We help IT Professionals succeed at work.

We've partnered with Certified Experts, Carl Webster and Richard Faulkner, to bring you a podcast all about Citrix Workspace, moving to the cloud, and analytics & intelligence. Episode 2 coming soon!Listen Now

x

How to implement SendKeys in C/C++

fitzy
fitzy asked
on
Medium Priority
4,149 Views
Last Modified: 2013-12-03
I'm developing a 16-bit Windows app.  I did a prototype in Visual Basic and used the SendKeys() function to send keystrokes to other applications.  Now I'm writing the real product using Visual C++ V1.52 and can't figure out how to do the SendKeys.  I've tried sending WM_CHAR, WM_KEYUP, WM_KEYDOWN messages without luck.

In particular, I'm putting a metafile on the clipboard and trying to paste it into another application.  In the prototype I just called SendKeys to send the Ctrl-Insert keystroke and it worked like a charm.

Can anyone please help me out????
Comment
Watch Question

Commented:
It should work. How do you get the window handle to which you would like to send the messages? Please note you should get the window handle that exactly processes key messages. For example, the edit window processes key messages instead of the main window does. The following tested code shows how to send the messages to Notepad.

    CWnd *pWnd = CWnd::FindWindow(NULL, "Untitled - Notepad");
    if (pWnd != NULL)
    {
        CWnd *pWndEdit = pWnd->GetWindow(GW_CHILD);
        if (pWndEdit != NULL)
        {
            pWndEdit->PostMessage(WM_KEYDOWN, VK_SPACE, 0x00390001UL);
            pWndEdit->PostMessage(WM_KEYUP, VK_SPACE, 0xC0390001UL);
            // or pWndEdit->PostMessage(WM_CHAR, VK_SPACE, 0x00390001UL);
           
            ::MessageBeep(-1);
        }
    }

Not the solution you were looking for? Getting a personalized solution is easy.

Ask the Experts

Author

Commented:
Recommending the call to GetWindow(GW_CHILD) was a good one and it did work with Notepad.  Unfortunately it does not work with other apps, though (e.g., Wordpad).  My  VB prototype  worked with everything I tried.  In the VB prototype I called
        AppActivate
then
        SendKeys

I need to make my app work with any destination application.  Do you have any recommendations?

Thanks!



Commented:
I see. Since you need to make your app work with any destination application, it is not so easy. You can do something like the following code,

    CWnd *pWnd = CWnd::FindWindow(NULL, "Document - Wordpad");
    if (pWnd != NULL)
    {
        pWnd->SendMessageToDescendants(WM_CHAR, VK_SPACE, 0x00390001UL);
       
        ::MessageBeep(-1);
    }

Let me explain further. Because SendMessageToDescendants uses SendMessage instead of PostMessage and SendMessage(WM_KEYDOWN), SendMessage(WM_KEYDOWN) do not generate WM_CHAR message, I use WM_CHAR directly. You can choose appropriate method depending on your program. You can also refer to MFC source code to see how SendMessageToDescendants works. You might want to write your own PostMessageToDescendants.

Initially, I thought the following code was the best way.

    CWnd *pWnd = CWnd::FindWindow(NULL, "Document - Wordpad");
    if (pWnd != NULL)
    {
        pWnd->SetActiveWindow();
       
        CWnd *pWndEdit = CWnd::GetFocus();
       
        if (pWndEdit != NULL)
        {
            pWndEdit->PostMessage(WM_KEYDOWN, VK_SPACE, 0x00390001UL);
            pWndEdit->PostMessage(WM_KEYUP, VK_SPACE, 0xC0390001UL);
           
            ::MessageBeep(-1);
        }
       
        this->SetActiveWindow();
    }

It does work if the destination application is 16-bit too. Unfortunately, pWndEdit is NULL if the destination application is 32-bit. It is OK if your application runs under Windows 3.1 only.

Access more of Experts Exchange with a free account
Thanks for using Experts Exchange.

Create a free account to continue.

Limited access with a free account allows you to:

  • View three pieces of content (articles, solutions, posts, and videos)
  • Ask the experts questions (counted toward content limit)
  • Customize your dashboard and profile

*This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.

OR

Please enter a first name

Please enter a last name

8+ characters (letters, numbers, and a symbol)

By clicking, you agree to the Terms of Use and Privacy Policy.