pdfcraft/crates/print/README.md

pdfcraft-print

Layer L4: printing (execution plan M10.5).

let pages = select_pages(count, Some("1-3, ii, 9-"), &labels, Subset::All, false)?;
let settings = Settings { pages, paper: PAPERS[0].1, layout: Layout::multiple(4), ..Default::default() };
let sheets = layout(&display_sizes, &settings)?;   // geometry only (previews)
let pdf = impose(&doc, &settings)?;                // the print-ready PDF
spool::submit(&pdf, &spool::Job { printer: None, copies: 2, ..Default::default() })?;

• Size: fit (to the sheet minus an 18 pt margin), actual size, shrink oversized, custom %; centred; auto orientation turns the sheet for landscape pages.
• Multiple: 2/4/6/9/16 (or any n) pages per sheet, horizontal/vertical (reversed) order, page borders, auto-rotation of pages that don't match the cell.
• Cut and stack (Multiple's page order): consecutive pages in each cell's pile, with aligned cut marks in the gutters. For example, 10 pages at 4 per sheet give [1, 4, 7, 10], [2, 5, 8, blank], [3, 6, 9, blank]. Print single-sided, keep sheets in output order, cut at the marks, then stack the cell piles from left to right, top to bottom. Blank cells can be discarded. Page ranges and Reverse pages are applied before imposition. Duplex imposition is not supported. Headless: doc_print with layout: "multiple", order: "cut-stack" and per_sheet: 4 (or any supported grid size), plus path or printer.
• Booklet: saddle-stitch imposition padded to a multiple of 4; both sides, front or back only; left or right binding.
• Poster: tile scale, overlap shared by neighbouring tiles, cut marks.
• Comments & forms: document, + markups, + stamps, or form fields only; annotations print only with their Print flag, drawn from their appearance streams (Algorithm 8.1).

Each source page becomes a Form XObject (its content wrapped in q/Q, plus the printable annotations); sheets place them with a clip. The result is a fresh, unencrypted, garbage-collected file (callers check the print permission).

spool talks to CUPS on macOS and Linux: printers come from lpstat -p -d (the queues) and lpstat -e (driverless destinations no queue exists for; CUPS builds a temporary one when the job arrives), jobs go to lp with copies, collation, duplex and monochrome options. The job is piped to lp on stdin and never written to a temp file, where another local user could read or swap it. On Windows the printers come from Win32_Printer and jobs are rendered by the in-box Windows.Data.Pdf and spooled by System.Drawing.Printing with the driver's own settings (both through powershell, so no Win32 API is called here); that job file exists for the seconds the spooler reads it, under a fresh unpredictable name. Each sheet prints at 100% on the driver's paper closest to its size, turned landscape when it is wide, and is rasterised at the printer's resolution (up to 600 dpi), not sent as vectors. Other platforms report that printing to a printer isn't available yet; the print-ready PDF can always be saved.

Not yet: the web spooler, print as image, poster labels, PostScript output, colour conversion for grayscale.

Architectural sheets and scale

The Paper menu and doc_print share Letter, Legal, Tabloid, A3/A4/A5 plus ARCH A/B/C/D/E1/E, ANSI C/D/E and ISO A0/A1/A2. ARCH D is 24 × 36 inches; ANSI D is 22 × 34 inches. Dimensions follow the HP DesignJet paper-size table. Automation accepts short names such as "ARCH D" (case-insensitive) or the full menu label. For example, doc_print with paper: "ARCH D", layout: "actual", orientation: "auto" and path: "plan.pdf" writes a print-ready PDF at 100%.

Match page at 100% uses the currently viewed document page to choose a standard sheet (either orientation, within 0.5 pt for rounded metric dimensions), Actual size and Auto orientation. It leaves the selected page range intact. It is disabled for a custom page size with no matching preset. One preset applies to the whole job; this is not per-page paper-source selection.

PDF scale describes the source-to-sheet transform in the previewed print-ready PDF, not measured physical output. Fit reserves an 18 pt margin and can reduce even a matching page. The current Windows backend still rasterises and can substitute paper/shrink a job if its driver lacks the requested size. These controls do not add #599's strict PrintTicket validation or vector spooler. Verify the driver's paper/scaling settings and physical calibration before relying on drawing scale.