pdf

name	pdf
description	Use this skill whenever the user wants to do anything with PDF files. This includes reading or extracting text/tables from PDFs, combining or merging multiple PDFs into one, splitting PDFs apart, rotating pages, adding watermarks, creating new PDFs, filling PDF forms, encrypting/decrypting PDFs, extracting images, and OCR on scanned PDFs to make them searchable. If the user mentions a .pdf file or asks to produce one, use this skill.
license	Proprietary. LICENSE.txt has complete terms

PDF Processing Guide

Overview

This guide covers essential PDF processing operations using Python libraries and command-line tools. For advanced features, JavaScript libraries, and detailed examples, see REFERENCE.md. If you need to fill out a PDF form, read FORMS.md and follow its instructions.

Quick Start

from pypdf import PdfReader, PdfWriter

# Read a PDF
reader = PdfReader("document.pdf")
print(f"Pages: {len(reader.pages)}")

# Extract text
text = ""
for page in reader.pages:
    text += page.extract_text()

Python Libraries

pypdf - Basic Operations

Merge PDFs

from pypdf import PdfWriter, PdfReader

writer = PdfWriter()
for pdf_file in ["doc1.pdf", "doc2.pdf", "doc3.pdf"]:
    reader = PdfReader(pdf_file)
    for page in reader.pages:
        writer.add_page(page)

with open("merged.pdf", "wb") as output:
    writer.write(output)

Split PDF

reader = PdfReader("input.pdf")
for i, page in enumerate(reader.pages):
    writer = PdfWriter()
    writer.add_page(page)
    with open(f"page_{i+1}.pdf", "wb") as output:
        writer.write(output)

Extract Metadata

reader = PdfReader("document.pdf")
meta = reader.metadata
print(f"Title: {meta.title}")
print(f"Author: {meta.author}")
print(f"Subject: {meta.subject}")
print(f"Creator: {meta.creator}")

Rotate Pages

reader = PdfReader("input.pdf")
writer = PdfWriter()

page = reader.pages[0]
page.rotate(90)  # Rotate 90 degrees clockwise
writer.add_page(page)

with open("rotated.pdf", "wb") as output:
    writer.write(output)

pdfplumber - Text and Table Extraction

Extract Text with Layout

import pdfplumber

with pdfplumber.open("document.pdf") as pdf:
    for page in pdf.pages:
        text = page.extract_text()
        print(text)

Extract Tables

with pdfplumber.open("document.pdf") as pdf:
    for i, page in enumerate(pdf.pages):
        tables = page.extract_tables()
        for j, table in enumerate(tables):
            print(f"Table {j+1} on page {i+1}:")
            for row in table:
                print(row)

Advanced Table Extraction

import pandas as pd

with pdfplumber.open("document.pdf") as pdf:
    all_tables = []
    for page in pdf.pages:
        tables = page.extract_tables()
        for table in tables:
            if table:  # Check if table is not empty
                df = pd.DataFrame(table[1:], columns=table[0])
                all_tables.append(df)

# Combine all tables
if all_tables:
    combined_df = pd.concat(all_tables, ignore_index=True)
    combined_df.to_excel("extracted_tables.xlsx", index=False)

reportlab - Create PDFs

Basic PDF Creation

from reportlab.lib.pagesizes import letter
from reportlab.pdfgen import canvas

c = canvas.Canvas("hello.pdf", pagesize=letter)
width, height = letter

# Add text
c.drawString(100, height - 100, "Hello World!")
c.drawString(100, height - 120, "This is a PDF created with reportlab")

# Add a line
c.line(100, height - 140, 400, height - 140)

# Save
c.save()

Create PDF with Multiple Pages

from reportlab.lib.pagesizes import letter
from reportlab.platypus import SimpleDocTemplate, Paragraph, Spacer, PageBreak
from reportlab.lib.styles import getSampleStyleSheet

doc = SimpleDocTemplate("report.pdf", pagesize=letter)
styles = getSampleStyleSheet()
story = []

