一、解析几何知识
以(0,0)为圆心，半径为100的圆，它的内接五边形就是它均分五等分的点连起来，坐标(x, y)分别为(100*sin(72°), 100*cos(72°))、(100*sin(72°*2), 100*cos(72°*2))……
二、重要函数介绍
1.BOOL Polyline(HDChdc,CONST POINT*lppt,intcPoints)
function：使用当前画笔描绘一系列线段
hdc：进行绘图的设备场景
lppt：CONST POINT结构体指针，用来表示X,Y坐标
cPoints：表示要连接几个点
2.BOOL PolyLineTo(HDC hdc, CONST POINT * apt, DWORD cpt);
function：使用目前位置作为开始点，并将目前位置设定为最后一根线的终点；如果不设置起点，默认是(0,0)为开始点
3.BOOL POLYGON(HDC HDC, CONST POINT *LPPOINTS, INT NCOUNT)；
function：使用当前画刷填充多边形
三、代码实现
#include "stdafx.h"#include "stdio.h"HINSTANCE hInst;HPEN hPen;HBRUSH hBru;POINT poly1[5],poly2[5],poly3[5];ATOMMyRegisterClass(HINSTANCE hInstance);BOOLInitInstance(HINSTANCE, int);LRESULT CALLBACKWndProc(HWND, UINT, WPARAM, LPARAM);voidMyPaint(HDC hdc);voidMyPaint1(HDC hdc,LPARAM lparam);int APIENTRY WinMain(HINSTANCE hInstance,HINSTANCE hPrevInstance,LPSTRlpCmdLine,int nCmdShow){MSG msg;MyRegisterClass(hInstance);if (!InitInstance (hInstance, nCmdShow)) {return FALSE;}while (GetMessage(&msg, NULL, 0, 0)) {TranslateMessage(&msg);DispatchMessage(&msg);}return msg.wParam;}ATOM MyRegisterClass(HINSTANCE hInstance){WNDCLASSEX wcex;wcex.cbSize = sizeof(WNDCLASSEX); wcex.style= CS_HREDRAW | CS_VREDRAW;wcex.lpfnWndProc= (WNDPROC)WndProc;wcex.cbClsExtra= 0;wcex.cbWndExtra= 0;wcex.hInstance= hInstance;wcex.hIcon= NULL;wcex.hCursor= NULL;wcex.hCursor= LoadCursor(NULL, IDC_ARROW);wcex.hbrBackground= (HBRUSH)(COLOR_WINDOW+1);wcex.lpszMenuName= NULL;wcex.lpszClassName= "canvas";wcex.hIconSm= NULL;return RegisterClassEx(&wcex);}BOOL InitInstance(HINSTANCE hInstance, int nCmdShow){HWND hWnd;HDC hdc;int i;const double pi = 3.1415926535;hInst = hInstance;hWnd = CreateWindow("canvas", "绘图窗口" , WS_OVERLAPPEDWINDOW,CW_USEDEFAULT, 0, CW_USEDEFAULT, 0, NULL, NULL, hInstance, NULL);if (!hWnd){return FALSE;}MoveWindow(hWnd,10,10,600,450,true);ShowWindow(hWnd, nCmdShow);UpdateWindow(hWnd);for(i=0;i<=4;i++){poly1[i].x = 100 + 100 * sin(i*72*pi/180);//初始化顶点数组poly1[i].y = 100 + 100 * cos(i*72*pi/180);poly2[i].x = poly1[i].x + 300;poly2[i].y = poly1[i].y;poly3[i].x = poly1[i].x + 180;poly3[i].y = poly1[i].y + 200;}hPen = CreatePen(PS_SOLID,5,RGB(255,0,0));hBru = CreateHatchBrush(HS_BDIAGONAL,RGB(0,255,0));hdc = GetDC(hWnd);MyPaint(hdc);ReleaseDC(hWnd,hdc);return TRUE;}void MyPaint(HDC hdc){SelectObject(hdc,hPen);SelectObject(hdc,hBru);Polyline(hdc,poly1,5);PolylineTo(hdc,poly2,5);Polygon(hdc,poly3,5);}void MyPaint1(HDC hdc,LPARAM lParam){int x,y;char str[20] = "";x = LOWORD(lParam);y = HIWORD(lParam);SetTextColor(hdc,RGB(255,0,0));TextOut(hdc,10,300,"鼠标坐标",strlen("鼠标坐标"));sprintf(str,"X坐标%d ",x);//将格式化的数据写入字符串TextOut(hdc,30,340,str,strlen(str));//在(30,30)处显示字符串sprintf(str,"Y坐标%d ",y);TextOut(hdc,30,360,str,strlen(str));}LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam){PAINTSTRUCT ps;HDC hdc;switch (message) {case WM_PAINT:hdc = BeginPaint(hWnd, &ps);MyPaint(hdc);EndPaint(hWnd, &ps);break;case WM_MOUSEMOVE:hdc = GetDC(hWnd);MyPaint1(hdc,lParam);ReleaseDC(hWnd,hdc);break;case WM_DESTROY:DeleteObject(hPen);DeleteObject(hBru);PostQuitMessage(0);break;default:return DefWindowProc(hWnd, message, wParam, lParam);}return 0;}
