C#创建ActiveX

一、目标

　　创建一个Demo，使用C#创建ActiveX达到屏幕截图并展示图片的效果。

二、步骤

　　1. 使用Visual Studio创建一个Class Libary项目

　　2. 向Project中Add一个New Item -> Interface，命名为IObjectSafety.cs，代码如下

namespace IEActiveX
{
    //为了让ActiveX控件获得客户端的信任，控件类需要实现一个名为“IObjectSafety”的接口。先创建该接口（注意，不能修改该接口的GUID值）
    [ComImport,Guid("CB5BDC81-93C1-11CF-8F20-00805F2CD064")]
    [InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
    public interface IObjectSafety
    {
        [PreserveSig]
        int GetInterfaceSafetyOptions(ref Guid riid, [MarshalAs(UnmanagedType.U4)] ref int pdwSupportedOptions, [MarshalAs(UnmanagedType.U4)] ref int pdwEnabledOptions);

        [PreserveSig()]
        int SetInterfaceSafetyOptions(ref Guid riid, [MarshalAs(UnmanagedType.U4)] int dwOptionSetMask, [MarshalAs(UnmanagedType.U4)] int dwEnabledOptions);
    }
}

　　3. 向Project中Add一个User Control...,命名为ScreenCapture.cs，代码如下

　　注意使用Guid工具生成下面的Guid

namespace IEActiveX
{
  [Guid("84F44957-3A18-4B1B-96BB-9D7D1D7B577E")] //使用VS工具里的GUID生成器生成唯一码
    public partial class ScreenCapture : UserControl,IObjectSafety
    {
        public ScreenCapture()
        {
            InitializeComponent();
        }
        #region IObjectSafety 成员
        private const string _IID_IDispatch = "{00020400-0000-0000-C000-000000000046}";
        private const string _IID_IDispatchEx = "{a6ef9860-c720-11d0-9337-00a0c90dcaa9}";
        private const string _IID_IPersistStorage = "{0000010A-0000-0000-C000-000000000046}";
        private const string _IID_IPersistStream = "{00000109-0000-0000-C000-000000000046}";
        private const string _IID_IPersistPropertyBag = "{37D84F60-42CB-11CE-8135-00AA004BB851}";

        private const int INTERFACESAFE_FOR_UNTRUSTED_CALLER = 0x00000001;
        private const int INTERFACESAFE_FOR_UNTRUSTED_DATA = 0x00000002;
        private const int S_OK = 0;
        private const int E_FAIL = unchecked((int)0x80004005);
        private const int E_NOINTERFACE = unchecked((int)0x80004002);

        private bool _fSafeForScripting = true;
        private bool _fSafeForInitializing = true;

        public int GetInterfaceSafetyOptions(ref Guid riid, [MarshalAs(UnmanagedType.U4)] ref int pdwSupportedOptions, [MarshalAs(UnmanagedType.U4)] ref int pdwEnabledOptions)
        {
            int result = E_FAIL;

            string strGuid = riid.ToString("B");
            pdwEnabledOptions = INTERFACESAFE_FOR_UNTRUSTED_CALLER | INTERFACESAFE_FOR_UNTRUSTED_DATA;
            switch (strGuid)
            {
                case _IID_IDispatch:
                case _IID_IDispatchEx:
                    result = S_OK;
                    pdwEnabledOptions = 0;
                    if (_fSafeForScripting)
                        pdwEnabledOptions = INTERFACESAFE_FOR_UNTRUSTED_CALLER;
                    break;
                case _IID_IPersistStorage:
                case _IID_IPersistStream:
                case _IID_IPersistPropertyBag:
                    result = S_OK;
                    pdwEnabledOptions = 0;
                    if (_fSafeForInitializing)
                        pdwEnabledOptions = INTERFACESAFE_FOR_UNTRUSTED_DATA;
                    break;
                default:
                    result = E_NOINTERFACE;
                    break;
            }
            return result;
        }

        public int SetInterfaceSafetyOptions(ref Guid riid, [MarshalAs(UnmanagedType.U4)] int dwOptionSetMask, [MarshalAs(UnmanagedType.U4)] int dwEnabledOptions)
        {
            int result = E_FAIL;

            string strGuid = riid.ToString("B");
            switch (strGuid)
            {
                case _IID_IDispatch:
                case _IID_IDispatchEx:
                    if (((dwEnabledOptions & dwOptionSetMask) == INTERFACESAFE_FOR_UNTRUSTED_CALLER) && _fSafeForScripting)
                        result = S_OK;
                    break;
                default:
                    result = E_NOINTERFACE;
                    break;
            }
            return result;
        }
        #endregion

        public string PrintScreen()
        {
            Image baseImage = new Bitmap(Screen.PrimaryScreen.Bounds.Width, Screen.PrimaryScreen.Bounds.Height);
            Graphics g = Graphics.FromImage(baseImage);
            g.CopyFromScreen(new Point(0, 0), new Point(0, 0), Screen.AllScreens[0].Bounds.Size);
            g.Dispose();
            baseImage.Save("D:\\screen.jpg", ImageFormat.Jpeg);
            Stream file = new FileStream("D:\\screen.jpg", FileMode.Open);
            BinaryReader bw = new BinaryReader(file);
            var buffer = new byte[file.Length];
            bw.Read(buffer, 0, buffer.Length);
            bw.Close();
            string b64 = Convert.ToBase64String(buffer);
            return b64;
        }
    }
}

　　4. 设置Project属性，

　　　　Application => "Make assembly COM-Visible"(使程序集COM可见)

　　　　Build =>"Register for COM interop"(为COM互操作注册)

　　5. 生成该解决方案，该ActiveX会注册到系统Register

　　6. 在Web中调用该ActiveX

　　注意下面的CLASSID="clsid:84F44957-3A18-4B1B-96BB-9D7D1D7B577E"> 必须和上面自己生成的一致

<!DOCTYPE html>
<html>
  <head>
    <title>Testing</title>

    <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
    <meta http-equiv="description" content="this is my page">
    <meta http-equiv="content-type" content="text/html; charset=UTF-8">
    <script>
        function jt(){
             var str="";
             try
             {
                var obj = document.getElementById("IEActiveX");
                 str=obj.PrintScreen();
             }
             catch(e)
            {
                alert(e);
                return;
            }

             var img=document.getElementById("img");
             img.src="data:image/jpeg;base64,"+str;//接受base64编码后的图片
        }
    </script>
  </head>

  <body>
      <OBJECT ID="IEActiveX" WIDTH="120" HEIGHT=20" CLASSID="clsid:84F44957-3A18-4B1B-96BB-9D7D1D7B577E"></OBJECT>
      <input type="button" value="ScreenCapture" onclick="jt();">
    <Image id ="img" />
  </body>
</html>

三、运行结果