# Add content
title = Paragraph("Report Title", styles['Title'])
story.append(title)
story.append(Spacer(1, 12))

body = Paragraph("This is the body of the report. " * 20, styles['Normal'])
story.append(body)
story.append(PageBreak())

# Page 2
story.append(Paragraph("Page 2", styles['Heading1']))
story.append(Paragraph("Content for page 2", styles['Normal']))

# Build PDF
doc.build(story)

CJK (Chinese/Japanese/Korean) Font Support

CRITICAL: ReportLab's built-in fonts (Helvetica, Times-Roman, Courier) do NOT support CJK characters. Using them renders Chinese/Japanese/Korean text as black boxes (□). You MUST register and use a CJK-capable font whenever the content may contain CJK characters.

Option 1 — Noto Sans CJK TTF (PREFERRED, best rendering quality):

from reportlab.pdfbase import pdfmetrics
from reportlab.pdfbase.ttfonts import TTFont
from reportlab.lib.styles import getSampleStyleSheet, ParagraphStyle
import glob

# Register Noto Sans CJK (installed in Docker via fonts-noto-cjk)
_CJK_FONT_CANDIDATES = [
    "/usr/share/fonts/opentype/noto/NotoSansCJKsc-Regular.otf",
    "/usr/share/fonts/opentype/noto/NotoSansCJK-Regular.ttc",
    "/usr/share/fonts/noto-cjk/NotoSansCJKsc-Regular.otf",
] + glob.glob("/usr/share/fonts/**/NotoSansCJK*Regular*", recursive=True)

_cjk_font_path = next((p for p in _CJK_FONT_CANDIDATES if __import__('os').path.exists(p)), None)
if _cjk_font_path:
    pdfmetrics.registerFont(TTFont("NotoSansCJK", _cjk_font_path))
    CJK_FONTNAME = "NotoSansCJK"
else:
    # Fallback to CID font (see Option 2)
    from reportlab.pdfbase.cidfonts import UnicodeCIDFont
    pdfmetrics.registerFont(UnicodeCIDFont("STSong-Light"))
    CJK_FONTNAME = "STSong-Light"

# Create CJK-aware styles
styles = getSampleStyleSheet()
styles.add(ParagraphStyle(name='CJK', fontName=CJK_FONTNAME, fontSize=12, leading=16))
styles.add(ParagraphStyle(name='CJKTitle', fontName=CJK_FONTNAME, fontSize=24, leading=30, spaceAfter=12))
styles.add(ParagraphStyle(name='CJKHeading', fontName=CJK_FONTNAME, fontSize=16, leading=20, spaceBefore=12, spaceAfter=6))

# Use in paragraphs
story.append(Paragraph("中文标题", styles['CJKTitle']))
story.append(Paragraph("这是中文正文内容。", styles['CJK']))

Option 2 — ReportLab CID Fonts (no TTF file needed, acceptable quality):

from reportlab.pdfbase import pdfmetrics
from reportlab.pdfbase.cidfonts import UnicodeCIDFont

pdfmetrics.registerFont(UnicodeCIDFont("STSong-Light"))  # Simplified Chinese
# Other CID fonts: "MSung-Light" (Traditional Chinese), "HeiseiMin-W3" (Japanese), "HYSMyeongJoNeatly-Medium" (Korean)

# Use in canvas
c.setFont("STSong-Light", 12)
c.drawString(100, 700, "这是中文文本")

IMPORTANT: When to use CJK fonts: Detect CJK characters in content and auto-switch:

import re
def has_cjk(text):
    return bool(re.search(r'[\u4e00-\u9fff\u3400-\u4dbf\u3000-\u303f\u3040-\u309f\u30a0-\u30ff\uac00-\ud7af]', text))

# Choose font based on content
fontName = CJK_FONTNAME if has_cjk(user_text) else "Helvetica"

Emoji & Symbol Font Support

CRITICAL: ReportLab's built-in fonts and CJK fonts do NOT include emoji characters (💎🔷⭐✅ etc.). Emoji will render as � (replacement character) or tofu boxes. The Docker image has NotoColorEmoji.ttf installed for emoji support.

