chart-image

# Chart Image Generator Generate PNG chart images from data using Vega-Lite. Perfect for headless server environments. ## Why This Skill? **Built for Fly.io / VPS / Docker deployments:** - ✅ **No native compilation** - Uses Sharp with prebuilt binaries (unlike `canvas` which requires build tools) - ✅ **No Puppeteer/browser** - Pure Node.js, no Chrome download, no headless browser overhead - ✅ **Lightweight** - ~15MB total dependencies vs 400MB+ for Puppeteer-based solutions - ✅ **Fast cold starts** - No browser spinup delay, generates charts in <500ms - ✅ **Works offline** - No external API calls (unlike QuickChart.io) ## Setup (one-time) ```bash cd /data/clawd/skills/chart-image/scripts && npm install ``` ## Quick Usage ```bash node /data/clawd/skills/chart-image/scripts/chart.mjs \ --type line \ --data '[{"x":"10:00","y":25},{"x":"10:30","y":27},{"x":"11:00","y":31}]' \ --title "Price Over Time" \ --output chart.png ``` ## Chart Types ### Line Chart (default) ```bash node chart.mjs --type line --data '[{"x":"A","y":10},{"x":"B","y":15}]' --output line.png ``` ### Bar Chart ```bash node chart.mjs --type bar --data '[{"x":"A","y":10},{"x":"B","y":15}]' --output bar.png ``` ### Area Chart ```bash node chart.mjs --type area --data '[{"x":"A","y":10},{"x":"B","y":15}]' --output area.png ``` ### Pie / Donut Chart ```bash # Pie node chart.mjs --type pie --data '[{"category":"A","value":30},{"category":"B","value":70}]' \ --category-field category --y-field va...