故事背景：Java組的小伙伴需要一個能在IE（還是6。。。）下截圖并返回給網頁的功能，但是IE做起來很麻煩（可能根本做不到），于是找到我寫一個ActiveX控件實現此功能，想著可能還有其他小伙伴需要這個功能，于是就PO出來，供需要的人使用，當然也可以作為學習C#編寫ActiveX的一個簡單入門教程（VC++效果更好）。
功能截圖如下：
代碼分為兩個核心部分：1、C#屏幕截圖；2、C#開發ActivX控件。
1、屏幕截圖，這個在網上找到了一個只需要5行代碼的實現（超級精簡），當然你也可以費點功夫實現自由區域截取圖片，截圖后保存到本地，然后使用二進制讀取jpg文件，并編碼為base64返回給網頁
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; } 2、c#開發ActiveX控件，網上示例比較多
先新建一個類庫，并設置項目屬性，COM可見
并為COM互注冊，這樣編譯完了會自動注冊COM控件
完成設置后，編寫代碼，如下：
using System;using System.Collections.Generic;using System.Text;using System.Runtime.InteropServices;namespace PrintScreenLib{ //為了讓ActiveX控件獲得客戶端的信任，控件類需要實現一個名為“IObjectSafety”的接口。先創建該接口（注意，不能修改該接口的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); }} 新建用戶控件，并派生IObjectSafe接口，接口實現是固定內容
[Guid("61D7F413-A1B2-48A9-B851-5BFBCF50280C")] //使用VS工具里的GUID生成器生成唯一碼 public partial class PSLib : UserControl, IObjectSafety { #region IObjectSafety 成員 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, ref int pdwSupportedOptions, ref int pdwEnabledOptions) { int Rslt = E_FAIL; string strGUID = riid.ToString("B"); pdwSupportedOptions = INTERFACESAFE_FOR_UNTRUSTED_CALLER | INTERFACESAFE_FOR_UNTRUSTED_DATA; switch (strGUID) { case _IID_IDispatch: case _IID_IDispatchEx: Rslt = S_OK; pdwEnabledOptions = 0; if (_fSafeForScripting == true) pdwEnabledOptions = INTERFACESAFE_FOR_UNTRUSTED_CALLER; break; case _IID_IPersistStorage: case _IID_IPersistStream: case _IID_IPersistPropertyBag: Rslt = S_OK; pdwEnabledOptions = 0; if (_fSafeForInitializing == true) pdwEnabledOptions = INTERFACESAFE_FOR_UNTRUSTED_DATA; break; default: Rslt = E_NOINTERFACE; break; } return Rslt; } public int SetInterfaceSafetyOptions(ref Guid riid, int dwOptionSetMask, int dwEnabledOptions) { int Rslt = E_FAIL; string strGUID = riid.ToString("B"); switch (strGUID) { case _IID_IDispatch: case _IID_IDispatchEx: if (((dwEnabledOptions & dwOptionSetMask) == INTERFACESAFE_FOR_UNTRUSTED_CALLER) && (_fSafeForScripting == true)) Rslt = S_OK; break; case _IID_IPersistStorage: case _IID_IPersistStream: case _IID_IPersistPropertyBag: if (((dwEnabledOptions & dwOptionSetMask) == INTERFACESAFE_FOR_UNTRUSTED_DATA) && (_fSafeForInitializing == true)) Rslt = S_OK; break; default: Rslt = E_NOINTERFACE; break; } return Rslt; } #endregion IE調用ActiveX控件：
<!DOCTYPE html><html> <head> <title>測試</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("MyActiveX"); str=obj.PrintScreen(); } catch(e) { alert(e); return; } var img=document.getElementById("img"); img.src="data:image/jpeg;base64,"+str;//接受base64編碼后的圖片 } </script> </head> <body> <OBJECT ID="MyActiveX" WIDTH="120" HEIGHT=20" CLASSID="CLSID:61D7F413-A1B2-48A9-B851-5BFBCF50280C"></OBJECT> <input type="button" value="截圖" onclick="jt();"> <Image id ="img" /> </body></html>
一個完整的ActvieX控件就完成了，這里沒有使用到事件，如果使用事件的話會更加麻煩一點。
以上就是本文的全部內容，希望對大家的學習有所幫助，也希望大家多多支持VEVB武林網。
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