X-Git-Url: https://git.carlh.net/gitweb/?a=blobdiff_plain;f=src%2Fsubtitle_asset.cc;h=19f7fa375e10020faf1ada0d2f736151a47d7e47;hb=6b0b06915c254637350dc14646ebc7d641ba1e60;hp=414825a4de8994e1aa0a9ba5d547c76c6747d4c3;hpb=ea629ead13e819b4ff5d5b5eba7b57520e8107e3;p=libdcp.git

diff --git a/src/subtitle_asset.cc b/src/subtitle_asset.cc
index 414825a4..19f7fa37 100644
--- a/src/subtitle_asset.cc
+++ b/src/subtitle_asset.cc
@@ -1,50 +1,63 @@
 /*
-    Copyright (C) 2012-2015 Carl Hetherington <cth@carlh.net>
+    Copyright (C) 2012-2016 Carl Hetherington <cth@carlh.net>
 
-    This program is free software; you can redistribute it and/or modify
+    This file is part of libdcp.
+
+    libdcp 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.
 
-    This program is distributed in the hope that it will be useful,
+    libdcp 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 this program; if not, write to the Free Software
-    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
-
+    along with libdcp.  If not, see <http://www.gnu.org/licenses/>.
+
+    In addition, as a special exception, the copyright holders give
+    permission to link the code of portions of this program with the
+    OpenSSL library under certain conditions as described in each
+    individual source file, and distribute linked combinations
+    including the two.
+
+    You must obey the GNU General Public License in all respects
+    for all of the code used other than OpenSSL.  If you modify
+    file(s) with this exception, you may extend this exception to your
+    version of the file(s), but you are not obligated to do so.  If you
+    do not wish to do so, delete this exception statement from your
+    version.  If you delete this exception statement from all source
+    files in the program, then also delete it here.
 */
 
 #include "raw_convert.h"
+#include "compose.hpp"
 #include "subtitle_asset.h"
+#include "subtitle_asset_internal.h"
 #include "util.h"
 #include "xml.h"
-#include "font_node.h"
-#include "text_node.h"
 #include "subtitle_string.h"
 #include "dcp_assert.h"
-#include "AS_DCP.h"
-#include "KM_util.h"
+#include <asdcp/AS_DCP.h>
+#include <asdcp/KM_util.h>
 #include <libxml++/nodes/element.h>
 #include <boost/algorithm/string.hpp>
+#include <boost/lexical_cast.hpp>
 #include <boost/shared_array.hpp>
 #include <boost/foreach.hpp>
-#include <fstream>
 
 using std::string;
 using std::list;
-using std::ostream;
-using std::ofstream;
-using std::stringstream;
 using std::cout;
 using std::cerr;
 using std::map;
+using std::distance;
 using boost::shared_ptr;
 using boost::shared_array;
 using boost::optional;
 using boost::dynamic_pointer_cast;
+using boost::lexical_cast;
 using namespace dcp;
 
 SubtitleAsset::SubtitleAsset ()
@@ -58,101 +71,284 @@ SubtitleAsset::SubtitleAsset (boost::filesystem::path file)
 
 }
 
-void
-SubtitleAsset::parse_subtitles (shared_ptr<cxml::Document> xml, list<shared_ptr<dcp::FontNode> > font_nodes)
+string
+string_attribute (xmlpp::Element const * node, string name)
 {
-	/* Make Subtitle objects to represent the raw XML nodes in a sane way */
-	ParseState parse_state;
-	examine_font_nodes (xml, font_nodes, parse_state);
+	xmlpp::Attribute* a = node->get_attribute (name);
+	if (!a) {
+		throw XMLError (String::compose ("missing attribute %1", name));
+	}
+	return string (a->get_value ());
 }
 
