1 using System;
2 using System.Collections.Generic;
3 using System.ComponentModel;
4 using System.Data;
5 using System.Drawing;
6 using System.Linq;
7 using System.Text;
8 using System.Threading.Tasks;
9 using System.Windows.Forms;
10 using System.Threading;
11
12 namespace tuxing
13 {
14 public partial class Form1 : Form
15 {
16 private Image picture;
17 private Point pictureLocation;
18
19 public Form1()
20 {
21 InitializeComponent();
22 // Enable drag-and-drop operations and
23 // add handlers for DragEnter and DragDrop.
24 this.AllowDrop = true;
25 this.DragDrop += new DragEventHandler(this.Form1_DragDrop);
26 this.DragEnter += new DragEventHandler(this.Form1_DragEnter);
27 }
28
29 private void Form1_DragDrop(object sender, DragEventArgs e)
30 {
31 //Handle FileDrop data.
32 if (e.Data.GetDataPresent(DataFormats.FileDrop))
33 {
34 // Assign the file names to a string array, in
35 // case the user has selected multiple files.
36 string[] files = (string[])e.Data.GetData(DataFormats.FileDrop);
37 //这里一定要是字符串数组。为什么？我不知道啊。。。求解
38 try
39 {
40 // Assign the first image to the picture variable.
41 this.picture = Image.FromFile(files[0]);
42 // Set the picture location equal to the drop point.
43 this.pictureLocation = this.PointToClient(new Point(e.X, e.Y));
44 //PointToClient()将指定屏幕点的位置计算成工作区坐标
45 }
46 catch (Exception ex)
47 {
48 MessageBox.Show(ex.Message);
49 return;
50 }
51 }
52
53 // Handle Bitmap data.
54 if (e.Data.GetDataPresent(DataFormats.Bitmap))
55 {
56 try
57 {
58 // Create an Image and assign it to the picture variable.
59 this.picture = (Image)e.Data.GetData(DataFormats.Bitmap);
60 //是不是这样，可以用GetData中数据中分别抽出地址，位图数据……
61 // Set the picture location equal to the drop point.
62 this.pictureLocation = this.PointToClient(new Point(e.X, e.Y));
63 }
64 catch (Exception ex)
65 {
66 MessageBox.Show(ex.Message);
67 return;
68 }
69 }
70 // Force the form to be redrawn with the image.
71 this.Invalidate();
72 }
73
74 private void Form1_DragEnter(object sender, DragEventArgs e)
75 {
76 // If the data is a file or a bitmap, display the copy cursor.
77 if (e.Data.GetDataPresent(DataFormats.Bitmap) ||
78 e.Data.GetDataPresent(DataFormats.FileDrop))
79 //GetDataPresent(),确定此实例中存储的数据是否与指定的格式关联，或是否可以转换成指定格式
80 {
81 e.Effect = DragDropEffects.Copy;
82 }
83 else
84 {
85 e.Effect = DragDropEffects.None;
86 }
87 }
88
89 protected override void OnPaint(PaintEventArgs e)
90 {
91 // If there is an image and it has a location,
92 // paint it when the Form is repainted.
93 base.OnPaint(e);
94 if (this.picture != null && this.pictureLocation != Point.Empty)
95 {
96 e.Graphics.DrawImage(this.picture, this.pictureLocation);
97 }
98 }
99 }
100 }
Invalidate
