在C++中，可以使用CoCreateInstance函数来创建COM接口的实例。
以下教程可以帮助你方便的在C#中实现同样的功能。
方法一、手动生成（适用于所有.NET版本）
1、确定要使用的COM接口
Windows中很多功能都是通过COM实现的，有时候我们想实现一些系统功能，但是又没有直接的Win32 API代调用，就可以寻找COM接口替代。
至于使用哪个COM接口，这个可以通过搜索引擎。
例如，我想设置桌面壁纸，就可以通过IDesktopWallpaper接口来实现。
2、查找COM接口的GUID
这里提供了几种方案
一、通过搜索引擎，常用的COM接口，可以通过搜索引擎直接搜索到GUID
二、对于不常用的COM接口，可能搜索引擎不能搜索到对应的GUID，我们可以创建一个Win32工程（需要Visual Studio安装C++桌面开发），然后输入CLSID_接口名称，再按F12就可以看到GUID。
例如：CLSID_DesktopWallpaper，按F12如下所示
三、如果电脑上没有安装C++桌面开发负载，可以访问stevemk14ebr的gist来进行搜索
3、接口声明
有了COM接口的GUID后，我们需要对COM接口进行声明
这里有几个方法可供参考：
一、通过C# + COM接口为关键进行进行搜索
例如搜索[C# IDesktopWallpaper]，然后在结果中查找，一般会有C#的接口声明，如果没找到相关结果，可以查看方法2
二、访问pinvoke.net搜索
我们打开https://www.pinvoke.net/，搜索IDesktopWallpaper
目前该网站已经停止维护，所以基本上搜索不出来。
三、访问MSDN文档，通过数据类型映射，自行声明COM接口
可以参考下面的文章：
https://learn.microsoft.com/en-us/previous-versions/dotnet/netframework-4.0/ac7ay120(v=vs.100)?redirectedfrom=MSDN
这种方法虽然比较麻烦，但也算是最终解决方案了。
需要注意的是，接口中涉及的类型也需要进行声明。
例如IDesktopWallpaper在C#中声明如下：
1 using System;
2 using System.Runtime.CompilerServices;
3 using System.Runtime.InteropServices;
4 using System.Text;
5
6 namespace IDesktopWallpaperWrapper.Win32
7 {
8 /// <summary>
9 /// The direction that the slideshow should advance.
10 /// </summary>
11 [ComVisible(true)]
12 public enum DESKTOP_SLIDESHOW_DIRECTION
13 {
14 /// <summary>
15 /// Advance the slideshow forward.
16 /// </summary>
17 DSD_FORWARD = 0,
18 /// <summary>
19 /// Advance the slideshow backward.
20 /// </summary>
21 DSD_BACKWARD = 1
22 }
23
24
25
26 /// <summary>
27 /// Specifies how the desktop wallpaper should be displayed.
28 /// </summary>
29 [ComVisible(true)]
30 public enum DESKTOP_WALLPAPER_POSITION
31 {
32 /// <summary>
33 /// Center the image; do not stretch.
34 /// </summary>
35 DWPOS_CENTER = 0,
36 /// <summary>
37 /// Tile the image across all monitors.
38 /// </summary>
39 DWPOS_TILE = 1,
40 /// <summary>
41 /// Stretch the image to exactly fit on the monitor.
42 /// </summary>
43 DWPOS_STRETCH = 2,
44 /// <summary>
45 /// Stretch the image to exactly the height or width of the monitor without changing its aspect ratio or cropping the image.
46 /// This can result in colored letterbox bars on either side or on above and below of the image.
47 /// </summary>
48 DWPOS_FIT = 3,
49 /// <summary>
50 /// Stretch the image to fill the screen, cropping the image as necessary to avoid letterbox bars.
51 /// </summary>
52 DWPOS_FILL = 4,
53 /// <summary>
54 /// Spans a single image across all monitors attached to the system.
55 /// </summary>
56 DWPOS_SPAN = 5
57 }
58
59
60
61 [ComVisible(true)]
62 [Flags]
63 public enum DESKTOP_SLIDESHOW_STATE
64 {
65 /// <summary>
66 /// Slideshows are enabled.
