分不多了，请帮帮忙！急！立即结帖！

我写了段代码，可是就是调用不了，请问怎么调用啊？


using System;
using System.Windows.Forms;
using System.Drawing;
using System.Diagnostics;
using System.Globalization;
using System.Drawing.Drawing2D;
using System.Collections;


namespace DrawTools
{
/// <summary>
/// DrawArc 的摘要说明。
/// </summary>
public class DrawArc : DrawTools.DrawPolygon
{
private Point startPoint;
private Point endPoint;

int width = 100;
int height = 200;
// Create start and sweep angles on ellipse.
int startAngle = 45;
int sweepAngle = 270;

private const string entryStart = "Start";
private const string entryEnd = "End";

public DrawArc()
{
ArrayList pointArray = new ArrayList();

startPoint.X = 0;
//startPoint.Y = 0;
//endPoint.X = 100;
endPoint.Y = 100;

Initialize();
}

public DrawArc(int x1, int y2)
{
ArrayList pointArray = new ArrayList();

startPoint.X = x1;
//startPoint.Y = y1;
//endPoint.X = x2;
endPoint.Y = y2;

Initialize();
}

public override void Draw(Graphics g)
{
g.SmoothingMode = SmoothingMode.AntiAlias;

Pen pen = new Pen(Color, PenWidth);

/// <summary>
///pen的DashStyle虚线样式的成员
///Custom 指定用户定义的自定义划线段样式。
///Dash 指定由划线段组成的直线。
///DashDot 指定由重复的划线点图案构成的直线。
///DashDotDot 指定由重复的划线点点图案构成的直线。
///Dot 指定由点构成的直线。
///Solid 指定实线。
/// </summary>
pen.DashStyle = System.Drawing.Drawing2D.DashStyle.Dot;

g.DrawArc(pen, startPoint.X, endPoint.Y, width, height, startAngle, sweepAngle);

pen.Dispose();
}

public void AddPoint(Point point)
{
ArrayList pointArray = new ArrayList();
pointArray.Add(point);
}

}
}


我想画弧线，其实就需要用
g.DrawArc(pen, startPoint.X, endPoint.Y, width, height, startAngle, sweepAngle);
这句，我是在另一个类调用这个的，可是老是说g不存在，我加了这句
Graphics g = new Graphics();可是未获取又说0参数，郁闷中，高手们帮帮忙吧！