C#编写ActiveX网页截图控件

2020-01-24 01:06:47

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故事背景：Java组的小伙伴需要一个能在IE（还是6。。。）下截图并返回给网页的功能，但是IE做起来很麻烦（可能根本做不到），于是找到我写一个ActiveX控件实现此功能，想着可能还有其他小伙伴需要这个功能，于是就PO出来，供需要的人使用，当然也可以作为学习C#编写ActiveX的一个简单入门教程（VC++效果更好）。
功能截图如下：

代码分为两个核心部分：1、C#屏幕截图；2、C#开发ActivX控件。
1、屏幕截图，这个在网上找到了一个只需要5行代码的实现（超级精简），当然你也可以费点功夫实现自由区域截取图片，截图后保存到本地，然后使用二进制读取jpg文件，并编码为base64返回给网页

 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#开发ActiveX控件，网上示例比较多
先新建一个类库，并设置项目属性，COM可见

并为COM互注册，这样编译完了会自动注册COM控件

完成设置后，编写代码，如下：

using System;using System.Collections.Generic;using System.Text;using System.Runtime.InteropServices;namespace PrintScreenLib{ //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); }}

新建用户控件，并派生IObjectSafe接口，接口实现是固定内容

 [Guid("61D7F413-A1B2-48A9-B851-5BFBCF50280C")] //使用VS工具里的GUID生成器生成唯一码 public partial class PSLib : UserControl, IObjectSafety { #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, 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调用ActiveX控件：

<!DOCTYPE html><html> <head> <title>测试</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编码后的图片 } </script> </head>  <body> <OBJECT ID="MyActiveX" WIDTH="120" HEIGHT=20" CLASSID="CLSID:61D7F413-A1B2-48A9-B851-5BFBCF50280C"></OBJECT> <input type="button" value="截图" onclick="jt();"> <Image id ="img" /> </body></html>

一个完整的ActvieX控件就完成了，这里没有使用到事件，如果使用事件的话会更加麻烦一点。

下载：屏幕截图ActivX控件

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持武林网。

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