-void
-SubtitleAsset::examine_subtitle_nodes (
-	shared_ptr<const cxml::Node> xml,
-	list<shared_ptr<dcp::SubtitleNode> > const & subtitle_nodes,
-	ParseState& parse_state
-	)
+optional<string>
+optional_string_attribute (xmlpp::Element const * node, string name)
 {
-	for (list<shared_ptr<dcp::SubtitleNode> >::const_iterator j = subtitle_nodes.begin(); j != subtitle_nodes.end(); ++j) {
-		parse_state.subtitle_nodes.push_back (*j);
-		examine_text_nodes (xml, (*j)->text_nodes, parse_state);
-		examine_font_nodes (xml, (*j)->font_nodes, parse_state);
-		parse_state.subtitle_nodes.pop_back ();
+	xmlpp::Attribute* a = node->get_attribute (name);
+	if (!a) {
+		return optional<string>();
 	}
+	return string (a->get_value ());
 }
 
-void
-SubtitleAsset::examine_font_nodes (
-	shared_ptr<const cxml::Node> xml,
-	list<shared_ptr<dcp::FontNode> > const & font_nodes,
-	ParseState& parse_state
-	)
+optional<bool>
+optional_bool_attribute (xmlpp::Element const * node, string name)
 {
-	for (list<shared_ptr<dcp::FontNode> >::const_iterator i = font_nodes.begin(); i != font_nodes.end(); ++i) {
+	optional<string> s = optional_string_attribute (node, name);
+	if (!s) {
+		return optional<bool> ();
+	}
 
-		parse_state.font_nodes.push_back (*i);
-		maybe_add_subtitle ((*i)->text, parse_state);
+	return (s.get() == "1" || s.get() == "yes");
+}
 
-		examine_subtitle_nodes (xml, (*i)->subtitle_nodes, parse_state);
+template <class T>
+optional<T>
+optional_number_attribute (xmlpp::Element const * node, string name)
+{
+	boost::optional<std::string> s = optional_string_attribute (node, name);
+	if (!s) {
+		return boost::optional<T> ();
+	}
+
+	std::string t = s.get ();
+	boost::erase_all (t, " ");
+	return raw_convert<T> (t);
+}
 
-		examine_font_nodes (xml, (*i)->font_nodes, parse_state);
-		examine_text_nodes (xml, (*i)->text_nodes, parse_state);
+SubtitleAsset::ParseState
+SubtitleAsset::font_node_state (xmlpp::Element const * node, Standard standard) const
+{
+	ParseState ps;
 
