winprint

A crate for printing to a Windows printer device using Windows API.

About Safety

This crate interfaces with several Windows API functions, necessitating the use of unsafe code blocks. Nevertheless, this crate is designed to be safe and sound to use. If you find any case that will break safety or soundness, please report it as a bug.

Development

Testing on Windows

Just run cargo test on a Windows machine, null printer will be automatically created and used for testing. The tests cover basic printer operations like getting printer information, writing to the printer, etc.

Three visual regression tests also run under the test-utils feature (plus pdfium for the PDF test):

• tests/visual_regression_pdfium.rs — PdfiumPrinter
• tests/visual_regression_xps.rs — XpsPrinter
• tests/visual_regression_image.rs — ImagePrinter

Each prints the matching origin file from test_data/visual_regression/<kind>/origin.* through a virtual Microsoft PWG Raster printer, decodes the PWG bitstream, and SSIM-compares each page against the corresponding expected.tiff rendered by a deliberately different renderer (Poppler for PDF, libgxps for XPS, ImageMagick for Image). That second-source property means a shared regression between renderer and baseline would have to coincidentally produce matching pixels for the test to silently pass. Set WINPRINT_DUMP_DIR=<path> to have failing tests dump the actual/expected page PNGs for inspection.

Day-to-day development never needs to regenerate these fixtures — the repo ships them and cargo test consumes them as-is. If you do need to rebuild them (e.g. after tweaking the source drawing or bumping a baseline renderer), run python utils/gen_visual_regression_data/run.py; see the README in that directory for tool prerequisites and determinism guarantees.

For testing with multiple features in one command, cargo hack may be used for convenience.

Testing on Linux Host

Since this crate is designed for Windows, it cannot be directly tested on a Linux host. However, a script is provided to run the test suite inside a Windows 11 VM on a Linux host.

Prerequisites: Docker with BuildKit, KVM support (/dev/kvm), and sufficient disk space & memory for the VM.

./utils/test-in-windows-vm/run.sh

The script will spins up a Windows VM and then run the test suite inside it. On first run it initializes the VM (very slowly). Subsequent runs reuse the cached VM state (relatively fast).

To clear the cached VM state, run with --destroy flag:

./utils/test-in-windows-vm/run.sh --destroy

License

Licensed under BSD 3 Clause

Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in this crate by you, shall be licensed as BSD 3 Clause, without any additional terms or conditions.

Craft Apps maintenance branch

This branch retains the upstream BSD-3-Clause licence and copyright notices. It is based on ArcticLampyrid/winprint.rs v0.2.1, commit 406ed733f15d60403d8d029035c807b5d8d33d31.

The narrow changes used by craft-print are:

• DXGI jobs retain the terminal package HRESULT, report failed/canceled states, and time out after two minutes waiting for a missing terminal notification after Close. An unsuccessful job requests cancellation; the status connection is unadvised before its COM apartment is released. The timeout does not bound calls into a printer driver or an interactive output-file dialog.
• WinPdfPrinter::print_with_progress(path, ticket, callback) reports (processed, total) after each successful Direct2D AddPage, preserving one job and its ticket. These counts measure page processing, never physical printing or terminal success. Existing FilePrinter::print remains a wrapper without progress.
• Completion regression tests cover a late failed HRESULT, cancellation, inconsistent completed HRESULT, missing notification, and repeated terminal notifications.

The shared completion state uses reference-counted Rust synchronization rather than an event HANDLE borrowed from the callback's lifetime. Applications must still check that printing's final Result is successful, even when progress reached its total.