Walkthrough: Displaying QuickInfo Tooltips

QuickInfo is an IntelliSense feature that displays method signatures and descriptions when a user moves the pointer over a method name. You can implement language-based features such as QuickInfo by defining the identifiers for which you want to provide QuickInfo descriptions, and then creating a tooltip in which to display the content. You can define QuickInfo in the context of a language service, or you can define your own file name extension and content type and display the QuickInfo for just that type, or you can display QuickInfo for an existing content type (such as "text"). This walkthrough shows how to display QuickInfo for the "text" content type.

The QuickInfo example in this walkthrough displays the tooltips when a user moves the pointer over a method name. This design requires you to implement these four interfaces:

• source interface

• source provider interface

• controller interface

• controller provider interface

  The source and controller providers are Managed Extensibility Framework (MEF) component parts, and are responsible for exporting the source and controller classes and importing services and brokers such as the ITextBufferFactoryService, which creates the tooltip text buffer, and the IQuickInfoBroker, which triggers the QuickInfo session.

  In this example, the QuickInfo source uses a hard-coded list of method names and descriptions, but in full implementations, the language service and the language documentation are responsible for providing that content.

Prerequisites

Starting in Visual Studio 2015, you do not install the Visual Studio SDK from the download center. It is included as an optional feature in Visual Studio setup. You can also install the VS SDK later on. For more information, see Installing the Visual Studio SDK.

Creating a MEF Project

To create a MEF project

1. Create a C# VSIX project. (In the New Project dialog, select Visual C# / Extensibility, then VSIX Project.) Name the solution QuickInfoTest.

2. Add an Editor Classifier item template to the project. For more information, see Creating an Extension with an Editor Item Template.

3. Delete the existing class files.

Implementing the QuickInfo Source

The QuickInfo source is responsible for collecting the set of identifiers and their descriptions and adding the content to the tooltip text buffer when one of the identifiers is encountered. In this example, the identifiers and their descriptions are just added in the source constructor.

To implement the QuickInfo source

1. Add a class file and name it TestQuickInfoSource.

2. Add a reference to Microsoft.VisualStudio.Language.IntelliSense.

3. Add the following imports.

   using System;
   using System.Collections.Generic;
   using System.Collections.ObjectModel;
   using System.ComponentModel.Composition;
   using Microsoft.VisualStudio.Language.Intellisense;
   using Microsoft.VisualStudio.Text;
   using Microsoft.VisualStudio.Text.Editor;
   using Microsoft.VisualStudio.Text.Operations;
   using Microsoft.VisualStudio.Text.Tagging;
   using Microsoft.VisualStudio.Utilities;
   

   Imports System
   Imports System.Collections.Generic
   Imports System.Linq
   Imports System.Text
   Imports System.Collections.ObjectModel
   Imports System.ComponentModel.Composition
   Imports Microsoft.VisualStudio.Language.Intellisense
   Imports Microsoft.VisualStudio.Text
   Imports Microsoft.VisualStudio.Text.Editor
   Imports Microsoft.VisualStudio.Text.Operations
   Imports Microsoft.VisualStudio.Text.Tagging
   Imports Microsoft.VisualStudio.Utilities
   

4. Declare a class that implements IQuickInfoSource, and name it TestQuickInfoSource.

   internal class TestQuickInfoSource : IQuickInfoSource
   

   Friend Class TestQuickInfoSource
       Implements IQuickInfoSource
   

5. Add fields for the QuickInfo source provider, the text buffer, and a set of method names and method signatures. In this example, the method names and signatures are initialized in the TestQuickInfoSource constructor.

   private TestQuickInfoSourceProvider m_provider;
   private ITextBuffer m_subjectBuffer;
   private Dictionary<string, string> m_dictionary;
   

   Private m_provider As TestQuickInfoSourceProvider
   Private m_subjectBuffer As ITextBuffer
   Private m_dictionary As Dictionary(Of String, String)
   

6. Add a constructor that sets the QuickInfo source provider and the text buffer, and populates the set of method names, and method signatures and descriptions.

