MultiThreading + SendKeys.Send() - C# Discussion Boards

1-Apr-12 14:47

I am attempting to create a Windows Form application that will select a window based on it handle. No problem here doing that.

Afterwards, the I used Thread.Sleep() to buy some time, then use SendKeys.Send(). Of course, without doing the work here on another Thread, my UI will hang on my application while the Thread sleeps.

Therefore, I wanted to create another Thread, which I did, and encapsulate the above work (Thread.Sleep and SendKeys.Send) to a method and send it to the Thread. Unfortunately, the SendKeys doesn't end up sending any text as a result.

Am I missing something rather remedial here? Does the SendKeys() have to come from the primary thread? I am also selecting another window, not my application, for the SendKeys() to target.

Thread oThread = new Thread(new ThreadStart(sendTheKeys());

//
// More code here not pertaining to the preceding Object.
//
//Some code not at all interacting with the following.

public static void sendTheKeys()
     {
         Thread.Sleep(5000);
         SendKeys.Send("Simple Text Message here!");
     }

Luc Pattyn1-Apr-12 15:21

1-Apr-12 15:21

Do you have any proof the thread got executed? I don't see any oThread.Start()...

BTW1: if that is all you need, you could as well use a System.Windows.Forms.Timer, have it tick once (after 5 sec), and stop it inside its Tick handler (which runs on the main thread).

BTW2: if the process you want to send data to is one your app has launched, you might be better off using Process.WaitForInputIdle() rather than delaying for a fixed amount of time.

Smile | :)

Luc Pattyn [My Articles] Nil Volentibus Arduum

Emptora2-Apr-12 11:20

2-Apr-12 11:20

It did, I started the thread using the exact code immediately after.

For further thought, I also tried using Task.Factory.StartNew();

I inserted some test code and the thread seems to execute just no SendKeys output.

For simplicity I will probably just set a timer for my couple of tasks, however at this point I'm just wondering if I'm doing something wrong or if it must run on the primary thread.

Luc Pattyn2-Apr-12 11:55

2-Apr-12 11:55

I performed a little experiment and indeed SendKeys seems to fail when called by anything but the main thread; I don't recall having read about such requirement though.

Smile | :)

Luc Pattyn [My Articles] Nil Volentibus Arduum

Emptora2-Apr-12 13:27

2-Apr-12 13:27

Do you happen to know of a function / method I could use that will run off of a secondary thread?

Thank you for the help.

Luc Pattyn2-Apr-12 13:42

2-Apr-12 13:42

I have no idea what you mean here.

This was my test code:

public class CPTest_SendKeys : CPTest {
    public override void Test(int arg) {
        if (arg==1) {
            runner();
        } else {
            BackgroundWorker bgw=new BackgroundWorker();
            bgw.DoWork+=new DoWorkEventHandler(bgw_DoWork);
            bgw.RunWorkerAsync();
        }
    }

    void bgw_DoWork(object sender, DoWorkEventArgs e) {
        runner();
    }

    private void runner() {
        Process p=Process.Start("notepad.exe");
        p.WaitForInputIdle();
        SendKeys.Send("abcd");
        log("sent");
    }
}

Luc Pattyn [My Articles] Nil Volentibus Arduum

Emptora3-Apr-12 12:26

3-Apr-12 12:26

Oh. All I'm asking is, absent of SendKeys, is there any other class or WinAPI that offers sending keystrokes to another application? Whether it be that the application has to be the foreground application or not?

Luc Pattyn3-Apr-12 12:42