using?System;
using?System.Collections.Generic;
using?System.ComponentModel;
using?System.Data;
using?System.Drawing;
using?System.Linq;
using?System.Text;
using?System.Threading.Tasks;
using?System.Windows.Forms;

namespace?ArcPointTest
{
????public?partial?class?ArcPointTest?:?Form
????{

????????Point?FirstPoint?=?new?Point（）;
????????Point?SecondPoint?=?new?Point（）;
????????Point?ThirdPoint?=?new?Point（）;

????????int?PointNum;


????????public?ArcPointTest（）
????????{
????????????InitializeComponent（）;
????????????PointNum?=?0;
????????}



????????private?void?MainForm_MouseClick（object?sender?MouseEventArgs?e）
????????{
????????????if?（e.Button?==?System.Windows.Forms.MouseButtons.Left）
????????????{
????????????????Graphics?g?=?this.CreateGraphics（）;
????????????????SolidBrush?m_Brush?=?new?SolidBrush（Color.Blue）;

????????????????g.SmoothingMode?=?System.Drawing.Drawing2D.SmoothingMode.AntiAlias;

????????????????if?（PointNum?==?0）
????????????????{
????????????????????FirstPoint.X?=?e.X;
????????????????????FirstPoint.Y?=?e.Y;
????????????????}

????????????????if?（PointNum?==?1）
????????????????{
????????????????????SecondPoint.X?=?e.X;
????????????????????SecondPoint.Y?=?e.Y;
????????????????}

????????????????if?（PointNum?==?2）
????????????????{
????????????????????ThirdPoint.X?=?e.X;
????????????????????ThirdPoint.Y?=?e.Y;
????????????????}

????????????????g.FillEllipse（m_Brush?e.X?-?3?e.Y?-?3?6?6）;

????????????????PointNum++;
????????????????if?（PointNum?==?3）
????????????????{
????????????????????PointNum?=?0;

????????????????????DrawArcFromThreePoint（g?FirstPoint.X?FirstPoint.Y?SecondPoint.X?SecondPoint.Y?ThirdPoint.X?ThirdPoint.Y）;
????????????????}

????????????}

????????}

????????/*
?????????*?利用三點(diǎn)坐標(biāo)獲得圓弧
?????????*/?

????????void?DrawArcFromThreePoint（Graphics?mImgGraph?int?x1?int?y1?int?x2?int?y2?int?x3?int?y3）
????????{
????????????double?a?=?x1?-?x2;
????????????double?b?=?y1?-?y2;
????????????double?c?=?x1?-?x3;
????????????double?d?=?y1?-?y3;
????????????double?e?=?（（x1?*?x1?-?x2?*?x2）?+?（y1?*?y1?-?y2?*?y2））?/?2.0;
????????????double?f?=?（（x1?*?x1?-?x3?*?x3）?+?（y1?*?y1?-?y3?*?y3））?/?2.0;

????????????double?det?=?b?*?c?-?a?*?d;
????????????if?（Math.Abs（det）?>?0.001）
????????????{
????????????????//x0y0為計(jì)算得到的原點(diǎn)
????????????????double?x0?=?-（d?*?e?-?b?*?f）?/?det;
????????????????double?y0?=?-（a?*?f?-?c?*?e）?/?det;

????????????????SolidBrush?OriginBrush?=?new?SolidBrush（Color.Blue）;
????????????????mImgGraph.FillEllipse（OriginBrush?（int）（x0?-?3）?（int）（y0?-?3）?6?6）;

????????????????double?radius?=?Math.Sqrt（（x1?-?x0）?*?（x1?-?x0）?+?（y1?-?y0）?*?（y1?-?y0））;

????????????????double?angle1;
????????????????double?angle2;
????????????????double?angle3;

????????????????double?sinValue1;
????????????????double?cosValue1;
????????????????double?sinValue2;
????????????????double?cosValue2;
?????????????

