以下内容为程序代码:

1 using System;
2 using System.Collections.Generic;
3 using System.ComponentModel;
4 using System.Data;
5 using System.Drawing;
6 using System.Text;
7 using System.Windows.Forms;
8 using System.Drawing.Drawing2D;
9
10 namespace WindowsFormsApplication1
11 {
12 public partial class Form1 : Form
13 {
14 public Form1()
15 {
16 InitializeComponent();
17 }
18
19 private void Form1_Load(object sender, EventArgs e)
20 {
21 ///＜summary＞
22 /// 设置不规则窗体
23 ///＜/summary＞
24 ///＜param name="sender"＞＜/param＞
25 ///＜param name="e"＞＜/param＞
26
27 //从指定的位图中获取alpha透明度大于 10 的区域
28 Bitmap img = (Bitmap)pictureBox1.Image;
29 GraphicsPath grapth = GetNoneTransparentRegion(img, 155);
30 this.Region = new Region(grapth);
31
32 //要显示的图片设置为窗体背景
33 this.BackgroundImage = pictureBox1.Image;
34 this.BackgroundImageLayout = ImageLayout.Zoom;
35
36 //在修改窗体尺寸之前设置窗体为无边框样式
37 this.FormBorderStyle = FormBorderStyle.None;
38 this.Width = pictureBox1.Image.Width;
39 this.Height = pictureBox1.Image.Height;
40 }
41 ///＜summary＞
42 /// 返回指定图片中的非透明区域(方法)
43 ///＜/summary＞
44 ///＜param name="img"＞位图＜/param＞
45 ///＜param name="alpha"＞alpha 小于等于该值的为透明＜/param＞
46 ///＜returns＞＜/returns＞
47 public static GraphicsPath GetNoneTransparentRegion(Bitmap img, byte alpha)
48 {
49 int height = img.Height;
50 int width = img.Width;
51 int xStart, xEnd;
52 GraphicsPath grpPath = new GraphicsPath();
53 for (int y = 0; y ＜ height; y++)
54 {
55 //逐行扫描
56 for (int x = 0; x ＜ width; x++)
57 {
58 //略过连续透明的部分
59 while (x ＜ width && img.GetPixel(x, y).A ＜= alpha)
60 {
61 x++;
62 }
63 //不透明部分；
64 xStart = x;
65 while (x ＜ width && img.GetPixel(x, y).A ＞ alpha)
66 {
67 x++;
68 }
69 xEnd = x;
70 if (img.GetPixel(x - 1, y).A ＞ alpha)
71 {
72 grpPath.AddRectangle(new Rectangle(xStart, y, xEnd - xStart, 1));
73 }
74 }
75 }
76 return grpPath;
77 }
78 }
79 }
80