-		parse_state.font_nodes.pop_back ();
+	if (standard == INTEROP) {
+		ps.font_id = optional_string_attribute (node, "Id");
+	} else {
+		ps.font_id = optional_string_attribute (node, "ID");
+	}
+	ps.size = optional_number_attribute<int64_t> (node, "Size");
+	ps.aspect_adjust = optional_number_attribute<float> (node, "AspectAdjust");
+	ps.italic = optional_bool_attribute (node, "Italic");
+	ps.bold = optional_string_attribute(node, "Weight").get_value_or("normal") == "bold";
+	if (standard == INTEROP) {
+		ps.underline = optional_bool_attribute (node, "Underlined");
+	} else {
+		ps.underline = optional_bool_attribute (node, "Underline");
+	}
+	optional<string> c = optional_string_attribute (node, "Color");
+	if (c) {
+		ps.colour = Colour (c.get ());
+	}
+	optional<string> const e = optional_string_attribute (node, "Effect");
+	if (e) {
+		ps.effect = string_to_effect (e.get ());
+	}
+	c = optional_string_attribute (node, "EffectColor");
+	if (c) {
+		ps.effect_colour = Colour (c.get ());
 	}
+
+	return ps;
+}
+
+SubtitleAsset::ParseState
+SubtitleAsset::text_node_state (xmlpp::Element const * node) const
+{
+	ParseState ps;
+
+	optional<float> hp = optional_number_attribute<float> (node, "HPosition");
+	if (!hp) {
+		hp = optional_number_attribute<float> (node, "Hposition");
+	}
+	if (hp) {
+		ps.h_position = hp.get () / 100;
+	}
+
+	optional<string> ha = optional_string_attribute (node, "HAlign");
+	if (!ha) {
+		ha = optional_string_attribute (node, "Halign");
+	}
+	if (ha) {
+		ps.h_align = string_to_halign (ha.get ());
+	}
+
+	optional<float> vp = optional_number_attribute<float> (node, "VPosition");
+	if (!vp) {
+		vp = optional_number_attribute<float> (node, "Vposition");
+	}
+	if (vp) {
+		ps.v_position = vp.get () / 100;
+	}
+
+	optional<string> va = optional_string_attribute (node, "VAlign");
+	if (!va) {
+		va = optional_string_attribute (node, "Valign");
+	}
+	if (va) {
+		ps.v_align = string_to_valign (va.get ());
+	}
+
+	optional<string> d = optional_string_attribute (node, "Direction");
+	if (d) {
+		ps.direction = string_to_direction (d.get ());
+	}
+
+	return ps;
+}
+
+SubtitleAsset::ParseState
+SubtitleAsset::subtitle_node_state (xmlpp::Element const * node, optional<int> tcr) const
+{
+	ParseState ps;
+	ps.in = Time (string_attribute(node, "TimeIn"), tcr);
+	ps.out = Time (string_attribute(node, "TimeOut"), tcr);
+	ps.fade_up_time = fade_time (node, "FadeUpTime", tcr);
+	ps.fade_down_time = fade_time (node, "FadeDownTime", tcr);
+	return ps;
+}
+
+Time
+SubtitleAsset::fade_time (xmlpp::Element const * node, string name, optional<int> tcr) const
+{
+	string const u = optional_string_attribute(node, name).get_value_or ("");
+	Time t;
+
+	if (u.empty ()) {
+		t = Time (0, 0, 0, 20, 250);
+	} else if (u.find (":") != string::npos) {
+		t = Time (u, tcr);
+	} else {
+		t = Time (0, 0, 0, lexical_cast<int> (u), tcr.get_value_or(250));
+	}
+
+	if (t > Time (0, 0, 8, 0, 250)) {
+		t = Time (0, 0, 8, 0, 250);
+	}
+
+	return t;
 }
 
 void
-SubtitleAsset::examine_text_nodes (
-	shared_ptr<const cxml::Node> xml,
-	list<shared_ptr<dcp::TextNode> > const & text_nodes,
-	ParseState& parse_state
-	)
+SubtitleAsset::parse_subtitles (xmlpp::Element const * node, list<ParseState>& state, optional<int> tcr, Standard standard)
 {
-	for (list<shared_ptr<dcp::TextNode> >::const_iterator i = text_nodes.begin(); i != text_nodes.end(); ++i) {
-		parse_state.text_nodes.push_back (*i);
-		maybe_add_subtitle ((*i)->text, parse_state);
-		examine_font_nodes (xml, (*i)->font_nodes, parse_state);
-		parse_state.text_nodes.pop_back ();
+	if (node->get_name() == "Font") {
+		state.push_back (font_node_state (node, standard));
+	} else if (node->get_name() == "Subtitle") {
+		state.push_back (subtitle_node_state (node, tcr));
+	} else if (node->get_name() == "Text") {
+		state.push_back (text_node_state (node));
+	} else if (node->get_name() == "SubtitleList") {
+		state.push_back (ParseState ());
+	} else {
+		throw XMLError ("unexpected node " + node->get_name());
 	}
+
+	xmlpp::Node::NodeList c = node->get_children ();
+	for (xmlpp::Node::NodeList::const_iterator i = c.begin(); i != c.end(); ++i) {
+		xmlpp::ContentNode const * v = dynamic_cast<xmlpp::ContentNode const *> (*i);
+		if (v) {
+			maybe_add_subtitle (v->get_content(), state);
+		}
+		xmlpp::Element const * e = dynamic_cast<xmlpp::Element const *> (*i);
+		if (e) {
+			parse_subtitles (e, state, tcr, standard);
+		}
+	}
+
+	state.pop_back ();
 }
 
 void
-SubtitleAsset::maybe_add_subtitle (string text, ParseState const & parse_state)
+SubtitleAsset::maybe_add_subtitle (string text, list<ParseState> const & parse_state)
 {
 	if (empty_or_white_space (text)) {
 		return;
 	}
 
