运行时鼠标移动，e.x应该有变化，它的值在哪里能看到呢
private void Form1_MouseDown(object sender,
System.Windows.Forms.MouseEventArgs e)
{
if (e.Button == MouseButtons.Left)
{
Graphics g1 = this.CreateGraphics(); // Create a Graphics object 创建一个Graphics对象
Pen linePen = new Pen(Color.Green, 1); // Create two pens创建两个钢笔
Pen ellipsePen = new Pen(Color.Red, 1);
startPoint = endPoint;
endPoint = new Point(e.X, e.Y);
g1.DrawLine(linePen, startPoint, endPoint);// Draw the line from the current point
// to the new point从当前点到新的点绘制一条直线
if (checkBox1.Checked) // If rectangle check box is cheked如果选中了Rectangle复选框，则绘制矩形来表示连接点
// Draw a rectangle to represent the point
{
g1.DrawRectangle(ellipsePen, e.X-2, e.Y-2, 4, 4);
}
else // Draw a circle to represent the point绘制一个圆来表示连接点
{
g1.DrawEllipse(ellipsePen,e.X-2, e.Y-2, 4, 4);
}
// Dispose释放对象
linePen.Dispose();
ellipsePen.Dispose();
g1.Dispose();
}
杲大胜 ...........勤!能!补!拙!........ 勤!勤!勤!.............
