Windows Programming...

[Harlequin]

I am completely new to Windows Programming.....

Plz explain me how does a window application work.....

I don't understand one thing in the following code.....when does WndProc() get called....i don't see any call in the code.........where is DefWindowProc() defined ...what are these new datatypes...like
LRESULT.......i do have a rough idea of what is going on in this code....


#include <windows.h>
const char g_szClassName[] = "myWindowClass";
// Step 4: the Window Procedure
LRESULT CALLBACK WndProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
switch(msg)
{
case WM_CLOSE:
DestroyWindow(hwnd);
break;
case WM_DESTROY:
PostQuitMessage(0);
break;
default:
return DefWindowProc(hwnd, msg, wParam, lParam);
}
return 0;
}


int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
LPSTR lpCmdLine, int nCmdShow)
{
WNDCLASSEX wc;
HWND hwnd;
MSG Msg;
//Step 1: Registering the Window Class
wc.cbSize = sizeof(WNDCLASSEX);
file:///C|/dona/forgers-win32-tutorial/tutorial/simple_window.html (1 of 8) [7/8/2003 4:34:44 PM]
Tutorial: A Simple Window
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 = g_szClassName;
wc.hIconSm = LoadIcon(NULL, IDI_APPLICATION);
if(!RegisterClassEx(&wc))
{
MessageBox(NULL, "Window Registration Failed!", "Error!",
MB_ICONEXCLAMATION | MB_OK);
return 0;
}
// Step 2: Creating the Window
hwnd = CreateWindowEx(
WS_EX_CLIENTEDGE,
g_szClassName,
"The title of my window",
WS_OVERLAPPEDWINDOW,
CW_USEDEFAULT, CW_USEDEFAULT, 240, 120,
NULL, NULL, hInstance, NULL);
if(hwnd == NULL)
{
MessageBox(NULL, "Window Creation Failed!", "Error!",
MB_ICONEXCLAMATION | MB_OK);
return 0;
}
ShowWindow(hwnd, nCmdShow);
UpdateWindow(hwnd);
// Step 3: The Message Loop
while(GetMessage(&Msg, NULL, 0, 0) > 0)
{
TranslateMessage(&Msg);
DispatchMessage(&Msg);
}
return Msg.wParam;
}

[Bazzy]

when does WndProc() get called

Any time a message is sent to your program - http://msdn.microsoft.com/en-us/library/ms632593%28VS.85%29.aspx -

where is DefWindowProc() defined

It is part of WinAPI. It responds with default actions to the messages - http://msdn.microsoft.com/en-us/library/ms633572%28VS.85%29.aspx -

what are these new datatypes...

They are typedefs of some built-in type - http://msdn.microsoft.com/en-us/library/aa383751%28VS.85%29.aspx -

[huzhanchi]

hi Harlequin

WndProc() is called by system, make the "CALLBACK"goto definition,you can see that it is defined with "_stdcall".the "WinMain()" is also a CALLBACK function ,just like "main()" in console

the "DefWindowProc() " is just an API .