+ int layout_width;
+ int layout_height;
+ layout->get_pixel_size (layout_width, layout_height);
+ layout_width *= xscale;
+ layout_height *= yscale;
+
+ int x = 0;
+ switch (subtitles.front().h_align ()) {
+ case dcp::HALIGN_LEFT:
+ /* h_position is distance between left of frame and left of subtitle */
+ x = subtitles.front().h_position() * target.width;
+ break;
+ case dcp::HALIGN_CENTER:
+ /* h_position is distance between centre of frame and centre of subtitle */
+ x = (0.5 + subtitles.front().h_position()) * target.width - layout_width / 2;
+ break;
+ case dcp::HALIGN_RIGHT:
+ /* h_position is distance between right of frame and right of subtitle */
+ x = (1.0 - subtitles.front().h_position()) * target.width - layout_width;
+ break;
+ }
+
+ int y = 0;
+ switch (subtitles.front().v_align ()) {
+ case dcp::VALIGN_TOP:
+ /* SMPTE says that v_position is the distance between top
+ of frame and top of subtitle, but this doesn't always seem to be
+ the case in practice; Gunnar Ásgeirsson's Dolby server appears
+ to put VALIGN_TOP subs with v_position as the distance between top
+ of frame and bottom of subtitle.
+ */
+ y = subtitles.front().v_position() * target.height - layout_height;
+ break;
+ case dcp::VALIGN_CENTER:
+ /* v_position is distance between centre of frame and centre of subtitle */
+ y = (0.5 + subtitles.front().v_position()) * target.height - layout_height / 2;
+ break;
+ case dcp::VALIGN_BOTTOM:
+ /* v_position is distance between bottom of frame and bottom of subtitle */
+ y = (1.0 - subtitles.front().v_position()) * target.height - layout_height;
+ break;
+ }
+
+ return PositionImage (image, Position<int> (max (0, x), max (0, y)));