excalidraw – OpenClaw Skill

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name: excalidraw description: Generate hand-drawn style diagrams, flowcharts, and architecture diagrams as PNG images from Excalidraw JSON

Excalidraw Diagram Generator

Generate beautiful hand-drawn style diagrams rendered as PNG images.

Workflow

1. Generate JSON — Write Excalidraw element array based on what the user wants
2. Save to file — Write JSON to /tmp/<name>.excalidraw
3. Render — node <skill_dir>/scripts/render.js /tmp/<name>.excalidraw /tmp/<name>.png
4. Send — Send the PNG via message tool with filePath

Quick Reference

node <skill_dir>/scripts/render.js input.excalidraw output.png

Element Types

Type	Shape	Key Props
rectangle	Box	x, y, width, height
ellipse	Oval	x, y, width, height
diamond	Decision	x, y, width, height
arrow	Arrow	connects shapes (see Arrow Binding below)
line	Line	x, y, points: [[0,0],[dx,dy]]
text	Label	x, y, text, fontSize, fontFamily (1=hand, 2=sans, 3=code)

Styling (all shapes)

{
  "strokeColor": "#1e1e1e",
  "backgroundColor": "#a5d8ff",
  "fillStyle": "hachure",
  "strokeWidth": 2,
  "roughness": 1,
  "strokeStyle": "solid"
}

fillStyle: hachure (diagonal lines), cross-hatch, solid roughness: 0=clean, 1=hand-drawn (default), 2=very sketchy

Arrow Binding (IMPORTANT)

Always use from/to bindings for arrows. The renderer auto-calculates edge intersection points — no manual coordinate math needed.

Simple arrow (straight, between two shapes)

{"type":"arrow","id":"a1","from":"box1","to":"box2","strokeColor":"#1e1e1e","strokeWidth":2,"roughness":1}

That's it. No x, y, or points needed. The renderer computes start/end at shape edges.

Multi-segment arrow (routed path with waypoints)

For arrows that need to go around obstacles, use absolutePoints with intermediate waypoints:

{
  "type":"arrow","id":"a2","from":"box3","to":"box1",
  "absolutePoints": true,
  "points": [[375,500],[30,500],[30,127],[60,127]],
  "strokeColor":"#1e1e1e","strokeWidth":2,"roughness":1
}

• First point = near source shape edge (will snap to actual edge)
• Last point = near target shape edge (will snap to actual edge)
• Middle points = absolute waypoint coordinates for routing

Arrow labels

Place a separate text element near the arrow midpoint:

{"type":"text","id":"label","x":215,"y":98,"width":85,"height":16,"text":"sends data","fontSize":10,"fontFamily":1,"strokeColor":"#868e96"}

Arrow styles

• "strokeStyle":"dashed" — dashed line
• "startArrowhead": true — bidirectional arrow

Template: Flowchart with Bindings

{
  "type": "excalidraw",
  "version": 2,
  "elements": [
    {"type":"rectangle","id":"start","x":150,"y":50,"width":180,"height":60,"strokeColor":"#1e1e1e","backgroundColor":"#b2f2bb","fillStyle":"hachure","strokeWidth":2,"roughness":1},
    {"type":"text","id":"t1","x":200,"y":65,"width":80,"height":30,"text":"Start","fontSize":20,"fontFamily":1,"strokeColor":"#1e1e1e"},

    {"type":"arrow","id":"a1","from":"start","to":"decision","strokeColor":"#1e1e1e","strokeWidth":2,"roughness":1},

    {"type":"diamond","id":"decision","x":140,"y":170,"width":200,"height":120,"strokeColor":"#1e1e1e","backgroundColor":"#ffec99","fillStyle":"hachure","strokeWidth":2,"roughness":1},
    {"type":"text","id":"t2","x":185,"y":215,"width":110,"height":30,"text":"Condition?","fontSize":18,"fontFamily":1,"strokeColor":"#1e1e1e","textAlign":"center"},

    {"type":"arrow","id":"a2","from":"decision","to":"process","strokeColor":"#1e1e1e","strokeWidth":2,"roughness":1},

    {"type":"rectangle","id":"process","x":150,"y":350,"width":180,"height":60,"strokeColor":"#1e1e1e","backgroundColor":"#a5d8ff","fillStyle":"hachure","strokeWidth":2,"roughness":1},
    {"type":"text","id":"t3","x":190,"y":365,"width":100,"height":30,"text":"Process","fontSize":20,"fontFamily":1,"strokeColor":"#1e1e1e"}
  ]
}

Layout Guidelines

• Node size: 140-200 × 50-70 px
• Diamond: 180-200 × 100-120 px (taller for text)
• Vertical spacing: 60-100 px between nodes
• Horizontal spacing: 80-120 px between nodes
• Text: Position inside shape manually (offset ~15-30px from top-left of shape)
• Arrow labels: Place as separate text elements near midpoint of arrow path

Color Palette

Fills: #a5d8ff (blue), #b2f2bb (green), #ffec99 (yellow), #ffc9c9 (red), #d0bfff (purple), #f3d9fa (pink), #fff4e6 (cream) Strokes: #1e1e1e (dark), #1971c2 (blue), #2f9e44 (green), #e8590c (orange), #862e9c (purple) Labels: #868e96 (gray, for annotations)

Tips

• Every element needs a unique id (required for binding!)
• Use from/to on arrows — don't calculate coordinates manually
• roughness:0 for clean diagrams, 1 for sketchy feel
• Text fontFamily:1 for hand-drawn, 3 for code
• Group related elements spatially, color-code by type
• For nested layouts, use a large background rectangle as a container