Superclassing Demo

#include <windows.h>

#define BUTTON1 1
#define BUTTON2 2


WNDPROC lpfnOldWndProc;

HWND hWnd;
HWND SuperClassedButton;
HWND normalButton;


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



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

MSG Msg;
WNDCLASSEX WndClsEx;



// Register main window

WndClsEx.cbSize = sizeof(WNDCLASSEX);
WndClsEx.style = CS_HREDRAW | CS_VREDRAW;
WndClsEx.lpfnWndProc = WndProc;
WndClsEx.cbClsExtra = 0;
WndClsEx.cbWndExtra = 0;
WndClsEx.hInstance = hInstance;
WndClsEx.hIcon = LoadIcon(NULL,IDI_APPLICATION);
WndClsEx.hCursor = LoadCursor(NULL,IDC_ARROW);
WndClsEx.hbrBackground =
(HBRUSH)GetStockObject(WHITE_BRUSH);
WndClsEx.lpszMenuName = NULL;
WndClsEx.lpszClassName = TEXT("WndMsg");
WndClsEx.hIconSm = LoadIcon(NULL,IDI_APPLICATION);


RegisterClassEx(&WndClsEx);



hWnd = CreateWindowEx(
0,
TEXT("WndMsg"),
TEXT("Superclass Example"),
WS_OVERLAPPEDWINDOW,
10,
10,
240,
140,
NULL,
NULL,
hInstance,
NULL);



ShowWindow(hWnd,nCmdShow);
UpdateWindow(hWnd);



// Normal button

normalButton = CreateWindow(
TEXT("BUTTON"),
TEXT("Normal"),
WS_CHILD | WS_VISIBLE | BS_PUSHBUTTON,
10,
10,
100,
80,
hWnd,
(HMENU)BUTTON1,
hInstance,
NULL);




// Create superclass

WNDCLASS wc;



// Get existing BUTTON class

GetClassInfo(
NULL,
TEXT("BUTTON"),
&wc);



// Save original button procedure

lpfnOldWndProc = wc.lpfnWndProc;



// Modify class information

wc.lpfnWndProc = SuperClassedButtonProc;
wc.lpszClassName = TEXT("MyButtonClass");
wc.hInstance = hInstance;



// Register new class

RegisterClass(&wc);




// Create superclassed button

SuperClassedButton = CreateWindow(
TEXT("MyButtonClass"),
TEXT("Super"),
WS_CHILD | WS_VISIBLE | BS_PUSHBUTTON,
120,
10,
100,
80,
hWnd,
(HMENU)BUTTON2,
hInstance,
NULL);



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


return Msg.wParam;

}





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

switch(Msg)
{

case WM_COMMAND:

switch(LOWORD(wParam))
{

case BUTTON1:

MessageBeep(MB_ICONEXCLAMATION);

break;


}

break;



case WM_DESTROY:

PostQuitMessage(0);

break;


default:

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

}


return 0;

}





// Superclassed button procedure

LRESULT CALLBACK SuperClassedButtonProc(
HWND hwnd,
UINT Msg,
WPARAM wParam,
LPARAM lParam)
{

switch(Msg)
{

case WM_LBUTTONUP:

MessageBeep(MB_OK);

break;


}


// Pass message back to BUTTON control

return CallWindowProc(
lpfnOldWndProc,
hwnd,
Msg,
wParam,
lParam);

}