?屬性????????????大小?????日期????時(shí)間???名稱
-----------?---------??----------?-----??----
?????目錄???????????0??2018-03-15?08:01??ArcPointTest\
?????目錄???????????0??2018-03-15?08:01??ArcPointTest\ArcPointTest\
?????文件?????????187??2018-03-15?08:01??ArcPointTest\ArcPointTest\App.config
?????文件????????3818??2018-03-15?08:11??ArcPointTest\ArcPointTest\ArcPointTest.csproj
?????文件????????2185??2018-03-15?08:35??ArcPointTest\ArcPointTest\MainForm.Designer.cs
?????文件????????6100??2018-03-15?08:35??ArcPointTest\ArcPointTest\MainForm.cs
?????文件????????5817??2018-03-15?08:35??ArcPointTest\ArcPointTest\MainForm.resx
?????文件?????????542??2018-03-15?08:01??ArcPointTest\ArcPointTest\Program.cs
?????目錄???????????0??2018-03-15?08:01??ArcPointTest\ArcPointTest\Properties\
?????文件????????1454??2018-03-15?08:01??ArcPointTest\ArcPointTest\Properties\AssemblyInfo.cs
?????文件????????2854??2018-03-15?08:01??ArcPointTest\ArcPointTest\Properties\Resources.Designer.cs
?????文件????????5612??2018-03-15?08:01??ArcPointTest\ArcPointTest\Properties\Resources.resx
?????文件????????1099??2018-03-15?08:01??ArcPointTest\ArcPointTest\Properties\Settings.Designer.cs
?????文件?????????249??2018-03-15?08:01??ArcPointTest\ArcPointTest\Properties\Settings.settings
?????目錄???????????0??2018-03-15?08:01??ArcPointTest\ArcPointTest\bin\
?????目錄???????????0??2018-03-15?08:22??ArcPointTest\ArcPointTest\bin\Debug\
?????文件???????10752??2018-03-15?08:35??ArcPointTest\ArcPointTest\bin\Debug\ArcPointTest.exe
?????文件?????????187??2018-03-15?08:01??ArcPointTest\ArcPointTest\bin\Debug\ArcPointTest.exe.config
?????文件???????26112??2018-03-15?08:35??ArcPointTest\ArcPointTest\bin\Debug\ArcPointTest.pdb
?????文件???????22984??2018-03-15?08:25??ArcPointTest\ArcPointTest\bin\Debug\ArcPointTest.vshost.exe
?????文件?????????187??2018-03-15?08:01??ArcPointTest\ArcPointTest\bin\Debug\ArcPointTest.vshost.exe.config
?????目錄???????????0??2018-03-15?08:36??ArcPointTest\ArcPointTest\bin\Release\
?????目錄???????????0??2018-03-15?08:01??ArcPointTest\ArcPointTest\obj\
?????目錄???????????0??2018-03-15?08:35??ArcPointTest\ArcPointTest\obj\Debug\
?????文件?????????180??2018-03-15?08:35??ArcPointTest\ArcPointTest\obj\Debug\ArcPointTest.ArcPointTest.resources
?????文件?????????180??2018-03-15?08:11??ArcPointTest\ArcPointTest\obj\Debug\ArcPointTest.Properties.Resources.resources
?????文件?????????742??2018-03-15?08:25??ArcPointTest\ArcPointTest\obj\Debug\ArcPointTest.csproj.FileListAbsolute.txt
?????文件????????1036??2018-03-15?08:35??ArcPointTest\ArcPointTest\obj\Debug\ArcPointTest.csproj.GenerateResource.Cache
?????文件????????2209??2018-03-15?08:01??ArcPointTest\ArcPointTest\obj\Debug\ArcPointTest.csprojResolveAssemblyReference.cache
?????文件???????10752??2018-03-15?08:35??ArcPointTest\ArcPointTest\obj\Debug\ArcPointTest.exe
?????文件???????26112??2018-03-15?08:35??ArcPointTest\ArcPointTest\obj\Debug\ArcPointTest.pdb
............此處省略8個(gè)文件信息