   public TestQuickInfoSource(TestQuickInfoSourceProvider provider, ITextBuffer subjectBuffer)
   {
       m_provider = provider;
       m_subjectBuffer = subjectBuffer;
   
       //these are the method names and their descriptions
       m_dictionary = new Dictionary<string, string>();
       m_dictionary.Add("add", "int add(int firstInt, int secondInt)\nAdds one integer to another.");
       m_dictionary.Add("subtract", "int subtract(int firstInt, int secondInt)\nSubtracts one integer from another.");
       m_dictionary.Add("multiply", "int multiply(int firstInt, int secondInt)\nMultiplies one integer by another.");
       m_dictionary.Add("divide", "int divide(int firstInt, int secondInt)\nDivides one integer by another.");
   }
   

   Public Sub New(ByVal provider As TestQuickInfoSourceProvider, ByVal subjectBuffer As ITextBuffer)
       m_provider = provider
       m_subjectBuffer = subjectBuffer
   
       'these are the method names and their descriptions
       m_dictionary = New Dictionary(Of String, String)()
       m_dictionary.Add("add", "int add(int firstInt, int secondInt)" & vbLf & "Adds one integer to another.")
       m_dictionary.Add("subtract", "int subtract(int firstInt, int secondInt)" & vbLf & "Subtracts one integer from another.")
       m_dictionary.Add("multiply", "int multiply(int firstInt, int secondInt)" & vbLf & "Multiplies one integer by another.")
       m_dictionary.Add("divide", "int divide(int firstInt, int secondInt)" & vbLf & "Divides one integer by another.")
   End Sub
   

7. Implement the AugmentQuickInfoSession method. In this example, the method finds the current word, or the previous word if the cursor is at the end of a line or a text buffer. If the word is one of the method names, the description for that method name is added to the QuickInfo content.

   public void AugmentQuickInfoSession(IQuickInfoSession session, IList<object> qiContent, out ITrackingSpan applicableToSpan)
   {
       // Map the trigger point down to our buffer.
       SnapshotPoint? subjectTriggerPoint = session.GetTriggerPoint(m_subjectBuffer.CurrentSnapshot);
       if (!subjectTriggerPoint.HasValue)
       {
           applicableToSpan = null;
           return;
       }
   
       ITextSnapshot currentSnapshot = subjectTriggerPoint.Value.Snapshot;
       SnapshotSpan querySpan = new SnapshotSpan(subjectTriggerPoint.Value, 0);
   
       //look for occurrences of our QuickInfo words in the span
       ITextStructureNavigator navigator = m_provider.NavigatorService.GetTextStructureNavigator(m_subjectBuffer);
       TextExtent extent = navigator.GetExtentOfWord(subjectTriggerPoint.Value);
       string searchText = extent.Span.GetText();
   
       foreach (string key in m_dictionary.Keys)
       {
           int foundIndex = searchText.IndexOf(key, StringComparison.CurrentCultureIgnoreCase);
           if (foundIndex > -1)
           {
               applicableToSpan = currentSnapshot.CreateTrackingSpan
                   (
                   //querySpan.Start.Add(foundIndex).Position, 9, SpanTrackingMode.EdgeInclusive
                                           extent.Span.Start + foundIndex, key.Length, SpanTrackingMode.EdgeInclusive
                   );
   
               string value;
               m_dictionary.TryGetValue(key, out value);
               if (value != null)
                   qiContent.Add(value);
               else
                   qiContent.Add("");
   
               return;
           }
       }
   
       applicableToSpan = null;
   }
   

   Public Sub AugmentQuickInfoSession(ByVal session As IQuickInfoSession, ByVal qiContent As IList(Of Object), ByRef applicableToSpan As ITrackingSpan) Implements IQuickInfoSource.AugmentQuickInfoSession
       ' Map the trigger point down to our buffer.
       Dim subjectTriggerPoint As System.Nullable(Of SnapshotPoint) = session.GetTriggerPoint(m_subjectBuffer.CurrentSnapshot)
       If Not subjectTriggerPoint.HasValue Then
           applicableToSpan = Nothing
           Exit Sub
       End If
   
