Fix problems when loading old projects with the new subtitle font code (#2271).

3 files changed, 76 insertions, 8 deletions

diff --git a/src/lib/check_content_job.cc b/src/lib/check_content_job.cc
index a789ed9e0..2b6e25da8 100644
--- a/src/lib/check_content_job.cc
+++ b/src/lib/check_content_job.cc
@@ -24,12 +24,14 @@
 #include "examine_content_job.h"
 #include "film.h"
 #include "job_manager.h"
+#include "string_text_file_content.h"
 #include <iostream>
 
 #include "i18n.h"
 
 
 using std::cout;
+using std::dynamic_pointer_cast;
 using std::make_shared;
 using std::shared_ptr;
 using std::string;
@@ -74,6 +76,14 @@ CheckContentJob::run ()
 		set_message (_("Some files have been changed since they were added to the project.\n\nThese files will now be re-examined, so you may need to check their settings."));
 	}
 
+	if (_film->last_written_by_earlier_than(2, 16, 14)) {
+		for (auto c: content) {
+			if (auto stf = dynamic_pointer_cast<StringTextFileContent>(c)) {
+				stf->check_font_ids();
+			}
+		}
+	}
+
 	set_progress (1);
 	set_state (FINISHED_OK);
 }
diff --git a/src/lib/string_text_file_content.cc b/src/lib/string_text_file_content.cc
index 95a282174..7ee870e18 100644
--- a/src/lib/string_text_file_content.cc
+++ b/src/lib/string_text_file_content.cc
@@ -60,6 +60,24 @@ StringTextFileContent::StringTextFileContent (cxml::ConstNodePtr node, int versi
 }
 
 
+static
+std::set<string>
+font_names(StringTextFile const& string_text_file)
+{
+	std::set<string> names;
+
+	for (auto const& subtitle: string_text_file.subtitles()) {
+		for (auto const& line: subtitle.lines) {
+			for (auto const& block: line.blocks) {
+				names.insert(block.font.get_value_or(""));
+			}
+		}
+	}
+
+	return names;
+}
+
+
 void
 StringTextFileContent::examine (shared_ptr<const Film> film, shared_ptr<Job> job)
 {
@@ -71,14 +89,7 @@ StringTextFileContent::examine (shared_ptr<const Film> film, shared_ptr<Job> job
 	/* Default to turning these subtitles on */
 	only_text()->set_use (true);
 
-	std::set<string> names;
-	for (auto const& subtitle: file.subtitles()) {
-		for (auto const& line: subtitle.lines) {
-			for (auto const& block: line.blocks) {
-				names.insert(block.font.get_value_or(""));
-			}
-		}
-	}
+	std::set<string> names = font_names(file);
 
 	for (auto name: names) {
 		optional<boost::filesystem::path> path;
@@ -148,3 +159,48 @@ StringTextFileContent::identifier () const
 	s += "_" + only_text()->identifier();
 	return s;
 }
+
+
+/** In 5a820bb8fae34591be5ac6d19a73461b9dab532a there were some changes to subtitle font management.
+ *
+ *  With StringTextFileContent we used to write a <Font> tag to the metadata with the id "font".  Users
+ *  could then set a font file that content should use, and (with some luck) it would end up in the DCP
+ *  that way.
+ *
+ *  After the changes we write a <Font> tag for every different font "id" (i.e. name) found in the source
+ *  file (including a <Font> with id "" in the .srt case where there are no font names).
+ *
+ *  However, this meant that making DCPs from old projects would fail, as the new code would see a font name
+ *  in the source, then lookup a Font object for it from the Content, and fail in doing so (since the content
+ *  only contains a font called "font").
+ *
+ *  To put it another way: after the changes, the code expects that any font ID (i.e. name) used in some content
+ *  will have a <Font> in the metadata and so a Font object in the TextContent.  Without that, making DCPs fails.
+ *
+ *  To work around this problem, this check_font_ids() is called for all subtitle content written by DoM versions
+ *  before 2.16.14.  We find all the font IDs in the content and map them all to the "legacy" font name (if there
+ *  is one).  This is more-or-less a re-examine()-ation, except that we try to preserve any settings that
+ *  the user had previously set up.
+ *
+ *  See #2271.
+ */
+void
+StringTextFileContent::check_font_ids()
+{
+	StringTextFile file (shared_from_this());
+	auto names = font_names(file);
+
+	auto content = only_text();
+	auto legacy_font_file = content->get_font("font")->file();
+
+	for (auto name: names) {
+		if (!content->get_font(name)) {
+			if (legacy_font_file) {
+				content->add_font(make_shared<Font>(name, *legacy_font_file));
+			} else {
+				content->add_font(make_shared<Font>(name));
+			}
+		}
+	}
+}
+
diff --git a/src/lib/string_text_file_content.h b/src/lib/string_text_file_content.h
index 9c7d4cea0..30f543381 100644
--- a/src/lib/string_text_file_content.h
+++ b/src/lib/string_text_file_content.h
@@ -50,6 +50,8 @@ public:
 	dcpomatic::DCPTime approximate_length () const override;
 	std::string identifier () const override;
 
+	void check_font_ids();
+
 private:
 	dcpomatic::ContentTime _length;
 };