Walkthrough: Displaying QuickInfo Tooltips

 

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The latest version of this topic can be found at 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.

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.

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.

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.

    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.

    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 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 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 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 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
    

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(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.

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

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.

    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 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.

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

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

  2. Import the IQuickInfoBroker as a property.

        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 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
    

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.

Walkthrough: Linking a Content Type to a File Name Extension

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