Ciao.
Io mi sto studiando le API WIN32 che sono in puro C, ma dovrebbero avere molto in comune con le MFC, essendo quest'ultime un'evoluzione ad oggetti delle prime. Ancora non ho trattato l'argomento, ma se ti interessa ti riporto un esempio preso dal famoso libro di Charles Petzold che tramite uso di timer genera un orologio con tanto di lancette (giusto per farti un'idea):
/*--------------------------------------
CLOCK.C -- Analog Clock Program
(c) Charles Petzold, 1998
--------------------------------------*/
#include <windows.h>
#include <math.h>
#define ID_TIMER 1
#define TWOPI (2 * 3.14159)
LRESULT CALLBACK WndProc (HWND, UINT, WPARAM, LPARAM) ;
int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance,
PSTR szCmdLine, int iCmdShow)
{
static TCHAR szAppName[] = TEXT ("Clock") ;
HWND hwnd;
MSG msg;
WNDCLASS wndclass ;
wndclass.style = CS_HREDRAW | CS_VREDRAW ;
wndclass.lpfnWndProc = WndProc ;
wndclass.cbClsExtra = 0 ;
wndclass.cbWndExtra = 0 ;
wndclass.hInstance = hInstance ;
wndclass.hIcon = NULL ;
wndclass.hCursor = LoadCursor (NULL, IDC_ARROW) ;
wndclass.hbrBackground = (HBRUSH) GetStockObject (WHITE_BRUSH) ;
wndclass.lpszMenuName = NULL ;
wndclass.lpszClassName = szAppName ;
if (!RegisterClass (&wndclass))
{
MessageBox (NULL, TEXT ("Program requires Windows NT!"),
szAppName, MB_ICONERROR) ;
return 0 ;
}
hwnd = CreateWindow (szAppName, TEXT ("Analog Clock"),
WS_OVERLAPPEDWINDOW,
CW_USEDEFAULT, CW_USEDEFAULT,
CW_USEDEFAULT, CW_USEDEFAULT,
NULL, NULL, hInstance, NULL) ;
ShowWindow (hwnd, iCmdShow) ;
UpdateWindow (hwnd) ;
while (GetMessage (&msg, NULL, 0, 0))
{
TranslateMessage (&msg) ;
DispatchMessage (&msg) ;
}
return msg.wParam ;
}
void SetIsotropic (HDC hdc, int cxClient, int cyClient)
{
SetMapMode (hdc, MM_ISOTROPIC) ;
SetWindowExtEx (hdc, 1000, 1000, NULL) ;
SetViewportExtEx (hdc, cxClient / 2, -cyClient / 2, NULL) ;
SetViewportOrgEx (hdc, cxClient / 2, cyClient / 2, NULL) ;
}
void RotatePoint (POINT pt[], int iNum, int iAngle)
{
int i ;
POINT ptTemp ;
for (i = 0 ; i < iNum ; i++)
{
ptTemp.x = (int) (pt[i].x * cos (TWOPI * iAngle / 360) +
pt[i].y * sin (TWOPI * iAngle / 360)) ;
ptTemp.y = (int) (pt[i].y * cos (TWOPI * iAngle / 360) -
pt[i].x * sin (TWOPI * iAngle / 360)) ;
pt[i] = ptTemp ;
}
}
void DrawClock (HDC hdc)
{
int iAngle ;
POINT pt[3] ;
for (iAngle = 0 ; iAngle < 360 ; iAngle += 6)
{
pt[0].x = 0 ;
pt[0].y = 900 ;
RotatePoint (pt, 1, iAngle) ;
pt[2].x = pt[2].y = iAngle % 5 ? 33 : 100 ;
pt[0].x -= pt[2].x / 2 ;
pt[0].y -= pt[2].y / 2 ;
pt[1].x = pt[0].x + pt[2].x ;
pt[1].y = pt[0].y + pt[2].y ;
SelectObject (hdc, GetStockObject (BLACK_BRUSH)) ;
Ellipse (hdc, pt[0].x, pt[0].y, pt[1].x, pt[1].y) ;
}
}
void DrawHands (HDC hdc, SYSTEMTIME * pst, BOOL fChange)
{
static POINT pt[3][5] = { 0, -150, 100, 0, 0, 600, -100, 0, 0, -150,
0, -200, 50, 0, 0, 800, -50, 0, 0, -200,
0, 0, 0, 0, 0, 0, 0, 0, 0, 800 } ;
int i, iAngle[3] ;
POINT ptTemp[3][5] ;
iAngle[0] = (pst->wHour * 30) % 360 + pst->wMinute / 2 ;
iAngle[1] = pst->wMinute * 6 ;
iAngle[2] = pst->wSecond * 6 ;
memcpy (ptTemp, pt, sizeof (pt)) ;
for (i = fChange ? 0 : 2 ; i < 3 ; i++)
{
RotatePoint (ptTemp[i], 5, iAngle[i]) ;
Polyline (hdc, ptTemp[i], 5) ;
}
}
LRESULT CALLBACK WndProc (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
static int cxClient, cyClient ;
static SYSTEMTIME stPrevious ;
BOOL fChange ;
HDC hdc ;
PAINTSTRUCT ps ;
SYSTEMTIME st ;
switch (message)
{
case WM_CREATE :
SetTimer (hwnd, ID_TIMER, 1000, NULL) ;
GetLocalTime (&st) ;
stPrevious = st ;
return 0 ;
case WM_SIZE :
cxClient = LOWORD (lParam) ;
cyClient = HIWORD (lParam) ;
return 0 ;
case WM_TIMER :
GetLocalTime (&st) ;
fChange = st.wHour != stPrevious.wHour ||
st.wMinute != stPrevious.wMinute ;
hdc = GetDC (hwnd) ;
SetIsotropic (hdc, cxClient, cyClient) ;
SelectObject (hdc, GetStockObject (WHITE_PEN)) ;
DrawHands (hdc, &stPrevious, fChange) ;
SelectObject (hdc, GetStockObject (BLACK_PEN)) ;
DrawHands (hdc, &st, TRUE) ;
ReleaseDC (hwnd, hdc) ;
stPrevious = st ;
return 0 ;
case WM_PAINT :
hdc = BeginPaint (hwnd, &ps) ;
SetIsotropic (hdc, cxClient, cyClient) ;
DrawClock (hdc) ;
DrawHands (hdc, &stPrevious, TRUE) ;
EndPaint (hwnd, &ps) ;
return 0 ;
case WM_DESTROY :
KillTimer (hwnd, ID_TIMER) ;
PostQuitMessage (0) ;
return 0 ;
}
return DefWindowProc (hwnd, message, wParam, lParam) ;
}