From b651392d70d7e37ce5a8a20da81d86e5d19aadd8 Mon Sep 17 00:00:00 2001
From: Carl Hetherington <cth@carlh.net>
Date: Sun, 15 Dec 2019 22:58:21 +0100
Subject: [PATCH] Add fix_empty_font_ids() to replace empty Font ids with a
 dummy string.

Back-ported from abf4f7577877254ecd7a1dc7955e0d7ca49ad07c in master.
---
 src/subtitle_asset.cc | 40 +++++++++++++++++++++++++++++++++++++++-
 src/subtitle_asset.h  |  2 ++
 src/subtitle_string.h |  4 ++++
 src/util.cc           | 17 +++++++++++++++++
 src/util.h            |  1 +
 test/util_test.cc     | 12 ++++++++++++
 6 files changed, 75 insertions(+), 1 deletion(-)

diff --git a/src/subtitle_asset.cc b/src/subtitle_asset.cc
index bb7b0b1c..083a8040 100644
--- a/src/subtitle_asset.cc
+++ b/src/subtitle_asset.cc
@@ -1,5 +1,5 @@
 /*
-    Copyright (C) 2012-2018 Carl Hetherington <cth@carlh.net>
+    Copyright (C) 2012-2019 Carl Hetherington <cth@carlh.net>
 
     This file is part of libdcp.
 
@@ -40,6 +40,7 @@
 #include "subtitle_string.h"
 #include "subtitle_image.h"
 #include "dcp_assert.h"
+#include "load_font_node.h"
 #include <asdcp/AS_DCP.h>
 #include <asdcp/KM_util.h>
 #include <libxml++/nodes/element.h>
@@ -655,3 +656,40 @@ SubtitleAsset::fonts_with_load_ids () const
 	}
 	return out;
 }
+
+/** Replace empty IDs in any <LoadFontId> and <Font> tags with
+ *  a dummy string.  Some systems give errors with empty font IDs
+ *  (see DCP-o-matic bug #1689).
+ */
+void
+SubtitleAsset::fix_empty_font_ids ()
+{
+	bool have_empty = false;
+	list<string> ids;
+	BOOST_FOREACH (shared_ptr<LoadFontNode> i, load_font_nodes()) {
+		if (i->id == "") {
+			have_empty = true;
+		} else {
+			ids.push_back (i->id);
+		}
+	}
+
+	if (!have_empty) {
+		return;
+	}
+
+	string const empty_id = unique_string (ids, "font");
+
+	BOOST_FOREACH (shared_ptr<LoadFontNode> i, load_font_nodes()) {
+		if (i->id == "") {
+			i->id = empty_id;
+		}
+	}
+
+	BOOST_FOREACH (shared_ptr<Subtitle> i, _subtitles) {
+		shared_ptr<SubtitleString> j = dynamic_pointer_cast<SubtitleString> (i);
+		if (j && j->font() && j->font().get() == "") {
+			j->set_font (empty_id);
+		}
+	}
+}
diff --git a/src/subtitle_asset.h b/src/subtitle_asset.h
index 59ed1165..9f137abe 100644
--- a/src/subtitle_asset.h
+++ b/src/subtitle_asset.h
@@ -101,6 +101,8 @@ public:
 
 	Time latest_subtitle_out () const;
 
+	void fix_empty_font_ids ();
+
 	virtual std::list<boost::shared_ptr<LoadFontNode> > load_font_nodes () const = 0;
 
 protected:
diff --git a/src/subtitle_string.h b/src/subtitle_string.h
index c274152b..7e84d103 100644
--- a/src/subtitle_string.h
+++ b/src/subtitle_string.h
@@ -125,6 +125,10 @@ public:
 		return _aspect_adjust;
 	}
 
+	void set_font (std::string id) {
+		_font = id;
+	}
+
 	void set_size (int s) {
 		_size = s;
 	}
diff --git a/src/util.cc b/src/util.cc
index d5b6cb9f..bce28f07 100644
--- a/src/util.cc
+++ b/src/util.cc
@@ -376,3 +376,20 @@ dcp::indent (xmlpp::Element* element, int initial)
 		element->add_child_text (last, "\n" + spaces(initial));
 	}
 }
+
+/** Try quite hard to find a string which starts with \ref base and is
+ *  not in \ref existing.
+ */
+string
+dcp::unique_string (list<string> existing, string base)
+{
+	int const max_tries = existing.size() + 1;
+	for (int i = 0; i < max_tries; ++i) {
+		string trial = String::compose("%1%2", base, i);
+		if (find(existing.begin(), existing.end(), trial) == existing.end()) {
+			return trial;
+		}
+	}
+
+	DCP_ASSERT (false);
+}
diff --git a/src/util.h b/src/util.h
index bc109c62..0bb36cb0 100644
--- a/src/util.h
+++ b/src/util.h
@@ -75,6 +75,7 @@ extern xmlpp::Node* find_child (xmlpp::Node const * node, std::string name);
 extern std::string openjpeg_version();
 extern std::string spaces (int n);
 extern void indent (xmlpp::Element* element, int initial);
+extern std::string unique_string (std::list<std::string> existing, std::string base);
 
 }
 
diff --git a/test/util_test.cc b/test/util_test.cc
index f95001b4..4f387aaf 100644
--- a/test/util_test.cc
+++ b/test/util_test.cc
@@ -23,6 +23,7 @@
 
 using std::ifstream;
 using std::string;
+using std::list;
 
 /** Test dcp::base64_decode */
 BOOST_AUTO_TEST_CASE (base64_decode_test)
@@ -122,3 +123,14 @@ BOOST_AUTO_TEST_CASE (private_key_fingerprint_test)
 {
 	BOOST_CHECK_EQUAL (dcp::private_key_fingerprint (dcp::file_to_string ("test/data/private.key")), "Jdz1bFpCcKI7R16Ccx9JHYytag0=");
 }
+
+BOOST_AUTO_TEST_CASE (unique_string_test)
+{
+	list<string> existing;
+	for (int i = 0; i < 16; i++) {
+		string s;
+		BOOST_CHECK_NO_THROW (s = dcp::unique_string(existing, "foo"));
+		BOOST_CHECK (find(existing.begin(), existing.end(), s) == existing.end());
+		existing.push_back (s);
+	}
+}
-- 
2.30.2