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

#include <Windows.h>
#include<tchar.h>
#include<string.h>
#include<math.h>
#include"resource.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");
    WndClass.lpszMenuName = MAKEINTRESOURCE(IDR_MENU1);
 
    RegisterClass(&WndClass);
 
    hwnd = CreateWindow(
        _T("Window Class Name"),
        _T("홍길동의 첫 번째 윈도우"),
        WS_OVERLAPPEDWINDOW,
        100,
        100,
        1000,
        1000,
        NULL,
        NULL,
        hInstance,
        NULL);
 
    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 HMENU hMenu, hSubMenu;
    static int answer;
    static int centerX[10], centerY[10];
    static int circleCount = 0;
    static int mX, mY;
    static bool isClick = false;
    static bool isCopy = false;
    static bool inCircle = false;
    switch (iMsg)
    {
    case WM_CREATE:
        hMenu = GetMenu(hwnd);
        centerX[0] = 20;
        centerY[0] = 20;
        hSubMenu = GetSubMenu(hMenu, 1);
        EnableMenuItem(hSubMenu, ID_EDITCOPY, MF_GRAYED);
        EnableMenuItem(hSubMenu, ID_EDITPASTE, MF_GRAYED);
        InvalidateRgn(hwnd, NULL, TRUE);
        break;
    case WM_COMMAND:
        switch (LOWORD(wParam))
        {
        case ID_EDITUNDO:        //편집취소
            answer=MessageBox(hwnd, _T("편집을 취소 하시겠습니까?"), _T("편집취소 선택"), MB_OKCANCEL);
            if (answer == IDOK)
            {
                circleCount--;
                InvalidateRgn(hwnd, NULL, TRUE);
            }
            break;
        case ID_EDITCOPY:
            isCopy = true;
            InvalidateRgn(hwnd, NULL, TRUE);
            break;
        case ID_EDITPASTE:
            isCopy = false;
            isClick = false;
            if(circleCount<9)
            circleCount++;
            centerX[circleCount] = centerX[circleCount - 1] + 50;
            centerY[circleCount] = centerY[circleCount - 1] + 50;
            InvalidateRgn(hwnd, NULL, TRUE);
            break;
        case ID_EXIT:            //끝내기
            answer = MessageBox(hwnd, _T("끝내시겠습니까?"), _T("끝내기 선택"), MB_OKCANCEL);
            if (answer == IDOK)
                PostQuitMessage(0);
            break;
        }
        break;
    case WM_LBUTTONDOWN:
        mX = LOWORD(lParam);
        mY = HIWORD(lParam);
        for (int i = 0; i <= circleCount; i++)
        {
            if (pow(mX - centerX[i], 2) + pow(mY - centerY[i], 2) < 400)
            {
                isClick = true;
                break;
            }
        }
        InvalidateRgn(hwnd, NULL, TRUE);
        break;
    case WM_PAINT:
        hdc = BeginPaint(hwnd, &ps);
        EnableMenuItem(hSubMenu, ID_EDITCOPY, isClick ? MF_ENABLED : MF_GRAYED);
        EnableMenuItem(hSubMenu, ID_EDITPASTE, isCopy ? MF_ENABLED : MF_GRAYED);
        for (int i = 0; i <= circleCount; i++)
            Ellipse(hdc, centerX[i] - 20, centerY[i] - 20, centerX[i] + 20, centerY[i] + 20);
        EndPaint(hwnd, &ps);
        break;
    case WM_DESTROY:
        PostQuitMessage(0);
        break;
 
    }
    return DefWindowProc(hwnd, iMsg, wParam, lParam);
}