draw.io Diagram Skill

1. Basic Rules

• •Edit only .drawio files
• •Do not directly edit .drawio.png files
• •Use auto-generated .drawio.png by pre-commit hook in slides

2. Font Settings

For diagrams used in Quarto slides, specify defaultFontFamily in mxGraphModel tag:

<mxGraphModel defaultFontFamily="Noto Sans JP" ...>

Also explicitly specify fontFamily in each text element's style attribute:

style="text;html=1;fontSize=27;fontFamily=Noto Sans JP;"

3. Conversion Commands

See conversion script at scripts/convert-drawio-to-png.sh.

# Convert all .drawio files
mise exec -- pre-commit run --all-files

# Convert specific .drawio file
mise exec -- pre-commit run convert-drawio-to-png --files assets/my-diagram.drawio

# Run script directly (using skill's script)
bash ~/.claude/skills/draw-io/scripts/convert-drawio-to-png.sh assets/diagram1.drawio

Internal command used:

drawio -x -f png -s 2 -t -o output.drawio.png input.drawio

4. Layout Adjustment

4.1. Coordinate Adjustment Steps

1. •Open .drawio file in text editor (plain XML format)
2. •Find mxCell for element to adjust (search by value attribute for text)
3. •Adjust coordinates in mxGeometry tag
   • •x: Position from left
   • •y: Position from top
   • •width: Width
   • •height: Height
4. •Run conversion and verify

4.2. Coordinate Calculation

• •Element center coordinate = y + (height / 2)
• •To align multiple elements, calculate and match center coordinates

5. Color Palette and Layout Patterns

These are auto-updatable reference files. See section 11 for update protocol.

• •Color Palette - Material Design colors and usage rules
• •Layout Guidelines - Pattern catalog (A-K) and AWS layout rules

6. Design Principles

6.0. Slide Diagram Constraints

For presentation slide diagrams (1920x1080 canvas):

• •YOU MUST: Set page="0" (transparent background)
• •YOU MUST: Use fontFamily=Noto Sans JP for all text
• •YOU MUST: Limit to 1-3 accent colors per diagram
• •YOU MUST: Include a takeaway bar at the bottom (Note or Primary color)
• •NEVER: Use more than 4 color roles in a single diagram

6.1. Basic Principles

• •Clarity: Create simple, visually clean diagrams
• •Consistency: Unify colors, fonts, icon sizes, line thickness
• •Accuracy: Do not sacrifice accuracy for simplification

6.2. Element Rules

• •Label all elements
• •Use arrows to indicate direction (prefer 2 unidirectional arrows over bidirectional)
• •Use latest official icons
• •Add legend to explain custom symbols

6.3. Accessibility

• •Ensure sufficient color contrast
• •Use patterns in addition to colors

6.4. Progressive Disclosure

Separate complex systems into staged diagrams:

6.5. Metadata

Include title, description, last updated, author, and version in diagrams.

7. Best Practices

7.1. Background Color

• •Remove background="#ffffff"
• •Transparent background adapts to various themes

7.2. Font Size

• •Use 1.5x standard font size (around 18px) for PDF readability

7.3. Japanese Text Width

• •Allow 30-40px per character
• •Insufficient width causes unintended line breaks

<!-- For 10-character text, allow 300-400px -->
<mxGeometry x="140" y="60" width="400" height="40" />

7.4. Arrow Placement

• •Always place arrows at back (position in XML right after Title)
• •Position arrows to avoid overlapping with labels
• •Keep arrow start/end at least 20px from label bottom edge

<!-- Title -->
<mxCell id="title" value="..." .../>

<!-- Arrows (back layer) -->
<mxCell id="arrow1" style="edgeStyle=..." .../>

<!-- Other elements (front layer) -->
<mxCell id="box1" .../>

7.5. Arrow Connection to Text Labels

For text elements, exitX/exitY don't work, so use explicit coordinates:

<!-- Good: Explicit coordinates with sourcePoint/targetPoint -->
<mxCell id="arrow" style="..." edge="1" parent="1">
  <mxGeometry relative="1" as="geometry">
    <mxPoint x="1279" y="500" as="sourcePoint"/>
    <mxPoint x="119" y="500" as="targetPoint"/>
    <Array as="points">
      <mxPoint x="1279" y="560"/>
      <mxPoint x="119" y="560"/>
    </Array>
  </mxGeometry>
</mxCell>

7.6. edgeLabel Offset Adjustment

Adjust offset attribute to distance arrow labels from arrows:

<!-- Place above arrow (negative value to distance) -->
<mxPoint x="0" y="-40" as="offset"/>

<!-- Place below arrow (positive value to distance) -->
<mxPoint x="0" y="40" as="offset"/>

7.7. Remove Unnecessary Elements

• •Remove decorative icons irrelevant to context
• •Example: If ECR exists, separate Docker icon is unnecessary

7.8. Labels and Headings

• •Service name only: 1 line
• •Service name + supplementary info: 2 lines with line break
• •Redundant notation (e.g., ECR Container Registry): shorten to 1 line
• •Use <br> tag for line breaks

7.9. Background Frame and Internal Element Placement

When placing elements inside background frames (grouping boxes), ensure sufficient margin.

