Walkthrough: Displaying QuickInfo Tooltips

Article
12/19/2012

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

To complete this walkthrough, you must install the Visual Studio 2012 SDK.

Note

For more information about the Visual Studio SDK, see Extending Visual Studio Overview. To find out how to download the Visual Studio SDK, see Visual Studio Extensibility Developer Center on the MSDN Web site.

Creating a MEF Project

To create a MEF project

Create an Editor Classifier project. Name the solution QuickInfoTest.
Open the Source.extension.vsixmanifest file in the VSIX Manifest Editor.
Make sure that the Content heading contains a MEF Component content type and that the Path is set to QuickInfoTest.dll.
Save and close Source.extension.vsixmanifest.
Add the following reference to the project, and set CopyLocal to false:

Microsoft.VisualStudio.Language.Intellisense
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

Add a class file and name it TestQuickInfoSource.

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

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;

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

Friend Class TestQuickInfoSource
    Implements IQuickInfoSource

internal class TestQuickInfoSource : IQuickInfoSource

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)

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

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

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.");
}

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)

            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

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
                );

            string value;
            m_dictionary.TryGetValue(key, out value);
            if (value != null)
                qiContent.Add(value);
            else
                qiContent.Add("");

            return;
        }
    }

    applicableToSpan = null;
}

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

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

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

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

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

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

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

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

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

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

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

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

Friend Class TestQuickInfoController
    Implements IIntellisenseController

internal class TestQuickInfoController : IIntellisenseController

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

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

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

internal TestQuickInfoController(ITextView textView, IList<ITextBuffer> subjectBuffers, TestQuickInfoControllerProvider provider)
{
    m_textView = textView;
    m_subjectBuffers = subjectBuffers;
    m_provider = provider;

    m_textView.MouseHover += this.OnTextViewMouseHover;
}

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

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);
        }
    }
}

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

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

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

public void ConnectSubjectBuffer(ITextBuffer subjectBuffer)
{
}

public void DisconnectSubjectBuffer(ITextBuffer subjectBuffer)
{
}

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

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

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

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

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

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

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

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

Build the solution.
When you run this project in the debugger, a second instance of Visual Studio is instantiated.
Create a text file and type some text that includes the words "add" and "subtract".
Move the pointer over one of the occurrences of "add". The signature and the description of the add method should be displayed.

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