Register emoji font and build a font-switching helper:

import re, os
from reportlab.pdfbase import pdfmetrics
from reportlab.pdfbase.ttfonts import TTFont

# Register emoji font (installed via fonts-noto-color-emoji)
_EMOJI_FONT_CANDIDATES = [
    "/usr/share/fonts/truetype/noto/NotoColorEmoji.ttf",
    "/usr/share/fonts/truetype/noto-color-emoji/NotoColorEmoji.ttf",
]
EMOJI_FONTNAME = None
for _p in _EMOJI_FONT_CANDIDATES:
    if os.path.exists(_p):
        try:
            pdfmetrics.registerFont(TTFont("NotoEmoji", _p))
            EMOJI_FONTNAME = "NotoEmoji"
        except Exception:
            pass
        break

# Detect emoji characters
_EMOJI_RE = re.compile(
    "["
    "\U0001F300-\U0001F9FF"  # Misc Symbols & Pictographs, Emoticons, etc.
    "\U00002702-\U000027B0"  # Dingbats
    "\U00002600-\U000026FF"  # Misc Symbols
    "\U0000FE00-\U0000FE0F"  # Variation Selectors
    "\U0000200D"             # ZWJ
    "\U0001FA00-\U0001FA6F"  # Chess Symbols, Extended-A
    "\U0001FA70-\U0001FAFF"  # Symbols Extended-A
    "]+"
)

def has_emoji(text):
    return bool(_EMOJI_RE.search(str(text)))

def safe_paragraph_text(text, body_font="NotoSansCJK"):
    """Wrap text with <font> tags for ReportLab Paragraph, switching to emoji font for emoji chars.
    If emoji font is not available, emoji chars are kept as-is (may render as tofu)."""
    if not EMOJI_FONTNAME or not has_emoji(text):
        return text
    parts = []
    last = 0
    for m in _EMOJI_RE.finditer(text):
        if m.start() > last:
            parts.append(text[last:m.start()])
        parts.append(f'<font name="{EMOJI_FONTNAME}">{m.group()}</font>')
        last = m.end()
    if last < len(text):
        parts.append(text[last:])
    return "".join(parts)

# Usage in Paragraph:
story.append(Paragraph(safe_paragraph_text("💎 优势分析 Strengths", body_font=CJK_FONTNAME), styles['CJKTitle']))

If the color emoji font fails to register (ReportLab may not fully support CBDT bitmap fonts), use Unicode geometric shapes as reliable substitutes — these are included in Noto Sans CJK:

Emoji	Substitute	Unicode	Description
💎🔷🔹	◆ or ◇	U+25C6 / U+25C7	Diamond
⭐🌟	★ or ☆	U+2605 / U+2606	Star
✅	✓	U+2713	Check mark
❌	✗	U+2717	Cross mark
🔴🟢🔵	●	U+25CF	Filled circle
🟡🟠🟣	○	U+25CB	Empty circle
▶️	▶	U+25B6	Triangle
📌	■	U+25A0	Square

Use drawString with colored fills for visual distinction:

c.setFillColor(colors.HexColor("#2196F3"))  # blue
c.setFont(CJK_FONTNAME, 14)
c.drawString(x, y, "◆")  # colored diamond as bullet
c.setFillColor(colors.black)
c.drawString(x + 18, y, "优势分析")

Do NOT strip or remove emoji from content — always attempt to render them. Use font switching first; fall back to geometric substitutes only if the emoji font cannot be registered.

