#include 
#include 
#include 
#include 
#include     LRESULT CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM);
int nTopXY(UINT, UINT);
int CountPoint = 0, N =0, i, tt=0;
int Pxy[40][2], p2[40][2], GrahamIndex=0;    const char* szAppName = "MyWndClass";
const int nBtn_ID = 1;
const int nBtn2_ID = 2;    char szText[60] = "點的個數";    int ccw(int x0,int y0,int x1,int y1,int x2,int y2)
{
        int dx1, dx2, dy1, dy2;
        dx1=x1-x0;
        dy1=y1-y0;                              // 第一線段的斜率 m1=dy1/dx1
        dx2=x2-x0;                              // 第二線段的斜率 m2=dy2/dx2
        dy2=y2-y0;
        if(dx1*dy2>dy1*dx2)
                return 1;
        if(dx1*dy2=0)
                        M--;
                M  ;
                temp[0]=p[M][0];
                temp[1]=p[M][1];// 將不是該凸面體的端點對調
                p[M][0]=p[i][0];
                p[M][1]=p[i][1];
                p[i][0]=temp[0];
                p[i][1]=temp[1];
        }
        return M;                                   // 傳回在凸多邊形上的頂點數
}    int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
    LPSTR lpCmdLine, int nCmdShow)
{
    WNDCLASSEX wc;
    HWND hwnd;
    MSG Msg;
    
    int wnd_W=420; 
    int wnd_H=330; 
   
    wc.cbSize        = sizeof(WNDCLASSEX);
    wc.style         = 0;
    wc.lpfnWndProc   = WndProc;
    wc.cbClsExtra    = 0;
    wc.cbWndExtra    = 0;
    wc.hInstance     = hInstance;
    wc.hIcon         = LoadIcon(NULL, IDI_APPLICATION);
    wc.hCursor       = LoadCursor(NULL, IDC_ARROW);
    wc.hbrBackground = (HBRUSH)(COLOR_WINDOW 1);
    wc.lpszMenuName  = NULL;
    wc.lpszClassName = szAppName;
    wc.hIconSm       = LoadIcon(NULL, IDI_APPLICATION);        if(!RegisterClassEx(&wc)) {
        MessageBox(NULL, "視窗類別登記失敗!", "發生錯誤!",
            MB_ICONEXCLAMATION | MB_OK);
        return 0;
    }
    
    hwnd = CreateWindowEx(
        WS_EX_CLIENTEDGE,
        szAppName,"XXX",WS_OVERLAPPEDWINDOW,
        nTopXY(wnd_W, GetSystemMetrics(SM_CXSCREEN)),
        nTopXY(wnd_H, GetSystemMetrics(SM_CYSCREEN)),
        wnd_W,wnd_H, NULL, NULL, hInstance, NULL);        if(hwnd == NULL) {
        MessageBox(NULL, "視窗建立失敗!", "發生錯誤!",MB_ICONEXCLAMATION | MB_OK);
        return 0;
    }        ShowWindow(hwnd, nCmdShow);
    UpdateWindow(hwnd);
    
    while(GetMessage(&Msg, NULL, 0, 0) > 0) {
        TranslateMessage(&Msg);
        DispatchMessage(&Msg);
    }
    return Msg.wParam;
}    LRESULT CALLBACK WndProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
        HWND hBtn, hBtn2;
        HDC hMyDC;
        PAINTSTRUCT        ps; 
        switch(msg) {
        case WM_CREATE:                              
                hBtn = CreateWindowEx(
                        WS_EX_CLIENTEDGE,TEXT("BUTTON"),"清除",
                        WS_CHILD | WS_BORDER | WS_VISIBLE | BS_DEFPUSHBUTTON ,
                        0, 0, 205, 30, hwnd,(HMENU) nBtn_ID,
                        ((LPCREATESTRUCT) lParam)->hInstance, NULL);
                
                if(hBtn == NULL) {
                        MessageBox(NULL, "按鈕建立失敗!", "發生錯誤!",
                                MB_ICONEXCLAMATION | MB_OK);
                        return 0;
                }
                
                hBtn2 = CreateWindowEx(
                        WS_EX_CLIENTEDGE,TEXT("BUTTON"),"執行",
                        WS_CHILD | WS_BORDER | WS_VISIBLE | BS_DEFPUSHBUTTON ,
                        205, 0, 205, 30, hwnd,(HMENU) nBtn2_ID,
                        ((LPCREATESTRUCT) lParam)->hInstance, NULL);
                
                if(hBtn == NULL) {
                        MessageBox(NULL, "按鈕建立失敗!", "發生錯誤!",
                                MB_ICONEXCLAMATION | MB_OK);
                        return 0;
                }
                return 0;
                break;
        
        case WM_COMMAND:
                switch(LOWORD(wParam)){
                case nBtn_ID:
                        //         SendMessage(hwnd,WM_CLOSE,0,0);
                        tt=CountPoint=N=GrahamIndex=0;
                        wsprintf(szText,"點的個數:%d",CountPoint);
                        InvalidateRect(hwnd, NULL, TRUE);
                        return 0;
                        break;
                
                case nBtn2_ID:
                        tt=1;
                        GrahamIndex=graham_scan(p2, N); 
                        InvalidateRect(hwnd, NULL, TRUE);
                        return 0;
                        break;
                }
                return 0;
                break;
                
                case WM_LBUTTONDOWN:
                        Pxy[CountPoint][0] = LOWORD(lParam);
                        p2[CountPoint][0] = LOWORD(lParam);
                        Pxy[CountPoint][1] = HIWORD(lParam);
                        p2[CountPoint][1] = 350-HIWORD(lParam);
                        CountPoint  ;
                        N = CountPoint;
                        InvalidateRect(hwnd, NULL, TRUE);
                        wsprintf(szText,"點的個數:%d",CountPoint);
                        UpdateWindow(hwnd);
                        return 0;
                        break;
                
                case WM_PAINT:
                        hMyDC=BeginPaint(hwnd, &ps);
                        for(i=0 ; i < CountPoint ; i  )
                                Ellipse(hMyDC, Pxy[i][0] 5,Pxy[i][1] 5,Pxy[i][0]-5,Pxy[i][1]-5);
                        if(tt==1) {
                                for(i=0 ; i