feat(document): fit a printed sheet to the paper the file states

[andiwand]

🤖 Generated with Claude Code

Stacked on #817 — review that first; this branch contains it.

The second part of #816: the file's own paper reaches the printed page. #817 fits the sheet to whatever paper it lands on, by capping the table's width — which never clips, but squeezes the column widths unevenly. This reads the paper the file states and scales the sheet by it, so the printed sheet keeps the proportions the document has.

What was missing

Sheet had no page layout, and no engine parsed one. The paper, orientation and margins an ods states for a sheet live on the master page its table style names — the same indirection a paragraph's page uses, and StyleRegistry::master_page_of_style already walked it for text roots, slides and drawing pages. Nothing asked it for a sheet.

What this adds

• Sheet::page_layout() — new on the public API, a new virtual on abstract::SheetAdapter, implemented by all five engines that provide sheets, and mirrored in the Python, JNI and Apple bindings (wasm binds no document elements). Real for ods; empty, with the reason, for xlsx, xls, .numbers and csv.
• translate_sheet states the factor the paper asks for, per sheet, as --odr-print-fit on the sheet's own table: the printable width (page less its side margins) over the sum of the column widths. Only ever down — a sheet that already fits is printed at its size, never enlarged.
• The print stylesheet applies it as zoom, which scales the layout, so rows still break across pages. fix(html): print a sheet onto the page, without our ruler #817's max-width cap stays behind it, as the guard for paper the file did not expect.

Measured

A 6-column sheet of 3in,1in,3in,1in,3in,1in on Letter with 1in margins, rendered by translate, printed with Chrome headless, columns measured from the PDF text positions:

	printed column widths	ratio (file says 3:1)	type size
#817's cap alone	127, 54, 128, 54, 127 pt	2.35 : 1	10pt
with the fit	117, 39, 117, 39, 117 pt	3.00 : 1	5.4pt

117pt is 216pt × 0.5417, and 0.5417 is exactly the 6.5in printable width over the 12in the sheet is wide — so the sheet prints at the scale the file's paper implies, undistorted.

What it does not do

Half the corpus states no paper. 22 of the 52 ods here carry fo:page-width; the rest state margins only and leave the paper to the printer. Those get no factor and keep #817's behaviour exactly. Reading a frontend-supplied paper from HtmlConfig — the Android side knows its PrintAttributes — is the obvious next increment, and would cover them.

No @page rule. Declaring the file's paper to the printer would want one, but a print path that honours CSS page size over the framework's own attributes has to be established per frontend first, and a view that renders several sheets has several answers. Left out deliberately.

xlsx is not wired up, and its pageSetup alone would buy nothing: a column width there is a ch, so no absolute content width can be summed to compare against the paper. Both halves are one follow-up.

Pagination — a wide sheet continuing onto further pages at full size, the way a spreadsheet application prints it — remains the open half of #816.

Tests

Document.ods_sheet_page_layout reads the paper off a real ods; Document.ods_sheet_page_layout_without_a_paper_size pins the common margins-only case. On the renderer, html.a_sheet_is_fitted_to_the_paper_the_file_states checks the factor against the file's numbers, and html.a_sheet_is_only_ever_fitted_down drives three inline flat-ods sheets — narrower than, exactly, and twice its paper.

Reference output is unchanged in what it renders: the new attribute is inert outside print, so no pixel moves and no pin advances.