-	if (parse_state.text_nodes.empty() || parse_state.subtitle_nodes.empty ()) {
-		return;
+	ParseState ps;
+	BOOST_FOREACH (ParseState const & i, parse_state) {
+		if (i.font_id) {
+			ps.font_id = i.font_id.get();
+		}
+		if (i.size) {
+			ps.size = i.size.get();
+		}
+		if (i.aspect_adjust) {
+			ps.aspect_adjust = i.aspect_adjust.get();
+		}
+		if (i.italic) {
+			ps.italic = i.italic.get();
+		}
+		if (i.bold) {
+			ps.bold = i.bold.get();
+		}
+		if (i.underline) {
+			ps.underline = i.underline.get();
+		}
+		if (i.colour) {
+			ps.colour = i.colour.get();
+		}
+		if (i.effect) {
+			ps.effect = i.effect.get();
+		}
+		if (i.effect_colour) {
+			ps.effect_colour = i.effect_colour.get();
+		}
+		if (i.h_position) {
+			ps.h_position = i.h_position.get();
+		}
+		if (i.h_align) {
+			ps.h_align = i.h_align.get();
+		}
+		if (i.v_position) {
+			ps.v_position = i.v_position.get();
+		}
+		if (i.v_align) {
+			ps.v_align = i.v_align.get();
+		}
+		if (i.direction) {
+			ps.direction = i.direction.get();
+		}
+		if (i.in) {
+			ps.in = i.in.get();
+		}
+		if (i.out) {
+			ps.out = i.out.get();
+		}
+		if (i.fade_up_time) {
+			ps.fade_up_time = i.fade_up_time.get();
+		}
+		if (i.fade_down_time) {
+			ps.fade_down_time = i.fade_down_time.get();
+		}
 	}
 
-	DCP_ASSERT (!parse_state.text_nodes.empty ());
-	DCP_ASSERT (!parse_state.subtitle_nodes.empty ());
-
-	dcp::FontNode effective_font (parse_state.font_nodes);
-	dcp::TextNode effective_text (*parse_state.text_nodes.back ());
-	dcp::SubtitleNode effective_subtitle (*parse_state.subtitle_nodes.back ());
+	if (!ps.in || !ps.out) {
+		/* We're not in a <Text> node; just ignore this content */
+		return;
+	}
 
 	_subtitles.push_back (
 		SubtitleString (
-			effective_font.id,
-			effective_font.italic.get_value_or (false),
-			effective_font.colour.get_value_or (dcp::Colour (255, 255, 255)),
-			effective_font.size,
-			effective_font.aspect_adjust.get_value_or (1.0),
-			effective_subtitle.in,
-			effective_subtitle.out,
-			effective_text.h_position,
-			effective_text.h_align,
-			effective_text.v_position,
-			effective_text.v_align,
+			ps.font_id,
+			ps.italic.get_value_or (false),
+			ps.bold.get_value_or (false),
+			ps.underline.get_value_or (false),
+			ps.colour.get_value_or (dcp::Colour (255, 255, 255)),
+			ps.size.get_value_or (42),
+			ps.aspect_adjust.get_value_or (1.0),
+			ps.in.get(),
+			ps.out.get(),
+			ps.h_position.get_value_or(0),
+			ps.h_align.get_value_or(HALIGN_CENTER),
+			ps.v_position.get_value_or(0),
+			ps.v_align.get_value_or(VALIGN_CENTER),
+			ps.direction.get_value_or (DIRECTION_LTR),
 			text,
-			effective_font.effect.get_value_or (NONE),
-			effective_font.effect_colour.get_value_or (dcp::Colour (0, 0, 0)),
-			effective_subtitle.fade_up_time,
-			effective_subtitle.fade_down_time
+			ps.effect.get_value_or (NONE),
+			ps.effect_colour.get_value_or (dcp::Colour (255, 255, 255)),
+			ps.fade_up_time.get_value_or(Time()),
+			ps.fade_down_time.get_value_or(Time())
 			)
 		);
 }
@@ -161,9 +357,9 @@ list<SubtitleString>
 SubtitleAsset::subtitles_during (Time from, Time to, bool starting) const
 {
 	list<SubtitleString> s;
-	for (list<SubtitleString>::const_iterator i = _subtitles.begin(); i != _subtitles.end(); ++i) {
-		if ((starting && from <= i->in() && i->in() < to) || (!starting && i->out() >= from && i->in() <= to)) {
-			s.push_back (*i);
+	BOOST_FOREACH (SubtitleString const & i, _subtitles) {
+		if ((starting && from <= i.in() && i.in() < to) || (!starting && i.out() >= from && i.in() <= to)) {
+			s.push_back (i);
 		}
 	}
 
