在两个PictureBox上划画，不被遮挡

Question

在一个Form里new了两个PictureBox,以这两个PictureBox的中心为两点，画一条直线，直线不能被PictureBox遮挡,这个要怎么做,

Answer 1

PictureBox加载图片，再找到两个PictureBox的中心用Graphics的pen画条线吧？ 

Answer 2

    //思路，采用Graphics对象的draw方法。Graphic对象的句柄设置成PictureBox1和PictureBox2所属的窗体，这样就能覆盖两个pictureBox
        private void button1_Click(object sender, EventArgs e)
        {
            //声明Graphics对象类
            Graphics g = Graphics.FromHwnd(this.Handle);
            //声明pen类，设置画笔的颜色
            Pen pen = new Pen(Color.Green);
            //设置画线的起点和终点。
            Point p1 = new Point(this.pictureBox1.Location.X + this.pictureBox1.Size.Width / 2, this.pictureBox1.Location.Y + this.pictureBox1.Size.Height/ 2);
            Point p2 = new Point(this.pictureBox2.Location.X + this.pictureBox2.Size.Width / 2, this.pictureBox2.Location.Y + this.pictureBox2.Size.Height / 2);
            //画线
            g.DrawLine(pen, p1, p2);
            
            
        }

Answer 3

画不出来的， pictureBox会盖住一切东西。

Answer 4

     //(1)代码使用前提，在主窗体上添加两个picturebox，分别命名为picturebox1,picturebox2
        //在主窗体上添加一个按钮,名为button1
        
        //（2）思路，PictureBox对象总是能覆盖Graphics对象，所以需要用Picture对象来充当“直线”。
        //使用picturebox.BringToFront()方法来将“直线”覆盖其他两个PictureBox
        private void button1_Click(object sender, EventArgs e)
        {
            //充当直线的PictureBox
            PictureBox p = new PictureBox();
            
            //设置“直线”的起点是pictureBox1的中点
            p.Location = new System.Drawing.Point(pictureBox1.Location.X + pictureBox1.Size.Width / 2, pictureBox1.Location.Y + pictureBox1.Size.Height / 2);
            
            //设置“直线”的长度是从pictureBox2中点到pictureBox1的中点的距离。
            //设置"直线"的宽度是5
            p.Size = new System.Drawing.Size(pictureBox2.Location.X + pictureBox2.Size.Width / 2 - pictureBox1.Location.X - pictureBox1.Size.Width / 2, 5);
            
            //设置“直线”的颜色是 红色
            p.BackColor = Color.Red;
            //将“直线”添加到窗体上
            this.Controls.Add(p);            //将“直线”移动到窗体最上方，覆盖掉另外两个pictureBox
            p.BringToFront();   
        }//（3）效果如下所示
http://hi.csdn.net/attachment/201101/2/7085318_12939803589ZI0.jpg