CSharp: Template Method Pattern

 

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/// <summary>  /// Summary description for Triangle.  /// Template Method Pattern 模板方法模式  ///20220918  /// geovindu,Geovin Du,涂聚文  /// </summary>  public abstract class Triangle  {        /// <summary>      ///      /// </summary>      private Point p1, p2, p3;      /// <summary>      ///      /// </summary>      protected Pen pen;      /// <summary>      ///      /// </summary>      /// <param name="a"></param>      /// <param name="b"></param>      /// <param name="c"></param>      public Triangle(Point a, Point b, Point c)      {          p1 = a;          p2 = b;          p3 = c;          pen = new Pen(Color.Black, 1);      }      /// <summary>      ///      /// </summary>      /// <param name="g"></param>      public virtual void draw(Graphics g)      {          g.DrawLine(pen, p1, p2);          Point c = draw2ndLine(g, p2, p3);          closeTriangle(g, c);      }      /// <summary>      ///      /// </summary>      /// <param name="g"></param>      /// <param name="a"></param>      /// <param name="b"></param>      /// <returns></returns>      public abstract Point draw2ndLine(Graphics g, Point a, Point b);      /// <summary>      ///      /// </summary>      /// <param name="g"></param>      /// <param name="c"></param>      public void closeTriangle(Graphics g, Point c)      {          g.DrawLine(pen, c, p1);      }  }

　　

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/// <summary>  /// Summary description for StdTriangle.  /// Template Method Pattern 模板方法模式  ///20220918  /// geovindu,Geovin Du,涂聚文  /// </summary>  public class StdTriangle : Triangle  {        /// <summary>      ///      /// </summary>      /// <param name="a"></param>      /// <param name="b"></param>      /// <param name="c"></param>      public StdTriangle(Point a, Point b, Point c) : base(a, b, c)      { }      /// <summary>      ///      /// </summary>      /// <param name="g"></param>      /// <param name="a"></param>      /// <param name="b"></param>      /// <returns></returns>      public override Point draw2ndLine(Graphics g, Point a, Point b)      {          g.DrawLine(pen, a, b);          return b;      }  }

　　

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/// <summary>  /// Summary description for IsocelesTriangle.  /// Template Method Pattern 模板方法模式  ///20220918  /// geovindu,Geovin Du,涂聚文  /// </summary>  public class IsocelesTriangle : Triangle  {      private Point newc;      private int newcx, newcy;      /// <summary>      ///      /// </summary>      /// <param name="a"></param>      /// <param name="b"></param>      /// <param name="c"></param>      public IsocelesTriangle(Point a, Point b, Point c)          : base(a, b, c)      {          float dx1, dy1, dx2, dy2, side1, side2;          float slope, intercept;          int incr;          dx1 = b.X - a.X;          dy1 = b.Y - a.Y;          dx2 = c.X - b.X;          dy2 = c.Y - b.Y;            side1 = calcSide(dx1, dy1);          side2 = calcSide(dx2, dy2);            if (side2 < side1)              incr = -1;          else              incr = 1;          slope = dy2 / dx2;          intercept = c.Y - slope * c.X;            //move point c so that this is an isoceles triangle          newcx = c.X;          newcy = c.Y;          while (Math.Abs(side1 - side2) > 1)          {              newcx = newcx + incr;    //iterate a pixel at a time until close              newcy = (int)(slope * newcx + intercept);              dx2 = newcx - b.X;              dy2 = newcy - b.Y;              side2 = calcSide(dx2, dy2);          }          newc = new Point(newcx, newcy);      }      /// <summary>      ///      /// </summary>      /// <param name="a"></param>      /// <param name="b"></param>      /// <returns></returns>      private float calcSide(float a, float b)      {          return (float)Math.Sqrt(a * a + b * b);      }      /// <summary>      ///      /// </summary>      /// <param name="g"></param>      /// <param name="b"></param>      /// <param name="c"></param>      /// <returns></returns>      public override Point draw2ndLine(Graphics g, Point b, Point c)      {          g.DrawLine(pen, b, newc);          return newc;      }    }

　　

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/// <summary> /// Template Method Pattern 模板方法模式 ///20220918 /// geovindu,Geovin Du,涂聚文 /// </summary> public partial class TemplateMethodPatternForm : Form {       private ArrayList triangles;     /// <summary>     ///     /// </summary>     private void init()     {         triangles = new ArrayList();         StdTriangle t1 = new StdTriangle(new Point(10, 10),             new Point(150, 50),             new Point(100, 75));         IsocelesTriangle t2 = new IsocelesTriangle(             new Point(150, 100), new Point(240, 40),             new Point(175, 150));         triangles.Add(t1);         triangles.Add(t2);         Pic.Paint += new PaintEventHandler(TPaint);     }     /// <summary>     ///     /// </summary>     /// <param name="sender"></param>     /// <param name="e"></param>     private void TPaint(object sender, System.Windows.Forms.PaintEventArgs e)     {         Graphics g = e.Graphics;         for (int i = 0; i < triangles.Count; i++)         {             Triangle t = (Triangle)triangles[i];             t.draw(g);         }     }     /// <summary>     ///     /// </summary>     public TemplateMethodPatternForm()     {         InitializeComponent();         init();     }     /// <summary>     ///     /// </summary>     /// <param name="sender"></param>     /// <param name="e"></param>     private void TemplateMethodPatternForm_Load(object sender, EventArgs e)     {       } }

　　

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