PDFextend

PDFextend is a tool to add margins with grid lines for annotation to a PDF document. These additional margins provide extra space for annotations in apps without infinite canvas (i.e. almost all of them: Notability, Flexcil, Xournal++, etc.). This can be useful when studying research papers or text books. The background of generated margins is configurable (empty, horizontal lines, square grid, dots).

PDFextend is available as web app (installable as PWA) or command line tool.

Tech

• Core and CLI in Rust.
• PDFium for PDF processing using the pdfium-render crate.
• Web app with MUI.
• Rust code compiled to WASM and used in web worker.

CLI Usage

Usage: pdfextend [OPTIONS] <INPUT> <OUTPUT>

Arguments:
  <INPUT>   Path to input PDF file
  <OUTPUT>  Path to output PDF file

Options:
  -l, --left <LEFT>              Extend document by <LEFT> to the left [default: 0]
  -r, --right <RIGHT>            Extend document by <RIGHT> to the right [default: 0]
  -t, --top <TOP>                Extend document by <TOP> to the top [default: 0]
  -b, --bottom <BOTTOM>          Extend document by <BOTTOM> to the bottom [default: 0]
  -s, --spacing <SPACING>        Spacing between grid lines [default: 5 mm]
  -w, --line-width <LINE_WIDTH>  Line width [default: 0.1 mm for lines, 0.7mm for dots]
  -u, --unit <UNIT>              Unit of the numeric parameters (pt = in/72) [default: mm] [possible values: mm, cm, in, pt]
  -g, --grid <GRID>              Add grid to the extended margins [possible values: lines, squares, dots]
  -e, --extra-page               Append an additional page with grid to the document
  -m, --mirror                   Swap <LEFT> and <RIGHT> for even pages
  -c, --color <COLOR>            Color of the grid lines (format: #A0B0C0 or #ABC for RGB, #A0 or #A for grayscale, # is optional) [default: #F0F0F0]
  -h, --help                     Print help information
  -V, --version                  Print version information

Building

CLI

cd pdfextend-cli
./getpdfium.sh  # NOTE: assumes Linux x64
cargo build --release

Web

cd pdfextend-web
wasm-pack build --target no-modules
cp pkg/pdfextend_web{.js,_bg.wasm} ../webapp/public
cd ../webapp
npm install
npm run build
npx wrangler pages publish dist

License compilation

cd licenses/
python license_aggregator.py > ../webapp/src/license.md
python license_aggregator.py > out.md
cat header.md out.md > out2.md
pandoc out2.md --pdf-engine=xelatex -o ../webapp/public/license.pdf