[핵심 API로 배우는 윈도우프로그래밍(강경우, 한빛아카데미)] 3장 4번 풀이

#include <Windows.h>
#include<tchar.h>
#include<string.h>
#include<math.h>
LRESULT CALLBACK WndProc(HWND hwnd, UINT iMsg, WPARAM wParam, LPARAM lParam);
 
int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpszCmdLine, int nCmdShow)
{
    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 = _T("Window Class Name");
 
    RegisterClass(&WndClass); //윈도우 클래스를 커널에 등록
 
    hwnd = CreateWindow( //윈도우 핸들값 반환
        _T("Window Class Name"), //윈도우 클래스 이름
        _T("홍길동의 첫 번째 윈도우"), //윈도우 타이틀이름
        WS_OVERLAPPEDWINDOW, //윈도우 스타일
        100, //윈도우 위치 x좌표
        100,//윈도우 위치 y좌표
        1000, //윈도우 가로크기
        1000, //윈도우 세로크기
        NULL, //부모 윈도우핸들
        NULL, //메뉴핸들
        hInstance, //응용프로그램 인스턴스
        NULL); //생성 윈도우 정보
 
    ShowWindow(hwnd, nCmdShow);
    UpdateWindow(hwnd);
 
    while (GetMessage(&msg, NULL, 0, 0))
    {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }
    return (int)msg.wParam;
}
 
LRESULT CALLBACK WndProc(HWND hwnd, UINT iMsg, WPARAM wParam, LPARAM lParam)
{
    HDC hdc;
    PAINTSTRUCT ps;
    static int headX = 60, headY = 20;
    static int tailX = 20, tailY = 20;
 
    static RECT rectView;
    static bool isGoing = false;
    static int Direction = 1;
    HPEN hPen, oldPen;
 
    switch (iMsg)
    {
    case WM_CREATE:
        GetClientRect(hwnd, &rectView); //윈도우 클라이언트 영역을 계산해 RECT변수에 저장
        break;
 
    case WM_KEYDOWN:
        if (wParam == VK_RIGHT && (tailX + 60) <= 600)
        {
            headX = tailX + 40;
            headY = tailY;
            Direction = 1;
        }
        else if (wParam == VK_LEFT && (tailX - 60) >= 0)
        {
            headX = tailX - 40;
            headY = tailY;
            Direction = 3;
        }
        else if (wParam == VK_UP && (tailY - 60) >= 0)
        {
            headX = tailX;
            headY = tailY-40;
            Direction = 4;
        }
        else if (wParam == VK_DOWN && (tailY + 60) <= 600)
        {
            headX = tailX;
            headY = tailY+40;
            Direction = 2;
        }
        if (wParam == VK_RETURN)
        {
            if (isGoing) isGoing = false;
            else isGoing = true;
 
            if (isGoing)
                SetTimer(hwnd, 1, 10, NULL);
            else
                KillTimer(hwnd, 1);
            InvalidateRgn(hwnd, NULL, TRUE);
            break;
        }
        InvalidateRgn(hwnd, NULL, TRUE);
        break;
 
    case WM_TIMER:
        if (Direction == 1 && (headX + 20) < 600) //오른
        {
            headX += 2;
            tailX = headX - 40;
        }
        else if (Direction == 3 && (headX - 20) > 0) //왼
        {
            headX -= 2;
            tailX = headX + 40;
        }
        else if (Direction == 4 && (headY - 20) > 0) //위
        {
            headY -= 2;
            tailY = headY + 40;
        }
        else if (Direction == 2 && (headY + 20) < 600) //아래
        {
            headY += 2;
            tailY = headY - 40;
        }
        InvalidateRgn(hwnd, NULL, TRUE);
        break;
 
    case WM_PAINT:
        hdc = BeginPaint(hwnd, &ps);
        Rectangle(hdc, 0, 0, 600, 600);
 
        hPen = CreatePen(PS_SOLID, 1, RGB(255, 0, 0)); //머리
        oldPen = (HPEN)SelectObject(hdc, hPen);    
        Ellipse(hdc, headX - 20, headY - 20, headX + 20, headY + 20);
        SelectObject(hdc, oldPen);                            
 
        hPen = CreatePen(PS_SOLID, 1, RGB(0, 0, 255)); //꼬리
        oldPen = (HPEN)SelectObject(hdc, hPen);        
        Ellipse(hdc, tailX - 20, tailY - 20, tailX + 20, tailY + 20);
        SelectObject(hdc, oldPen);                            
 
        
        DeleteObject(hPen);                            
        EndPaint(hwnd, &ps);
        break;
    case WM_DESTROY:
        PostQuitMessage(0);
        break;
 
    }
    return DefWindowProc(hwnd, iMsg, wParam, lParam);
}