Thread: Moving the mouse with SendMessage / PostMessage

Hi,
I have a few questions:

1. What is the difference between SendMessage and PostMessage?

2. Am I using SendMessage correctly? I want to emulate mouse movement in a certain window while still being able to use the computer.

Code:

#include <iostream>
#include <windows.h>
using namespace std;

int main() {
    POINT btn;
    HWND mWindow;
    cout<<"Set Mouse Over button and press ENTER";
    cin.get();
    GetCursorPos(&btn);
    cout<<"\nAfter Pressing ENTER, you have 5 seconds to set focus to the correct window.";
    cin.get();
    Sleep(5000);
    mWindow = GetFocus();

   SendMessage(mWindow,WM_MOUSEMOVE,0,MAKELPARAM(btn.x,btn.y));
   SendMessage(mWindow,WM_LBUTTONDOWN,0,MAKELPARAM(btn.x,btn.y));
   SendMessage(mWindow,WM_LBUTTONUP,0,MAKELPARAM(btn.x,btn.y));
   return 0;
}

Please DO NOT suggest SendInput / mouse_event. They do not do what I am looking for. (AKA they hijack the mouse)

Thanks!

The SendMessage function sends the specified message to a window or windows. It calls the window procedure for the specified window and does not return until the window procedure has processed the message.

The PostMessage function places (posts) a message in the message queue associated with the thread that created the specified window and returns without waiting for the thread to process the message.

Does it work? It looks like your calls to SendMessage are correct, and it looks like it would work, but looks can be deceiving.

1. PostMessage() does not wait for the message to be processed.

2. The messages WM_MOUSEMOVE, WM_LBUTTONDOWN, WM_LBUTTONUP take coordinates in client area of the window. Therefore, I don't think it is possible to hit the (X) with them. (Since the (X) is not within the client area of the window.) Try the corresponding WM_NC* messages. (ie, WM_NCLBUTTONDOWN)

Why not just send a WM_CLOSE?

Edit : Just a note, the WM_NC* messages take slightly different parameters... be sure to look the messages up first.

Originally Posted by comwiz

Please DO NOT suggest SendInput / mouse_event. They do not do what I am looking for. (AKA they hijack the mouse)

They "hijack" your mouse for a microsecond, yes...

What about mouse_event?