C# 在两个不同控件之间拖放

Question

我们有一个触发 DoDragDrop 方法的 ListView 控件。我们有另一个控件，它是一个 TreeView 控件，它有一个 DragDrop 方法。问题在于 DragDrop 方法的 sender 参数不是 ListView，尽管 ListView 启动了 DoDragDrop 方法。相反，发送者是 TreeView 本身。知道为什么发件人不正确吗？

Answer 1

阿马尔，

正如 tyranid 所说，“发送者”是触发事件的控件。此控件绝不是开始拖动的控件，而是接受拖动的控件。

一个例子:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace WindowsFormsApplication2
{
    /// <summary>
    /// There's button 1 and button 2... button 1 is meant to start the dragging. Button 2 is meant to accept it
    /// </summary>
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        /// <summary>
        /// This is when button 1 starts the drag
        /// </summary>
        private void button1_MouseDown(object sender, MouseEventArgs e)
        {
            this.DoDragDrop(this, DragDropEffects.Copy);
        }

        /// <summary>
        /// This is when button 2 accepts the drag
        /// </summary>
        private void button2_DragEnter(object sender, DragEventArgs e)
        {
            e.Effect = DragDropEffects.Copy;
        }


        /// <summary>
        /// This is when the drop happens
        /// </summary>
        private void button2_DragDrop(object sender, DragEventArgs e)
        {
            // sender is always button2
        }

    }
}