Extract and fix closed text display logic (#2857).

This was buggy, but here it is extracted, fixed and gains a basic test.

3 files changed, 189 insertions, 0 deletions

diff --git a/src/lib/closed_text_display.cc b/src/lib/closed_text_display.cc
new file mode 100644
index 000000000..7ec8d5d8a
--- /dev/null
+++ b/src/lib/closed_text_display.cc
@@ -0,0 +1,128 @@
+/*
+    Copyright (C) 2024 Carl Hetherington <cth@carlh.net>
+
+    This file is part of DCP-o-matic.
+
+    DCP-o-matic is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    DCP-o-matic is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with DCP-o-matic.  If not, see <http://www.gnu.org/licenses/>.
+
+*/
+
+
+#include "butler.h"
+#include "closed_text_display.h"
+#include "constants.h"
+#include "dcp_text_track.h"
+#include "dcpomatic_time.h"
+#include "string_text.h"
+#include "text_ring_buffers.h"
+
+
+using std::weak_ptr;
+using boost::optional;
+
+
+void
+ClosedTextDisplay::set_butler(weak_ptr<Butler> butler)
+{
+	_butler = butler;
+}
+
+
+class ClosedTextSorter
+{
+public:
+	bool operator() (StringText const & a, StringText const & b)
+	{
+		return from_top(a) < from_top(b);
+	}
+
+private:
+	float from_top (StringText const & c) const
+	{
+		switch (c.v_align()) {
+		case dcp::VAlign::TOP:
+			return c.v_position();
+		case dcp::VAlign::CENTER:
+			return c.v_position() + 0.5;
+		case dcp::VAlign::BOTTOM:
+			return 1.0 - c.v_position();
+		}
+		DCPOMATIC_ASSERT (false);
+		return 0;
+	}
+};
+
+
+bool
+ClosedTextDisplay::update(dcpomatic::DCPTime time, optional<DCPTextTrack> track)
+{
+	bool changed = false;
+
+	/* Clear _current if it should not be visible */
+	if (!_current.empty() && _current_period && !_current_period->contains(time)) {
+		_current = {};
+		_current_period = {};
+		changed = true;
+	}
+
+	/* Fill next if necessary and possible */
+	if (_next.empty() && track) {
+		if (auto butler = _butler.lock()) {
+			optional<TextRingBuffers::Data> data;
+			while (auto d = butler->get_closed_caption()) {
+				if (d->track == *track && d->period.to > time) {
+					data = d;
+					break;
+				}
+			}
+
+			if (data) {
+				auto to_show = data->text.string;
+				std::sort(to_show.begin(), to_show.end(), ClosedTextSorter());
+
+				auto j = to_show.begin();
+				int k = 0;
+				while (j != to_show.end() && k < MAX_CLOSED_CAPTION_LINES) {
+					_next.push_back(j->text());
+					++j;
+					++k;
+				}
+
+				_next_period = data->period;
+			}
+		}
+	}
+
+	/* Swap next in if it's time */
+	if (_next_period && _next_period->contains(time)) {
+		_current = _next;
+		_current_period = _next_period;
+		_next = {};
+		_next_period = {};
+		changed = true;
+	}
+
+	return changed;
+}
+
+
+void
+ClosedTextDisplay::clear()
+{
+	_current = {};
+	_current_period = {};
+	_next = {};
+	_next_period = {};
+}
+
diff --git a/src/lib/closed_text_display.h b/src/lib/closed_text_display.h
new file mode 100644
index 000000000..f2cf7dd11
--- /dev/null
+++ b/src/lib/closed_text_display.h
@@ -0,0 +1,60 @@
+/*
+    Copyright (C) 2024 Carl Hetherington <cth@carlh.net>
+
+    This file is part of DCP-o-matic.
+
+    DCP-o-matic is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    DCP-o-matic is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with DCP-o-matic.  If not, see <http://www.gnu.org/licenses/>.
+
+*/
+
+
+#include "dcpomatic_time.h"
+#include <memory>
+#include <string>
+#include <vector>
+
+
+class Butler;
+class DCPTextTrack;
+class Film;
+
+
+/** @class ClosedTextDisplay
+ *  @brief Helper for displaying closed text from a butler.
+ *
+ *  This class extracts the logic used by the closed text dialogue box,
+ *  mostly to make it more easily testable.
+ */
+class ClosedTextDisplay
+{
+public:
+	void clear();
+	void set_butler(std::weak_ptr<Butler> butler);
+
+	/** Set up the display for a particular time and text track */
+	bool update(dcpomatic::DCPTime time, boost::optional<DCPTextTrack> track);
+
+	/** @return the current closed text lines that should be shown */
+	std::vector<std::string> const& current() const {
+		return _current;
+	}
+
+private:
+	std::weak_ptr<Butler> _butler;
+	std::vector<std::string> _current;
+	boost::optional<dcpomatic::DCPTimePeriod> _current_period;
+	std::vector<std::string> _next;
+	boost::optional<dcpomatic::DCPTimePeriod> _next_period;
+};
+
diff --git a/src/lib/wscript b/src/lib/wscript
index 87a1ca787..7b00468e8 100644
--- a/src/lib/wscript
+++ b/src/lib/wscript
@@ -52,6 +52,7 @@ sources = """
           cinema.cc
           cinema_sound_processor.cc
           change_signaller.cc
+          closed_text_display.cc
           collator.cc
           colour_conversion.cc
           config.cc