/*
de Casteljau算法的具体描述：
Input: array P[0:n]of n+1 control points and a real number u in [0,1]
Output: point oncurve, C(u)
Working: pointarray Q[0:n]
for i=0 to n do
Q[i] = P[i]
for k=1 to ndo // the times of recursion isn!
for i=0 to n-k do
Q[i] = (1-u)Q[i] +uQ[i+1]
return Q[0];
*/
// DrawBezierLine.cpp : 定义应用程序的入口点。
#include <assert.h>
#define MAX_LOADSTRING 100
int ctpt_max=100;
int indexct=0; //指向待写入的控制点
POINT * ctptArray=NULL; //控制多边形数组
int ndegree=4; //次数
void addCtPoint(POINTpt)
{
if (ctptArray==NULL)
{
ctptArray=(POINT *)malloc(ctpt_max*sizeof(POINT));
}
else
{
if (indexct>=ctpt_max)
{
ctpt_max=2*ctpt_max;
realloc(ctptArray,ctpt_max);
}
}
ctptArray[indexct++]=pt;
}
/**
*@funcname:de_Casteljau_bezier
*@Access: public
*@brief:
*@param:POINT * ctArray :控制曲线数组起点指针
*@param:int n：贝塞尔次数
*@param:double u：细分的u值
*@param:POINT * pt：输出的线上点
*@return :void
*/
void de_Casteljau_bezier(POINT*ctArray, intn,doubleu,POINT*pt)
{
int i=0;
int k=0;
POINT* pV=(POINT*)malloc(n*sizeof(POINT));
if (pV==NULL)
{
assert("申请内存出错"&&0);
}
for (i=0;i<=n;i++)
{
pV[i]=ctArray[i];
}
for (k=1;k<=n;k++)
{
for ( i = 0; i <=n-k; i++)
{
pV[i].x=(long)((1-u)*pV[i].x+u*pV[i+1].x);
pV[i].y=(long)((1-u)*pV[i].y+u*pV[i+1].y);
}
}
*pt=pV[0];
}
// 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
// 此代码模块中包含的函数的前向声明:
ATOM MyRegisterClass(HINSTANCE hInstance);
BOOL InitInstance(HINSTANCE, int);
LRESULT CALLBACK WndProc(HWND,UINT, WPARAM,LPARAM);
INT_PTR CALLBACK About(HWND,UINT, WPARAM,LPARAM);
int APIENTRY _tWinMain(_In_ HINSTANCEhInstance,
_In_opt_HINSTANCE hPrevInstance,
_In_LPTSTR lpCmdLine,
_In_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_DRAWBEZIERLINE, szWindowClass, MAX_LOADSTRING);
MyRegisterClass(hInstance);
//执行应用程序初始化:
if(!InitInstance (hInstance,nCmdShow))
{
returnFALSE;
}
hAccelTable = LoadAccelerators(hInstance, MAKEINTRESOURCE(IDC_DRAWBEZIERLINE));
//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。
//
ATOM MyRegisterClass(HINSTANCEhInstance)
{
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_DRAWBEZIERLINE));
wcex.hCursor = LoadCursor(NULL, IDC_ARROW);
wcex.hbrBackground = (HBRUSH)(COLOR_WINDOW+1);
wcex.lpszMenuName = MAKEINTRESOURCE(IDC_DRAWBEZIERLINE);
wcex.lpszClassName = szWindowClass;
wcex.hIconSm = LoadIcon(wcex.hInstance,MAKEINTRESOURCE(IDI_SMALL));
returnRegisterClassEx(&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(HINSTANCEhInstance, intnCmdShow)
{
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;
}
void OnLButtonDown(UINT nFlags,POINT point)
{
addCtPoint(point);
}
//
// 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)
{
intwmId, wmEvent;
PAINTSTRUCT ps;
HDC hdc;
POINT pt;
inti=0;
HPEN hpen;
POINT ptOnline;
switch(message)
{
caseWM_COMMAND:
wmId = LOWORD(wParam);
wmEvent = HIWORD(wParam);
//分析菜单选择:
switch(wmId)
{
caseIDM_ABOUT:
DialogBox(hInst,MAKEINTRESOURCE(IDD_ABOUTBOX),hWnd, About);
break;
caseIDM_EXIT:
DestroyWindow(hWnd);
break;
default:
returnDefWindowProc(hWnd,message, wParam,lParam);
}
break;
caseWM_PAINT:
if(indexct<2)
{
break;
}
hdc = BeginPaint(hWnd, &ps);
//TODO: 在此添加任意绘图代码...
hpen=CreatePen(PS_SOLID,0.5,RGB(255,0,0));
SelectObject(hdc,hpen);
for(i=0;i<indexct-1;i++)
{
::MoveToEx(hdc,ctptArray[i].x,ctptArray[i].y,NULL);
::LineTo(hdc,ctptArray[i+1].x,ctptArray[i+1].y);
}
if(indexct>ndegree)
{
for(i=0;i<indexct-ndegree;i+=ndegree)
{
for(double t=0.0;t<=1.0;)
{
de_Casteljau_bezier(ctptArray+i,ndegree,t,&ptOnline);
SetPixel(hdc,ptOnline.x,ptOnline.y,RGB(0,255,0));
t+=0.001;
}
}
}
EndPaint(hWnd,&ps);
break;
caseWM_LBUTTONDOWN:
pt.x= GET_X_LPARAM( lParam);
pt.y= GET_Y_LPARAM( lParam);
OnLButtonDown( wParam,pt );
::InvalidateRect(hWnd,NULL,TRUE);
break;
caseWM_RBUTTONDOWN:
indexct=0;
::InvalidateRect(hWnd,NULL,TRUE);
break;
caseWM_DESTROY:
PostQuitMessage(0);
break;
default:
returnDefWindowProc(hWnd,message, wParam,lParam);
}
return0;
}
// “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)
{
caseWM_INITDIALOG:
return(INT_PTR)TRUE;
caseWM_COMMAND:
if(LOWORD(wParam)== IDOK || LOWORD(wParam) == IDCANCEL)
{
EndDialog(hDlg,LOWORD(wParam));
return(INT_PTR)TRUE;
}
break;
}
return(INT_PTR)FALSE;
}
