A video generation system used dynamic syntax highlighting to render code segments with proper language-specific colors. However, the system failed to apply syntax highlighting, rendering all code in default gray colors despite using a Pygments lexer.
Issue
Dynamic syntax highlighting did not apply language-specific colors, causing all code segments to appear in monochromatic gray. Users reported issues where early frames of code animations lacked syntax coloring, failing to distinguish keywords, functions, and strings visually.
Culprit
The language detection logic incorrectly relied on the first character of each segment to determine the language. When segments began with separator characters (e.g., newlines) that lacked language information, the entire segment was marked as having no language, preventing Pygments from executing tokenization and applying syntax colors.
Solution
Look-Ahead Language Detection
A fix was implemented to scan subsequent characters within the same segment to identify the first non-separator character with a valid language:
- Language Assignment: If the first character lacks language information, the system scans forward within the same segment to find the first valid language.
- Tokenization: Ensures the Pygments lexer processes segments with valid language assignments, applying proper syntax highlighting.
- Dynamic Updates: Supports partial code states by allowing syntax highlighting to update as new context becomes available.
Key Features
- Dynamic Tokenization: Re-runs the lexer on visible characters only, ensuring real-time updates.
- Partial Code Handling: Displays incomplete syntax highlighting for partial code, mimicking real-time IDE behavior.
- Retroactive Updates: Previously rendered characters update dynamically as new context arrives.
Results
The fix successfully restored syntax highlighting:
- Before: All code rendered in default gray.
- After: Keywords in distinct colors (e.g., orange), functions in yellow, strings in green.
This solution ensures accurate syntax visualization while maintaining dynamic rendering capabilities for code animations.