Appereance of the message box due to the change of the window size

Hi. I'm new to windows programming, so I need some help.

We had homework, and I did everything but one thing that I can't figure out.
I need to change something in the code so that the message box doesn't appear all the time when I re-size the window, because doing so it allows me to re-size only for one pixel at time.. and not more.


This is the code for my program:

Code:

#include <windows.h>
#include <WINUSER.h>
#include <stdio.h>

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

int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance,
        PSTR szCmdLine, int iCmdShow)
{
    HWND         hwnd ;
    MSG          msg ;
    WNDCLASS     wc ;

    wc.style         = CS_HREDRAW | CS_VREDRAW ;
    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) GetStockObject (WHITE_BRUSH) ;
    wc.lpszMenuName  = NULL ;
    wc.lpszClassName = "Moja klasa";

    if (!RegisterClass (&wc))
    {
        MessageBox (NULL, "Greska u registraciji klase",
                "Greska", MB_ICONERROR) ;
        return 0 ;
    }
    hwnd = CreateWindow ("Moja klasa",  // ime windows klase
            "Zadaca 1", // tekst u Window title bar-u
            WS_OVERLAPPEDWINDOW, // stil prozora
            100,              // inicijalna x koordinata
            100,              // inicijalna y koordinata
            320,              // inicijalna sirina prozora
            250,              // inicijalna visina prozora
            NULL,            // handle na vlasnika (parent) prozora
            NULL,            // window menu handle
            hInstance,     // handle na instancu aplikacije
            NULL) ;        // dodatni kreacioni parametri
    ShowWindow (hwnd, iCmdShow) ;
    UpdateWindow (hwnd) ;

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

LRESULT CALLBACK WndProc (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    static int cxClient, cyClient;
    HDC hdc;
    static PAINTSTRUCT ps;
    static RECT invalid;
    char poruka[] = "Homework";
    static SIZE sz;
    static char pismo[100];

    switch (message)
    {
        case WM_CREATE:
             hdc = GetDC(hwnd);
             GetTextExtentPoint32(hdc,poruka,strlen(poruka),&sz);
             ReleaseDC(hwnd,hdc);
             return 0;

        case WM_SIZE:
             cxClient = LOWORD(lParam);
             cyClient = HIWORD(lParam);

             return 0;

        case WM_PAINT:
             hdc = BeginPaint(hwnd,&ps);
             GetClientRect(hwnd,&invalid);
             TextOut(hdc,(cxClient - sz.cx),(cyClient -  sz.cy),poruka,strlen(poruka));
             sprintf(pismo,"The size of the invalid area is:\n x=%ld \n y=%ld " ,invalid.right,invalid.bottom);

             MessageBox (NULL, pismo,"Greska",   MB_ICONEXCLAMATION) ;
             EndPaint(hwnd,&ps);
             return 0;

        case WM_DESTROY:
             PostQuitMessage (0) ;
             return 0 ;

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

Now if you run it you will see that as soon as you try to re-size the window (unless you maximize), the message box appears so you can move only for one pixel at time.
And what I would want to is for me to be able to move it as much as I want to, and then only when I stop that it shows me the size of the invalid area.

Thanks in advance (:

Welllll you could comment out lines 81 and 83, recompile and test....see what happens...

Really... it's pretty obvious.

But then I get rid of the message box and that's not what I need. I need to re-size and still have the message box.

I've copied the wrong code here, and now I see why my question made no sense.
This was supposed to be the case:

Code:

case WM_PAINT:
            hdc = BeginPaint(hwnd,&ps);

            TextOut(hdc,(cxClient - sz.cx),(cyClient - sz.cy),poruka,strlen(poruka));
            sprintf(pismo,"Velicina invalidnog podrucija je:\n x=%d \n y=%d " ,ps.rcPaint.right-ps.rcPaint.left,ps.rcPaint.bottom-ps.rcPaint.top);

            MessageBox (NULL, pismo,"Greska", MB_ICONEXCLAMATION) ;

            EndPaint(hwnd,&ps);
            return 0;

We've figured it out today, but so thanks anyways (:

Why would not not just display the message box at the end of resizing by processing the WM_EXITSIZEMOVE message?

Message boxes in WM_PAINT are going to pop up at very unexpected times because repainting is a low priority message that is also sent in many other circumstances...

A list of windows messages and their functions is HERE