       Dim currentSnapshot As ITextSnapshot = subjectTriggerPoint.Value.Snapshot
       Dim querySpan As New SnapshotSpan(subjectTriggerPoint.Value, 0)
   
       'look for occurrences of our QuickInfo words in the span
       Dim navigator As ITextStructureNavigator = m_provider.NavigatorService.GetTextStructureNavigator(m_subjectBuffer)
       Dim extent As TextExtent = navigator.GetExtentOfWord(subjectTriggerPoint.Value)
       Dim searchText As String = extent.Span.GetText()
   
       For Each key As String In m_dictionary.Keys
           Dim foundIndex As Integer = searchText.IndexOf(key, StringComparison.CurrentCultureIgnoreCase)
           If foundIndex > -1 Then
               'applicableToSpan = currentSnapshot.CreateTrackingSpan(querySpan.Start.Add(foundIndex).Position, 9, SpanTrackingMode.EdgeInclusive)
   
               applicableToSpan = currentSnapshot.CreateTrackingSpan(extent.Span.Start + foundIndex, key.Length, SpanTrackingMode.EdgeInclusive)
               Dim value As String = ""
               m_dictionary.TryGetValue(key, value)
               If value IsNot Nothing Then
                   qiContent.Add(value)
               Else
                   qiContent.Add("")
               End If
   
               Exit Sub
           End If
       Next
   
       applicableToSpan = Nothing
   End Sub
   

8. You must also implement a Dispose() method, since IQuickInfoSource implements IDisposable:

   private bool m_isDisposed;
   public void Dispose()
   {
       if (!m_isDisposed)
       {
           GC.SuppressFinalize(this);
           m_isDisposed = true;
       }
   }
   

   Private m_isDisposed As Boolean
   Public Sub Dispose() Implements IDisposable.Dispose
       If Not m_isDisposed Then
           GC.SuppressFinalize(Me)
           m_isDisposed = True
       End If
   End Sub
   

Implementing a QuickInfo Source Provider

The provider of the QuickInfo source serves primarily to export itself as a MEF component part and instantiate the QuickInfo source. Because it is a MEF component part, it can import other MEF component parts.

To implement a QuickInfo source provider

1. Declare a QuickInfo source provider named TestQuickInfoSourceProvider that implements IQuickInfoSourceProvider, and export it with a NameAttribute of "ToolTip QuickInfo Source", an OrderAttribute of Before="default", and a ContentTypeAttribute of "text".

   [Export(typeof(IQuickInfoSourceProvider))]
   [Name("ToolTip QuickInfo Source")]
   [Order(Before = "Default Quick Info Presenter")]
   [ContentType("text")]
   internal class TestQuickInfoSourceProvider : IQuickInfoSourceProvider
   

   <Export(GetType(IQuickInfoSourceProvider))> _
   <Name("ToolTip QuickInfo Source")> _
   <Order(Before:=" Default Quick Info Presenter")> _
   <ContentType("text")> _
   Friend Class TestQuickInfoSourceProvider
       Implements IQuickInfoSourceProvider
   

2. Import two editor services, ITextStructureNavigatorSelectorService and ITextBufferFactoryService, as properties of TestQuickInfoSourceProvider.

   [Import]
   internal ITextStructureNavigatorSelectorService NavigatorService { get; set; }
   
   [Import]
   internal ITextBufferFactoryService TextBufferFactoryService { get; set; }
   

   Private _NavigatorService As ITextStructureNavigatorSelectorService
   <Import()> _
   Friend Property NavigatorService() As ITextStructureNavigatorSelectorService
       Get
           Return _NavigatorService
       End Get
       Set(ByVal value As ITextStructureNavigatorSelectorService)
           _NavigatorService = value
       End Set
   End Property
   
   Private _TextBufferFactoryService As ITextBufferFactoryService
   <Import()> _
   Friend Property TextBufferFactoryService() As ITextBufferFactoryService
       Get
           Return _TextBufferFactoryService
       End Get
       Set(ByVal value As ITextBufferFactoryService)
           _TextBufferFactoryService = value
       End Set
   End Property
   