• •YOU MUST: Internal elements must have at least 30px margin from frame boundary
• •YOU MUST: Account for rounded corners (rounded=1) and stroke width
• •YOU MUST: Always visually verify PNG output for overflow

Coordinate calculation verification:

Background frame: y=20, height=400 -> range is y=20-420
Internal element top: frame y + 30 or more (e.g., y=50)
Internal element bottom: frame y + height - 30 or less (e.g., up to y=390)

Bad example (may overflow):

<!-- Background frame -->
<mxCell id="bg" style="rounded=1;strokeWidth=3;...">
  <mxGeometry x="500" y="20" width="560" height="400" />
</mxCell>
<!-- Text: y=30 is too close to frame top (y=20) -->
<mxCell id="label" value="Title" style="text;...">
  <mxGeometry x="510" y="30" width="540" height="35" />
</mxCell>

Good example (sufficient margin):

<!-- Background frame -->
<mxCell id="bg" style="rounded=1;strokeWidth=3;...">
  <mxGeometry x="500" y="20" width="560" height="430" />
</mxCell>
<!-- Text: y=50 is 30px from frame top (y=20) -->
<mxCell id="label" value="Title" style="text;...">
  <mxGeometry x="510" y="50" width="540" height="35" />
</mxCell>

8. Reference

• •Color Palette - auto-updatable
• •Layout Guidelines - auto-updatable
• •AWS Icons
• •AWS Icon Search Script

AWS icon search examples:

python ~/.claude/skills/draw-io/scripts/find_aws_icon.py ec2
python ~/.claude/skills/draw-io/scripts/find_aws_icon.py lambda

9. Checklist

• • No background color set (page="0")
• • Font size appropriate (larger recommended)
• • Arrows placed at back layer
• • Arrows not overlapping labels (verify in PNG)
• • Arrow start/end sufficiently distant from labels (at least 20px)
• • Arrows not penetrating boxes or icons (verify in PNG)
• • Internal elements not overflowing background frame (verify in PNG)
• • 30px+ margin between background frame and internal elements
• • AWS service names are official names/correct abbreviations
• • AWS icons are latest version (mxgraph.aws4.*)
• • No unnecessary elements remaining
• • Visually verified PNG conversion

10. Visual Quality Review Workflow

After creating or editing a .drawio file, run this review loop:

1. •

   Convert to PNG:

   sh

   drawio -x -f png -s 2 -t -o output.drawio.png input.drawio
   

2. •

   Read the PNG with the Read tool (Claude can view images)

3. •

   Check against the checklist in section 9

4. •

   If issues found, fix the .drawio XML and repeat from step 1

Key items to verify visually:

• •Elements not overflowing background frames
• •Arrows not penetrating boxes or overlapping labels
• •Text not truncated or line-breaking unexpectedly
• •Color palette consistent with references/color-palette.md
• •Sufficient whitespace between elements

11. Self-Update Protocol

This skill maintains auto-updatable reference files that evolve as new .drawio files are created.

11.1. Auto-Updatable Files

11.2. Triggers

Execute self-update after:

1. •Creating a new .drawio file
2. •Significantly editing an existing .drawio file
3. •User explicitly requests skill update

11.3. Update Procedure

1. Read the created/edited .drawio file
2. Extract style attributes from all mxCell elements
3. Detect:
   a. New colors (fillColor/strokeColor/fontColor not in color-palette.md)
      → Add to references/color-palette.md with semantic role
   b. New layout pattern (structure doesn't match known patterns A-K)
      → Add to references/layout-guidelines.md with name and diagram
   c. New best practice (fix applied during quality review)
      → Append to SKILL.md section 7
   d. New checklist item (repeated issue caught in review)
      → Append to SKILL.md section 9
4. Update "Last updated" and "Source files analyzed" metadata
5. Report changes to user

11.4. Detection Rules

Color detection:

1. Parse all style="..." attributes in .drawio XML
2. Extract fillColor, strokeColor, fontColor values
3. Compare against known colors in references/color-palette.md
4. If unknown color found:
   - Check if it belongs to Material Design family
   - Assign semantic role based on context
   - Add to palette table

Pattern detection:

1. Count vertex elements (boxes) and edge elements (arrows)
2. Analyze nesting (parent-child relationships)
3. Check spatial arrangement (horizontal/vertical/radial)
4. Compare against known patterns A-K in layout-guidelines.md
5. If no match:
   - Name the pattern based on structure
   - Create ASCII diagram
   - Add to appropriate category

11.5. Metadata Format

Each auto-updatable file ends with:

---

Last updated: YYYY-MM-DD
Source files analyzed:

- repo/path/to/\*.drawio

12. Image Display in reveal.js Slides

Add auto-stretch: false to YAML header:

---
title: "Your Presentation"
format:
  revealjs:
    auto-stretch: false
---

This ensures correct image display on mobile devices.