@@ -180,9 +376,9 @@ Time
 SubtitleAsset::latest_subtitle_out () const
 {
 	Time t;
-	for (list<SubtitleString>::const_iterator i = _subtitles.begin(); i != _subtitles.end(); ++i) {
-		if (i->out() > t) {
-			t = i->out ();
+	BOOST_FOREACH (SubtitleString const & i, _subtitles) {
+		if (i.out() > t) {
+			t = i.out ();
 		}
 	}
 
@@ -209,7 +405,8 @@ SubtitleAsset::equals (shared_ptr<const Asset> other_asset, EqualityOptions opti
 	return true;
 }
 
-struct SubtitleSorter {
+struct SubtitleSorter
+{
 	bool operator() (SubtitleString const & a, SubtitleString const & b) {
 		if (a.in() != b.in()) {
 			return a.in() < b.in();
@@ -218,147 +415,144 @@ struct SubtitleSorter {
 	}
 };
 
+void
+SubtitleAsset::pull_fonts (shared_ptr<order::Part> part)
+{
+	if (part->children.empty ()) {
+		return;
+	}
+
+	/* Pull up from children */
+	BOOST_FOREACH (shared_ptr<order::Part> i, part->children) {
+		pull_fonts (i);
+	}
+
+	if (part->parent) {
+		/* Establish the common font features that each of part's children have;
+		   these features go into part's font.
+		*/
+		part->font = part->children.front()->font;
+		BOOST_FOREACH (shared_ptr<order::Part> i, part->children) {
+			part->font.take_intersection (i->font);
+		}
+
+		/* Remove common values from part's children's fonts */
+		BOOST_FOREACH (shared_ptr<order::Part> i, part->children) {
+			i->font.take_difference (part->font);
+		}
+	}
+
+	/* Merge adjacent children with the same font */
+	list<shared_ptr<order::Part> >::const_iterator i = part->children.begin();
+	list<shared_ptr<order::Part> > merged;
+
+	while (i != part->children.end()) {
+
+		if ((*i)->font.empty ()) {
+			merged.push_back (*i);
+			++i;
+		} else {
+			list<shared_ptr<order::Part> >::const_iterator j = i;
+			++j;
+			while (j != part->children.end() && (*i)->font == (*j)->font) {
+				++j;
+			}
+			if (distance (i, j) == 1) {
+				merged.push_back (*i);
+				++i;
+			} else {
+				shared_ptr<order::Part> group (new order::Part (part, (*i)->font));
+				for (list<shared_ptr<order::Part> >::const_iterator k = i; k != j; ++k) {
+					(*k)->font.clear ();
+					group->children.push_back (*k);
+				}
+				merged.push_back (group);
+				i = j;
+			}
+		}
+	}
+
+	part->children = merged;
+}
+
 /** @param standard Standard (INTEROP or SMPTE); this is used rather than putting things in the child
  *  class because the differences between the two are fairly subtle.
  */
 void
-SubtitleAsset::subtitles_as_xml (xmlpp::Element* root, int time_code_rate, Standard standard) const
+SubtitleAsset::subtitles_as_xml (xmlpp::Element* xml_root, int time_code_rate, Standard standard) const
 {
 	list<SubtitleString> sorted = _subtitles;
 	sorted.sort (SubtitleSorter ());
 
