CODEWITHSUNDEEP
c#winformsprocesshandle
NoName
NoName

Reputation: 8025

WinForms: Is any way to get window handle before Application.Run(new Form1())?

I have a winforms, before Application.Run(new Form1()) I send message to other app

[DllImport("user32.dll")]
public static extern long SendMessage(IntPtr Handle, int Msg, int wParam, int lParam);

but I cannot get window handle, I tried:

IntPtr Handle = Process.GetCurrentProcess().Handle;

but sometime it returm wrong handle.
How can I do this? Thank you very much!

Upvotes: 1

Views: 1487

Answers (2)

pescolino
pescolino

Reputation: 3123

The first argument of the SendMessage function is the handle of the window that will receive the message. Process.GetCurrentProcess().Handle returns the native handle of the current process. That's not a window handle.

Application.Run starts the message loop for the application. Since you want to send a message to another application your application doesn't need a message loop at all. You need however the handle to the other application's window.

The following example shows how to close the main window of another app using SendMessage:

[DllImport("user32.dll")]
public static extern long SendMessage(IntPtr Handle, int Msg, int wParam, int lParam);

public const int WM_CLOSE = 0x0010;

private static void Main()
{
    var processes = Process.GetProcessesByName("OtherApp");
    if (processes.Length > 0)
    {
        IntPtr handle = processes[0].MainWindowHandle;
        SendMessage(handle, WM_CLOSE, 0, 0);
    }
}

Upvotes: 1

RogerN
RogerN

Reputation: 3821

If you're trying to send a message to a different application then you need to get its window handle instead of the window handle belonging to your own process. Use Process.GetProcessesByName to find a specific process, and then use the MainWindowHandle property to get the window handle. Note that MainWindowHandle is not the same as Handle, as the latter refers to the process handle rather than the window handle.

Upvotes: 1

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