Walkthrough: Creating a Margin Glyph
You can customize the appearance of editor margins by using custom editor extensions. This walkthrough puts a custom glyph on the indicator margin whenever the word "todo" appears in a code comment.
Prerequisites
To complete this walkthrough, you must install the Visual Studio 2010 SDK.
Nota
For more information about the Visual Studio SDK, see Visual Studio Integration SDK. To find out how to download the Visual Studio SDK, see Visual Studio Extensibility Developer Center on the MSDN Web site.
Creating a Managed Extensibility Framework (MEF) Project
To create a MEF project
Create a Visual C# or Visual Basic Editor Classifier project. Name the solution TodoGlyphTest.
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 TodoGlyphTest.dll.
Save and close Source.extension.vsixmanifest.
Remove the existing class files.
Defining the Glyph
Define a glyph by implementing the IGlyphFactory interface.
To define the glyph
Add a class file and name it TodoGlyphFactory.
Add the following imports.
Imports System.ComponentModel.Composition Imports System.Windows Imports System.Windows.Shapes Imports System.Windows.Media Imports System.Windows.Controls Imports Microsoft.VisualStudio.Text Imports Microsoft.VisualStudio.Text.Editor Imports Microsoft.VisualStudio.Text.Formatting Imports Microsoft.VisualStudio.Text.Tagging Imports Microsoft.VisualStudio.Utilities
using System.ComponentModel.Composition; using System.Windows; using System.Windows.Shapes; using System.Windows.Media; using System.Windows.Controls; using Microsoft.VisualStudio.Text; using Microsoft.VisualStudio.Text.Editor; using Microsoft.VisualStudio.Text.Formatting; using Microsoft.VisualStudio.Text.Tagging; using Microsoft.VisualStudio.Utilities;
Add a class named TodoGlyphFactory that implements IGlyphFactory.
Friend Class TodoGlyphFactory Implements IGlyphFactory
internal class TodoGlyphFactory : IGlyphFactory
Add a private field that defines the dimensions of the glyph.
Const m_glyphSize As Double = 16.0
const double m_glyphSize = 16.0;
Implement GenerateGlyph by defining the glyph user interface (UI) element. TodoTag is defined later in this walkthrough.
Public Function GenerateGlyph(ByVal line As IWpfTextViewLine, ByVal tag As IGlyphTag) As System.Windows.UIElement Implements IGlyphFactory.GenerateGlyph ' Ensure we can draw a glyph for this marker. If tag Is Nothing OrElse Not (TypeOf tag Is TodoTag) Then Return Nothing End If Dim ellipse As Ellipse = New Ellipse() ellipse.Fill = Brushes.LightBlue ellipse.StrokeThickness = 2 ellipse.Stroke = Brushes.DarkBlue ellipse.Height = m_glyphSize ellipse.Width = m_glyphSize Return ellipse End Function
public UIElement GenerateGlyph(IWpfTextViewLine line, IGlyphTag tag) { // Ensure we can draw a glyph for this marker. if (tag == null || !(tag is TodoTag)) { return null; } System.Windows.Shapes.Ellipse ellipse = new Ellipse(); ellipse.Fill = Brushes.LightBlue; ellipse.StrokeThickness = 2; ellipse.Stroke = Brushes.DarkBlue; ellipse.Height = m_glyphSize; ellipse.Width = m_glyphSize; return ellipse; }
Add a class named TodoGlyphFactoryProvider that implements IGlyphFactoryProvider. Export this class with a NameAttribute of "TodoGlyph", an OrderAttribute of After VsTextMarker, a ContentTypeAttribute of "code", and a TagTypeAttribute of TodoTag.
<Export(GetType(IGlyphFactoryProvider)), Name("TodoGlyph"), Order(After:="VsTextMarker"), ContentType("code"), TagType(GetType(TodoTag))> Friend NotInheritable Class TodoGlyphFactoryProvider Implements IGlyphFactoryProvider
[Export(typeof(IGlyphFactoryProvider))] [Name("TodoGlyph")] [Order(After = "VsTextMarker")] [ContentType("code")] [TagType(typeof(TodoTag))] internal sealed class TodoGlyphFactoryProvider : IGlyphFactoryProvider
Implement the GetGlyphFactory method by instantiating the TodoGlyphFactory.
Public Function GetGlyphFactory(ByVal view As IWpfTextView, ByVal margin As IWpfTextViewMargin) As IGlyphFactory Implements IGlyphFactoryProvider.GetGlyphFactory Return New TodoGlyphFactory() End Function
public IGlyphFactory GetGlyphFactory(IWpfTextView view, IWpfTextViewMargin margin) { return new TodoGlyphFactory(); }
Defining a Todo Tag and Tagger
Define the relationship between the UI element that you defined in the previous steps and the indicator margin by creating a tag type and tagger, and exporting it by using a tagger provider.
To define a todo tag and tagger
Add a new class to the project and name it TodoTagger.
Add the following imports.
Imports System Imports System.Collections.Generic Imports System.ComponentModel.Composition Imports Microsoft.VisualStudio.Text Imports Microsoft.VisualStudio.Text.Tagging Imports Microsoft.VisualStudio.Text.Editor Imports Microsoft.VisualStudio.Text.Classification Imports Microsoft.VisualStudio.Utilities
using System; using System.Collections.Generic; using System.ComponentModel.Composition; using Microsoft.VisualStudio.Text; using Microsoft.VisualStudio.Text.Tagging; using Microsoft.VisualStudio.Text.Editor; using Microsoft.VisualStudio.Text.Classification; using Microsoft.VisualStudio.Utilities;
Add a class named TodoTag.
