using System;using System.Collections.Generic;using System.ComponentModel;using System.Data;using System.Drawing;using System.Drawing.Drawing2D;using System.Linq;using System.Text;using System.Threading.Tasks;using System.Windows.Forms;namespace ExerciseUIPrj.controls{  public partial class LoadControl : Control  {    Color beginColor = Color.Blue;    Color endColor = Color.Red;    int wid = 10;    int curindex = 0;    Timer timer;    int instervel = 200;    string loadStr = "loading....";    public LoadControl()    {      InitializeComponent();      SetStyle(ControlStyles.UserPaint | ControlStyles.AllPaintingInWmPaint|ControlStyles.OptimizedDoubleBuffer, true);      this.MinimumSize = new Size(40, 80);      if (!DesignMode)      {        Start();      }    }    public void Start()    {      if (timer == null)      {        timer = new Timer();        timer.Interval = instervel;        timer.Tick += Timer_Tick;      }      timer.Enabled = true;    }    public void Stop()    {      if (timer != null)      {        timer.Enabled = false;      }    }    void Timer_Tick(object sender, EventArgs e)    {      curindex++;      curindex = curindex >= wid ? 0 : curindex;      Refresh();    }    //計算各種圈圈相關    Point getPoint(double d, double r, Point center)    {      int x = (int)(r * Math.Cos(d * Math.PI / 180.0));      int y = (int)(r * Math.Sin(d * Math.PI / 180.0));      return new Point(center.X + x, center.Y - y);    }    GraphicsPath getPath(Point a, Point b)    {      Point c, d, e, f;      int h = 2;      Vertical(a, b, h, out c, out d);      Vertical(b, a, h, out e, out f);      GraphicsPath path = new GraphicsPath();      path.AddPolygon(new Point[] { c, d, e, f });      path.CloseAllFigures();      return path;    }    bool Vertical(Point pointa, Point pointb, double R, out Point pointc, out Point pointd)    {      pointc = new Point();      pointd = new Point();      try      {        //（X-xa)^2+(Y-ya)^2=R*R  距離公式        //(X-xa)*(xb-xa)+(Y-ya)*(yb-ya)=0  垂直        //解方程得兩點即為所求點        var cx = pointa.X - (pointb.Y - pointa.Y) * R / Distance(pointa, pointb);        var cy = pointa.Y + (pointb.X - pointa.X) * R / Distance(pointa, pointb);        var dx = pointa.X + (pointb.Y - pointa.Y) * R / Distance(pointa, pointb);        var dy = pointa.Y - (pointb.X - pointa.X) * R / Distance(pointa, pointb);        pointc = new Point((int)cx, (int)cy);        pointd = new Point((int)dx, (int)dy);        return true;      }      catch      {        //如果A,B兩點重合會報錯，那樣就返回false        return false;      }    }    double Distance(double xa, double ya, double xb, double yb)    {      double L;      L = Math.Sqrt(Math.Pow(xa - xb, 2) + Math.Pow(ya - yb, 2));      return L;    }    double Distance(Point pa, Point pb)    {      return Distance(pa.X, pa.Y, pb.X, pb.Y);    }    GraphicsPath getPath(double d, double r, Point c)    {      var p1 = getPoint(d, r / 2.0, c);      var p2 = getPoint(d, r, c);      return getPath(p1, p2);    }    //算漸變色    Color[] getColors()    {      int dr = (int)((endColor.R - beginColor.R) / (double)wid);      int dg = (int)((endColor.G - beginColor.G) / (double)wid);      int db = (int)((endColor.B - beginColor.B) / (double)wid);      List<Color> colors = new List<Color>();      for (int i = 0; i < wid; i++)      {        colors.Add(Color.FromArgb(beginColor.R + dr * i, beginColor.G + dg * i, beginColor.B + db * i));      }      return colors.ToArray();    }    //畫圈圈    void drawRect(Graphics g)    {      int r = (int)(Size.Height / 2.0);      Point center = new Point(r, r);      var colors = getColors();      int findex = curindex;      for (int i = 0; i < wid; i++)      {        double d = (360.0 / wid) * i;        var p = getPath(d, r, center);        int cindex = findex + i;        cindex = cindex >= wid ? cindex - wid : cindex;        g.FillPath(new SolidBrush(colors[cindex]), p);      }    }    //畫字符串    void drawString(Graphics g)    {      if (Size.Height >= Size.Width) return;      Rectangle rect = new Rectangle(new Point(Size.Height, 0), new Size(Size.Width - Size.Height, Size.Height));      StringFormat sf = new StringFormat();      sf.Alignment = StringAlignment.Center;      sf.LineAlignment = StringAlignment.Center;      g.DrawString(loadStr, Font, Brushes.Black, rect,sf);    }    protected override void OnPaint(PaintEventArgs pe)    {      base.OnPaint(pe);      Graphics g = pe.Graphics;      g.SmoothingMode = SmoothingMode.HighQuality;      g.PixelOffsetMode = PixelOffsetMode.HighQuality;      drawRect(g);      drawString(g);    }    protected override void OnSizeChanged(EventArgs e)    {      base.OnSizeChanged(e);      if (Size.Height > Size.Width)      {        Size = new Size(Size.Height, Size.Height);      }    }  }}