From 0beaf6245ef0c1462cbe7eaf6faeabb651b68de3 Mon Sep 17 00:00:00 2001
From: Carl Hetherington <cth@carlh.net>
Date: Sun, 28 Dec 2025 01:21:20 +0100
Subject: Fix closed caption layout in the presence of italics / other markup
 (#3067).

---
 src/lib/layout_closed_captions.cc | 15 +++++++++++++-
 test/closed_caption_test.cc       | 43 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 57 insertions(+), 1 deletion(-)

diff --git a/src/lib/layout_closed_captions.cc b/src/lib/layout_closed_captions.cc
index 0f55f79f5..858b91c39 100644
--- a/src/lib/layout_closed_captions.cc
+++ b/src/lib/layout_closed_captions.cc
@@ -22,10 +22,12 @@
 #include "dcpomatic_assert.h"
 #include "layout_closed_captions.h"
 #include "string_text.h"
+#include "util.h"
 
 
 using std::string;
 using std::vector;
+using boost::optional;
 
 
 vector<string>
@@ -48,8 +50,19 @@ layout_closed_captions(vector<StringText> text)
 	std::sort(text.begin(), text.end(), [&](StringText const & a, StringText const & b) { return from_top(a) < from_top(b); });
 
 	vector<string> strings;
+	string current;
+	optional<float> last_position;
 	for (auto const& t: text) {
-		strings.push_back(t.text());
+		if (last_position && !text_positions_close(*last_position, t.v_position()) && !current.empty()) {
+			strings.push_back(current);
+			current = "";
+		}
+		current += t.text();
+		last_position = t.v_position();
+	}
+
+	if (!current.empty()) {
+		strings.push_back(current);
 	}
 
 	return strings;
diff --git a/test/closed_caption_test.cc b/test/closed_caption_test.cc
index c8ef6865d..dc75bc5bd 100644
--- a/test/closed_caption_test.cc
+++ b/test/closed_caption_test.cc
@@ -20,6 +20,8 @@
 
 
 #include "lib/film.h"
+#include "lib/layout_closed_captions.h"
+#include "lib/string_text.h"
 #include "lib/string_text_file_content.h"
 #include "lib/text_content.h"
 #include "test.h"
@@ -32,6 +34,7 @@
 
 using std::list;
 using std::make_shared;
+using std::vector;
 
 
 /** Basic test that Interop closed captions are written */
@@ -121,3 +124,43 @@ BOOST_AUTO_TEST_CASE (closed_caption_test2)
 
 	cl.run ();
 }
+
+
+BOOST_AUTO_TEST_CASE(closed_captions_with_italics_test)
+{
+	vector<StringText> text = {
+		{
+			{
+				{}, false, true, true, {}, 42, 1, dcp::Time(0, 0, 0, 0, 24), dcp::Time(0, 0, 1, 0, 24),
+				0, dcp::HAlign::CENTER,
+				0, dcp::VAlign::CENTER,
+				0,
+				{}, dcp::Direction::LTR, "Hello ", dcp::Effect::NONE, {}, {}, {}, 0, {}
+			}, 1, {}, dcp::SubtitleStandard::SMPTE_2014
+		},
+		{
+			{
+				{}, true, true, true, {}, 42, 1, dcp::Time(0, 0, 0, 0, 24), dcp::Time(0, 0, 1, 0, 24),
+				0, dcp::HAlign::CENTER,
+				0, dcp::VAlign::CENTER,
+				0,
+				{}, dcp::Direction::LTR, "world", dcp::Effect::NONE, {}, {}, {}, 0, {}
+			}, 1, {}, dcp::SubtitleStandard::SMPTE_2014
+		},
+		{
+			{
+				{}, false, true, true, {}, 42, 1, dcp::Time(0, 0, 0, 0, 24), dcp::Time(0, 0, 1, 0, 24),
+				0, dcp::HAlign::CENTER,
+				4, dcp::VAlign::CENTER,
+				0,
+				{}, dcp::Direction::LTR, "It's a new line", dcp::Effect::NONE, {}, {}, {}, 0, {}
+			}, 1, {}, dcp::SubtitleStandard::SMPTE_2014
+		}
+	};
+
+	auto const strings = layout_closed_captions(text);
+	BOOST_REQUIRE_EQUAL(strings.size(), 2U);
+	BOOST_CHECK_EQUAL(strings[0], "Hello world");
+	BOOST_CHECK_EQUAL(strings[1], "It's a new line");
+}
+
-- 
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