Рисование в окне

#include<windows.h>
#include<tchar.h>
static int x=0, y=0;
HINSTANCE hI;
int Flag;
LRESULT CALLBACK WndProc(HWND hWnd, UINT mess, WPARAM wP, LPARAM lP);
INT CALLBACK WinMain(HINSTANCE hInst, HINSTANCE hPrev, LPSTR lpCmdline, int nCmdShow)
{
    hI=hInst;
    WNDCLASSEX wc;
    wc.cbSize = sizeof(WNDCLASSEX);
    wc.style = CS_HREDRAW | CS_VREDRAW;
    wc.lpfnWndProc = WndProc;
    wc.cbClsExtra = 0;
    wc.cbWndExtra = 0;
    wc.hInstance = hInst;
    wc.hIcon = LoadIcon(NULL, IDI_APPLICATION);
    wc.hCursor = LoadCursor(NULL, IDC_ARROW);
    wc.hbrBackground = (HBRUSH)(COLOR_WINDOW+1);
    wc.lpszMenuName = NULL;
    wc.lpszClassName = _TEXT("Клас1");
    wc.hIconSm = LoadIcon(NULL, IDI_APPLICATION);
    if(!RegisterClassEx(&wc))
        MessageBox(NULL, _TEXT("no class has been registered"),_TEXT("cdfv"), NULL);
    HWND hWnd;
    hWnd = CreateWindowEx(0, _TEXT("Клас1"), _TEXT("Окно"), WS_OVERLAPPEDWINDOW, 10, 10, 500, 300, NULL, NULL, hInst, NULL);
    ShowWindow(hWnd, nCmdShow);
    MSG msg;
    while(GetMessage(&msg, NULL, 0, 0))
    {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }
    return msg.wParam;
}
LRESULT CALLBACK WndProc(HWND hWnd, UINT mess, WPARAM wP, LPARAM lP)
{
    PAINTSTRUCT ps;
    RECT rect;
    HBRUSH hBrush;
    HPEN hPen;
    HFONT hFont;
    HDC hdc;
    switch(mess)
    {
    case WM_DESTROY: {PostQuitMessage(0); break;}
    case WM_PAINT: {
        hdc=BeginPaint(hWnd,&ps);
        Ellipse(hdc,x,y,x+100,y+100);
        EndPaint(hWnd,&ps);
        break;
                   }
    case WM_LBUTTONDOWN:
        {
            x=LOWORD(lP);
            y=HIWORD(lP);
            InvalidateRect(hWnd,0,1);
            break;
 
        }
    default: return DefWindowProc(hWnd, mess, wP, lP);
    }
    return 0;
}