3. Implement TryCreateQuickInfoSource to return a new TestQuickInfoSource.

   public IQuickInfoSource TryCreateQuickInfoSource(ITextBuffer textBuffer)
   {
       return new TestQuickInfoSource(this, textBuffer);
   }
   

   Public Function TryCreateQuickInfoSource(ByVal textBuffer As ITextBuffer) As IQuickInfoSource Implements IQuickInfoSourceProvider.TryCreateQuickInfoSource
       Return New TestQuickInfoSource(Me, textBuffer)
   End Function
   

Implementing a QuickInfo Controller

QuickInfo controllers determine when QuickInfo should be displayed. In this example, QuickInfo is displayed when the pointer is over a word that corresponds to one of the method names. The QuickInfo controller implements a mouse hover event handler that triggers a QuickInfo session.

To implement a QuickInfo controller

1. Declare a class that implements IIntellisenseController, and name it TestQuickInfoController.

   internal class TestQuickInfoController : IIntellisenseController
   

   Friend Class TestQuickInfoController
       Implements IIntellisenseController
   

2. Add private fields for the text view, the text buffers represented in the text view, the QuickInfo session, and the QuickInfo controller provider.

   private ITextView m_textView;
   private IList<ITextBuffer> m_subjectBuffers;
   private TestQuickInfoControllerProvider m_provider;
   private IQuickInfoSession m_session;
   

   Private m_textView As ITextView
   Private m_subjectBuffers As IList(Of ITextBuffer)
   Private m_provider As TestQuickInfoControllerProvider
   Private m_session As IQuickInfoSession
   

3. Add a constructor that sets the fields and adds the mouse hover event handler.

   internal TestQuickInfoController(ITextView textView, IList<ITextBuffer> subjectBuffers, TestQuickInfoControllerProvider provider)
   {
       m_textView = textView;
       m_subjectBuffers = subjectBuffers;
       m_provider = provider;
   
       m_textView.MouseHover += this.OnTextViewMouseHover;
   }
   

   Friend Sub New(ByVal textView As ITextView, ByVal subjectBuffers As IList(Of ITextBuffer), ByVal provider As TestQuickInfoControllerProvider)
       m_textView = textView
       m_subjectBuffers = subjectBuffers
       m_provider = provider
   
       AddHandler m_textView.MouseHover, AddressOf Me.OnTextViewMouseHover
   End Sub
   

4. Add the mouse hover event handler that triggers the QuickInfo session.

   private void OnTextViewMouseHover(object sender, MouseHoverEventArgs e)
   {
       //find the mouse position by mapping down to the subject buffer
       SnapshotPoint? point = m_textView.BufferGraph.MapDownToFirstMatch
            (new SnapshotPoint(m_textView.TextSnapshot, e.Position),
           PointTrackingMode.Positive,
           snapshot => m_subjectBuffers.Contains(snapshot.TextBuffer),
           PositionAffinity.Predecessor);
   
       if (point != null)
       {
           ITrackingPoint triggerPoint = point.Value.Snapshot.CreateTrackingPoint(point.Value.Position,
           PointTrackingMode.Positive);
   
           if (!m_provider.QuickInfoBroker.IsQuickInfoActive(m_textView))
           {
               m_session = m_provider.QuickInfoBroker.TriggerQuickInfo(m_textView, triggerPoint, true);
           }
       }
   }
   

   Private Sub OnTextViewMouseHover(ByVal sender As Object, ByVal e As MouseHoverEventArgs)
       'find the mouse position by mapping down to the subject buffer
       Dim point As System.Nullable(Of SnapshotPoint) = m_textView.BufferGraph.MapDownToFirstMatch(New SnapshotPoint(m_textView.TextSnapshot, e.Position), PointTrackingMode.Positive, Function(snapshot) m_subjectBuffers.Contains(snapshot.TextBuffer), PositionAffinity.Predecessor)
   
       If point IsNot Nothing Then
           Dim triggerPoint As ITrackingPoint = point.Value.Snapshot.CreateTrackingPoint(point.Value.Position, PointTrackingMode.Positive)
   
