Global Sublassing Example

Copy

#include <windows.h>

#define BUTTON1 1
#define BUTTON2 2

WNDPROC OldWndProc;

HWND hiddenButton;
HWND button;


LRESULT CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM);
LRESULT CALLBACK SubClassProc(HWND, UINT, WPARAM, LPARAM);



int WINAPI WinMain(
HINSTANCE hInstance,
HINSTANCE hPrevInstance,
LPSTR lpCmdLine,
int nCmdShow)
{

    WNDCLASSEX wc;
    MSG msg;


    wc.cbSize = sizeof(WNDCLASSEX);
    wc.style = 0;
    wc.lpfnWndProc = WndProc;
    wc.cbClsExtra = 0;
    wc.cbWndExtra = 0;
    wc.hInstance = hInstance;
    wc.hIcon = LoadIcon(NULL, IDI_APPLICATION);
    wc.hCursor = LoadCursor(NULL, IDC_ARROW);
    wc.hbrBackground = (HBRUSH)(COLOR_WINDOW+1);
    wc.lpszMenuName = NULL;
    wc.lpszClassName = TEXT("myWindowClass");
    wc.hIconSm = LoadIcon(NULL, IDI_APPLICATION);


    RegisterClassEx(&wc);



    CreateWindowEx(
        WS_EX_CLIENTEDGE,
        TEXT("myWindowClass"),
        TEXT("Global Subclass"),
        WS_VISIBLE | WS_OVERLAPPEDWINDOW,
        CW_USEDEFAULT,
        CW_USEDEFAULT,
        240,
        180,
        NULL,
        NULL,
        hInstance,
        NULL);



    while(GetMessage(&msg,NULL,0,0)>0)
    {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }


    return msg.wParam;
}





LRESULT CALLBACK WndProc(
HWND hwnd,
UINT msg,
WPARAM wParam,
LPARAM lParam)
{

switch(msg)
{

case WM_CREATE:
{

    /*
       Create hidden BUTTON window.
       This gives us the BUTTON class information.
    */

    hiddenButton = CreateWindow(
        TEXT("BUTTON"),
        TEXT("Hidden"),
        WS_CHILD,
        0,
        0,
        0,
        0,
        hwnd,
        (HMENU)BUTTON1,
        GetModuleHandle(NULL),
        NULL);



    /*
       Replace the BUTTON class procedure.
       All buttons created afterwards
       will use SubClassProc.
    */

    OldWndProc =
    (WNDPROC)SetClassLong(
        hiddenButton,
        GCL_WNDPROC,
        (LONG)SubClassProc);



    /*
       This button is created after the class
       procedure has been changed.
       It will use SubClassProc.
    */

    button = CreateWindow(
        TEXT("BUTTON"),
        TEXT("Button 1"),
        WS_CHILD |
        WS_VISIBLE |
        BS_PUSHBUTTON,
        10,
        10,
        100,
        50,
        hwnd,
        (HMENU)BUTTON2,
        GetModuleHandle(NULL),
        NULL);


    break;
}



case WM_DESTROY:
{

    /*
       Restore original BUTTON procedure.
       Important because BUTTON is a system class.
    */

    SetClassLong(
        hiddenButton,
        GCL_WNDPROC,
        (LONG)OldWndProc);



    PostQuitMessage(0);

    break;
}

}


return DefWindowProc(hwnd,msg,wParam,lParam);

}






LRESULT CALLBACK SubClassProc(
HWND hwnd,
UINT uMsg,
WPARAM wParam,
LPARAM lParam)
{

switch(uMsg)
{

case WM_LBUTTONDOWN:

    MessageBeep(MB_ICONEXCLAMATION);

    break;

}


// send message to original BUTTON procedure

return CallWindowProc(
        OldWndProc,
        hwnd,
        uMsg,
        wParam,
        lParam);

}