+ return fade_factor;
+}
+
+
+static int
+x_position (StringText const& first, int target_width, int layout_width)
+{
+ int x = 0;
+ switch (first.h_align ()) {
+ case dcp::HAlign::LEFT:
+ /* h_position is distance between left of frame and left of subtitle */
+ x = first.h_position() * target_width;
+ break;
+ case dcp::HAlign::CENTER:
+ /* h_position is distance between centre of frame and centre of subtitle */
+ x = (0.5 + first.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 - first.h_position()) * target_width - layout_width;
+ break;
+ }
+
+ return x;
+}
+
+
+
+static int
+y_position (StringText const& first, int target_height, int layout_height)
+{
+ int y = 0;
+ switch (first.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 = first.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 + first.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 - first.v_position()) * target_height - layout_height;
+ break;
+ }
+
+ return y;
+}
+