Walkthrough: Displaying SmartTags

1. Create an Editor Classifier project. Name the solution SmartTagTest.

2. Open the source.extension.vsixmanifest file in the VSIX Manifest Editor.

3. Make sure that the Content heading contains a MEF Component content type and that the Path is set to SmartTagTest.dll.

4. Save and close source.extension.vsixmanifest.

5. Add the following reference to the project, and set CopyLocal to false:

   Microsoft.VisualStudio.Language.Intellisense

6. Delete the existing class files.

1. Add a class file and name it TestSmartTag.

2. Add the following imports:

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   using System;
   using System.Collections.Generic;
   using System.ComponentModel.Composition;
   using System.Collections.ObjectModel;
   using System.Windows.Media;
   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;
   

3. Add a class named TestSmartTag that inherits from SmartTag.

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   internal class TestSmartTag : SmartTag
   

4. Add a constructor for this class that calls the base constructor with a SmartTagType of Factoid, which will cause a blue line to appear under the first character of a word. (If you use Ephemeral, a red line will appear under the last character of the word.)

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   public TestSmartTag(ReadOnlyCollection<SmartTagActionSet> actionSets) :
       base(SmartTagType.Factoid, actionSets) { }
   

5. Add a class named TestSmartTagger that inherits from ITagger<T> of type TestSmartTag, and implements IDisposable.

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   internal class TestSmartTagger : ITagger<TestSmartTag>, IDisposable
   

6. Add the following private fields to the tagger class.

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   private ITextBuffer m_buffer;
   private ITextView m_view;
   private TestSmartTaggerProvider m_provider;
   private bool m_disposed;
   

7. Add a constructor that sets the private fields, and subscribes to the LayoutChanged event.

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   public TestSmartTagger(ITextBuffer buffer, ITextView view, TestSmartTaggerProvider provider)
   {
       m_buffer = buffer;
       m_view = view;
       m_provider = provider;
       m_view.LayoutChanged += OnLayoutChanged;
   }
   

8. Implement GetTags so that the tag is created for the current word. (This method also calls a private method GetSmartTagActions that is explained later.)

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   public IEnumerable<ITagSpan<TestSmartTag>> GetTags(NormalizedSnapshotSpanCollection spans)
   {
       ITextSnapshot snapshot = m_buffer.CurrentSnapshot;
       if (snapshot.Length == 0)
           yield break; //don't do anything if the buffer is empty 
   
       //set up the navigator
       ITextStructureNavigator navigator = m_provider.NavigatorService.GetTextStructureNavigator(m_buffer);
   
       foreach (var span in spans)
       {
           ITextCaret caret = m_view.Caret;
           SnapshotPoint point;
   
           if (caret.Position.BufferPosition > 0)
               point = caret.Position.BufferPosition - 1;
           else 
               yield break;
   
           TextExtent extent = navigator.GetExtentOfWord(point);
           //don't display the tag if the extent has whitespace 
           if (extent.IsSignificant)
               yield return new TagSpan<TestSmartTag>(extent.Span, new TestSmartTag(GetSmartTagActions(extent.Span)));
           else yield break;
       }
   }
   

9. Add a GetSmartTagActions method to set up the smart tag actions. The actions themselves are implemented in later steps.

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   private ReadOnlyCollection<SmartTagActionSet> GetSmartTagActions(SnapshotSpan span)
   {
       List<SmartTagActionSet> actionSetList = new List<SmartTagActionSet>();
       List<ISmartTagAction> actionList = new List<ISmartTagAction>();
   
       ITrackingSpan trackingSpan = span.Snapshot.CreateTrackingSpan(span, SpanTrackingMode.EdgeInclusive);
       actionList.Add(new UpperCaseSmartTagAction(trackingSpan));
       actionList.Add(new LowerCaseSmartTagAction(trackingSpan));
       SmartTagActionSet actionSet = new SmartTagActionSet(actionList.AsReadOnly());
       actionSetList.Add(actionSet);
       return actionSetList.AsReadOnly();
   }
   

10. Declare the SmartTagsChanged event.

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    public event EventHandler<SnapshotSpanEventArgs> TagsChanged;
    

