Screen Saver Starter Kit

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

namespace DcamScreenSaver
{
    abstract class Worm
    {
        #region constants & variables
        
        // static variables
        protected static Size __szScr = Globals.ScreenSize;
        protected static int __iMaxWormLen = 40;
        protected static int __iWormSize = 9;
        protected static int __iWormStepMin = 1, __iWormStepMax = 5;
        protected static Bitmap __bmpBlack = null;

        // variables for each instance
        protected Bitmap _bmpElement = new Bitmap( __iWormSize, __iWormSize );
        protected Point[] _pntArrElements = null;

        #endregion // constants & variables

        #region constructors & destructors

        static Worm()
        {
            // the black "eaten" element of a worm 
            __bmpBlack = new Bitmap( __iWormSize, __iWormSize );
            __bmpBlack.MakeTransparent( Color.White );
            Graphics g = Graphics.FromImage( __bmpBlack );
            g.FillEllipse( Brushes.Black, 0, 0, __bmpBlack.Width - 1, __bmpBlack.Height - 1 );
            g.Dispose();
        }

        public Worm( Point pntXStart )
        {
            // instantiate a random number of elements and set all start position to the passed one
            _pntArrElements = new Point[ Globals.Rand.Next( 5, __iMaxWormLen ) ];
            for( int i = 0; i < _pntArrElements.Length; i++ )
            {
                _pntArrElements[ i ] = pntXStart;
            }

            // create the bitmap for the elements of this worm with a random color, 
            // but not black ("eaten" background) or white (transparent)
            Color col = Color.FromArgb( Globals.Rand.Next( 1, 255 ),
                Globals.Rand.Next( 1, 255 ), Globals.Rand.Next( 1, 255 ) );
            _bmpElement = new Bitmap( __iWormSize, __iWormSize );
            _bmpElement.MakeTransparent( Color.White );
            Graphics g = Graphics.FromImage( _bmpElement );
            SolidBrush br = new SolidBrush( col );
            g.FillEllipse( br, 0, 0, __iWormSize - 1, __iWormSize - 1 );
            g.DrawEllipse( Pens.Black, 0, 0, __iWormSize - 1, __iWormSize - 1 );
            br.Dispose();
            g.Dispose();
        }

        public virtual void Dispose()
        {
            if( _bmpElement != null ) _bmpElement.Dispose();
        }

        #endregion // constructors & destructors

        #region methods

        public abstract void CalcNewPosition();

        public void Move()
        {
            // draw the last element in black
            Globals.Graph.DrawImage( __bmpBlack, _pntArrElements[ _pntArrElements.Length - 1 ].X,
                _pntArrElements[ _pntArrElements.Length - 1 ].Y );

            // move all element positions one towards the head of the worm (beginning of the array)
            for( int i = _pntArrElements.Length - 1; i > 0; i-- )
            {
                _pntArrElements[ i ] = _pntArrElements[ i - 1 ];
            }

            // calculate a new position for the head of the worm (beginning of the array) and draw it
            CalcNewPosition();
            Globals.Graph.DrawImage( _bmpElement, _pntArrElements[ 0 ].X, _pntArrElements[ 0 ].Y );
        }

        #endregion // methods

    }

}