[핵심 API로 배우는 윈도우프로그래밍(강경우, 한빛아카데미)] 3장 9번 풀이(미완성)

#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
        1200, //윈도우 가로크기
        700, //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 centerX = 0, mX = 0, centerY = 0, mY = 0;
    static bool InCircle = false;
    static bool Drag= false;
    HBRUSH hBrush, orgBrush;
    static int red[30] = { 0, }, green[30] = { 255, }, blue[30] = { 0, };
    static int x[30], y[30], R[30];
 
    switch (iMsg)
    {
    case WM_CREATE:
        for (int i = 0; i < 30; i++)
        {
            red[i] = 0;
            green[i] = 255;
            blue[i] = 0;
            x[i] = rand() % 1200;
            y[i] = rand() % 700;
            R[i] = rand() % 70 + 10;
        }
        SetTimer(hwnd, 1, 100, NULL);
        break;
 
    case WM_KEYDOWN:
        break;
    case WM_LBUTTONDOWN:
        Drag = true;
        mX = LOWORD(lParam);    
        mY = HIWORD(lParam);
 
        if ((pow(mX - centerX, 2) + pow(mY - centerY, 2)) < pow(50, 2))
            InCircle = true;
 
        InvalidateRgn(hwnd, NULL, TRUE);
        break;
    case WM_LBUTTONUP:
        mX = LOWORD(lParam);
        mY = HIWORD(lParam);
 
        InCircle = false;
        Drag = false;
        InvalidateRgn(hwnd, NULL, TRUE);
        break;
    case WM_TIMER:
        //InvalidateRgn(hwnd, NULL, TRUE);
        break;
    case WM_MOUSEMOVE:
        if (InCircle)
        {
            centerX = mX = LOWORD(lParam);
            centerY = mY = HIWORD(lParam);
        }
        for (int i = 0; i < 30; i++)
        {
            if (pow(centerX - x[i], 2) + pow(centerY - y[i], 2) < pow(50 + R[i], 2))
            {
                red[i] = 255;
                green[i] = 0;
                blue[i] = 0;
            }
        }
        InvalidateRgn(hwnd, NULL, TRUE);
        break;
    case WM_PAINT:
        hdc = BeginPaint(hwnd, &ps);
        orgBrush= CreateSolidBrush(RGB(255,255,255));
        for (int i = 0; i < 30; i++)
        {
            hBrush = CreateSolidBrush(RGB(red[i], green[i], blue[i]));        
            SelectObject(hdc, hBrush);        
            //SelectObject(hdc, (HBRUSH)GetStockObject(RGB(0, 255, 0)));
            Ellipse(hdc, x[i] - R[i], y[i]- R[i], x[i] + R[i], y[i]+ R[i]);
        }
        SelectObject(hdc, orgBrush);                
        Ellipse(hdc, centerX - 50, centerY - 50, centerX + 50, centerY + 50); //주인공
 
 
        DeleteObject(hBrush);                
        EndPaint(hwnd, &ps);
        break;
    case WM_DESTROY:
        PostQuitMessage(0);
        break;
 
    }
    return DefWindowProc(hwnd, iMsg, wParam, lParam);
}