C#的拖拽

本文将以Winform为例

有两个主要的事件:

DragEnter 拖拽到区域中触发的事件

DragDrop 当拖拽落下的时候出发此事件

饮水思源

参考博客: http://www.cnblogs.com/gossip/archive/2010/02/22/1671126.html

Demo 模拟拖拽上传

我们在开发中有时候回用到拖拽上传的功能，例如QQ邮箱上传附件的时候，博客园Mark Down编辑器上传图片的时候。

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

namespace StudyDrag
{
    public partial class frmDragUpload : Form
    {
        public frmDragUpload()
        {
            InitializeComponent();
        }

        /// <summary>
        /// 初始化属性
        /// </summary>
        void Init()
        {
            //设置为允许拖拽
            this.AllowDrop = true;
        }

        /// <summary>
        /// 注册事件
        /// </summary>
        void RegisteEvent()
        {
            this.DragEnter += FrmDragUpload_DragEnter;
            this.DragDrop += FrmDragUpload_DragDrop;
        }

        /// <summary>
        /// 当在此区域拖动落下的时候出发
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void FrmDragUpload_DragDrop(object sender, DragEventArgs e)
        {
            //获取拖动的数据
            IDataObject ido = e.Data;
            //如果拖动的数据是文件类型
            if (ido.GetDataPresent(DataFormats.FileDrop))
            {
                //获取文件的路径
                string[] paths = (string[])ido.GetData(DataFormats.FileDrop);

                //执行我们想要执行的业务逻辑，读取上传到服务器等等。
                foreach (var item in paths)
                {
                    Console.WriteLine(item);
                }
                MessageBox.Show("上传成功!");
            }
            else
            {
                MessageBox.Show("上传类型错误!");
            }
        }

        /// <summary>
        /// 当拖动到此区域的时候触发
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void FrmDragUpload_DragEnter(object sender, DragEventArgs e)
        {
            //设置拖动的影响为：从拖动源复制到拖动的目标
            e.Effect = DragDropEffects.Copy;
        }

        /// <summary>
        /// 窗体初始化
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void frmDragUpload_Load(object sender, EventArgs e)
        {
            this.Init();
            this.RegisteEvent();
        }
    }
}

Demo 2 ListView拖拽到TreeView上

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

namespace StudyDrag
{
    public partial class frmDragListView : Form
    {
        public frmDragListView()
        {
            InitializeComponent();
        }

        /// <summary>
        /// 初始化属性
        /// </summary>
        void Init()
        {
            this.lbDep.AllowDrop = true;
            this.tvDep.AllowDrop = true;
        }

        /// <summary>
        /// 加载一些数据
        /// </summary>
        void LoadData()
        {
            for (int i = 1; i <= 10; i++)
            {
                string itemValue = "有关部门" + i.ToString();
                this.lbDep.Items.Add(itemValue);
            }
        }

        void RegisterEvent()
        {
            this.tvDep.DragDrop += TvDep_DragDrop;
            this.tvDep.DragEnter += TvDep_DragEnter;
        }

        /// <summary>
        /// 当拖拽进入到该区域的时候出发的事件
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void TvDep_DragEnter(object sender, DragEventArgs e)
        {
            e.Effect = DragDropEffects.Copy;
        }

        /// <summary>
        /// 当完成退拽时触发的事件
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void TvDep_DragDrop(object sender, DragEventArgs e)
        {
            string item = (string)e.Data.GetData(DataFormats.Text);
            this.tvDep.Nodes.Add(item);
        }

        /// <summary>
        /// 窗体初始化
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void frmDragListView_Load(object sender, EventArgs e)
        {
            Init();
            LoadData();
            RegisterEvent();
        }

        /// <summary>
        /// 鼠标点击的的时候开始执行拖拽操作
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void lbDep_MouseDown(object sender, MouseEventArgs e)
        {
            if (lbDep.SelectedItem == null)
            {
                return;
            }
			
            lbDep.DoDragDrop(lbDep.SelectedItem, DragDropEffects.Copy);
        }
    }
}

源码下载

我的码云:https://git.oschina.net/ShareKnowledge/drag