| LRESULT DefWindowProc(hwnd, uMsg, wParam, lParam) | |||||
| HWND hwnd; | /* handle of window, */ | ||||
| UINT uMsg; | /* type of message, */ | ||||
| WPARAM wParam; | /* first message parameter | */ | |||
| LPARAM lParam; | /* second message parameter | */ | |||
The DefWindowProc function calls the default window procedure. The default window procedure provides default processing for any window messages that an application does not process. This function ensures that every message is processed. It should be called with the same parameters as those received by the window procedure.
hwnd
Identifies the window that received the message.
uMsg
Specifies the message.
wParam
Specifies 16 bits of additional message-dependent information.
lParam
Specifies 32 bits of additional message-dependent information.
The return value is the result of the message processing and depends on the message sent.
The source code for the DefWindowProc function is provided on the Microsoft Windows 3.1 Software Development Kit (SDK) disks.
The following example shows a typical window procedure. A switch statement is used to process individual messages. All messages not processed are passed on to the DefWindowProc function.
LONG FAR PASCAL MainWndProc(hwnd, message, wParam, lParam)
HWND hwnd; /* handle of window */
WORD message; /* type of message */
WORD wParam; /* additional information */
LONG lParam; /* additional information */
{
switch (message) {
/*
* Process whatever messages you want here and send the
* rest to DefWindowProc.
*/
default:
return (DefWindowProc(hwnd, message, wParam, lParam));