C#編寫ActiveX網(wǎng)頁(yè)截圖控件

來(lái)源：本站原創(chuàng)|時(shí)間：2020-01-10|欄目：C#教程|點(diǎn)擊：次

故事背景：Java組的小伙伴需要一個(gè)能在IE（還是6。。。）下截圖并返回給網(wǎng)頁(yè)的功能，但是IE做起來(lái)很麻煩（可能根本做不到），于是找到我寫一個(gè)ActiveX控件實(shí)現(xiàn)此功能，想著可能還有其他小伙伴需要這個(gè)功能，于是就PO出來(lái)，供需要的人使用，當(dāng)然也可以作為學(xué)習(xí)C#編寫ActiveX的一個(gè)簡(jiǎn)單入門教程（VC++效果更好）。
功能截圖如下：

代碼分為兩個(gè)核心部分：1、C#屏幕截圖；2、C#開發(fā)ActivX控件。
1、屏幕截圖，這個(gè)在網(wǎng)上找到了一個(gè)只需要5行代碼的實(shí)現(xiàn)（超級(jí)精簡(jiǎn)），當(dāng)然你也可以費(fèi)點(diǎn)功夫?qū)崿F(xiàn)自由區(qū)域截取圖片，截圖后保存到本地，然后使用二進(jìn)制讀取jpg文件，并編碼為base64返回給網(wǎng)頁(yè)

 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(fā)ActiveX控件，網(wǎng)上示例比較多
先新建一個(gè)類庫(kù)，并設(shè)置項(xiàng)目屬性，COM可見(jiàn)

并為COM互注冊(cè)，這樣編譯完了會(huì)自動(dòng)注冊(cè)COM控件

完成設(shè)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(shí)現(xiàn)一個(gè)名為“IObjectSafety”的接口。先創(chuàng)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(shí)現(xiàn)是固定內(nèi)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(diào)用ActiveX控件：

<!DOCTYPE html>
<html>
 <head>
 <title>測(cè)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(gè)完整的ActvieX控件就完成了，這里沒(méi)有使用到事件，如果使用事件的話會(huì)更加麻煩一點(diǎn)。

下載：屏幕截圖ActivX控件

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