Text: preserve signed insets and scale only when both are non-negative

Address review finding: keep signed insets unchanged when their sum fits,
scaling opposing insets proportionally only when both in the pair are
non-negative and their sum exceeds the box dimension.

crates/text/src/layout.rs

@@ -94,18 +94,18 @@ impl BoxGeom {
             text_rect
         };
         // Insets wider than the shape scale down proportionally to fit inside it (#1632).
-        let (mut ins_l, mut ins_r) = (bp.inset_l.unwrap_or(7.2).max(0.0), bp.inset_r.unwrap_or(7.2).max(0.0));
-        let (mut ins_t, mut ins_b) = (bp.inset_t.unwrap_or(3.6).max(0.0), bp.inset_b.unwrap_or(3.6).max(0.0));
+        let (mut ins_l, mut ins_r) = (bp.inset_l.unwrap_or(7.2), bp.inset_r.unwrap_or(7.2));
+        let (mut ins_t, mut ins_b) = (bp.inset_t.unwrap_or(3.6), bp.inset_b.unwrap_or(3.6));
         let w = r.width().max(0.0);
         let total_x = ins_l + ins_r;
-        if total_x > w && total_x > 0.0 {
+        if ins_l >= 0.0 && ins_r >= 0.0 && total_x > w && total_x > 0.0 {
             let s = w / total_x;
             ins_l *= s;
             ins_r *= s;
         }
         let h = r.height().max(0.0);
         let total_y = ins_t + ins_b;
-        if total_y > h && total_y > 0.0 {
+        if ins_t >= 0.0 && ins_b >= 0.0 && total_y > h && total_y > 0.0 {
             let s = h / total_y;
             ins_t *= s;
             ins_b *= s;

crates/text/src/tests.rs

@@ -1949,3 +1949,18 @@ fn insets_wider_than_the_shape_scale_down_within_the_shape_bounds() {
     // The text center must remain inside the 14.17 pt wide shape, not pushed ~127.5 pt to the right.
     assert!((0.0..=14.17).contains(&mid), "line center {mid} should be within [0, 14.17]");
 }
+
+/// #1632: signed insets (e.g. negative left inset with positive right inset) are preserved when
+/// their sum fits within the shape bounds.
+#[test]
+fn signed_insets_are_preserved_when_they_fit() {
+    let (p, mut sh) = setup("Text", 100.0, 50.0);
+    sh.ph = None;
+    let bp = &mut sh.text.as_mut().unwrap().body;
+    bp.inset_l = Some(-10.0);
+    bp.inset_r = Some(10.0);
+    sh.text.as_mut().unwrap().paragraphs[0].props = deckcraft_model::text::ParaProps { align: Some(Align::Left), ..Default::default() };
+    let l = lay(&p, &sh, 100.0, 50.0);
+    assert_eq!(l.lines.len(), 1);
+    assert_eq!(l.inner.x0, -10.0);
+}