Fix DCP content font ID allocation to cope with DCPs that have multiple fonts

with the same name in the same reel (#2600).

Previously we had this id_for_font_in_reel() which would give an ID
of N_font-ID.  This means we got duplicate font IDs.

Here we replace that method with FontAllocator, which gives an ID of
N_font-ID for the first font and M_font-ID, where M is a number higher than
the highest reel index.  The idea is to support the required new IDs
without breaking exisiting projects.

There is some documentation of how it works  in doc/design/fonts

1 files changed, 72 insertions, 0 deletions

diff --git a/test/font_id_allocator_test.cc b/test/font_id_allocator_test.cc
new file mode 100644
index 000000000..7c93c6b78
--- /dev/null
+++ b/test/font_id_allocator_test.cc
@@ -0,0 +1,72 @@
+/*
+    Copyright (C) 2023 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 "lib/font_id_allocator.h"
+#include <boost/test/unit_test.hpp>
+
+
+BOOST_AUTO_TEST_CASE(font_id_allocator_test_without_disambiguation)
+{
+	FontIDAllocator allocator;
+
+	/* Reel 0 has just one asset with two fonts */
+	allocator.add_font(0, "asset1", "font");
+	allocator.add_font(0, "asset1", "font2");
+
+	/* Reel 1 has two assets each with two more fonts */
+	allocator.add_font(1, "asset2", "font");
+	allocator.add_font(1, "asset2", "font2");
+	allocator.add_font(1, "asset3", "font3");
+	allocator.add_font(1, "asset3", "font4");
+
+	allocator.allocate();
+
+	BOOST_CHECK(allocator.font_id(0, "asset1", "font") == "0_font");
+	BOOST_CHECK(allocator.font_id(0, "asset1", "font2") == "0_font2");
+	BOOST_CHECK(allocator.font_id(1, "asset2", "font") == "1_font");
+	BOOST_CHECK(allocator.font_id(1, "asset2", "font2") == "1_font2");
+	BOOST_CHECK(allocator.font_id(1, "asset3", "font3") == "1_font3");
+	BOOST_CHECK(allocator.font_id(1, "asset3", "font4") == "1_font4");
+}
+
+
+BOOST_AUTO_TEST_CASE(font_id_allocator_test_with_disambiguation)
+{
+	FontIDAllocator allocator;
+
+	/* Reel 0 has two assets each with a font with the same ID (perhaps a subtitle and a ccap).
+	 * This would have crashed DCP-o-matic before the FontIDAllocator change (bug #2600)
+	 * so it's OK if the second font gets a new index that we didn't see before.
+	 */
+	allocator.add_font(0, "asset1", "font");
+	allocator.add_font(0, "asset2", "font");
+
+	/* Reel 1 has one asset with another font */
+	allocator.add_font(1, "asset3", "font1");
+
+	allocator.allocate();
+
+	BOOST_CHECK(allocator.font_id(0, "asset1", "font") == "0_font");
+	/* This should get a prefix that is higher than any reel index */
+	BOOST_CHECK(allocator.font_id(0, "asset2", "font") == "2_font");
+	BOOST_CHECK(allocator.font_id(1, "asset3", "font1") == "1_font1");
+}
+