Moving the mouse with SendMessage / PostMessage

This is a discussion on Moving the mouse with SendMessage / PostMessage within the Windows Programming forums, part of the Platform Specific Boards category; Hi, I have a few questions: 1. What is the difference between SendMessage and PostMessage? 2. Am I using SendMessage ...

  1. #1
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    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!
    Last edited by comwiz; 07-31-2007 at 11:22 PM.

  2. #2
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    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.
    Last edited by Bleech; 07-31-2007 at 11:30 PM. Reason: your*

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  3. #3
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    No, it doesn't. For example, I tested it with notepad. I shrunk the notepad window so I just saw the Toolbar, put the console window on the other side of my screen. I set my mouse over the (X) on the notepad window and pressed enter. I pressed enter again and Clicked on the notepad window to set focus to it. Waited 5 seconds and my program just exited. It did not click the button.

  4. #4
    int x = *((int *) NULL); Cactus_Hugger's Avatar
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    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.
    Last edited by Cactus_Hugger; 08-01-2007 at 01:26 AM.
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  5. #5
    I Write C++ Apps, Sue Me.
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    Just tried it again with a button inside of my web browser. I don't know what is wrong. Everything builds w/o error.

    Another question:
    Does the cursor just have to be inside the client area of the application inorder for GetCapture to retrieve the window handle? Or does it have to have focus?

  6. #6
    Reverse Engineer maxorator's Avatar
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    Quote Originally Posted by comwiz View Post
    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...
    "The Internet treats censorship as damage and routes around it." - John Gilmore

  7. #7
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    Quote Originally Posted by maxorator View Post
    They "hijack" your mouse for a microsecond, yes...
    It's not so much the mouse hijacking, I want to be able to still use my computer while still sending mouse info the the desired window.

  8. #8
    Tropical Coder Darryl's Avatar
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    What about mouse_event?

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