凸包算法(Graham算法）实现，带图形

// 凸包.cpp : 定义应用程序的入口点。//#include "stdafx.h"#include "凸包.h"using namespace std;#define MAX_LOADSTRING 100#define MAXPOINTS 13// 全局变量:HINSTANCE hInst;// 当前实例TCHAR szTitle[MAX_LOADSTRING];// 标题栏文本TCHAR szWindowClass[MAX_LOADSTRING];// 主窗口类名typedef vector<POINT> PTARRAY;PTARRAY vecSrc;// 此代码模块中包含的函数的前向声明:ATOMMyRegisterClass(HINSTANCE hInstance);BOOLInitInstance(HINSTANCE, int);LRESULT CALLBACKWndProc(HWND, UINT, WPARAM, LPARAM);INT_PTR CALLBACKAbout(HWND, UINT, WPARAM, LPARAM);//判断两个点是否相等bool operator==(const POINT &pt1,const POINT & pt2){return (pt1.x==pt2.x &&pt1.y==pt2.y );}bool CompareVector(const POINT & pt1,const POINT & pt2){float m1=sqrt((float)(pt1.x *pt1.x +pt1.y *pt1.y));float m2=sqrt((float)(pt2.x *pt2.x +pt2.y *pt2.y));//两个向量分别与(1,0)求内积float v1=pt1.x /m1,v2=pt2.x /m2;return (v1>v2||v1==v2&&m1<m2);}void CalConvexHULL(PTARRAY &vecSrc){if(vecSrc.size ()<3){return ;}//查找基点POINT ptBase=vecSrc.front ();//将第一个点预设为最小的for(PTARRAY::iterator i =vecSrc.begin ()+1;i!=vecSrc.end ();i++){if(i->y <ptBase.y ||(i->y ==ptBase.y &&i->x <ptBase.x))ptBase=*i;}//计算出各点与基点构成的向量for(PTARRAY::iterator i=vecSrc.begin ();i!=vecSrc.end ();){if(*i==ptBase){i=vecSrc.erase (i);}else{i->x-=ptBase.x;i->y-=ptBase.y;i++;}}sort(vecSrc.begin(),vecSrc.end (),&CompareVector);vecSrc.erase (unique(vecSrc.begin (),vecSrc.end()),vecSrc.end ());//计算得到首尾依次相连的向量for(PTARRAY::reverse_iterator ri=vecSrc.rbegin ();ri!=vecSrc.rend ()-1;ri++){PTARRAY::reverse_iterator riNext=ri+1;ri->x -=riNext->x;ri->y -=riNext->y;}for(PTARRAY::iterator i=vecSrc.begin ()+1;i!=vecSrc.end();i++){for(PTARRAY::iterator iLast=i-1;iLast!=vecSrc.begin();){//计算叉积int v1=i->x *iLast->y;int v2=i->y *iLast->x;if(v1<v2||(v1==v2&&i->x*iLast->x >0&&i->y *iLast->y >0)){break;}i->x +=iLast->x;i->y +=iLast->y;iLast=(i=vecSrc.erase (iLast))-1;}}vecSrc.front ().x+=ptBase.x;vecSrc.front ().y+=ptBase.y;for(PTARRAY::iterator i=vecSrc.begin ()+1;i!=vecSrc.end ();i++){i->x +=(i-1)->x;i->y+=(i-1)->y;}vecSrc.push_back (ptBase);}int APIENTRY _tWinMain(HINSTANCE hInstance,                     HINSTANCE hPrevInstance,                     LPTSTR    lpCmdLine,                     int       nCmdShow){UNREFERENCED_PARAMETER(hPrevInstance);UNREFERENCED_PARAMETER(lpCmdLine); // TODO: 在此放置代码。MSG msg;HACCEL hAccelTable;// 初始化全局字符串LoadString(hInstance, IDS_APP_TITLE, szTitle, MAX_LOADSTRING);LoadString(hInstance, IDC_MY, szWindowClass, MAX_LOADSTRING);MyRegisterClass(hInstance);// 执行应用程序初始化:if (!InitInstance (hInstance, nCmdShow)){return FALSE;}hAccelTable = LoadAccelerators(hInstance, MAKEINTRESOURCE(IDC_MY));// 主消息循环:while (GetMessage(&msg, NULL, 0, 0)){if (!TranslateAccelerator(msg.hwnd, hAccelTable, &msg)){TranslateMessage(&msg);DispatchMessage(&msg);}}return (int) msg.wParam;}////  函数: MyRegisterClass()////  目的: 注册窗口类。////  注释:////    仅当希望//    此代码与添加到 Windows 95 中的“RegisterClassEx”//    函数之前的 Win32 系统兼容时，才需要此函数及其用法。调用此函数十分重要，//    这样应用程序就可以获得关联的//    “格式正确的”小图标。