+ span += "alpha=\"" + dcp::raw_convert<string>(int(floor(fade_factor * 65534)) + 1) + "\" ";
+ span += "color=\"#" + subtitle.colour().to_rgb_string() + "\"";
+ if (!extra_attribute.empty()) {
+ span += " " + extra_attribute;
+ }
+ span += ">";
+ span += text;
+ span += "</span>";
+ return span;
+ };
+
+ string out;
+ for (auto const& i: subtitles) {
+ if (std::abs(i.space_before()) > dcp::SPACE_BEFORE_EPSILON) {
+ /* We need to insert some horizontal space into the layout. The only way I can find to do this
+ * is to write a " " with some special letter_spacing. As far as I can see, such a space will
+ * be written with letter_spacing either side. This means that to get a horizontal space x we
+ * need to write a " " with letter spacing (x - s) / 2, where s is the width of the " ".
+ */
+ auto layout = create_layout();
+ setup_layout(layout, font_name, make_span(i, " ", {}));
+ int space_width;
+ int dummy;
+ layout->get_pixel_size(space_width, dummy);
+ auto spacing = ((i.space_before() * i.size_in_pixels(target_height) - space_width) / 2) * pixels_to_1024ths_point;
+ out += make_span(i, " ", "letter_spacing=\"" + dcp::raw_convert<string>(spacing) + "\"");
+ }
+
+ out += make_span(i, i.text(), {});