Pelles C forum

C language => Windows questions => Topic started by: PabloMack on March 15, 2019, 06:14:34 PM

Title: How do I define WinProc?
Post by: PabloMack on March 15, 2019, 06:14:34 PM

I am writing my first Win32 program in Pelles C. How do I define WindowProc?
This is the callback function that is passed to RegisterClass.

The definition I have used for Watcom is what is given in the MicroSoft website:

LRESULT CALLBACK WindowProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam);

The 64-bit Pelles C compiler is giving me the following error message:

error #2168: Operands of '=' have incompatible types 'long long int __stdcall (*)(HWND, unsigned int, unsigned long long int, long long int)' and 'void *'.

Title: Re: How do I define WinProc?
Post by: TimoVJL on March 15, 2019, 06:40:49 PM

Working example:

Code: [Select]

#define WIN32_LEAN_AND_MEAN
#include <windows.h>

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

TCHAR *szAppName = TEXT("WinFrame");
TCHAR *szFrameClass = TEXT("cWinFrame");
HWND hFrame;
HANDLE hInst;

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
LPSTR lpCmdLine, int nCmdShow)
{
WNDCLASSEX wcx;
MSG msg;

wcx.cbSize = sizeof(WNDCLASSEX);
wcx.style = CS_HREDRAW | CS_VREDRAW;
wcx.lpfnWndProc = WndProc;
wcx.cbClsExtra = 0;
wcx.cbWndExtra = 0;
wcx.hInstance = hInstance;
wcx.hIcon = LoadIcon(NULL, IDI_APPLICATION);
wcx.hCursor = LoadCursor(NULL, IDC_ARROW);
wcx.hbrBackground= (HBRUSH)COLOR_APPWORKSPACE+1;
wcx.lpszMenuName = NULL;
wcx.lpszClassName= szFrameClass;
wcx.hIconSm = 0;

if (!RegisterClassEx(&wcx))
return 0;
hInst = hInstance;

hFrame = CreateWindowEx(0, szFrameClass, szAppName,
WS_OVERLAPPEDWINDOW,
CW_USEDEFAULT, CW_USEDEFAULT,
CW_USEDEFAULT, CW_USEDEFAULT,
NULL, NULL, hInst, NULL);
if(!hFrame) return 0;
ShowWindow(hFrame, nCmdShow);
//UpdateWindow(hFrame);

while(GetMessage(&msg, NULL, 0, 0))
{
TranslateMessage(&msg);
DispatchMessage(&msg);
}
return msg.wParam;
}

LRESULT CALLBACK WndProc(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
switch(uMsg) {
// case WM_CREATE:
case WM_DESTROY:
PostQuitMessage(0);
return(0);
}
return DefWindowProc(hWnd, uMsg, wParam, lParam);
}


Title: Re: How do I define WinProc?
Post by: Jokaste on May 24, 2019, 01:11:05 PM

Or replace

Quote

wcx.lpfnWndProc = WndProc;

with

Quote

wcx.lpfnWndProc = DefWindowProc;

if the window does nothing particular. You don't have to write a WndProc in that case.

Title: Re: How do I define WinProc?
Post by: Abraham on June 21, 2019, 07:24:18 AM

Clearly, like TimoVJL showed without stating, you are missing your function prototype by having the function below WinMain.

I prefer to have WinMain at the bottom of my source code so that I do not have to deal with having prototypes. Even though a prototype is just a copy and paste of a single line.