Subscripts and Superscripts

IMPORTANT: Never use Unicode subscript/superscript characters (₀₁₂₃₄₅₆₇₈₉, ⁰¹²³⁴⁵⁶⁷⁸⁹) in ReportLab PDFs. The built-in fonts do not include these glyphs, causing them to render as solid black boxes.

Instead, use ReportLab's XML markup tags in Paragraph objects:

from reportlab.platypus import Paragraph
from reportlab.lib.styles import getSampleStyleSheet

styles = getSampleStyleSheet()

# Subscripts: use <sub> tag
chemical = Paragraph("H<sub>2</sub>O", styles['Normal'])

# Superscripts: use <super> tag
squared = Paragraph("x<super>2</super> + y<super>2</super>", styles['Normal'])

For canvas-drawn text (not Paragraph objects), manually adjust font the size and position rather than using Unicode subscripts/superscripts.

Command-Line Tools

pdftotext (poppler-utils)

# Extract text
pdftotext input.pdf output.txt

# Extract text preserving layout
pdftotext -layout input.pdf output.txt

# Extract specific pages
pdftotext -f 1 -l 5 input.pdf output.txt  # Pages 1-5

qpdf

# Merge PDFs
qpdf --empty --pages file1.pdf file2.pdf -- merged.pdf

# Split pages
qpdf input.pdf --pages . 1-5 -- pages1-5.pdf
qpdf input.pdf --pages . 6-10 -- pages6-10.pdf

# Rotate pages
qpdf input.pdf output.pdf --rotate=+90:1  # Rotate page 1 by 90 degrees

# Remove password
qpdf --password=mypassword --decrypt encrypted.pdf decrypted.pdf

pdftk (if available)

# Merge
pdftk file1.pdf file2.pdf cat output merged.pdf

# Split
pdftk input.pdf burst

# Rotate
pdftk input.pdf rotate 1east output rotated.pdf

Common Tasks

Extract Text from Scanned PDFs

# Requires: pip install pytesseract pdf2image
import pytesseract
from pdf2image import convert_from_path

# Convert PDF to images
images = convert_from_path('scanned.pdf')

# OCR each page
text = ""
for i, image in enumerate(images):
    text += f"Page {i+1}:\n"
    text += pytesseract.image_to_string(image)
    text += "\n\n"

print(text)

Add Watermark

from pypdf import PdfReader, PdfWriter

# Create watermark (or load existing)
watermark = PdfReader("watermark.pdf").pages[0]

# Apply to all pages
reader = PdfReader("document.pdf")
writer = PdfWriter()

for page in reader.pages:
    page.merge_page(watermark)
    writer.add_page(page)

with open("watermarked.pdf", "wb") as output:
    writer.write(output)

Extract Images

# Using pdfimages (poppler-utils)
pdfimages -j input.pdf output_prefix

# This extracts all images as output_prefix-000.jpg, output_prefix-001.jpg, etc.

Password Protection

from pypdf import PdfReader, PdfWriter

reader = PdfReader("input.pdf")
writer = PdfWriter()

for page in reader.pages:
    writer.add_page(page)

# Add password
writer.encrypt("userpassword", "ownerpassword")

with open("encrypted.pdf", "wb") as output:
    writer.write(output)

Quick Reference

Task	Best Tool	Command/Code
Merge PDFs	pypdf	writer.add_page(page)
Split PDFs	pypdf	One page per file
Extract text	pdfplumber	page.extract_text()
Extract tables	pdfplumber	page.extract_tables()
Create PDFs	reportlab	Canvas or Platypus
Command line merge	qpdf	qpdf --empty --pages ...
OCR scanned PDFs	pytesseract	Convert to image first
Fill PDF forms	pdf-lib or pypdf (see FORMS.md)	See FORMS.md

Next Steps

• For advanced pypdfium2 usage, see REFERENCE.md
• For JavaScript libraries (pdf-lib), see REFERENCE.md
• If you need to fill out a PDF form, follow the instructions in FORMS.md
• For troubleshooting guides, see REFERENCE.md