Text: draw a saved shrink scale as it is

PowerPoint fits shrink-on-overflow text again only when the text changes,
never when a file opens: it draws the saved fontScale/lnSpcReduction even
where our metrics would call the text overflowing (trailing empty
paragraphs at full size, substituted fonts). Shrinking further on open made
saved decks text smaller than PowerPoints (74 % instead of 85 % on a real
deck). With no saved scale, or once an edit has reset it, the text is
fitted as before.

crates/text/src/lib.rs

@@ -835,8 +835,13 @@ pub fn layout(ctx: &Ctx, shape: &Shape, body: &TextBody, opts: &Opts) -> TextLay
         _ => (1.0, 0.0),
     };
     let mut l = layout_scaled(ctx, shape, body, &bp, opts, scale0, reduce0);
+    // A scale PowerPoint saved is drawn as it is: PowerPoint fits the text again only when it
+    // changes (and editing resets the saved scale), not when a file opens, even where our
+    // metrics would call it overflowing (trailing empty paragraphs, substituted fonts).
+    let saved = scale0 < 1.0 || reduce0 > 0.0;
     if let (AutoFit::Shrink { .. }, false) = (autofit, opts.no_shrink)
         && l.overflow
+        && !saved
     {
         // Binary search the largest scale that fits (steps like 90%, 80%… with line reduction).
         let (mut lo, mut hi) = (0.1_f64, scale0);

crates/text/src/tests.rs

@@ -62,12 +62,16 @@ fn saved_shrink_scale_is_drawn() {
     sh.text.as_mut().unwrap().body.autofit = Some(AutoFit::Shrink { font_scale: 0.625, line_reduction: 0.2 });
     let l = lay(&p, &sh, 600.0, 300.0);
     assert_eq!((l.font_scale, l.line_reduction), (0.625, 0.2));
-    // Text that doesn't fit even at the saved scale shrinks further.
+    // Text our metrics find overflowing at the saved scale is still drawn at it, as PowerPoint
+    // draws it until the text changes; with no saved scale it shrinks to fit.
     let text = (0..30).map(|i| format!("Line number {i}")).collect::<Vec<_>>().join("\n");
     let (p, mut sh) = setup(&text, 600.0, 200.0);
     sh.text.as_mut().unwrap().body.autofit = Some(AutoFit::Shrink { font_scale: 0.9, line_reduction: 0.1 });
     let l = lay(&p, &sh, 600.0, 200.0);
-    assert!(l.font_scale < 0.9 && l.line_reduction >= 0.1, "{} {}", l.font_scale, l.line_reduction);
+    assert_eq!((l.font_scale, l.line_reduction), (0.9, 0.1));
+    sh.text.as_mut().unwrap().body.autofit = Some(AutoFit::Shrink { font_scale: 1.0, line_reduction: 0.0 });
+    let l = lay(&p, &sh, 600.0, 200.0);
+    assert!(l.font_scale < 0.9, "{}", l.font_scale);
     // Nonsense saved values are ignored.
     let (p, mut sh) = setup("Short", 600.0, 300.0);
     sh.text.as_mut().unwrap().body.autofit = Some(AutoFit::Shrink { font_scale: f64::NAN, line_reduction: 5.0 });