fix(edit): setting a paragraph's width no longer panics on text larger than a page (#4110)

rewrite_block clamps a requested paragraph width between the text's
size in user space (size * k) and the largest page PDF allows
(14 400 pt). f64::clamp panics when its minimum is the larger, so text
set above 14 400 pt crashed the app as soon as its paragraph was given
a width. The size comes from the file (`20000 Tf`, or `1 Tf` scaled up
by `Tm`) or from the request (the automation tools pass `size`
through).

The lower bound is now capped at 14 400 pt too, so such a paragraph
gets the widest width allowed. `f64::min` also turns a NaN size into
the cap.

Test: a 20000 pt Tf, a 1 pt Tf scaled 20000x by Tm, and a requested
size of 20000 pt each take a width of 200 without panicking (all three
panicked before).

Reported-by: BS.ehlas.cz

Co-authored-by: Brandon Thomas <echelon@gmail.com>

crates/edit/src/tests.rs

@@ -6356,6 +6356,24 @@ fn reading_keeps_dotted_leader_entries_whole_and_in_order() {
     );
 }
 
+/// Text set larger than the widest page PDF allows (14 400 pt) panicked when its paragraph was given
+/// a width: the width is clamped between the font size and 14 400 pt, and `f64::clamp` panics when
+/// its minimum is the larger. The width is now capped at 14 400 pt whatever the font size: from the
+/// file (`Tf`, or a small `Tf` scaled up by `Tm`) or asked for (the automation tools pass it through).
+#[test]
+fn width_on_a_paragraph_set_larger_than_a_page_is_capped_not_a_panic() {
+    let wide = text::BlockStyle { width: Some(200.0), ..Default::default() };
+    let huge = text::BlockStyle { size: Some(20_000.0), width: Some(200.0), ..Default::default() };
+    for (content, style) in [
+        ("BT /F2 20000 Tf 72 700 Td (ab) Tj ET", &wide),
+        ("BT /F2 1 Tf 20000 0 0 20000 72 700 Tm (ab) Tj ET", &wide),
+        ("BT /F2 12 Tf 72 700 Td (ab) Tj ET", &huge),
+    ] {
+        let mut doc = text_page(content);
+        text::rewrite_block(&mut doc, 0, 0, None, style).unwrap();
+    }
+}
+
 #[test]
 fn added_text_is_wrapped_once_per_write() {
     let mut doc = fixture();

crates/edit/src/text.rs

@@ -2780,8 +2780,9 @@ fn rewrite_block_from(
     // A paragraph keeps its width (or takes the one asked for); a single line grows to the right
     // (to the left when right-to-left), up to the page's margin.
     let width = match style.width {
-        // Capped at the largest page PDF allows (14 400 pt).
-        Some(w) if w.is_finite() => w.clamp(size * k, 14_400.0),
+        // Capped at the largest page PDF allows (14 400 pt), even for text set larger than that
+        // (`clamp` panics when its minimum is the larger, or NaN).
+        Some(w) if w.is_finite() => w.clamp((size * k).min(14_400.0), 14_400.0),
         Some(_) => return Err(EditError::Invalid("the paragraph's width must be a number".into())),
         // Turned text: the page's margins are along another axis. A single line grows (below).
         None if !upright => (frame[2] - frame[0]).max(size * k),