-	string const xmlns = standard == SMPTE ? "dcst" : "";
+	/* Gather our subtitles into a hierarchy of Subtitle/Text/String objects, writing
+	   font information into the bottom level (String) objects.
+	*/
 
-	/* XXX: script, underlined, weight not supported */
+	shared_ptr<order::Part> root (new order::Part (shared_ptr<order::Part> ()));
+	shared_ptr<order::Subtitle> subtitle;
+	shared_ptr<order::Text> text;
 
-	optional<string> font;
-	bool italic = false;
-	Colour colour;
-	int size = 0;
-	float aspect_adjust = 1.0;
-	Effect effect = NONE;
-	Colour effect_colour;
-	int spot_number = 1;
 	Time last_in;
 	Time last_out;
 	Time last_fade_up_time;
 	Time last_fade_down_time;
+	HAlign last_h_align;
+	float last_h_position;
+	VAlign last_v_align;
+	float last_v_position;
+	Direction last_direction;
+
+	BOOST_FOREACH (SubtitleString const & i, sorted) {
+		if (!subtitle ||
+		    (last_in != i.in() ||
+		     last_out != i.out() ||
+		     last_fade_up_time != i.fade_up_time() ||
+		     last_fade_down_time != i.fade_down_time())
+			) {
+
+			subtitle.reset (new order::Subtitle (root, i.in(), i.out(), i.fade_up_time(), i.fade_down_time()));
+			root->children.push_back (subtitle);
+
+			last_in = i.in ();
+			last_out = i.out ();
+			last_fade_up_time = i.fade_up_time ();
+			last_fade_down_time = i.fade_down_time ();
+			text.reset ();
+		}
 
-	xmlpp::Element* font_element = 0;
-	xmlpp::Element* subtitle_element = 0;
+		if (!text ||
+		    last_h_align != i.h_align() ||
+		    fabs(last_h_position - i.h_position()) > ALIGN_EPSILON ||
+		    last_v_align != i.v_align() ||
+		    fabs(last_v_position - i.v_position()) > ALIGN_EPSILON ||
+		    last_direction != i.direction()
+			) {
+
+			text.reset (new order::Text (subtitle, i.h_align(), i.h_position(), i.v_align(), i.v_position(), i.direction()));
+			subtitle->children.push_back (text);
+
+			last_h_align = i.h_align ();
+			last_h_position = i.h_position ();
+			last_v_align = i.v_align ();
+			last_v_position = i.v_position ();
+			last_direction = i.direction ();
+		}
 
-	for (list<SubtitleString>::iterator i = sorted.begin(); i != sorted.end(); ++i) {
+		text->children.push_back (shared_ptr<order::String> (new order::String (text, order::Font (i, standard), i.text())));
+	}
 
-		/* We will start a new <Font>...</Font> whenever some font property changes.
-		   I suppose we should really make an optimal hierarchy of <Font> tags, but
-		   that seems hard.
-		*/
+	/* Pull font changes as high up the hierarchy as we can */
 
-		bool const font_changed =
-			font          != i->font()          ||
-			italic        != i->italic()        ||
-			colour        != i->colour()        ||
-			size          != i->size()          ||
-			fabs (aspect_adjust - i->aspect_adjust()) > ASPECT_ADJUST_EPSILON ||
-			effect        != i->effect()        ||
-			effect_colour != i->effect_colour();
-
-		if (font_changed) {
-			font = i->font ();
-			italic = i->italic ();
-			colour = i->colour ();
-			size = i->size ();
-			aspect_adjust = i->aspect_adjust ();
-			effect = i->effect ();
-			effect_colour = i->effect_colour ();
-		}
+	pull_fonts (root);
 
