| name | omk-pdf-gen |
| description | Generate professional PDF documents with correct CJK (Chinese/Japanese/Korean) rendering. Trigger when user says 'generate PDF', 'create PDF', 'export PDF', '生成 PDF', '导出 PDF', '做个 PDF', 'make a PDF', or when any task requires producing a PDF file. Also trigger when user mentions PDF formatting issues, garbled text, or font problems.
|
PDF Generation Skill
Trigger Examples
- "帮我生成一个报价 PDF"
- "把这个内容导出成 PDF"
- "PDF 中文乱码怎么办"
- "generate a comparison PDF for this customer"
- "create a budget proposal PDF"
Approach: HTML + weasyprint
Use HTML + CSS → weasyprint pipeline. Do NOT use reportlab for documents containing CJK text.
Why:
- reportlab CID fonts (STSong-Light) have incomplete glyph coverage — symbols like
• render as garbage (e.g. "煉")
- reportlab cannot read macOS SIP-protected TTC fonts (PingFang etc.)
- reportlab
canvas API requires manual coordinate positioning — fragile and ugly
- weasyprint uses system fontconfig — correct font resolution out of the box
Workflow
Step 1: Write HTML string in Python
HTML = """\
<!DOCTYPE html>
<html lang="zh">
<head><meta charset="utf-8">
<style>
@page { size: A4; margin: 2cm 2.2cm; }
body { font-family: "Hiragino Sans GB", "Heiti SC", "Noto Sans CJK SC", sans-serif; ... }
</style></head>
<body>...</body></html>
"""
Step 2: Write to temp HTML, convert, clean up
import subprocess, os
html_tmp = output_path.replace('.pdf', '.html')
with open(html_tmp, 'w', encoding='utf-8') as f:
f.write(HTML)
subprocess.run(['weasyprint', html_tmp, output_path], check=True)
os.remove(html_tmp)
Font Rules (Critical)
| Platform | CSS font-family | Notes |
|---|
| macOS | "Hiragino Sans GB", "Heiti SC" | Verified via fc-list :lang=zh |
| Linux | "Noto Sans CJK SC", "WenQuanYi Micro Hei" | Install fonts-noto-cjk if missing |
| Fallback | sans-serif | Always include as last resort |
Never use these in weasyprint CSS:
-apple-system — weasyprint doesn't understand Apple system font aliases"PingFang SC" — fontconfig often can't resolve it even though macOS has it"STSong-Light" — CID font name, not a real font family for CSS
Before generating, verify CJK fonts are available:
fc-list :lang=zh family | head -10
Styling Best Practices
Use standard HTML elements — weasyprint handles them well:
<table> with CSS border-collapse: collapse for data tables<ul>/<li> for bullet lists (no manual bullet symbols needed)<h1>-<h3> for headings<hr> for dividers- CSS
@page for margins and page size
Recommended CSS skeleton
@page { size: A4; margin: 2cm 2.2cm; }
body { font-family: "Hiragino Sans GB", "Heiti SC", "Noto Sans CJK SC", sans-serif;
font-size: 11pt; color: #1a1a2e; line-height: 1.7; }
h1 { font-size: 22pt; text-align: center; }
h3 { font-size: 13pt; color: #1a73e8; }
table { width: 100%; border-collapse: collapse; font-size: 10pt; }
th { background: #1a73e8; color: #fff; padding: 7pt 10pt; text-align: left; }
td { padding: 6pt 10pt; border-bottom: 1px solid #e5e7eb; }
tr:nth-child(even) td { background: #f8f9fa; }
When reportlab IS acceptable
English-only documents where you need precise programmatic layout (charts, diagrams, pixel-perfect positioning). Use platypus (SimpleDocTemplate + Paragraph + Table), never raw canvas API.
Reference: tools/gen-73strings-pdfs.py — good example of reportlab platypus for English PDFs.
Anti-Patterns (from real incidents)
| Don't | Why | Do Instead |
|---|
| reportlab + STSong-Light for CJK | • → "煉", incomplete glyphs | weasyprint + system fonts |
reportlab canvas manual positioning | Fragile coordinates, misaligned text | weasyprint or reportlab platypus |
CSS font-family: -apple-system | weasyprint can't resolve it | Use "Hiragino Sans GB" |
CSS font-family: "PingFang SC" | fontconfig often fails to find it | Use "Hiragino Sans GB" |
| Helvetica-Bold for table headers with CJK | CJK chars render as ■■■ | Use CJK font + font-weight: bold |
| Hardcode font without checking | Fails on different OS | Run fc-list :lang=zh first |
Output
Place generated script in tools/gen-<name>-pdf.py. The script should:
- Define HTML as a string constant
- Write temp HTML → call weasyprint → remove temp HTML
- Print the output path on success
