1 files changed, 111 insertions, 0 deletions
diff --git a/src/lib/subtitle.cc b/src/lib/subtitle.cc
new file mode 100644
index 000000000..f0d77c511
--- /dev/null
+++ b/src/lib/subtitle.cc
@@ -0,0 +1,111 @@
+/*
+    Copyright (C) 2012 Carl Hetherington <cth@carlh.net>
+
+    This program 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,
+    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.
+
+*/
+
+#include "subtitle.h"
+#include "image.h"
+#include "exceptions.h"
+#include "film_state.h"
+
+using namespace std;
+using namespace boost;
+
+Subtitle::Subtitle (AVSubtitle const & sub)
+{
+	/* subtitle PTS in seconds */
+	float const packet_time = (sub.pts / AV_TIME_BASE) + float (sub.pts % AV_TIME_BASE) / 1e6;
+	
+	/* hence start time for this sub */
+	_from = packet_time + (double (sub.start_display_time) / 1e3);
+	_to = packet_time + (double (sub.end_display_time) / 1e3);
+
+	for (unsigned int i = 0; i < sub.num_rects; ++i) {
+		_images.push_back (shared_ptr<SubtitleImage> (new SubtitleImage (sub.rects[i])));
+	}
+}
+
+/** @param t Time in seconds from the start of the film */
+bool
+Subtitle::displayed_at (double t)
+{
+	return t >= _from && t <= _to;
+}
+
+SubtitleImage::SubtitleImage (AVSubtitleRect const * rect)
+	: _position (rect->x, rect->y)
+	, _image (new SimpleImage (PIX_FMT_RGBA, Size (rect->w, rect->h)))
+{
+	if (rect->type != SUBTITLE_BITMAP) {
+		throw DecodeError ("non-bitmap subtitles not yet supported");
+	}
+
+	/* Start of the first line in the subtitle */
+	uint8_t* sub_p = rect->pict.data[0];
+	/* sub_p looks up into a RGB palette which is here */
+	uint32_t const * palette = (uint32_t *) rect->pict.data[1];
+	/* Start of the output data */
+	uint32_t* out_p = (uint32_t *) _image->data()[0];
+	
+	for (int y = 0; y < rect->h; ++y) {
+		uint8_t* sub_line_p = sub_p;
+		for (int x = 0; x < rect->w; ++x) {
+			*out_p++ = palette[*sub_line_p++];
+		}
+		sub_p += rect->pict.linesize[0];
+	}
+}
+
+Rectangle
+transformed_subtitle_area (
+	float target_x_scale, float target_y_scale,
+	Rectangle sub_area, int subtitle_offset, float subtitle_scale
+	)
+{
+	Rectangle tx;
+
+	sub_area.y += subtitle_offset;
+
+	/* We will scale the subtitle by the same amount as the video frame, and also by the additional
+	   subtitle_scale
+	*/
+	tx.w = sub_area.w * target_x_scale * subtitle_scale;
+	tx.h = sub_area.h * target_y_scale * subtitle_scale;
+
+	/* Then we need a corrective translation, consisting of two parts:
+	 *
+	 * 1.  that which is the result of the scaling of the subtitle by target_x_scale and target_y_scale; this will be
+	 *     sub_area.x * target_x_scale and sub_area.y * target_y_scale.
+	 *
+	 * 2.  that to shift the origin of the scale by subtitle_scale to the centre of the subtitle; this will be
+	 *     (width_before_subtitle_scale * (1 - subtitle_scale) / 2) and
+	 *     (height_before_subtitle_scale * (1 - subtitle_scale) / 2).
+	 *
+	 * Combining these two translations gives these expressions.
+	 */
+	
+	tx.x = target_x_scale * (sub_area.x + (sub_area.w * (1 - subtitle_scale) / 2));
+	tx.y = target_y_scale * (sub_area.y + (sub_area.h * (1 - subtitle_scale) / 2));
+
+	return tx;
+}
+
+Rectangle
+SubtitleImage::area () const
+{
+	return Rectangle (_position.x, _position.y, _image->size().width, _image->size().height);
+}