在hellowrold程序基础上绘制一个圆

只需修改OnPaint方法

LONG OnPaint(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
 PAINTSTRUCT ps;
 HDC hdc;
 RECT rect;

 HPEN hpen;

 GetClientRect(hWnd,&rect);
 hdc = BeginPaint(hWnd,&ps);
  //hpen = GetStockPen(BLACK_PEN);     //两种创建画笔的方法
 hpen = CreatePen(PS_SOLID,2,RGB(0XFF,0X00,0X00));
 HGDIOBJ oldpen = SelectObject(hdc,hpen);
 Ellipse(hdc,10,10,200,200);
 SelectObject(hdc,oldpen);
 DeleteObject(hpen);

 EndPaint(hWnd,&ps);
 return TRUE;
}