From 89fbc8d186378cd72ab3e9a259073d45b7b993ad Mon Sep 17 00:00:00 2001
From: Carl Hetherington <cth@carlh.net>
Date: Thu, 16 Feb 2023 21:56:22 +0100
Subject: Change how whitespace in subtitles is handled.

Previously we would discard any whitespace subtitle content we found.
This had the side-effect of making a verification test fail (checking
that at least one subtitle is in each reel; blank subtitles are often
used to avoid this warning).

Here we take any subtitle content, whitespace or not, inside a
<Text> or <Image> node which I think is a little more correct.
---
 src/subtitle_asset.cc |  6 +++++-
 src/util.cc           | 13 -------------
 src/util.h            |  5 -----
 test/data/subs5.xml   | 13 +++++++++++++
 test/verify_test.cc   | 18 ++++++++++++++++++
 5 files changed, 36 insertions(+), 19 deletions(-)
 create mode 100644 test/data/subs5.xml

diff --git a/src/subtitle_asset.cc b/src/subtitle_asset.cc
index f707c665..4baa7b06 100644
--- a/src/subtitle_asset.cc
+++ b/src/subtitle_asset.cc
@@ -324,7 +324,11 @@ SubtitleAsset::parse_subtitles (xmlpp::Element const * node, vector<ParseState>&
 void
 SubtitleAsset::maybe_add_subtitle (string text, vector<ParseState> const & parse_state, float space_before, Standard standard)
 {
-	if (empty_or_white_space (text)) {
+	auto wanted = [](ParseState const& ps) {
+		return ps.type && (ps.type.get() == ParseState::Type::TEXT || ps.type.get() == ParseState::Type::IMAGE);
+	};
+
+	if (find_if(parse_state.begin(), parse_state.end(), wanted) == parse_state.end()) {
 		return;
 	}
 
diff --git a/src/util.cc b/src/util.cc
index b58035ea..9cc35ad6 100644
--- a/src/util.cc
+++ b/src/util.cc
@@ -158,19 +158,6 @@ dcp::make_digest (boost::filesystem::path filename, function<void (float)> progr
 }
 
 
-bool
-dcp::empty_or_white_space (string s)
-{
-	for (size_t i = 0; i < s.length(); ++i) {
-		if (s[i] != ' ' && s[i] != '\n' && s[i] != '\t') {
-			return false;
-		}
-	}
-
-	return true;
-}
-
-
 void
 dcp::init (optional<boost::filesystem::path> given_resources_directory)
 {
diff --git a/src/util.h b/src/util.h
index 451957d8..8261a812 100644
--- a/src/util.h
+++ b/src/util.h
@@ -84,11 +84,6 @@ extern std::string make_digest (boost::filesystem::path filename, boost::functio
 
 extern std::string make_digest (ArrayData data);
 
-/** @param s A string
- *  @return true if the string contains only space, newline or tab characters, or is empty
- */
-extern bool empty_or_white_space (std::string s);
-
 extern bool ids_equal (std::string a, std::string b);
 extern std::string remove_urn_uuid (std::string raw);
 
diff --git a/test/data/subs5.xml b/test/data/subs5.xml
new file mode 100644
index 00000000..d75583b9
--- /dev/null
+++ b/test/data/subs5.xml
@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<DCSubtitle Version="1.0">
+<SubtitleID>12345678-9abc-def0-1234-56789abcdef0</SubtitleID>
+<MovieTitle>Frobozz</MovieTitle>
+<ReelNumber>1</ReelNumber>
+<Language>English</Language>
+<LoadFont Id="Arial" URI="Arial.ttf"/>
+<Font Id="Arial">
+<Subtitle SpotNumber="1" TimeIn="00:00:04:100" TimeOut="00:00:05:199" FadeUpTime="0" FadeDownTime="0">
+    <Text HAlign="center" HPosition="0.00" VAlign="top" VPosition="40.00" Direction="horizontal"> </Text>
+</Subtitle>
+</Font>
+</DCSubtitle>
diff --git a/test/verify_test.cc b/test/verify_test.cc
index cde49830..396a1ef5 100644
--- a/test/verify_test.cc
+++ b/test/verify_test.cc
@@ -825,6 +825,24 @@ BOOST_AUTO_TEST_CASE(verify_interop_subtitle_asset_with_no_subtitles)
 }
 
 
+BOOST_AUTO_TEST_CASE(verify_interop_subtitle_asset_with_single_space_subtitle)
+{
+	path const dir("build/test/verify_interop_subtitle_asset_with_single_space_subtitle");
+	prepare_directory(dir);
+	copy_file("test/data/subs5.xml", dir / "subs.xml");
+	auto asset = make_shared<dcp::InteropSubtitleAsset>(dir / "subs.xml");
+	auto reel_asset = make_shared<dcp::ReelInteropSubtitleAsset>(asset, dcp::Fraction(24, 1), 16 * 24, 0);
+	write_dcp_with_single_asset(dir, reel_asset, dcp::Standard::INTEROP);
+
+	check_verify_result (
+		{ dir },
+		{
+			{ dcp::VerificationNote::Type::BV21_ERROR, dcp::VerificationNote::Code::INVALID_STANDARD },
+		});
+
+}
+
+
 BOOST_AUTO_TEST_CASE (verify_valid_smpte_subtitles)
 {
 	path const dir("build/test/verify_valid_smpte_subtitles");
-- 
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