Walkthrough: Creating a Margin Glyph
The new home for Visual Studio documentation is Visual Studio 2017 Documentation on docs.microsoft.com.
The latest version of this topic can be found at 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.
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.
Create a C# VSIX project. (In the New Project dialog, select Visual C# / Extensibility, then VSIX Project.) Name the solution
TodoGlyphTest.Add an Editor Classifier project item. For more information, see Creating an Extension with an Editor Item Template.
Delete the existing class files.
Define a glyph by implementing the IGlyphFactory interface.
To define the glyph
Add a class file and name it
TodoGlyphFactory.Add the following using declarations.
Add a class named
TodoGlyphFactorythat implements IGlyphFactory.Add a private field that defines the dimensions of the glyph.
Implement
GenerateGlyphby defining the glyph user interface (UI) element.TodoTagis defined later in this walkthrough.Add a class named
TodoGlyphFactoryProviderthat implements IGlyphFactoryProvider. Export this class with a NameAttribute of "TodoGlyph", an OrderAttribute of After VsTextMarker, a ContentTypeAttribute of "code", and a TagTypeAttribute of TodoTag.Implement the GetGlyphFactory method by instantiating the
TodoGlyphFactory.
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 file to the project and name it
TodoTagger.Add the following imports.
Add a class named
TodoTag.Modify the class named
TodoTaggerthat implements ITagger<T> of typeTodoTag.To the
TodoTaggerclass, add private fields for an IClassifier and for the text to find in the classification spans.Add a constructor that sets the 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.Declare a
TagsChangedevent.Add a class named
TodoTaggerProviderthat implements ITaggerProvider, and export it with a ContentTypeAttribute of "code" and a TagTypeAttribute of TodoTag.Import the IClassifierAggregatorService.
Implement the CreateTagger<T> method by instantiating the
TodoTagger.
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.