本文演示了在C#中使用畫筆的源代碼，供大家參考使用。下面的源代碼中首先定義了一個矩形類（Rectangle），這個類從Shape類中派生出來，在類中定義了兩個變量成員來代表畫筆的起點和終點。

public class Rectangle : Shape
{
        protected Point m_Start; 
        protected Point m_End; 
        public Rectangle(Point start, Point end, Color fgColor) 
        { 
                m_Start = start; 
                m_End = end; 
                m_Color = fgColor; 
        } 
        public override void Draw(Form canvas) 
        { 
                if (canvas == null) 
                { 
                        return; 
                } 
                InitializeGraphics(canvas); 
                Point startPoint = canvas.PointToScreen(m_Start); 
                Point endPoint = canvas.PointToScreen(m_End); 
                MainForm mainForm = (MainForm)canvas; 
                Color bgColor = GetBackgroundColor(m_Color); 
                Size rectSize = new Size(m_End.X - m_Start.X, m_End.Y - m_Start.Y); 
                System.Drawing.Rectangle rectToDraw = new System.Drawing.Rectangle(startPoint, rectSize); 
                ControlPaint.DrawReversibleFrame(rectToDraw, bgColor, FrameStyle.Thick); 
        }
}