: pinvoke.net: sendmessage (user32)[^]

Post: pinvoke.net: postmessage (user32)[^]

Because it is a broadcast message the HWnd parameter does not count (I think). simply pass 0 or null....

John Smith 27 6-Apr-23 9:59am

I get an error that can't convert "null" to HandleRef.

0x01AA 6-Apr-23 10:19am

[Deleted]... wait a moment

0x01AA 6-Apr-23 10:41am

Try something like this. I will not google it for you ;) And of course set the right parameters where I simply put a 0
[DllImport("user32.dll", SetLastError = true, CharSet = CharSet.Auto)]
static extern bool PostMessage(IntPtr hWnd, uint Msg, IntPtr wParam, IntPtr lParam);

private void button1_Click(object sender, EventArgs e)
{
PostMessage(new IntPtr(), 0, (IntPtr)0, (IntPtr)0);
}

John Smith 27 6-Apr-23 11:02am

I changed it to work correctly, duplicate my answer of your code and I will accept it plz, thx a lot.

0x01AA 6-Apr-23 11:28am

You are welcome. Which of your two answers?

John Smith 27 6-Apr-23 11:33am

The one with TurnOnScreenSaver();

3 solutions

Solution 4

This is what the user named: 0x01AA suggested in a link and comments and I changed stuff in it, works like magic:

using System;
using System.Runtime.InteropServices;

namespace ScreenSaverAndLockScreen
{
    static class Program
    {
        /// <summary>
        /// The main entry point for the application.
        /// </summary>
        [STAThread]
        static void Main()
        {
            TurnOnScreenSaver();
        }

        public const uint WM_SYSCOMMAND = 0x112;
        public const uint SC_SCREENSAVE = 0xF140;


        [DllImport("User32.dll")]
        static extern bool PostMessage(HandleRef hWnd, uint Msg, IntPtr wParam, IntPtr lParam);


        public enum SpecialHandles
        {
            //HWND_DESKTOP = 0x0,
            HWND_BROADCAST = 0xFFFF
        }

        public static void TurnOnScreenSaver()
        {
            PostMessage(
                new HandleRef(null, new IntPtr((int)SpecialHandles.HWND_BROADCAST)),
                WM_SYSCOMMAND,
                new IntPtr( SC_SCREENSAVE),
                new IntPtr( 0));
        }
    }
}

Posted 6-Apr-23 3:04am

John Smith 27

Updated 6-Apr-23 5:01am

v4

Comments

0x01AA 6-Apr-23 9:08am

Wait wait... Don't post things like this as an answer. There are crazy nit picking members around here which will downvote something like that (as you can see :( ).
Use 'improve question' in your original question to post information like this.

And btw. looks like you did not replaced SendMessage by PostMessage....

PIEBALDconsult 6-Apr-23 10:50am

Testify!

0x01AA 6-Apr-23 10:53am

What exactly? Nit pickings or Send vs. Post ;P :D

Add a Solution

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

0x01AA · Accepted Answer · 2023-04-06T05:33:00

See all the coments...

Looks like PostMessage instead of SendMessage was the solution and solved by OP.

Comment snippet:
Try something like this. I will not google it for you ;) And of course set the right parameters where I simply put a 0.

[DllImport("user32.dll", SetLastError = true, CharSet = CharSet.Auto)]
static extern bool PostMessage(IntPtr hWnd, uint Msg, IntPtr wParam, IntPtr lParam);

private void button1_Click(object sender, EventArgs e)
{
PostMessage(new IntPtr(), 0, (IntPtr)0, (IntPtr)0);
}

This based on this CP Article: Programmatically Turning on the Screen Saver[^]

[Edit]
Correction from OP:

PostMessage(
new HandleRef(null, new IntPtr((int)SpecialHandles.HWND_BROADCAST)),
WM_SYSCOMMAND,
new IntPtr( SC_SCREENSAVE),
new IntPtr( 0));

John Smith 27 · Accepted Answer · 2023-04-06T01:59:00

This isn't a perfect way but it worked for me, I run the screensaver and hide every screen the user has with a black borderless maximized topmost form and then when the user logs back in detect this event and exit the application and the black forms exit too, it works for me and I'm using it as I can't find another option, I keep it here for the benefits of others to learn stuff from it...

using System;
using System.Diagnostics;
using System.IO;
using System.Runtime.InteropServices;
using Microsoft.Win32;
using System.Windows.Forms;
using System.Collections.Generic;


namespace LockAndStartScreenSaver
{
    static class Program
    {
        /// <summary>
        /// The main entry point for the application.
        /// </summary>
        [STAThread]
        static void Main()
        {



            Microsoft.Win32.SystemEvents.SessionSwitch += new Microsoft.Win32.SessionSwitchEventHandler(SystemEvents_SessionSwitch);


            if (screenSaverKey != null)
            {
                string screenSaverFilePath = screenSaverKey.GetValue("SCRNSAVE.EXE", string.Empty).ToString();
                if (!string.IsNullOrEmpty(screenSaverFilePath) && File.Exists(screenSaverFilePath))
                {
                    Process screenSaverProcess = Process.Start(new ProcessStartInfo(screenSaverFilePath, "/s"));  // "/s" for full-screen mode


                    foreach (Screen s in Screen.AllScreens)
                    {
                        lstForms.Add(new FormMainHide(s.Bounds.X, s.Bounds.Y));//FormMainHide is a borderless topmost maximized black form to hide the screens
                        lstForms[lstForms.Count - 1].Show();
                    }

                    screenSaverProcess.WaitForExit();  // Wait for the screensaver to be dismissed by the user

                    LockWorkStation();

                    Application.Run();
                }
            }
        }







        static void SystemEvents_SessionSwitch(object sender, Microsoft.Win32.SessionSwitchEventArgs e)
        {
            //if (e.Reason == SessionSwitchReason.SessionLock)
            //{
                //I left my desk
                //Console.WriteLine("I left my desk");
            //}
            else if (e.Reason == SessionSwitchReason.SessionUnlock)
            {
                //I returned to my desk
                Application.Exit();
            }
        }








        [DllImport("user32")]
        static public extern void LockWorkStation();


        static List<FormMainHide> lstForms = new List<FormMainHide>();

        static RegistryKey screenSaverKey = Registry.CurrentUser.OpenSubKey(@"Control Panel\Desktop");
    }
}

How to make an exe file in C# that locks the screen and starts screensaver immediately?

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How to make an exe file in C# that locks the screen and starts screensaver immediately?

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