我希望编写一个 Visual Studio 插件，当在类或类型上调用 F1 帮助时，它可以拦截默认的在线帮助命令并获取 MSDN 库 URL。
例如，假设我将光标放在关键字字符串上并按 F1，它通常会自动打开浏览器并导航到字符串引用类型的帮助文档。我想在传递给浏览器的 URL 到达浏览器之前获取它。
是否可以编写一个可以拦截默认 F1 帮助命令的 Visual Studio 插件/扩展 ??
如果上述可以完成，有任何关于从哪里开始的指示吗？
大约十年前，当我在微软工作时，我为Visual Studio 2005中最初的“Online F1”功能编写了规范。所以我的知识有些权威，但也可能已经过时了。 ;-)
您无法更改 Visual Studio 正在使用的 URL（至少我不知道如何更改它），但您可以简单地编写另一个加载项来窃取 F1 键绑定，使用与默认的 F1 处理程序会执行此操作，并将用户定向到您自己的 URL 或应用程序。
首先，一些有关在线 F1 如何运作的信息：
msdn.microsoft.com/query/dev11.query?
appId=Dev11IDEF1&
l=EN-US&
k=k(width);
k(vs.csseditor);
k(TargetFrameworkMoniker-.NETFramework,Version%3Dv4.0);
k(DevLang-CSS)&
rd=true
上面的“k”参数包含 Visual Studio 内部的帮助上下文。帮助上下文包含“关键字”（文本字符串）和“属性”（名称/值对），Visual Studio 中的各个窗口使用它们来告诉 IDE 用户现在正在做什么。
CSS 编辑器推送了两个关键字：我选择的“width”和“vs.csseditor”，MSDN 可以将其用作“后备”，例如，如果在 MSDN 上找不到我的选择。
还有一些上下文过滤属性：（
-分隔符将名称/值对中的名称与值分开）
TargetFrameworkMoniker-NETFramework,Version=v4.0
DevLang-CSS
这些确保 F1 加载正确语言或技术的页面，在本例中为 CSS。 （.NET 4.0 的另一个过滤器存在，因为我加载的项目面向 .NET 4.0）
注意上下文是有序的。 “width”关键字比它下面的关键字更重要。
MSDN 上的实际帮助内容具有元数据（由编写文档的团队手动设置），其中包含与该页面关联的关键字和名称/值上下文属性。例如，MSDN 上的
css width 属性文档，当它存储在 MSDN 服务器上时，具有与其关联的关键字列表（在本例中为：“width”）和上下文属性列表（在本例中为：“DevLang” =CSS”）。页面可以有多个关键字（例如“System.String”、“String”）和多个上下文属性（例如“DevLang=C#”、“DevLang=VB”等）。 当关键字列表到达 MSDN Online F1 服务时，算法是这样的，但需要注意的是，它在过去几年中可能已经发生了变化：
取第一个关键词
接管F1键绑定
using System;
using Extensibility;
using EnvDTE;
using EnvDTE80;
using Microsoft.VisualStudio.CommandBars;
using System.Resources;
using System.Reflection;
using System.Globalization;
using System.Collections;
using System.Collections.Generic;
using System.Text;
namespace ReplaceF1
{
/// <summary>The object for implementing an Add-in.</summary>
/// <seealso class='IDTExtensibility2' />
public class Connect : IDTExtensibility2, IDTCommandTarget
{
/// <summary>Implements the constructor for the Add-in object. Place your initialization code within this method.</summary>
public Connect()
{
}
MsdnExplorer.MainWindow Explorer = new MsdnExplorer.MainWindow();
/// <summary>Implements the OnConnection method of the IDTExtensibility2 interface. Receives notification that the Add-in is being loaded.</summary>
/// <param term='application'>Root object of the host application.</param>
/// <param term='connectMode'>Describes how the Add-in is being loaded.</param>
/// <param term='addInInst'>Object representing this Add-in.</param>
/// <seealso class='IDTExtensibility2' />
public void OnConnection(object application, ext_ConnectMode connectMode, object addInInst, ref Array custom)
{
_applicationObject = (DTE2)application;
_addInInstance = (AddIn)addInInst;
if(connectMode == ext_ConnectMode.ext_cm_UISetup)
{
object []contextGUIDS = new object[] { };
Commands2 commands = (Commands2)_applicationObject.Commands;
string toolsMenuName;
try
{
// If you would like to move the command to a different menu, change the word "Help" to the
// English version of the menu. This code will take the culture, append on the name of the menu
// then add the command to that menu. You can find a list of all the top-level menus in the file
// CommandBar.resx.
ResourceManager resourceManager = new ResourceManager("ReplaceF1.CommandBar", Assembly.GetExecutingAssembly());
CultureInfo cultureInfo = new System.Globalization.CultureInfo(_applicationObject.LocaleID);
string resourceName = String.Concat(cultureInfo.TwoLetterISOLanguageName, "Help");
toolsMenuName = resourceManager.GetString(resourceName);
}
catch
{
//We tried to find a localized version of the word Tools, but one was not found.
// Default to the en-US word, which may work for the current culture.
toolsMenuName = "Help";
}
//Place the command on the tools menu.
