Can't use "SaveDC" and "RestoreDC" function in other message handling code?

I am trying to set my preferred device context properties in a message WM_CREATE

and then use it in a message WM_PAINT

. My method is to use the features SaveDC

and RestoreDC

in reports WM_CREATE

, and WM_PAINT

, respectively. But the result doesn't match my need. I really need to show a circle in the center of the client area.

#include <windows.h>

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

int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance,
                    PSTR szCmdLine, int iCmdShow)
{
     static TCHAR szAppName[] = TEXT ("HelloWin") ;
     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         = LoadIcon (NULL, IDI_APPLICATION) ;
     wndclass.hCursor       = LoadCursor (NULL, IDC_ARROW) ;
     wndclass.hbrBackground = (HBRUSH) GetStockObject (WHITE_BRUSH) ;
     wndclass.lpszMenuName  = NULL ;
     wndclass.lpszClassName = szAppName ;

     if (!RegisterClass (&wndclass))
     {
          MessageBox (NULL, TEXT ("This program requires Windows NT!"), 
                      szAppName, MB_ICONERROR) ;
          return 0 ;
     }

     hwnd = CreateWindow (szAppName,                  // window class name
                          TEXT ("The Hello Program"), // window caption
                          WS_OVERLAPPEDWINDOW,        // window style
                          CW_USEDEFAULT,              // initial x position
                          CW_USEDEFAULT,              // initial y position
                          CW_USEDEFAULT,              // initial x size
                          CW_USEDEFAULT,              // initial y size
                          NULL,                       // parent window handle
                          NULL,                       // window menu handle
                          hInstance,                  // program instance handle
                          NULL) ;                     // creation parameters

     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)
{
     HDC         hdc ;
     PAINTSTRUCT ps ;
     RECT rect;
     static int nSavedDC;

     switch (message)
     {          
     case WM_CREATE:
         hdc = GetDC(hwnd);
         SetMapMode(hdc, MM_LOMETRIC);
         GetClientRect(hwnd, &rect);
         SetViewportOrgEx(hdc, rect.right/2, rect.bottom/2, NULL);
         nSavedDC = SaveDC(hdc);         //I want to save the current state of device context to be used in WM_PAINT message.
         ReleaseDC(hwnd, hdc);
         return 0;

     case WM_PAINT:
          hdc = BeginPaint (hwnd, &ps) ;
          RestoreDC(hdc, nSavedDC);       //Restore the the state of device context which is saved in WM_CREATE message.
          Ellipse(hdc, -100, 100, 100, -100);
          EndPaint (hwnd, &ps) ;
          return 0 ;

     case WM_DESTROY:
          PostQuitMessage (0) ;
          return 0 ;
     }
     return DefWindowProc (hwnd, message, wParam, lParam) ;
}