#1609: write page margins as their decimals

The page margins are kept as f32 and were widened to f64 when written,
so a 0.3-inch margin was saved as left="0.30000001192092896" (and 1.1
as 1.100000023841858). Each margin now goes through its shortest
decimal form first, so the file says 0.3, as Excel writes it.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

crates/xlsx/src/sheet_write.rs

@@ -370,7 +370,12 @@ fn write_sheet_printing<'a>(s: &mut String, sheet: &'a Sheet, rels: &mut Rels, o
     }
     // Unmodelled content kept from the source file (printer settings, controls, OLE objects…).
     let kept = crate::passthrough::SheetKept::write(sheet, rels, out);
-    let m = |i: usize| num(p.margins.get(i).copied().unwrap_or(0.75) as f64);
+    // Margins are kept as f32: widen each through its shortest decimal, so 0.3 is written as
+    // `0.3`, as Excel writes it, and not as `0.30000001192092896` (#1609).
+    let m = |i: usize| {
+        let inches = p.margins.get(i).copied().unwrap_or(0.75);
+        num(inches.to_string().parse::<f64>().unwrap_or(f64::from(inches)))
+    };
     let _ =
         write!(s, "<pageMargins left=\"{}\" right=\"{}\" top=\"{}\" bottom=\"{}\" header=\"{}\" footer=\"{}\"/>", m(0), m(1), m(2), m(3), m(4), m(5));
     s.push_str("<pageSetup");

crates/xlsx/src/tests/page_order.rs

@@ -61,3 +61,15 @@ fn down_then_over_writes_no_page_order() {
     wb.sheet_mut(0).unwrap().print.page_order = PageOrder::DownThenOver;
     assert!(!sheet_xml(&write_xlsx(&wb).unwrap()).contains("pageOrder"));
 }
+
+#[test]
+fn page_margins_are_written_as_their_decimals() {
+    // #1609 item 7: the f32 margins were widened to f64, so 0.3 came out as 0.30000001192092896.
+    let body = r#"<sheetData/><pageMargins left="0.3" right="0.25" top="1.1" bottom="0.75" header="0.3" footer="0.3"/>"#;
+    let (wb, _) = read_xlsx(&minimal(body, &[], "", "")).unwrap();
+    let xml = sheet_xml(&write_xlsx(&wb).unwrap());
+    assert!(xml.contains(r#"<pageMargins left="0.3" right="0.25" top="1.1" bottom="0.75" header="0.3" footer="0.3"/>"#), "{xml}");
+    // The default sheet writes Excel's default margins exactly.
+    let xml = sheet_xml(&write_xlsx(&Workbook::new()).unwrap());
+    assert!(xml.contains(r#"<pageMargins left="0.7" right="0.7" top="0.75" bottom="0.75" header="0.3" footer="0.3"/>"#), "{xml}");
+}

