代码：

using System;  using System.Collections.Generic;  using System.ComponentModel;  using System.Data;  using System.Drawing;  using System.Text;  using System.Windows.Forms;  using System.IO;
  
namespace TestKeyPress  {   public partial class Form2 : Form   {   public Form2()   {   InitializeComponent();   }
  
    private void textBox1_DragEnter(object sender, DragEventArgs e)   {   e.Effect = DragDropEffects.Copy;   }
  
 private void textBox1_DragDrop(object sender, DragEventArgs e)   {   //DataFormats.FileDrop确定你拖动过去的是文件回或者文件夹   if (e.Data.GetDataPresent(DataFormats.FileDrop))   {   string realpath = ((System.Array)e.Data.GetData(DataFormats.FileDrop)).GetValue(0).ToString();   //从拖动数据里得到路径   //MessageBox.Show(realpath);测试路径   string p = Path.GetExtension(realpath);   //MessageBox.Show(p);测试路径   if (p == ".jpg")   {   //StreamReader sr = new StreamReader(realpath);读取方式，放弃使用   Image im = Image.FromFile(realpath);   int h = im.Height;   int w = im.Width;   this.pictureBox1.Height = h;   this.pictureBox1.Width = w;   this.pictureBox1.BackgroundImageLayout = ImageLayout.Stretch;   this.pictureBox1.BackgroundImage = im;   //将读取到的图片放到picturebox里   //this.pictureBox1.Location = new Point(130 - pictureBox1.Width, 85 - pictureBox1.Height);   Point pnl = new Point(this.panel1.Width / 2, this.panel1.Height / 2);   Point pic = new Point();   pic.X = pnl.X - pictureBox1.Width / 2;   pic.Y = pnl.Y - pictureBox1.Height / 2;   this.pictureBox1.Location = pic;   //上面的代码是将图片的中心和panel的中心对齐   //this.pictureBox1.Location = new Point(85 ,76);   }   }   else   {   MessageBox.Show("please select jpg");   }   //MessageBox.Show(e.Data.GetType().ToString());   }   //放大功能   private void button1_Click(object sender, EventArgs e)   {   Image im = this.pictureBox1.BackgroundImage;   //im.M   pictureBox1.Height = (int)(pictureBox1.Height * 1.2);   pictureBox1.Width = (int)(pictureBox1.Width * 1.2);   Point pnl = new Point(this.panel1.Width / 2, this.panel1.Height / 2);   Point pic = new Point();   pic.X = pnl.X - pictureBox1.Width / 2;   pic.Y = pnl.Y - pictureBox1.Height / 2;   this.pictureBox1.Location = pic;   }   //缩小功能   private void button2_Click(object sender, EventArgs e)   {   Image im = this.pictureBox1.BackgroundImage;   //im.M   pictureBox1.Height = (int)(pictureBox1.Height * 0.85);   pictureBox1.Width = (int)(pictureBox1.Width * 0.85);   Point pnl = new Point(this.panel1.Width / 2, this.panel1.Height / 2);   Point pic = new Point();   pic.X = pnl.X - pictureBox1.Width / 2;   pic.Y = pnl.Y - pictureBox1.Height / 2;   this.pictureBox1.Location = pic;   }   private Point start;   private Point end;   //下面的函数实现，图片在panel里可以拖动   private void panel1_MouseDown(object sender, MouseEventArgs e)   {   if (e.Button == MouseButtons.Left)   {   start = new Point(e.X, e.Y);   end = start;   }   }      private void panel1_MouseUp(object sender, MouseEventArgs e)   {   end = new Point(e.X, e.Y);   int picx = this.pictureBox1.Location.X;   int picy = this.pictureBox1.Location.Y;   picx += end.X - start.X;   picy += end.Y - start.Y;   this.pictureBox1.Location = new Point(picx, picy);   }   }  }
  

数据拖动，主要是在接受数据的地方添加DragEnter和DragDrop事件，必须将接受数据的地方设置为AllowDrop=true，如果在一个窗体内拖动，选择数据的地方也要设置AllowDrop=true，

转自：http://blog.csdn.net/luolunz/article/details/7905193