11. Implement the OnLayoutChanged event handler to raise the TagsChanged event, which causes GetTags to be called.

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    private void OnLayoutChanged(object sender, TextViewLayoutChangedEventArgs e)
    {
        ITextSnapshot snapshot = e.NewSnapshot;
        //don't do anything if this is just a change in case 
        if (!snapshot.GetText().ToLower().Equals(e.OldSnapshot.GetText().ToLower()))
        {
            SnapshotSpan span = new SnapshotSpan(snapshot, new Span(0, snapshot.Length));
            EventHandler<SnapshotSpanEventArgs> handler = this.TagsChanged;
            if (handler != null)
            {
                handler(this, new SnapshotSpanEventArgs(span));
            }
        }
    }
    

12. Implement the Dispose method so that it unsubscribes from the LayoutChanged event.

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    public void Dispose()
    {
        Dispose(true);
        GC.SuppressFinalize(this);
    }
    
    private void Dispose(bool disposing)
    {
        if (!this.m_disposed)
        {
            if (disposing)
            {
                m_view.LayoutChanged -= OnLayoutChanged;
                m_view = null;
            }
    
            m_disposed = true;
        }
    }
    

1. Add a class named TestSmartTagTaggerProvider that inherits from IViewTaggerProvider. Export it with a ContentTypeAttribute of "text", a OrderAttribute of Before="default", and a TagTypeAttribute of SmartTag.

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   [Export(typeof(IViewTaggerProvider))]
   [ContentType("text")]
   [Order(Before = "default")]
   [TagType(typeof(SmartTag))]
   internal class TestSmartTaggerProvider : IViewTaggerProvider
   

2. Import the ITextStructureNavigatorSelectorService as a property.

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   [Import(typeof(ITextStructureNavigatorSelectorService))]
   internal ITextStructureNavigatorSelectorService NavigatorService { get; set; }
   

3. Implement the CreateTagger<T> method.

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   public ITagger<T> CreateTagger<T>(ITextView textView, ITextBuffer buffer) where T : ITag
   {
       if (buffer == null || textView == null)
       {
           return null;
       }
   
       //make sure we are tagging only the top buffer 
       if (buffer == textView.TextBuffer)
       {
           return new TestSmartTagger(buffer, textView, this) as ITagger<T>;
       }
       else return null;
   }
   

• Create two classes, the first named UpperCaseSmartTagAction and the second named LowerCaseSmartTagAction. Both classes implement ISmartTagAction.

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  internal class UpperCaseSmartTagAction : ISmartTagAction
  

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  internal class LowerCaseSmartTagAction : ISmartTagAction
  

Both classes are alike except that one calls ToUpper and the other calls ToLower. The following steps cover only the uppercase action class, but you must implement both classes. Use the steps for implementing the uppercase action as a pattern for implementing the lowercase action.

1. Declare a set of private fields.

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   private ITrackingSpan m_span;
   private string m_upper;
   private string m_display;
   private ITextSnapshot m_snapshot;
   

2. Add a constructor that sets the fields.

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   public UpperCaseSmartTagAction(ITrackingSpan span)
   {
       m_span = span;
       m_snapshot = span.TextBuffer.CurrentSnapshot;
       m_upper = span.GetText(m_snapshot).ToUpper();
       m_display = "Convert to upper case";
   }
   

3. Implement the properties as follows.

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   public string DisplayText
   {
       get { return m_display; }
   }
   public ImageSource Icon
   {
       get { return null; }
   }
   public bool IsEnabled
   {
       get { return true; }
   }
   
   public ISmartTagSource Source
   {
       get;
       private set;
   }
   
   public ReadOnlyCollection<SmartTagActionSet> ActionSets
   {
       get { return null; }
   }
   

4. Implement the Invoke method by replacing the text in the span with its uppercase equivalent.

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   public void Invoke()
   {
       m_span.TextBuffer.Replace(m_span.GetSpan(m_snapshot), m_upper);
   }
   

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.

   A blue line should be displayed under the first letter of the first word of the text.

4. Move the pointer over the blue line.

   A button should be displayed near the pointer.

5. When you click the button, two suggested actions should be displayed: Convert to upper case and Convert to lower case. If you click the first action, all the text in the current word should be converted to upper case. If you click the second action, all the text should be converted to lower case.