(精华)2020年6月26日 C#类库 图片操作帮助类

using System;
using System.Drawing;
using System.Drawing.Imaging;
using System.IO;
using System.Text.RegularExpressions;

namespace Core.Util
{
    /// <summary>
    /// 图片操作帮助类
    /// </summary>
    public class ImgHelper
    {
        /// <summary>
        /// 从文件获取图片
        /// </summary>
        /// <param name="fileName">文件名</param>
        /// <returns></returns>
        public static Image GetImgFromFile(string fileName)
        {
            return Image.FromFile(fileName);
        }

        /// <summary>
        /// 从base64字符串读入图片
        /// </summary>
        /// <param name="base64">base64字符串</param>
        /// <returns></returns>
        public static Image GetImgFromBase64(string base64)
        {
            byte[] bytes = Convert.FromBase64String(base64);
            MemoryStream memStream = new MemoryStream(bytes);
            Image img = Image.FromStream(memStream);

            return img;
        }

        /// <summary>
        /// 从URL格式的Base64图片获取真正的图片
        /// 即去掉data:image/jpg;base64,这样的格式
        /// </summary>
        /// <param name="base64Url">图片Base64的URL形式</param>
        /// <returns></returns>
        public static Image GetImgFromBase64Url(string base64Url)
        {
            string base64 = GetBase64String(base64Url);

            return GetImgFromBase64(base64);
        }

        /// <summary>
        /// 压缩图片
        /// 注:等比压缩
        /// </summary>
        /// <param name="img">原图片</param>
        /// <param name="width">压缩后宽度</param>
        /// <returns></returns>
        public static Image CompressImg(Image img, int width)
        {
            return CompressImg(img, width, (int)(((double)width) / img.Width * img.Height));
        }

        /// <summary>
        /// 压缩图片
        /// </summary>
        /// <param name="img">原图片</param>
        /// <param name="width">压缩后宽度</param>
        /// <param name="height">压缩后高度</param>
        /// <returns></returns>
        public static Image CompressImg(Image img, int width, int height)
        {
            Bitmap bitmap = new Bitmap(img, width, height);

            return bitmap;
        }

        /// <summary>
        /// 将图片转为base64字符串
        /// 默认使用jpg格式
        /// </summary>
        /// <param name="img">图片对象</param>
        /// <returns></returns>
        public static string ToBase64String(Image img)
        {
            return ToBase64String(img, ImageFormat.Jpeg);
        }

        /// <summary>
        /// 将图片转为base64字符串
        /// 使用指定格式
        /// </summary>
        /// <param name="img">图片对象</param>
        /// <param name="imageFormat">指定格式</param>
        /// <returns></returns>
        public static string ToBase64String(Image img, ImageFormat imageFormat)
        {
            MemoryStream memStream = new MemoryStream();
            img.Save(memStream, imageFormat);
            byte[] bytes = memStream.ToArray();
            string base64 = Convert.ToBase64String(bytes);

            return base64;
        }

        /// <summary>
        /// 将图片转为base64字符串
        /// 默认使用jpg格式,并添加data:image/jpg;base64,前缀
        /// </summary>
        /// <param name="img">图片对象</param>
        /// <returns></returns>
        public static string ToBase64StringUrl(Image img)
        {
            return "data:image/jpg;base64," + ToBase64String(img, ImageFormat.Jpeg);
        }

        /// <summary>
        /// 将图片转为base64字符串
        /// 使用指定格式,并添加data:image/jpg;base64,前缀
        /// </summary>
        /// <param name="img">图片对象</param>
        /// <param name="imageFormat">指定格式</param>
        /// <returns></returns>
        public static string ToBase64StringUrl(Image img, ImageFormat imageFormat)
        {
            string base64 = ToBase64String(img, imageFormat);

            return $"data:image/{imageFormat.ToString().ToLower()};base64,{base64}";
        }

        /// <summary>
        /// 获取真正的图片base64数据
        /// 即去掉data:image/jpg;base64,这样的格式
        /// </summary>
        /// <param name="base64UrlStr">带前缀的base64图片字符串</param>
        /// <returns></returns>
        public static string GetBase64String(string base64UrlStr)
        {
            string parttern = "^(data:image/.*?;base64,).*?$";

            var match = Regex.Match(base64UrlStr, parttern);
            if (match.Groups.Count > 1)
                base64UrlStr = base64UrlStr.Replace(match.Groups[1].ToString(), "");

            return base64UrlStr;
        }
    }
}

  

 

  
1
  
2
  
3
  
4
  
5
  
6
  
7
  
8
  
9
  
10
  
11
  
12
  
13
  
14
  
15
  
16
  
17
  
18
  
19
  
20
  
21
  
22
  
23
  
24
  
25
  
26
  
27
  
28
  
29
  
30
  
31
  
32
  
33
  
34
  
35
  
36
  
37
  
38
  
39
  
40
  
41
  
42
  
43
  
44
  
45
  
46
  
47
  
48
  
49
  
50
  
51
  
52
  
53
  
54
  
55
  
56
  
57
  
58
  
59
  
60
  
61
  
62
  
63
  
64
  
65
  
66
  
67
  
68
  
69
  
70
  
71
  
72
  
73
  
74
  
75
  
76
  
77
  
78
  
79
  
80
  
81
  
82
  
83
  
84
  
85
  
86
  
87
  
88
  
89
  
90
  
91
  
92
  
93
  
94
  
95
  
96
  
97
  
98
  
99
  
100
  
101
  
102
  
103
  
104
  
105
  
106
  
107
  
108
  
109
  
110
  
111
  
112
  
113
  
114
  
115
  
116
  
117
  
118
  
119
  
120
  
121
  
122
  
123
  
124
  
125
  
126
  
127
  
128
  
129
  
130
  
131
  
132
  
133
  
134
  
135
  
136
  
137
  
138
  
139
  
140
  
141
  
142
  
143
  
144
  
145
  
146
  
147
 

文章来源: codeboy.blog.csdn.net，作者：愚公搬代码，版权归原作者所有，如需转载，请联系作者。

原文链接：codeboy.blog.csdn.net/article/details/106969477