From 1ec71c1bf0ec062db9982df87546729854ec0f54 Mon Sep 17 00:00:00 2001
From: mtlcl410 <2368091+mtlcl410@users.noreply.github.com>
Date: Mon, 9 Nov 2026 10:11:02 +0800
Subject: [PATCH] M12: an XFA caption beside its field wraps in its reserve
 (XFA 3.3 p. 645) (#5109)

---
 crates/xfa/src/layout/measure.rs |  6 ++++--
 crates/xfa/src/tests.rs          | 14 ++++++++++++++
 2 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/crates/xfa/src/layout/measure.rs b/crates/xfa/src/layout/measure.rs
index 7751012b8b..0200059910 100644
--- a/crates/xfa/src/layout/measure.rs
+++ b/crates/xfa/src/layout/measure.rs
@@ -247,10 +247,12 @@ impl Layouter<'_> {
         match self.caption_reserve(f, inner_w, ctx) {
             Some((Placement::Top | Placement::Bottom, r)) => ui + r,
             Some((placement, r)) => {
-                // A check box's caption without a reserve is drawn in all the box leaves.
+                // A check box's caption without a reserve is drawn in all the box leaves; any
+                // other caption beside the widget is as wide as its reserve (XFA 3.3 p. 645), the
+                // width `draw_field` gives it.
                 let w = match auto_check_reserve(f, placement, inner_w, None) {
                     Some(auto) => auto,
-                    None => inner_w - r,
+                    None => r.min(inner_w),
                 };
                 let cap = f.caption.as_ref().map(|c| {
                     let rich = match &c.value {
diff --git a/crates/xfa/src/tests.rs b/crates/xfa/src/tests.rs
index 43d6633c56..d7cfd1ca83 100644
--- a/crates/xfa/src/tests.rs
+++ b/crates/xfa/src/tests.rs
@@ -3030,6 +3030,20 @@ fn a_flowed_subform_is_as_tall_as_its_content_whatever_its_minimum_height() {
     assert!((top("") - flowed - (216.0 - 14.4)).abs() < 0.01, "{} against {flowed}", top(""));
 }
 
+#[test]
+fn a_caption_beside_a_check_box_wraps_in_its_reserve() {
+    // A 7.5in check box whose right-hand caption reserves 6.5in: two lines of text, not one or
+    // two words to a line in the 1in the box keeps. The field after it follows directly.
+    let words = "Applicant does not authorize the office to permit a participating office access to the application as filed. ".repeat(2);
+    let body = format!(
+        r#"<subform name="body" layout="tb" w="7.5in"><field name="opt" w="7.5in" minH="0.3in"><ui><checkButton/></ui><caption placement="right" reserve="6.5in"><value><text>{words}</text></value></caption></field><field name="who" w="3in" h="0.4in"><ui><textEdit/></ui></field></subform>"#
+    );
+    let form = layout_xml(&one_area_form(r#"layout="tb""#, &body)).unwrap();
+    let w = widgets(&form.pages[0]);
+    let gap = w[1].rect.y - w[0].rect.y;
+    assert!(gap < 72.0, "the check box took {gap}pt");
+}
+
 #[test]
 fn the_form_packet_restores_a_caption_a_script_changed() {
     let body = r#"<subform name="body" layout="tb" w="7.5in"><field name="bar" w="2in" h="0.3in"><ui><button/></ui><caption><value><text>Show Bar</text></value></caption></field></subform>"#;