C/C++ - Simple Win32 App

This is just a simple setup for a simple win32 app. I didnt really do much explaining but i did include some comments on whats going on at a particular place. I will hopefully get a simple opengl tutorial up soon, building off this framework. If want a more in-depth explaination on how all this code works do a search on google.com.

Code:

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#define WIN32_LEAN_AND_MEAN  //cut down on windows

#include <windows.h>  //our windows library


//================================================================================
//event handler
//the event handler processes messages from windows
//ex.  Key Press,MouseMove, Close, ETC ...
//================================================================================

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

switch(message)
{
case WM_CLOSE:
PostQuitMessage(0); //send message to close program
return 0;
break;

}

return DefWindowProc(hwnd,message,wParam,lParam);
}

//================================================================================
//program entry point
//This is where the program actually starts
//We need to setup up a windows class then register it
//after you register it you can create your window
//================================================================================

int WINAPI WinMain(HINSTANCE hInstance,HINSTANCE hPrevInstance,LPSTR lpCmdLine, int nShowCmd)
{
WNDCLASSEX winClass;  //windows class
HWND hwnd; //windows handle
MSG msg;  //message
bool done;  //status of app

//window class structure
winClass.cbSize = sizeof(WNDCLASSEX);
winClass.style = CS_HREDRAW | CS_VREDRAW;
winClass.lpfnWndProc = WndProc;
winClass.cbClsExtra = 0;
winClass.cbWndExtra = 0;
winClass.hInstance = hInstance;
winClass.hIcon = LoadIcon(NULL, IDI_APPLICATION);
winClass.hCursor = LoadCursor(NULL,IDC_ARROW);
winClass.hbrBackground = NULL;
winClass.lpszMenuName = NULL;
winClass.lpszClassName = "MyClass";
winClass.hIconSm = LoadIcon(NULL, IDI_WINLOGO);

//register our windows class
if (!RegisterClassEx(&winClass))
    return 0;

//once class is registered create window
hwnd = CreateWindowEx(NULL,      //extended style
                      "MyClass",  //class name
                      "Win32 App",//app name
                      WS_OVERLAPPEDWINDOW |  WS_VISIBLE|  //style
                      WS_SYSMENU | WS_CLIPCHILDREN |
                      WS_CLIPSIBLINGS,
                      100,100, //x y coordinates
                      400,400,  //height and width
                      NULL,    //handle to parent
                      NULL,    //handle to menu
                      hInstance,  //app instance
                      NULL);    //no extra params

//check to see if hwnd failed or not
if (!hwnd)
return 0;

ShowWindow(hwnd,SW_SHOW);  //show window
UpdateWindow(hwnd);  //update the window

done = false;  //start of loop
//================================================================================
//Message Loop
//This loop is specially setup for something like Directx/Opengl Render functions but it can but used for a normal app too
//================================================================================




while (!done)
{
PeekMessage(&msg,hwnd,NULL,NULL,PM_REMOVE);

if (msg.message == WM_QUIT)
{
done = true;
}
else
{
//do what you want
TranslateMessage(&msg);
DispatchMessage(&msg);
}
}
return msg.wParam;
}

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I thought PeekMessage returned immediately, using a return value to indicate the presence of a message in the queue.

From first looks this looks more suitable for a full-screen graphical program like a game, as you mentioned, but inefficient for a normal program.

Something like this could be more appropriate:

Code:

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while(GetMessage(&msg, hwnd, NULL, NULL) > 0) {
    Translate...
    Dispatch...
}

---

GetMessage() returns 0 on WM_QUIT, and -1 on error. MSDN says:

Quote:

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Warning

Because the return value can be nonzero, zero, or -1, avoid code like this:

Code:

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while (GetMessage( lpMsg, hWnd, 0, 0)) ...

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The possibility of a -1 return value means that such code can lead to fatal application errors. Instead, use code like this:

Code:

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BOOL bRet;

while( (bRet = GetMessage( &msg, NULL, 0, 0 )) != 0)
{
    if (bRet == -1)
    {
        // handle the error and possibly exit
    }
    else
    {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }
}

---

---

I usually treat -1 or 0 as cause for quitting, however you may wish to attempt to correct any error states.

yea i should of mentioned that. thanks for letting me know.

Explaination(cause im bored):

PeekMessage() basically continues even if there is no message in the queue, perfect for functions like Rendering.

GetMessage() basically stalls your app until there is a message. So there would work, if like your app was event based.

You might want to move a few things around.

Replace this:

Code:

---

done = false;  //start of loop
//================================================================================
//Message Loop
//This loop is specially setup for something like Directx/Opengl Render functions but it can but used for a normal app too
//================================================================================




while (!done)
{
PeekMessage(&msg,hwnd,NULL,NULL,PM_REMOVE);

if (msg.message == WM_QUIT)
{
done = true;
}
else
{
//do what you want
TranslateMessage(&msg);
DispatchMessage(&msg);
}
}
return msg.wParam;
}

---

with This:

Code:

---

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

return msg.wParam;

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And add this to your window proc function:

Code:

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case WM_DESTROY:
        PostQuitMessage(0);
        return 0;

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Good Day!