//Find the MenuBar command bar, which is the top-level command bar holding all the main menu items:
Microsoft.VisualStudio.CommandBars.CommandBar menuBarCommandBar = ((Microsoft.VisualStudio.CommandBars.CommandBars)_applicationObject.CommandBars)["MenuBar"];
//Find the Tools command bar on the MenuBar command bar:
CommandBarControl toolsControl = menuBarCommandBar.Controls[toolsMenuName];
CommandBarPopup toolsPopup = (CommandBarPopup)toolsControl;
//This try/catch block can be duplicated if you wish to add multiple commands to be handled by your Add-in,
// just make sure you also update the QueryStatus/Exec method to include the new command names.
try
{
//Add a command to the Commands collection:
Command command = commands.AddNamedCommand2(_addInInstance,
"ReplaceF1",
"MSDN Advanced F1",
"Brings up context-sensitive Help via the MSDN Add-in",
true,
59,
ref contextGUIDS,
(int)vsCommandStatus.vsCommandStatusSupported+(int)vsCommandStatus.vsCommandStatusEnabled,
(int)vsCommandStyle.vsCommandStylePictAndText,
vsCommandControlType.vsCommandControlTypeButton);
command.Bindings = new object[] { "Global::F1" };
}
catch(System.ArgumentException)
{
//If we are here, then the exception is probably because a command with that name
// already exists. If so there is no need to recreate the command and we can
// safely ignore the exception.
}
}
}
/// <summary>Implements the OnDisconnection method of the IDTExtensibility2 interface. Receives notification that the Add-in is being unloaded.</summary>
/// <param term='disconnectMode'>Describes how the Add-in is being unloaded.</param>
/// <param term='custom'>Array of parameters that are host application specific.</param>
/// <seealso class='IDTExtensibility2' />
public void OnDisconnection(ext_DisconnectMode disconnectMode, ref Array custom)
{
}
/// <summary>Implements the OnAddInsUpdate method of the IDTExtensibility2 interface. Receives notification when the collection of Add-ins has changed.</summary>
/// <param term='custom'>Array of parameters that are host application specific.</param>
/// <seealso class='IDTExtensibility2' />
public void OnAddInsUpdate(ref Array custom)
{
}
/// <summary>Implements the OnStartupComplete method of the IDTExtensibility2 interface. Receives notification that the host application has completed loading.</summary>
/// <param term='custom'>Array of parameters that are host application specific.</param>
/// <seealso class='IDTExtensibility2' />
public void OnStartupComplete(ref Array custom)
{
}
/// <summary>Implements the OnBeginShutdown method of the IDTExtensibility2 interface. Receives notification that the host application is being unloaded.</summary>
/// <param term='custom'>Array of parameters that are host application specific.</param>
/// <seealso class='IDTExtensibility2' />
public void OnBeginShutdown(ref Array custom)
{
}
/// <summary>Implements the QueryStatus method of the IDTCommandTarget interface. This is called when the command's availability is updated</summary>
/// <param term='commandName'>The name of the command to determine state for.</param>
/// <param term='neededText'>Text that is needed for the command.</param>
/// <param term='status'>The state of the command in the user interface.</param>
/// <param term='commandText'>Text requested by the neededText parameter.</param>
/// <seealso class='Exec' />
public void QueryStatus(string commandName, vsCommandStatusTextWanted neededText, ref vsCommandStatus status, ref object commandText)
{
if(neededText == vsCommandStatusTextWanted.vsCommandStatusTextWantedNone)
{
if(commandName == "ReplaceF1.Connect.ReplaceF1")
{
status = (vsCommandStatus)vsCommandStatus.vsCommandStatusSupported|vsCommandStatus.vsCommandStatusEnabled;
return;
}
}
}
/// <summary>Implements the Exec method of the IDTCommandTarget interface. This is called when the command is invoked.</summary>
/// <param term='commandName'>The name of the command to execute.</param>
/// <param term='executeOption'>Describes how the command should be run.</param>
/// <param term='varIn'>Parameters passed from the caller to the command handler.</param>
/// <param term='varOut'>Parameters passed from the command handler to the caller.</param>
/// <param term='handled'>Informs the caller if the command was handled or not.</param>
/// <seealso class='Exec' />
public void Exec(string commandName, vsCommandExecOption executeOption, ref object varIn, ref object varOut, ref bool handled)
{
if(executeOption == vsCommandExecOption.vsCommandExecOptionDoDefault)
{
if (commandName == "ReplaceF1.Connect.ReplaceF1")
{
// Get a reference to Solution Explorer.
Window activeWindow = _applicationObject.ActiveWindow;
ContextAttributes contextAttributes = activeWindow.DTE.ContextAttributes;
contextAttributes.Refresh();
List<string> attributes = new List<string>();
try
{
ContextAttributes highPri = contextAttributes == null ? null : contextAttributes.HighPriorityAttributes;
highPri.Refresh();
if (highPri != null)
{
foreach (ContextAttribute CA in highPri)
{
List<string> values = new List<string>();
foreach (string value in (ICollection)CA.Values)
{
values.Add(value);
}
string attribute = CA.Name + "=" + String.Join(";", values.ToArray());
attributes.Add(CA.Name + "=");
}
}
}
catch (System.Runtime.InteropServices.COMException e)
{
// ignore this exception-- means there's no High Pri values here
string x = e.Message;
}
catch (System.Reflection.TargetInvocationException e)
{
// ignore this exception-- means there's no High Pri values here
string x = e.Message;
}
catch (System.Exception e)
{
System.Windows.Forms.MessageBox.Show(e.Message);
// ignore this exception-- means there's no High Pri values here
string x = e.Message;
}
// fetch context attributes that are not high-priority
foreach (ContextAttribute CA in contextAttributes)
{
List<string> values = new List<string>();
foreach (string value in (ICollection)CA.Values)
{
values.Add (value);
}
string attribute = CA.Name + "=" + String.Join(";", values.ToArray());
attributes.Add (attribute);
}
// Replace this call with whatever you want to do with the help context info
HelpHandler.HandleF1 (attributes);
}
}
}
private DTE2 _applicationObject;
private AddIn _addInInstance;
}
}