67 /// </summary>
68 DSS_ENABLED = 1,
69 /// <summary>
70 /// A slideshow is currently configured.
71 /// </summary>
72 DSS_SLIDESHOW = 2,
73 /// <summary>
74 /// A remote session has temporarily disabled the slideshow.
75 /// </summary>
76 DSS_DISABLED_BY_REMOTE_SESSION = 4
77 }
78
79
80
81 /// <summary>
82 /// COM interface providing methods for managing the desktop wallpaper.
83 /// Instantiate this COM interface with DesktopWallpaper wrapper class instead.
84 /// </summary>
85 /// <remarks>
86 /// Windows 8 or later is required in order to access this interface.
87 /// </remarks>
88 [ComImport]
89 [Guid("b92b56a9-8b55-4e14-9a89-0199bbb6f93b")]
90 [InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
91 public interface IDesktopWallpaper
92 {
93 // As with any COM import, method ordering is crucial to the functioning of the interface.
94 // The code ordering below must be maintained, else an AccessViolationException can be thrown.
95
96 //[MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
97 void SetWallpaper([MarshalAs(UnmanagedType.LPWStr)] string monitorID, [MarshalAs(UnmanagedType.LPWStr)] string wallpaper);
98
99 //[MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
100 [return: MarshalAs(UnmanagedType.LPWStr)]
101 StringBuilder GetWallpaper([MarshalAs(UnmanagedType.LPWStr)] string monitorID);
102
103 //[MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
104 [return: MarshalAs(UnmanagedType.LPWStr)]
105 StringBuilder GetMonitorDevicePathAt(uint monitorIndex);
106
107 [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
108 uint GetMonitorDevicePathCount();
109
110 //[MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
111 RECT GetMonitorRECT([MarshalAs(UnmanagedType.LPWStr)] string monitorID);
112
113 //[MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
114 void SetBackgroundColor(uint color);
115
116 //[MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
117 uint GetBackgroundColor();
118
119 //[MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
120 void SetPosition([MarshalAs(UnmanagedType.I4)] DESKTOP_WALLPAPER_POSITION position);
121
122 //[MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
123 [return: MarshalAs(UnmanagedType.I4)]
124 DESKTOP_WALLPAPER_POSITION GetPosition();
125
126 //[MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
127 void SetSlideshow(IShellItemArray items);
128 //void SetSlideshow(IntPtr items);
129
130 //[MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
131 IShellItemArray GetSlideshow();
132 //IntPtr GetSlideshow();
133
134 //[MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
135 void SetSlideshowOptions(uint options, uint slideshowTick);
136
137 //[MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
138 void GetSlideshowOptions(out uint options, out uint slideshowTick);
139
140 // NOT IMPLEMENTED BY COCLASS
141 //[MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
142 void AdvanceSlideshow([MarshalAs(UnmanagedType.LPWStr)] string monitorID, [MarshalAs(UnmanagedType.I4)] DESKTOP_SLIDESHOW_DIRECTION direction);
143
144 //[MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
145 DESKTOP_SLIDESHOW_STATE GetStatus();
146
147 //[MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
148 void Enable([MarshalAs(UnmanagedType.Bool)] bool enable);
149 }
150 }
4、定义类
这个步骤和步骤3类似，但是不需要定义类的成员函数。
1 [ComImport]
2 [Guid("b92b56a9-8b55-4e14-9a89-0199bbb6f93b")]
3
4 public class DesktopWallpaper
5 {
6
7 }
5、使用
1 IDesktopWallpaper desktopWallpaper = (IDesktopWallpaper)new DesktopWallpaper(); 2 3 //调用成员函数 4 desktopWallpaper.xxxx();
方法二、自动生成（适用于.NET6+版本）
标签：Runtime,MethodImpl,C#,MethodImplOptions,接口,InternalCall,COM,MethodCodeType From： https://www.cnblogs.com/zhaotianff/p/18657903