Programmatically press a button on another application (C, Windows)

Question

I\'m trying to use the following code to press a button on my other application:

HWND ButtonHandle;
if( (wnd = FindWindow(0, \"Do you want to save?\")) )
{   
           


        

Answer 1

if you sure ButtonHandle are valid handle you can use pair WM_LBUTTONDOWN and WM_LBUTTONUP message instead of BN_CLICKED

HWND ButtonHandle;
if( (wnd = FindWindow(0, "Do you want to save?")) )
{   
    SendMessage(ButtonHandle, WM_LBUTTONDOWN, MK_LBUTTON, 0);
    SendMessage(ButtonHandle, WM_LBUTTONUP, MK_LBUTTON, 0);
}

Answer 2

When I have to do these kind of things I use SendKeys. It is VB-ish and C# provides a nice interface to use but for C/C++ you'll have to do it <this way>. What is nice with it is that you could write scripts and run them instead of hard coding it in your code.

Answer 3

A non-C approach: Use Java and the java.awt.Robot class to move the mouse around perform real clicks (I guess there is something in the Windows World for this, too). Problem: You have to know where your button is :D

Answer 4

You can use sendkeys (as tr3 said) to send mouse clicks, which is different than using SendMessage. It is also less direct and more hack-ish, but is useful for automation (in VBS).

Also, just a guess but the problem could be that your message handling is broken somewhere by not calling the base class member. Example:

void CMyClass::OnMessageY(CWnd *cwnd)
{
    CBaseClass::OnMessageY(cwnd);
    //... my code
}

Answer 5

Access Denied errors on SendMessage or PostMessage make no sense unless the process sending the message is running at a lower integrity level than the target process.

This should not be happening unless the process that owns the target window is being run "asAdministrator" or is a service. And its damn hard for services to create windows on the interactive desktop with Windows 6 and up.

You can do some reading about Integrity Levels Here if they apply even remotely to this situation. Internet Explorer is about the only other application that 'opts in' to the integrity security model by purposely lowering the integrity level of itself in order to sandbox itself more effectively.

Answer 6

If you can raise the window containing the button you can send raw mouse event to a position within the boundaries of button.

There are two function to simulate mouse event SendInput and mouse_event. I recommend using mouse_event function. To raise a window you can use ShowWindow. I don't know how to get the handle of a button, but if you have its hWnd its easy to find its absolute position using GetWindowRect function. Try using these, if you run into any problems I will be glad to help.

Or define a custom WM within your application window to handle save request. WM_CUSTOM or WM_USER (cant remember which) marks the start of user defined window messages.