WM_KEYDOWN

#include <windows.h>

LRESULT CALLBACK WndProc(HWND,UINT,WPARAM,LPARAM);
HINSTANCE g_hInst;
LPSTR lpszClass="KeyDown";

int APIENTRY WinMain(HINSTANCE hInstance,HINSTANCE hPrevInstance
         ,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)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,0,0,0)) {
        TranslateMessage(&Message);
        DispatchMessage(&Message);
    }
    return Message.wParam;
}

LRESULT CALLBACK WndProc(HWND hWnd,UINT iMessage,WPARAM wParam,LPARAM lParam)
{
    HDC hdc;
    PAINTSTRUCT ps;
    static int x=100;        // static은 재 정의가 없다.
    static int y=100;
    switch(iMessage) {
    case WM_KEYDOWN:
        MessageBeep(0);        // Beep
        switch(wParam) {
        case VK_LEFT:        // Keyboard left arrow
            x-=8;
            break;
        case VK_RIGHT:        // right arrow
            x+=8;
            break;
        case VK_UP:            // up arrow
            y-=8;
            break;
        case VK_DOWN:        // down arrow
            y+=8;
            break;
        }
        InvalidateRect(hWnd,NULL,TRUE);        //    Windows handle, Widnows Regen full, background regen True False check
        //InvalidateRect(hWnd,NULL,FALSE);
        return 0;
    case WM_PAINT:
        hdc=BeginPaint(hWnd,&ps);
        TextOut(hdc,x,y,"A",1);        // Because number 3 argument InvalidateRect
        EndPaint(hWnd,&ps);
        return 0;
    case WM_DESTROY:
        PostQuitMessage(0);
        return 0;
    }
    return(DefWindowProc(hWnd,iMessage,wParam,lParam));
}