Overlays add additional visual information on top of your code graph. They change node colors, sizes, or add badges based on external data.
What Are Overlays?
An overlay is a visual layer that augments the base graph with additional data:
| Overlay | Data Source | Visual Effect |
|---|
| Git Activity | Git history | Color by change frequency |
| Test Coverage | Coverage reports | Color by coverage % |
| Complexity | Static analysis | Size by complexity |
| Code Ownership | Git blame | Color by author/team |
Available Overlays
Built-in Overlays
# List available overlays
curl http://localhost:5050/api/overlays
{
"plugins": [
{
"id": "git-activity",
"name": "Git Activity",
"description": "Visualize code churn from git history",
"overlays": [
{
"id": "churn",
"name": "Change Frequency",
"type": "color",
"legend": { "low": "#22c55e", "high": "#ef4444" }
}
]
},
{
"id": "test-coverage",
"name": "Test Coverage",
"description": "Show test coverage percentages",
"overlays": [
{
"id": "coverage",
"name": "Line Coverage",
"type": "color",
"legend": { "0%": "#ef4444", "50%": "#f59e0b", "100%": "#22c55e" }
}
]
}
]
}
Applying an Overlay
Via UI
- Click the “Overlays” button in the toolbar
- Select an overlay from the list
- Click “Apply”
Via API
# Apply git activity overlay
curl -X POST http://localhost:5050/api/overlays/git-activity/apply
# Check application status
curl http://localhost:5050/api/overlays/git-activity/status
Via CLI
codegraph overlay apply git-activity
codegraph overlay apply test-coverage --report coverage.xml
Git Activity Overlay
Shows which parts of your codebase change most frequently.
Setup
# Apply git activity (analyzes last 6 months by default)
codegraph overlay apply git-activity
# Custom time range
codegraph overlay apply git-activity --since "2024-01-01" --until "2024-06-01"
What It Shows
| Metric | Visual | Meaning |
|---|
| Change frequency | Color (green → red) | How often this file changes |
| Lines changed | Node size | Total lines added/removed |
| Authors | Badge | Number of contributors |
High churn + many authors often indicates problematic code that’s hard to maintain.
Test Coverage Overlay
Visualize which code is tested.
Setup
First, generate a coverage report:
# Using coverlet
dotnet test --collect:"XPlat Code Coverage"
codegraph overlay apply test-coverage --report ./TestResults/*/coverage.cobertura.xml
What It Shows
| Coverage | Color |
|---|
| 0-30% | Red |
| 30-70% | Yellow |
| 70-90% | Light green |
| 90-100% | Green |
Complexity Overlay
Highlight complex code that might need refactoring.
Setup
codegraph overlay apply complexity
Metrics
| Metric | Description |
|---|
| Cyclomatic complexity | Number of decision points |
| Cognitive complexity | How hard to understand |
| Lines of code | Raw size |
Code Ownership Overlay
See who owns which parts of the codebase.
Setup
codegraph overlay apply ownership
# With team mapping
codegraph overlay apply ownership --teams teams.json
teams.json:
{
"teams": {
"Platform": ["alice@example.com", "bob@example.com"],
"Product": ["carol@example.com", "dave@example.com"]
}
}
What It Shows
- Each team gets a unique color
- Shared ownership shows blended colors
- Orphaned code (no recent commits) shows gray
Removing Overlays
Via UI
- Click “Overlays” button
- Click “Remove” next to active overlay
Via API
curl -X DELETE http://localhost:5050/api/overlays/git-activity/apply
Via CLI
codegraph overlay remove git-activity
Combining Overlays
You can have multiple overlays active:
# Apply multiple overlays
codegraph overlay apply git-activity
codegraph overlay apply test-coverage --report coverage.xml
# In UI, overlays can be toggled independently
Creating Custom Overlays
See the Custom Overlays guide to create your own.
What’s Next?
GPU Layout
Speed up layout for large graphs
Custom Overlays
Create your own overlay plugins
