Course 2DCis: 2D-Computer Graphics with C# Chapter C4: The Complete Code of the Animation Project Copyright © by V. Miszalok, last update: 2011-09-13

Copy all this code into an empty Form1.cs of a new Windows Application C#-project anim1 and clear Form1.Designer.cs and Program.cs.

using System;
using System.Drawing;
using System.Windows.Forms;
using System.Collections;

public class Form1 : Form
{ [STAThread] static void Main() { Application.Run( new Form1() ); }
  static Graphics g, bitmap_g;
  static Bitmap bitmap;
  static Single zoom       = 1.01f;
  static Single cosinus    = (Single)Math.Cos( Math.PI/180.0 );
  static Single sinus      = (Single)Math.Sin( Math.PI/180.0 );
  static Brush  redbrush   = new SolidBrush( Color.Red );
  static Pen    blackpen   = SystemPens.ControlText;
  static Font   arial10    = new Font( "Arial", 10 );
  static Int32  myWidth, myHeight;
  static PointF[] pf;
  ArrayList polygon = new ArrayList();
  Point p0, p1;
  Timer myTimer = new Timer();

  public Form1()
  { Text = "Anim1: Draw an Endless Animation";
    Width = 800;
    Height = 600;
    g = this.CreateGraphics();
    SetStyle(ControlStyles.ResizeRedraw,true);
    myTimer.Tick += new EventHandler( OnTimer );
    myTimer.Interval = 1;
  }
  protected override void OnMouseDown( MouseEventArgs e )
  { myTimer.Stop();
    polygon.Clear(); Invalidate();
    p0 = e.Location;
    polygon.Add( p0 );
  }
  protected override void OnMouseMove( MouseEventArgs e )
  { if ( e.Button == MouseButtons.None ) return;
    p1 = e.Location;
    Int32 dx = p1.X - p0.X;
    Int32 dy = p1.Y - p0.Y;
    if ( dx*dx + dy*dy < 100 ) return;
    g.DrawLine( blackpen, p0, p1 );
    polygon.Add( p1 );
    p0 = p1;
  }
  protected override void OnMouseUp( MouseEventArgs e )
  { if ( polygon.Count < 2 ) return;
    pf = new PointF[polygon.Count];
    for ( Int32 i=0; i < polygon.Count; i++ ) pf[i] = (Point)polygon[i];
    myTimer.Start();
  }
  protected override void OnPaint( PaintEventArgs e )
  { e.Graphics.DrawString( "Press the left mouse button and move!", Font,
                           redbrush, Width/2-50, 0 );
  }
  protected override void OnResize( System.EventArgs e )
  { g = this.CreateGraphics();
    g.Clear( SystemColors.Control );
    myWidth  = ClientRectangle.Width;
    myHeight = ClientRectangle.Height;
    if ( bitmap != null ) bitmap.Dispose();
    bitmap = new Bitmap( myWidth, myHeight );
    if ( bitmap_g != null ) bitmap_g.Dispose();
    bitmap_g = Graphics.FromImage( bitmap );
  }
  protected static void OnTimer( Object myObject, EventArgs myEventArgs )
  { Single x, y, xmin, ymin, xmax, ymax, xmid, ymid;
    xmin = xmax = pf[0].X;
    ymin = ymax = pf[0].Y;
    for ( Int32 i=1; i < pf.Length; i++ )
    { x = pf[i].X;
      y = pf[i].Y;
      if ( x < xmin ) xmin = x;
      if ( x > xmax ) xmax = x;
      if ( y < ymin ) ymin = y;
      if ( y > ymax ) ymax = y;
    }
    xmid = (xmin+xmax) / 2;
    ymid = (ymin+ymax) / 2;
    if ( xmin < 0 || ymin < 0 || xmax > myWidth || ymax > myHeight )
    { //g.Clear( SystemColors.Control );
      g.DrawString( "Press the left mouse button and move!",
                    arial10, redbrush, 320, 0 );
      zoom = 0.99f;
    }
    if ( xmax - xmin < 50 || ymax - ymin < 50 )
    { //g.Clear( SystemColors.Control );
      zoom = 1.01f;
    }
    for ( Int32 i=0; i < pf.Length; i++ )
    { x = pf[i].X - xmid;
      y = pf[i].Y - ymid;
      x *= zoom;
      y *= zoom;
      Single xx = x*cosinus - y*sinus;
      Single yy = x*sinus + y*cosinus;
      pf[i].X = xx + xmid;
      pf[i].Y = yy + ymid;
    }
    bitmap_g.FillRectangle( SystemBrushes.Control, 0, 0, myWidth, myHeight );
    bitmap_g.DrawLines( blackpen, pf );
    g.DrawImage( bitmap, 0, 0 ); //en bloc transfer
  }
}