[핵심 API로 배우는 윈도우프로그래밍(강경우, 한빛아카데미)] 3장 8번 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;
    HPEN hPen, oldPen;
    static int startX = 20, startY = 20;
    static int oldX = 20, oldY = 20, endX, endY;
    static int mx = 0, my = 0;
    static bool Drag = false;
    static int centerX = 20, centerY = 20;
 
    switch (iMsg)
    {
    case WM_CREATE:
        break;
 
    case WM_KEYDOWN:
        break;
 
    case WM_LBUTTONDOWN:
        Drag = true;
        mx = HIWORD(lParam);
        my = LOWORD(lParam);
        //InvalidateRgn(hwnd, NULL, TRUE);
        break;
    case WM_LBUTTONUP:
        Drag = false;
        mx = LOWORD(lParam);
        my = HIWORD(lParam);
        oldX = endX = 20;
        oldY = endY = 20;
        SetTimer(hwnd, 1, 10, NULL);
        InvalidateRgn(hwnd, NULL, TRUE);
        break;
    case WM_TIMER:
        if (centerX == mx&&centerY == my)
            KillTimer(hwnd, 1);
        else
        {
            if (mx > centerX)
                centerX += 1;
            else
                centerX -= 1;
            if (my > centerY)
                centerY += 1;
            else
                centerY -= 1;
        }
        InvalidateRgn(hwnd, NULL, TRUE);
        break;
    case WM_MOUSEMOVE:
        hdc = GetDC(hwnd);
 
        if (Drag)
        {
            SetROP2(hdc, R2_XORPEN);                                //XOR을 래스터 연산으로 설정
            SelectObject(hdc, (HPEN)GetStockObject(WHITE_PEN));        //hdc에 흰색펜을 등록
            //SelectObject(hdc, (HBRUSH)GetStockObject(BLACK_BRUSH)); //hdc에 검은색 브러시를 등록
            endX = LOWORD(lParam);
            endY = HIWORD(lParam);
 
            MoveToEx(hdc, startX, startY, NULL);
            LineTo(hdc, oldX, oldY);
            MoveToEx(hdc, startX, startY, NULL);
            LineTo(hdc, endX, endY);
            oldX = endX;
            oldY = endY;
            //InvalidateRgn(hwnd, NULL, TRUE); 깜빡임 방지
        }
        ReleaseDC(hwnd, hdc);
        break;
    case WM_PAINT:
        hdc = BeginPaint(hwnd, &ps);
        Ellipse(hdc, centerX-20, centerY-20, centerX+20, centerY+20);
        MoveToEx(hdc, startX, startY, NULL);
        LineTo(hdc, oldX, oldY);
 
        EndPaint(hwnd, &ps);
        break;
    case WM_DESTROY:
        PostQuitMessage(0);
        break;
 
    }
    return DefWindowProc(hwnd, iMsg, wParam, lParam);
}