           If Not m_provider.QuickInfoBroker.IsQuickInfoActive(m_textView) Then
               m_session = m_provider.QuickInfoBroker.TriggerQuickInfo(m_textView, triggerPoint, True)
           End If
       End If
   End Sub
   

5. Implement the Detach method so that it removes the mouse hover event handler when the controller is detached from the text view.

   public void Detach(ITextView textView)
   {
       if (m_textView == textView)
       {
           m_textView.MouseHover -= this.OnTextViewMouseHover;
           m_textView = null;
       }
   }
   

   Public Sub Detach(ByVal textView As ITextView) Implements IIntellisenseController.Detach
       If m_textView Is textView Then
           AddHandler m_textView.MouseHover, AddressOf Me.OnTextViewMouseHover
           m_textView = Nothing
       End If
   End Sub
   

6. Implement the ConnectSubjectBuffer method and the DisconnectSubjectBuffer method as empty methods for this example.

   public void ConnectSubjectBuffer(ITextBuffer subjectBuffer)
   {
   }
   
   public void DisconnectSubjectBuffer(ITextBuffer subjectBuffer)
   {
   }
   

   Public Sub ConnectSubjectBuffer(ByVal subjectBuffer As ITextBuffer) Implements IIntellisenseController.ConnectSubjectBuffer
   
   End Sub
   
   Public Sub DisconnectSubjectBuffer(ByVal subjectBuffer As ITextBuffer) Implements IIntellisenseController.DisconnectSubjectBuffer
   
   End Sub
   

Implementing the QuickInfo Controller Provider

The provider of the QuickInfo controller serves primarily to export itself as a MEF component part and instantiate the QuickInfo controller. Because it is a MEF component part, it can import other MEF component parts.

To implement the QuickInfo controller provider

1. Declare a class named TestQuickInfoControllerProvider that implements IIntellisenseControllerProvider, and export it with a NameAttribute of "ToolTip QuickInfo Controller" and a ContentTypeAttribute of "text":

   [Export(typeof(IIntellisenseControllerProvider))]
   [Name("ToolTip QuickInfo Controller")]
   [ContentType("text")]
   internal class TestQuickInfoControllerProvider : IIntellisenseControllerProvider
   

   <Export(GetType(IIntellisenseControllerProvider))> _
   <Name("ToolTip QuickInfo Controller")> _
   <ContentType("text")> _
   Friend Class TestQuickInfoControllerProvider
       Implements IIntellisenseControllerProvider
   

2. Import the IQuickInfoBroker as a property.

   [Import]
   internal IQuickInfoBroker QuickInfoBroker { get; set; }
   

   Private _QuickInfoBroker As IQuickInfoBroker
   <Import()> _
   Friend Property QuickInfoBroker() As IQuickInfoBroker
       Get
           Return _QuickInfoBroker
       End Get
       Set(ByVal value As IQuickInfoBroker)
           _QuickInfoBroker = value
       End Set
   End Property
   

3. Implement the TryCreateIntellisenseController method by instantiating the QuickInfo controller.

   public IIntellisenseController TryCreateIntellisenseController(ITextView textView, IList<ITextBuffer> subjectBuffers)
   {
       return new TestQuickInfoController(textView, subjectBuffers, this);
   }
   

   Public Function TryCreateIntellisenseController(ByVal textView As ITextView, ByVal subjectBuffers As IList(Of ITextBuffer)) As IIntellisenseController Implements IIntellisenseControllerProvider.TryCreateIntellisenseController
       Return New TestQuickInfoController(textView, subjectBuffers, Me)
   End Function
   

Building and Testing the Code

To test this code, build the QuickInfoTest solution and run it in the experimental instance.

To build and test the QuickInfoTest solution

1. Build the solution.

2. When you run this project in the debugger, a second instance of Visual Studio is instantiated.

3. Create a text file and type some text that includes the words "add" and "subtract".

4. Move the pointer over one of the occurrences of "add". The signature and the description of the add method should be displayed.

See Also

Walkthrough: Linking a Content Type to a File Name Extension