-		if (!font_element || font_changed) {
-			font_element = root->add_child ("Font", xmlns);
-			if (font) {
-				if (standard == SMPTE) {
-					font_element->set_attribute ("ID", font.get ());
-				} else {
-					font_element->set_attribute ("Id", font.get ());
-				}
-			}
-			font_element->set_attribute ("Italic", italic ? "yes" : "no");
-			font_element->set_attribute ("Color", colour.to_argb_string());
-			font_element->set_attribute ("Size", raw_convert<string> (size));
-			if (fabs (aspect_adjust - 1.0) > ASPECT_ADJUST_EPSILON) {
-				font_element->set_attribute ("AspectAdjust", raw_convert<string> (aspect_adjust));
-			}
-			font_element->set_attribute ("Effect", effect_to_string (effect));
-			font_element->set_attribute ("EffectColor", effect_colour.to_argb_string());
-			font_element->set_attribute ("Script", "normal");
-			if (standard == SMPTE) {
-				font_element->set_attribute ("Underline", "no");
-			} else {
-				font_element->set_attribute ("Underlined", "no");
-			}
-			font_element->set_attribute ("Weight", "normal");
-		}
+	/* Write XML */
 
-		if (!subtitle_element || font_changed ||
-		    (last_in != i->in() ||
-		     last_out != i->out() ||
-		     last_fade_up_time != i->fade_up_time() ||
-		     last_fade_down_time != i->fade_down_time()
-			    )) {
-
-			subtitle_element = font_element->add_child ("Subtitle", xmlns);
-			subtitle_element->set_attribute ("SpotNumber", raw_convert<string> (spot_number++));
-			subtitle_element->set_attribute ("TimeIn", i->in().rebase(time_code_rate).as_string(standard));
-			subtitle_element->set_attribute ("TimeOut", i->out().rebase(time_code_rate).as_string(standard));
-			if (standard == SMPTE) {
-				subtitle_element->set_attribute ("FadeUpTime", i->fade_up_time().rebase(time_code_rate).as_string(standard));
-				subtitle_element->set_attribute ("FadeDownTime", i->fade_down_time().rebase(time_code_rate).as_string(standard));
-			} else {
-				subtitle_element->set_attribute ("FadeUpTime", raw_convert<string> (i->fade_up_time().as_editable_units(time_code_rate)));
-				subtitle_element->set_attribute ("FadeDownTime", raw_convert<string> (i->fade_down_time().as_editable_units(time_code_rate)));
-			}
+	order::Context context;
+	context.time_code_rate = time_code_rate;
+	context.standard = standard;
+	context.spot_number = 1;
 
-			last_in = i->in ();
-			last_out = i->out ();
-			last_fade_up_time = i->fade_up_time ();
-			last_fade_down_time = i->fade_down_time ();
-		}
-
-		xmlpp::Element* text = subtitle_element->add_child ("Text", xmlns);
-		if (i->h_align() != HALIGN_CENTER) {
-			if (standard == SMPTE) {
-				text->set_attribute ("Halign", halign_to_string (i->h_align ()));
-			} else {
-				text->set_attribute ("HAlign", halign_to_string (i->h_align ()));
-			}
-		}
-		if (i->h_position() > ALIGN_EPSILON) {
-			if (standard == SMPTE) {
-				text->set_attribute ("Hposition", raw_convert<string> (i->h_position() * 100, 6));
-			} else {
-				text->set_attribute ("HPosition", raw_convert<string> (i->h_position() * 100, 6));
-			}
-		}
-		if (standard == SMPTE) {
-			text->set_attribute ("Valign", valign_to_string (i->v_align()));
-		} else {
-			text->set_attribute ("VAlign", valign_to_string (i->v_align()));
-		}
-		if (i->v_position() > ALIGN_EPSILON) {
-			if (standard == SMPTE) {
-				text->set_attribute ("Vposition", raw_convert<string> (i->v_position() * 100, 6));
-			} else {
-				text->set_attribute ("VPosition", raw_convert<string> (i->v_position() * 100, 6));
-			}
-		} else {
-			if (standard == SMPTE) {
-				text->set_attribute ("Vposition", "0");
-			} else {
-				text->set_attribute ("VPosition", "0");
-			}
-		}
-		text->add_child_text (i->text());
-	}
+	root->write_xml (xml_root, context);
 }
 
 map<string, Data>