Rows: a big font isn't counted twice when the sheet's default height already fits it

auto_row_height estimated a line of a bigger font by scaling the sheet's
default row height by size / 11. When the sheet's default already fits
that font, the font counted twice: Excel for Mac saves rows of 16pt text
with defaultRowHeight="21" (28px) and no ht, and opening such a file
fitted every row to 40.7px, 1.45 times Excel's height. Rows mixing Middle
and Bottom aligned cells then looked misaligned.

The estimate now scales an 11pt row's height (DEFAULT_ROW_HEIGHT), so
those rows open at 29px, and rows on a 15pt-default sheet still grow to
their font (#833).

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

crates/engine/src/cmd/mod.rs

@@ -484,7 +484,9 @@ pub fn auto_row_height(wb: &mut Workbook, si: usize, row: u32) {
     for (c, cell) in sh.cells.row(row, 0, gridcraft_core::MAX_COLS - 1) {
         let st = wb.styles.get(cell.style);
         let size = st.font.size;
-        let line = (size * 1.8).round().max(default * size / gridcraft_model::DEFAULT_FONT_SIZE);
+        // Scaled from an 11pt row's height, not the sheet's default: a sheet whose default
+        // already fits a bigger font (21pt rows for 16pt text) would otherwise scale it twice.
+        let line = (size * 1.8).round().max(gridcraft_model::DEFAULT_ROW_HEIGHT * size / gridcraft_model::DEFAULT_FONT_SIZE);
         let mut lines = 1.0f32;
         if !cell.value.is_empty() || cell.formula.is_some() {
             let text = crate::display::cell_text(wb, sh, CellRef::new(row, c));

crates/engine/src/tests.rs

@@ -1150,6 +1150,26 @@ fn open_leaves_plain_workbooks_untouched() {
     assert!(sh.rows.values().all(|i| i.size.is_none()), "no row gains a height entry");
 }
 
+#[test]
+fn open_fits_big_font_rows_from_the_font_not_the_sheet_default() {
+    // Excel saves a sheet whose rows hold 16pt text with a 21pt (28px) default row height and no
+    // `ht` on rows of that height. Those rows already fit their font: they open at about 28px,
+    // not scaled up again by 16/11 to 41px.
+    let mut wb = gridcraft_model::Workbook::new();
+    let big = wb.styles.derive(gridcraft_model::StyleId::DEFAULT, |s| s.font.size = 16.0);
+    let sh = wb.sheet_mut(0).unwrap();
+    sh.default_row_height = 28.0;
+    sh.set_value(CellRef::new(4, 0), Value::text("SANTANDER"));
+    sh.set_style(CellRef::new(4, 0), big);
+    let bytes = gridcraft_xlsx::write_xlsx(&wb).unwrap();
+    let mut s = Session::new();
+    s.execute("file.open", json!({"name": "tall-default.xlsx", "base64": crate::io::base64_encode(&bytes)})).unwrap();
+    let sh = s.doc().unwrap().wb.active().unwrap();
+    assert_eq!(sh.default_row_height, 28.0);
+    let h = sh.row_height(4);
+    assert!((28.0..30.0).contains(&h), "a 16pt row on a 28px-default sheet opens at about 28px, got {h}");
+}
+
 #[test]
 fn tables_and_structured_refs() {
     let mut s = s();