docs/file-format-parity.md

@@ -1,6 +1,6 @@
 # File-format parity
 
-> **Last reviewed:** 2026-11-01 · **Last updated:** 2026-11-02 · **Change:** minor (Python cells in `.xlsx` as [MS-XLSX] specifies, `_xlfn._xlws.PY(…)` naming code in the Python part, with cached values, and in GridCraft JSON, with limits on open; earlier: equations in xlsx as Office Math with a marker in `descr` so an edit made in Excel reads back, read back only up to the equation source cap, and a brace with a label and a script on its other side keeps both; Symbol font in PDF; earlier: XLSX reads and writes Page Setup's page order, `pageSetup pageOrder`, and PDF export follows it; earlier: chart data tables: native c:dTable import/export; earlier: XLSX workbook-view selection, normalized tab ratios and sheet-edit regressions; fidelity estimates unchanged; earlier: formulas from Google Sheets' XLSX export open as the original formula instead of `IFERROR(__xludf.DUMMYFUNCTION(…),…)` when GridCraft calculates every function in it, and save as it; `file.exportCsv {values: true}` writes raw values for automation; .xls dialog sheets are skipped instead of read as worksheets; `.xls` import reads each sheet's display options from WINDOW2: right-to-left, gridlines, headings, zeros, formulas; XLSX text boxes and shapes keep their paragraphs' right-to-left direction on save; CSV/TSV/TXT can open with every field kept as text via `file.open {csvAsText}`; formulas over Excel's 8,192 characters, and `%` or call chains past the nesting limit, are parse errors instead of stack overflows when a file is opened; XLSX PivotTables read and write `rowGrandTotals`/`colGrandTotals` the way Excel does, so a table saved with only one grand total opens with the right one; HTML export keeps right-to-left; CSV and text import detects likely Windows-1256 Arabic when invalid UTF-8 has Arabic byte runs; other invalid UTF-8 remains Windows-1252; HTML export places pictures and charts, as inline SVG, at their anchors; earlier: `file.exportCsv {values: true}` writes raw values for automation; .xls dialog sheets are skipped instead of read as worksheets; `.xls` import reads each sheet's display options from WINDOW2: right-to-left, gridlines, headings, zeros, formulas; XLSX text boxes and shapes keep their paragraphs' right-to-left direction on save; CSV/TSV/TXT can open with every field kept as text via `file.open {csvAsText}`; formulas over Excel's 8,192 characters, and `%` or call chains past the nesting limit, are parse errors instead of stack overflows when a file is opened; XLSX PivotTables read and write `rowGrandTotals`/`colGrandTotals` the way Excel does, so a table saved with only one grand total opens with the right one; HTML export keeps right-to-left; CSV and text import detects likely Windows-1256 Arabic when invalid UTF-8 has Arabic byte runs; other invalid UTF-8 remains Windows-1252; HTML export places pictures and charts, as inline SVG, at their anchors; CSV and text open detects each column's date order from values that read only one way, warns when every date is ambiguous, and keeps a column with both kinds as text (#2765)) · **Target:** Microsoft Excel (Microsoft 365), Excel for Mac 16.113.4
+> **Last reviewed:** 2026-11-01 · **Last updated:** 2026-11-03 · **Change:** minor (XLSX page margins are written as their decimals, `0.3` rather than `0.30000001192092896`; earlier: Python cells in `.xlsx` as [MS-XLSX] specifies, `_xlfn._xlws.PY(…)` naming code in the Python part, with cached values, and in GridCraft JSON, with limits on open; earlier: equations in xlsx as Office Math with a marker in `descr` so an edit made in Excel reads back, read back only up to the equation source cap, and a brace with a label and a script on its other side keeps both; Symbol font in PDF; earlier: XLSX reads and writes Page Setup's page order, `pageSetup pageOrder`, and PDF export follows it; earlier: chart data tables: native c:dTable import/export; earlier: XLSX workbook-view selection, normalized tab ratios and sheet-edit regressions; fidelity estimates unchanged; earlier: formulas from Google Sheets' XLSX export open as the original formula instead of `IFERROR(__xludf.DUMMYFUNCTION(…),…)` when GridCraft calculates every function in it, and save as it; `file.exportCsv {values: true}` writes raw values for automation; .xls dialog sheets are skipped instead of read as worksheets; `.xls` import reads each sheet's display options from WINDOW2: right-to-left, gridlines, headings, zeros, formulas; XLSX text boxes and shapes keep their paragraphs' right-to-left direction on save; CSV/TSV/TXT can open with every field kept as text via `file.open {csvAsText}`; formulas over Excel's 8,192 characters, and `%` or call chains past the nesting limit, are parse errors instead of stack overflows when a file is opened; XLSX PivotTables read and write `rowGrandTotals`/`colGrandTotals` the way Excel does, so a table saved with only one grand total opens with the right one; HTML export keeps right-to-left; CSV and text import detects likely Windows-1256 Arabic when invalid UTF-8 has Arabic byte runs; other invalid UTF-8 remains Windows-1252; HTML export places pictures and charts, as inline SVG, at their anchors; earlier: `file.exportCsv {values: true}` writes raw values for automation; .xls dialog sheets are skipped instead of read as worksheets; `.xls` import reads each sheet's display options from WINDOW2: right-to-left, gridlines, headings, zeros, formulas; XLSX text boxes and shapes keep their paragraphs' right-to-left direction on save; CSV/TSV/TXT can open with every field kept as text via `file.open {csvAsText}`; formulas over Excel's 8,192 characters, and `%` or call chains past the nesting limit, are parse errors instead of stack overflows when a file is opened; XLSX PivotTables read and write `rowGrandTotals`/`colGrandTotals` the way Excel does, so a table saved with only one grand total opens with the right one; HTML export keeps right-to-left; CSV and text import detects likely Windows-1256 Arabic when invalid UTF-8 has Arabic byte runs; other invalid UTF-8 remains Windows-1252; HTML export places pictures and charts, as inline SVG, at their anchors; CSV and text open detects each column's date order from values that read only one way, warns when every date is ambiguous, and keeps a column with both kinds as text (#2765)) · **Target:** Microsoft Excel (Microsoft 365), Excel for Mac 16.113.4
 
 Every format Excel opens or saves, with GridCraft's read and write support, fidelity and tests.
 Part of [target-app-parity.md](target-app-parity.md). **File formats: ~50% ready, 80–120 h**
@@ -155,6 +155,7 @@ refresh. Counted under features (Get & Transform, ~10% ready), not here.
 
 | Date | Change | Summary |
 |---|---|---|
+| 2026-11-03 | minor | XLSX `pageMargins` are written as the decimals they were read or set as (`0.3`, as Excel writes them), not as the f64 widening of the stored f32 (`0.30000001192092896`) (#1609 item 7) |
 | 2026-11-02 | minor | Python cells: `.xlsx` reads and writes `_xlfn._xlws.PY(i,0 or 1)` with the code in the Python part (and reads the string-literal form) with cached values and spills, other formats adopt PY formulas, GridCraft JSON keeps the whole cell, and opening limits code size, result size and spill ranges |
 | 2026-11-02 | trivial | An equation without Office Math takes its stored source only while its text, paragraphs included, is what the writer wrote for it; a paragraph split that changes no character reads back as a text box with the split text |
 | 2026-11-02 | trivial | Each equation box carries the marker of its own body in its description, the Office Math box and the plain-text fallback alike, and the reader takes the stored source only while the body it reads matches the marker: the text of an equation without Office Math that another application edited reads back as a text box with the edited text instead of the stale source |