키 입력과 무효 영역

#include<windows.h>

LRESULT CALLBACK WndProc(HWND,UINT,WPARAM,LPARAM);
HINSTANCE g_hInst;
LPCTSTR lpszClass=TEXT("first");

int APIENTRY WinMain(HINSTANCE hInstance,HINSTANCE hPrevlnstance, LPSTR lpszCmdParam, int nCmdShow)
{
 HWND hWnd;
 MSG Message;
 WNDCLASS WndClass;
 g_hInst=hInstance;
 
 WndClass.cbClsExtra=0;
 WndClass.cbWndExtra=0;
 WndClass.hbrBackground=(HBRUSH)GetStockObject(WHITE_BRUSH);
 WndClass.hCursor=LoadCursor(NULL,IDC_ARROW);
 WndClass.hIcon=LoadIcon(NULL,IDI_APPLICATION);
 WndClass.hInstance=hInstance;
 WndClass.lpfnWndProc=WndProc;
 WndClass.lpszClassName=lpszClass;
 WndClass.lpszMenuName=NULL;
 WndClass.style=CS_HREDRAW|CS_VREDRAW;
 RegisterClass(&WndClass);
 
 hWnd=CreateWindow(lpszClass,lpszClass,WS_OVERLAPPEDWINDOW,CW_USEDEFAULT,CW_USEDEFAULT,CW_USEDEFAULT,CW_USEDEFAULT,NULL,
  (HMENU)NULL,hInstance,NULL);
 
 ShowWindow(hWnd,nCmdShow);
 
 while(GetMessage(&Message,NULL,0,0))
 {
  TranslateMessage(&Message);
  DispatchMessage(&Message);
 }
 return (int)Message.wParam;
}

LRESULT CALLBACK WndProc(HWND hWnd,UINT iMessage,WPARAM WParam,LPARAM IParam)
{
 HDC hdc;
 PAINTSTRUCT ps;
 static TCHAR str[256];
 int len=0;
 static int x = 100;
 static int y = 100;
 switch(iMessage)
 {
  case WM_DESTROY:
   PostQuitMessage(0);
   return 0;
   

  case WM_KEYDOWN:
   switch(WParam){
   case VK_UP:
    y-=15;
    break;
   case VK_DOWN:
    y+=15;
    break;
   case VK_LEFT:
    x-=15;
    break;
   case VK_RIGHT:
    x+=15;
    break;

   }
  //무효영역

  InvalidateRect(hWnd,NULL,FALSE); // 덧붙이기
  //InvalidateRect(hWnd,NULL,TRUE); 전체 갱신
  return 0;

  case WM_PAINT:
   hdc = BeginPaint(hWnd,&ps);
   TextOut(hdc,x,y,"A",1);
   EndPaint(hWnd,&ps);
   return 0;
 }
 return(DefWindowProc(hWnd,iMessage,WParam,IParam));
}