//ATOM MyRegisterClass(HINSTANCE hInstance){WNDCLASSEX wcex;wcex.cbSize = sizeof(WNDCLASSEX);wcex.style= CS_HREDRAW | CS_VREDRAW;wcex.lpfnWndProc= WndProc;wcex.cbClsExtra= 0;wcex.cbWndExtra= 0;wcex.hInstance= hInstance;wcex.hIcon= LoadIcon(hInstance, MAKEINTRESOURCE(IDI_MY));wcex.hCursor= LoadCursor(NULL, IDC_ARROW);wcex.hbrBackground= (HBRUSH)(COLOR_WINDOW+1);wcex.lpszMenuName= MAKEINTRESOURCE(IDC_MY);wcex.lpszClassName= szWindowClass;wcex.hIconSm= LoadIcon(wcex.hInstance, MAKEINTRESOURCE(IDI_SMALL));return RegisterClassEx(&wcex);}////   函数: InitInstance(HINSTANCE, int)////   目的: 保存实例句柄并创建主窗口////   注释:////        在此函数中，我们在全局变量中保存实例句柄并//        创建和显示主程序窗口。//BOOL InitInstance(HINSTANCE hInstance, int nCmdShow){   HWND hWnd;   hInst = hInstance; // 将实例句柄存储在全局变量中   hWnd = CreateWindow(szWindowClass, szTitle, WS_OVERLAPPEDWINDOW,      CW_USEDEFAULT, 0, CW_USEDEFAULT, 0, NULL, NULL, hInstance, NULL);   if (!hWnd)   {      return FALSE;   }   ShowWindow(hWnd, nCmdShow);   UpdateWindow(hWnd);   return TRUE;}////  函数: WndProc(HWND, UINT, WPARAM, LPARAM)////  目的: 处理主窗口的消息。////  WM_COMMAND- 处理应用程序菜单//  WM_PAINT- 绘制主窗口//  WM_DESTROY- 发送退出消息并返回////LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam){int wmId, wmEvent;PAINTSTRUCT ps;HDC hdc;HPEN pen,oldPen;HBRUSH brush,oldBrush;static int iCount=0;switch (message){case WM_LBUTTONDOWN:if(iCount<MAXPOINTS){POINT point;point.x=LOWORD(lParam);point.y=HIWORD(lParam);vecSrc.push_back (point);iCount++;hdc=GetDC(hWnd);brush=CreateSolidBrush(RGB(255,0,0));oldBrush=(HBRUSH)SelectObject(hdc,brush);Ellipse(hdc,LOWORD(lParam)-5,HIWORD(lParam)-5,LOWORD(lParam)+5,HIWORD(lParam)+5);SelectObject(hdc,oldBrush);DeleteObject(brush);ReleaseDC(hWnd,hdc);}else{InvalidateRect(hWnd,NULL,false);}break;case WM_COMMAND:wmId    = LOWORD(wParam);wmEvent = HIWORD(wParam);// 分析菜单选择:switch (wmId){case IDM_ABOUT:DialogBox(hInst, MAKEINTRESOURCE(IDD_ABOUTBOX), hWnd, About);break;case IDM_EXIT:DestroyWindow(hWnd);break;default:return DefWindowProc(hWnd, message, wParam, lParam);}break;case WM_PAINT:hdc = BeginPaint(hWnd, &ps);// TODO: 在此添加任意绘图代码...if(iCount>0){CalConvexHULL(vecSrc);pen=CreatePen(PS_SOLID,2,RGB(0,255,0));oldPen=(HPEN)SelectObject(hdc,pen);MoveToEx(hdc,vecSrc[0].x,vecSrc[0].y,NULL);for(PTARRAY::iterator  i=vecSrc.begin ()+1;i!=vecSrc.end();i++){LineTo(hdc,i->x,i->y);}LineTo(hdc,vecSrc[0].x ,vecSrc[0].y);SelectObject(hdc,oldPen);}EndPaint(hWnd, &ps);break;case WM_DESTROY:PostQuitMessage(0);break;default:return DefWindowProc(hWnd, message, wParam, lParam);}return 0;}// “关于”框的消息处理程序。INT_PTR CALLBACK About(HWND hDlg, UINT message, WPARAM wParam, LPARAM lParam){UNREFERENCED_PARAMETER(lParam);switch (message){case WM_INITDIALOG:return (INT_PTR)TRUE;case WM_COMMAND:if (LOWORD(wParam) == IDOK || LOWORD(wParam) == IDCANCEL){EndDialog(hDlg, LOWORD(wParam));return (INT_PTR)TRUE;}break;}return (INT_PTR)FALSE;}

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