Friend Class TodoTag Implements IGlyphTag Public Sub New() MyBase.New() End Sub End Class
internal class TodoTag : IGlyphTag
Modify the class named TodoTagger that implements ITagger<T> of type TodoTag.
Friend Class TodoTagger Implements ITagger(Of TodoTag)
internal class TodoTagger : ITagger<TodoTag>
To the TodoTagger class, add private fields for an IClassifier and for the text to find in the classification spans.
Private m_classifier As IClassifier Private Const m_searchText As String = "todo"
private IClassifier m_classifier; private const string m_searchText = "todo";
Add a constructor that sets the classifier.
Friend Sub New(ByVal classifier As IClassifier) m_classifier = classifier End Sub
internal TodoTagger(IClassifier classifier) { m_classifier = classifier; }
Implement the GetTags method by finding all the classification spans whose names include the word "comment" and whose text includes the search text. Whenever the search text is found, yield back a new TagSpan<T> of type TodoTag.
Private Function GetTags(ByVal spans As NormalizedSnapshotSpanCollection) As IEnumerable(Of ITagSpan(Of TodoTag)) Implements ITagger(Of TodoTag).GetTags Dim list As List(Of ITagSpan(Of TodoTag)) list = New List(Of ITagSpan(Of TodoTag))() For Each span As SnapshotSpan In spans 'look at each classification span \ For Each classification As ClassificationSpan In m_classifier.GetClassificationSpans(span) 'if the classification is a comment If classification.ClassificationType.Classification.ToLower().Contains("comment") Then 'if the word "todo" is in the comment, 'create a new TodoTag TagSpan Dim index As Integer = classification.Span.GetText().ToLower().IndexOf(m_searchText) If index <> -1 Then list.Add(New TagSpan(Of TodoTag)(New SnapshotSpan(classification.Span.Start + index, m_searchText.Length), New TodoTag())) End If End If Next classification Next span Return list End Function
IEnumerable<ITagSpan<TodoTag>> ITagger<TodoTag>.GetTags(NormalizedSnapshotSpanCollection spans) { foreach (SnapshotSpan span in spans) { //look at each classification span \ foreach (ClassificationSpan classification in m_classifier.GetClassificationSpans(span)) { //if the classification is a comment if (classification.ClassificationType.Classification.ToLower().Contains("comment")) { //if the word "todo" is in the comment, //create a new TodoTag TagSpan int index = classification.Span.GetText().ToLower().IndexOf(m_searchText); if (index != -1) { yield return new TagSpan<TodoTag>(new SnapshotSpan(classification.Span.Start + index, m_searchText.Length), new TodoTag()); } } } } }
Declare a TagsChanged event.
Public Event TagsChanged(ByVal sender As Object, ByVal e As Microsoft.VisualStudio.Text.SnapshotSpanEventArgs) Implements Microsoft.VisualStudio.Text.Tagging.ITagger(Of TodoTag).TagsChanged
public event EventHandler<SnapshotSpanEventArgs> TagsChanged;
Add a class named TodoTaggerProvider that implements ITaggerProvider, and export it with a ContentTypeAttribute of "code" and a TagTypeAttribute of TodoTag.
<Export(GetType(ITaggerProvider)), ContentType("code"), TagType(GetType(TodoTag))> Friend Class TodoTaggerProvider Implements ITaggerProvider
[Export(typeof(ITaggerProvider))] [ContentType("code")] [TagType(typeof(TodoTag))] class TodoTaggerProvider : ITaggerProvider
Import the IClassifierAggregatorService.
<Import()> Friend AggregatorService As IClassifierAggregatorService
[Import] internal IClassifierAggregatorService AggregatorService;
Implement the CreateTagger<T> method by instantiating the TodoTagger.
Public Function CreateTagger(Of T As Microsoft.VisualStudio.Text.Tagging.ITag)(ByVal buffer As Microsoft.VisualStudio.Text.ITextBuffer) As Microsoft.VisualStudio.Text.Tagging.ITagger(Of T) Implements Microsoft.VisualStudio.Text.Tagging.ITaggerProvider.CreateTagger If buffer Is Nothing Then Throw New ArgumentNullException("buffer") End If Return TryCast(New TodoTagger(AggregatorService.GetClassifier(buffer)), ITagger(Of T)) End Function
public ITagger<T> CreateTagger<T>(ITextBuffer buffer) where T : ITag { if (buffer == null) { throw new ArgumentNullException("buffer"); } return new TodoTagger(AggregatorService.GetClassifier(buffer)) as ITagger<T>; }
Building and Testing the Code
To test this code, build the TodoGlyphTest solution and run it in the experimental instance.
To build and test the TodoGlyphTest solution
Build the solution.
Run the project by pressing F5. A second instance of Visual Studio is instantiated.
Make sure that the indicator margin is showing. (On the Tools menu, click Options. On the Text Editor page, make sure that Indicator margin is selected.)
Open a code file that has comments. Add the word "todo" to one of the comment sections.
A light blue circle that has a dark blue outline should appear in the indicator margin to the left of the code window.
Change History
Date |
History |
Reason |
---|---|---|
July 2010 |
Fixed Visual Basic code. |
Content bug fix. |