PDF Watermark

Convert PPT/PPTX to PDF and add customizable watermarks. Supports diagonal/grid/center layouts, adjustable font size, opacity, rotation, and color. Trigger words: 加水印、转PDF、PDF水印、导出PDF、水印工具、add watermark、convert to PDF、PDF watermark. Includes a mobile-friendly web UI for real-time parameter tuning.

PDF Watermark / PDF 水印工具

Convert PPTX → PDF and add customizable diagonal watermarks to every page. 将 PPT/PPTX 转为 PDF 并添加自定义水印。

Dependencies / 依赖

• LibreOffice (soffice, headless mode for PPTX→PDF conversion)
  • macOS: brew install --cask libreoffice
  • Linux: sudo apt install libreoffice
  • Windows: Download from libreoffice.org
• Python 3: PyPDF2, reportlab

  bash

  pip3 install PyPDF2 reportlab
  

• Fonts: Auto-detected per platform
  • macOS: STHeiti (built-in)
  • Linux: Noto Sans CJK / WenQuanYi (install fonts-noto-cjk or fonts-wqy-zenhei if missing)
  • Windows: SimSun (built-in)
  • Fallback: Helvetica (ASCII only, CJK characters will not render)

Usage / 用法

Method 1: PPTX → PDF + Watermark (one step) / 一步到位

bash

python3 {baseDir}/scripts/pptx_to_pdf_watermark.py input.pptx output.pdf [config.json]

Method 2: Add watermark to existing PDF / 给已有 PDF 加水印

bash

python3 {baseDir}/scripts/pptx_to_pdf_watermark.py input.pdf output.pdf [config.json]

Method 3: Preview watermark layout / 预览水印效果

bash

python3 {baseDir}/scripts/pptx_to_pdf_watermark.py --preview [config.json] preview.pdf

Method 4: Convert PPTX to PDF only (no watermark) / 仅转 PDF

bash

soffice --headless --convert-to pdf --outdir <output_dir> <input.pptx>

Configuration / 配置参数

All parameters are optional. Without a config file, defaults are used. 所有参数可选，不提供 config.json 则使用默认值。

json

{
  "text": "内部资料 请勿外传",
  "fontSize": 60,
  "opacity": 0.15,
  "rotation": 45,
  "color": [0.5, 0.5, 0.5],
  "pattern": "diagonal",
  "repeatX": 3,
  "repeatY": 3,
  "offsetX": 200,
  "offsetY": 200
}

Parameter	Description	Default
text	Watermark text / 水印文字	"内部资料 请勿外传"
fontSize	Font size in pt / 字号	60
opacity	Transparency 0-1 / 透明度	0.15
rotation	Rotation in degrees / 旋转角度	45
color	RGB values 0-1 / 颜色	[0.5, 0.5, 0.5]
pattern	Layout: diagonal / grid / center / 布局模式	"diagonal"
repeatX	Grid horizontal count / 网格水平重复	3
repeatY	Grid vertical count / 网格垂直重复	3
offsetX	Diagonal spacing X / 对角线间距	200
offsetY	Diagonal spacing Y / 对角线间距	200

Layout Patterns / 布局模式

• diagonal: Center + 4 offset copies (5 total). Best for standard pages.
• grid: Uniform X×Y grid across the page. Best for dense coverage.
• center: Single centered watermark. Best for minimalist style.

Web UI (Optional) / 调参界面（可选）

A mobile-friendly web UI is included for real-time parameter tuning: 内置手机端调参界面，支持实时预览：

bash

# Start local server
cd {baseDir} && python3 -m http.server 8088

# Open in browser
# Mobile UI: http://localhost:8088/watermark-mobile.html
# Desktop UI: http://localhost:8088/watermark-ui.html

Tune parameters in the UI, copy the generated JSON config, and pass it to the script. 在界面中调好参数，复制 JSON 配置，传给脚本即可。

Remote Access (Optional) / 远程访问（可选）

To tune parameters from a phone outside localhost, use a tunnel service like cloudflared: 如需手机远程访问调参界面，可使用隧道工具：

bash

brew install cloudflared  # macOS
cloudflared tunnel --url http://127.0.0.1:8088

This is entirely optional. The script works standalone without the web UI. 此为可选功能，脚本本身无需 Web UI 即可独立运行。

How It Works / 工作原理

1. PPTX → PDF: LibreOffice headless mode converts the presentation.
2. Watermark PDF: reportlab generates a watermark overlay page with the configured parameters.
3. Merge: PyPDF2 merges the watermark onto every page of the source PDF.
4. Output: Final watermarked PDF is written to the specified path.

Principles / 原则

• Non-destructive: Never modifies the input file / 不修改原始文件
• Cross-platform: Auto-detects OS-appropriate fonts / 自动适配各平台字体
• Configurable: All parameters have sensible defaults / 所有参数有合理默认值
• Standalone: Script runs without the web UI / 脚本独立运行，不依赖 Web UI