Print Bridge

Share a USB printer — and its scanner — with every phone and laptop in the house.

No new hardware. No cloud. No app on the phone.

---

Plenty of printers still sold today speak nothing but USB, and the cheap ones cannot rasterise a page on their own — the PC does that and sends pixels down the cable. That makes them invisible to AirPrint, to Mopria, and to every "just print from your phone" feature of the last decade.

Print Bridge puts the PC in the middle. It answers the protocols phones already speak, renders each job itself, and hands the result to the printer driver that is already installed.

   iPhone · Android · Mac · laptop
                 │
                 │   Wi-Fi — IPP + Bonjour  (printing)
                 │           eSCL + Bonjour (scanning)
                 ▼
        ┌──────────────────────┐
        │   Windows PC         │
        │   Print Bridge       │
        │   ├ PDFium  renders  │
        │   └ GDI     prints   │
        └──────────┬───────────┘
                   │  USB
                   ▼
        host-based printer / MFP

What you get

Print from anything	Share → Print on an iPhone, Mopria on Android, or Add Printer on a laptop. The printer appears on its own.
Scan to anything	Files → Scan Documents on iOS, Mopria Scan on Android. Put a page on the glass, tap, get a PDF.
Card sheets	Tile a CNIC, passport photo or business card at exact millimetre sizes, with cut marks. Add a back image and it lays out a mirrored second sheet so both sides line up after the flip.
True physical size	A page laid out at 210 × 297 mm measures 210 × 297 mm on paper. The bridge knows the printer's resolution and the margin it cannot reach.
Nothing else to install	PDFium renders, Windows prints. No Acrobat, no SumatraPDF, no vendor software.
Stays out of the way	Starts at logon, lives in the tray. Or build it as one .exe and double-click it.

Quick start

1. Plug the printer in and make sure Windows itself can print to it — install the driver and print a Windows test page first. Print Bridge shares printers Windows already has; it does not replace a driver.
2. Download this repository (or grab the .exe from Releases).
3. Double-click Start Print Bridge.bat. It finds or installs Python, fetches the PDF engine, opens the firewall ports, and starts.
4. On your phone: Share → Print. The printer is there.

Leave the window open, or run Install Autostart.bat once and it starts at every logon with no window at all.

Check it works

Start Print Bridge.bat --test-page

Prints one page: a border 10 mm from every edge, a 100 mm square in the middle, ticks every 10 mm. Hold a ruler against it and you know the whole chain is right.

How it prints

Most bridges of this kind shell out to another PDF application. This one does the work itself, which is what makes the rest possible:

• PDFium — the engine inside Chrome — rasterises each page at the printer's own resolution.
• The bitmap goes straight to a printer device context through GDI, placed against the sheet rather than against whatever the driver felt like.
• Pages are handed over with zero copies: an A4 page at 600 dpi is 139 MB, and copying that per sheet is the difference between working and thrashing on an old machine.

Owning that step buys exact sizing, the duplex edge the client actually asked for, and reverse page order in a single job.

If PDFium is missing the bridge falls back to SumatraPDF, and failing that to whatever owns the PrintTo verb. The banner always says which is live.

When the printer will not print

Some printers stop drawing jobs down after an interrupted one. Everything after that queues up and nothing comes out — which looks like a bug here and is not. Print Bridge asks the spooler and tells you:

Clear the queue cancels everything waiting and takes the printer off pause. There is a matching item in the tray menu, and --clear-queue from a console.

Options

Argument	Effect
--printer "NAME"	Share a specific printer. Repeat for several.
--all-printers	Share every printer installed on this PC
--name "Study printer"	The name phones will show
--pin 1234	Require a code before anything prints or scans
--test-page	Print one measurable page and exit
--clear-queue	Cancel everything waiting, un-pause, exit
--debug-print	Log what the driver is told and what it answers
--no-scanner	Do not offer the scanner
--simulate	Print nothing; save each job to a file
--list	List printers with port, driver and tags, then exit

The full manual covers the rest, including two-sided printing, quality settings and troubleshooting.

Requirements

• Windows 7 or later. One codebase — older Windows is handled by fallbacks, not a separate build. The win7/ folder holds a launcher that installs the last Python that runs there.
• Python 3.8 or later, installed by the launcher if missing.
• pypdfium2 and zeroconf, also installed by the launcher.
• A printer with a working Windows driver.

Building the single .exe

Build EXE.bat

Produces dist\Print Bridge.exe — one file containing Python, the PDF engine and the web page. CI builds the same thing on every push and attaches it to tagged releases.

Tests

python -m unittest discover -s tests

57 tests, and they run on any platform: everything Windows-only is behind a guard that declines rather than failing. They cover page placement in every scaling mode, the card-sheet geometry, PDF and JPEG writing, the eSCL protocol, and a rule that every ctypes call declares its argument types — which exists because forgetting once cost a day.

Contributing

Bug reports from printers I cannot test against are especially welcome. See CONTRIBUTING.md for how to report one and how the code is laid out, SECURITY.md for what this exposes on your network, and CODE_OF_CONDUCT.md for the house rules.

Licence

MIT — see LICENSE.

Built by Hafi — @hafeee44-lab.

Standing on PDFium (BSD/Apache) via pypdfium2, python-zeroconf, and SumatraPDF as an optional fallback.