Implementing Custom Syntax Highlighting in ScintillaNET ScintillaNET is a popular .NET wrapper for the Scintilla text editing component, providing advanced editing features like code folding, margin markers, and, most importantly, syntax highlighting. While ScintillaNET supports many languages out-of-the-box, developers often need to implement custom syntax highlighting for domain-specific languages (DSLs) or proprietary formats.
This article guides you through the process of setting up custom highlighting, focusing on styling, keyword identification, and applying styles to text. Prerequisites A .NET application (Windows Forms or WPF) ScintillaNET Nuget package installed 1. Understanding Scintilla Styles
Scintilla works by assigning a numeric “style” to specific character ranges. A style is a set of visual attributes: Font name/size Bold/Italic/Underline You must define these styles before applying them to text.
// Example: Setting up basic styles private void InitStyles(Scintilla scintilla) { scintilla.StyleResetDefault(); scintilla.Styles[Style.Default].Font = “Consolas”; scintilla.Styles[Style.Default].Size = 10; scintilla.StyleClearAll(); // Apply default to all // Define custom styles scintilla.Styles[1].ForeColor = Color.Blue; scintilla.Styles[1].Bold = true; // For keywords scintilla.Styles[2].ForeColor = Color.Green; // For comments } Use code with caution. 2. Implementing the Lexer
A “Lexer” is the engine that breaks text into tokens (keywords, operators, strings) and assigns styles. For custom syntax, you have two options:
Use an existing lexer: Use a similar language lexer (e.g., CPP lexer for a C-like language) and configure keywords.
Use the Container Lexer: Manually tell Scintilla how to style every character. Method A: Configuring an Existing Lexer
If your custom language is similar to C#, you can use the built-in C# lexer and just update the keywords.
scintilla.Lexer = Lexer.Cpp; // Set Keywords (0 is typically for primary keywords) scintilla.SetKeywords(0, “if else while for return mycustomkeyword”); // Style the keywords using the built-in C++ keyword style index (5) scintilla.Styles[Style.Cpp.Word].ForeColor = Color.Blue; Use code with caution. Method B: The Container Lexer (True Custom Highlighting)
For completely custom syntax, set the lexer to Lexer.Container. This tells Scintilla that your code will handle the styling.
scintilla.Lexer = Lexer.Container; // Hook into the StyleNeeded event scintilla.StyleNeeded += Scintilla_StyleNeeded; Use code with caution.
Inside the StyleNeeded event, you define the logic to style text:
private void Scintilla_StyleNeeded(object sender, StyleNeededEventArgs e) { var scintilla = (Scintilla)sender; var startPos = scintilla.GetEndStyled(); var endPos = e.Position; // Basic example: Style all text starting with ‘#’ as comments for (int i = startPos; i < endPos; i++) { char c = (char)scintilla.GetCharAt(i); if (c == ‘#’) { // Apply style 2 (previously defined green) to the end of the line scintilla.StartStyling(i); scintilla.SetStyling(10, 2); } } } Use code with caution. 3. Applying Changes and Performance
When using Lexer.Container, the StyleNeeded event triggers only for visible text, making it efficient. However, ensure your lexing logic inside StyleNeeded is fast to prevent editing lag.
Always use scintilla.StartStyling(pos) to set the starting point, followed by scintilla.SetStyling(length, styleID) to apply styles.
Implementing custom syntax highlighting involves three steps: Define Styles via scintilla.Styles. Set the Lexer to Lexer.Container (for manual control).
Implement StyleNeeded to parse text and apply styles using SetStyling.
For more in-depth examples, you can check the ScintillaNET Wiki for community-submitted styling examples [2].
If you are looking to do this for a specific language, let me know which one so I can give you a tailored example! Saved time Comprehensive Inappropriate Not working
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