拖拽生成控件副本

public class Form1
{
    //计数变量，说明输出了第N个Button
    private int count = 1;
    private void Form1_Load(System.Object sender, System.EventArgs e)
    {
        //窗体自身支持接受拖拽来的控件
        this.AllowDrop = true;
    }

    private void Button1_MouseDown(System.Object sender, System.Windows.Forms.MouseEventArgs e)
    {
        //左键的话，标志位为true（表示拖拽开始）
        if ((e.Button == System.Windows.Forms.MouseButtons.Left))
        {
            Button1.DoDragDrop(Button1, DragDropEffects.Copy | DragDropEffects.Move);
            //形成拖拽效果，移动+拷贝的组合效果
        }
    }

    private void Form1_DragEnter(System.Object sender, System.Windows.Forms.DragEventArgs e)
    {
        //当Button被拖拽到WinForm上时候，鼠标效果出现
        if ((e.Data.GetDataPresent(typeof(Button))))
        {
            e.Effect = DragDropEffects.Copy;
        }
    }

    private void Form1_DragDrop(System.Object sender, System.Windows.Forms.DragEventArgs e)
    {
        //拖放完毕之后，自动生成新控件
        Button btn = new Button();
        btn.Size = Button1.Size;
        btn.Location = this.PointToClient(new Point(e.X, e.Y));
        //用这个方法计算出客户端容器界面的X，Y坐标。否则直接使用X，Y是屏幕坐标
        this.Controls.Add(btn);
        btn.Text = "按钮" + count.ToString();
        count = count + 1;
    }
    public Form1()
    {
        DragDrop += Form1_DragDrop;
        DragEnter += Form1_DragEnter;
        Load += Form1_Load;
    }
}