(More) properly support MarginV in SSA/ASS.

[libsub.git] / src / ssa_reader.cc

diff --git a/src/ssa_reader.cc b/src/ssa_reader.cc
index 03798034b3cdfe0435c7a54382d78bcea894d23e..03d20dd53f1c2f055e624497f431c41acb697b6b 100644 (file)
--- a/src/ssa_reader.cc
+++ b/src/ssa_reader.cc
@@ -274,9 +274,12 @@ SSAReader::parse_line (RawSubtitle base, string line, int play_res_x, int play_r
                current.vertical_position.reference = BOTTOM_OF_SCREEN;
        }
 
-       if (!current.vertical_position.proportional) {
-               current.vertical_position.proportional = 0;
-       }
+       /* Any vertical_position that is set in base (and therefore current) is a margin, which
+        * we need to ignore if we end up vertically centering this subtitle.
+        * Clear out vertical_position from current; we'll re-add it from base later
+        * if required.
+        */
+       current.vertical_position.proportional = 0;
 
        /* We must have a font size, as there could be a margin specified
           in pixels and in that case we must know how big the subtitle
@@ -299,20 +302,6 @@ SSAReader::parse_line (RawSubtitle base, string line, int play_res_x, int play_r
        /* Imagine that the screen is 792 points (i.e. 11 inches) high (as with DCP) */
        double const line_size = current.font_size.proportional(792) * 1.2;
 
-       /* Tweak vertical_position accordingly */
-       switch (current.vertical_position.reference.get()) {
-       case TOP_OF_SCREEN:
-       case TOP_OF_SUBTITLE:
-               /* Nothing to do */
-               break;
-       case VERTICAL_CENTRE_OF_SCREEN:
-               current.vertical_position.proportional = current.vertical_position.proportional.get() - ((line_breaks + 1) * line_size) / 2;
-               break;
-       case BOTTOM_OF_SCREEN:
-               current.vertical_position.proportional = current.vertical_position.proportional.get() + line_breaks * line_size;
-               break;
-       }
-
        for (size_t i = 0; i < line.length(); ++i) {
                char const c = line[i];
                switch (state) {
@@ -363,6 +352,28 @@ SSAReader::parse_line (RawSubtitle base, string line, int play_res_x, int play_r
                subs.push_back (current);
        }
 
+       /* Now we definitely know the vertical position reference we can finish off the position */
+       for (auto& sub: subs) {
+               switch (sub.vertical_position.reference.get()) {
+               case TOP_OF_SCREEN:
+               case TOP_OF_SUBTITLE:
+                       /* Just re-add any margins we came in with */
+                       sub.vertical_position.proportional = sub.vertical_position.proportional.get() + base.vertical_position.proportional.get_value_or(0);
+                       break;
+               case VERTICAL_CENTRE_OF_SCREEN:
+                       /* Margins are ignored, but we need to centre */
+                       sub.vertical_position.proportional = sub.vertical_position.proportional.get() - ((line_breaks + 1) * line_size) / 2;
+                       break;
+               case BOTTOM_OF_SCREEN:
+                       /* Re-add margins and account for each line */
+                       sub.vertical_position.proportional =
+                               sub.vertical_position.proportional.get()
+                               + base.vertical_position.proportional.get_value_or(0)
+                               + line_breaks * line_size;
+                       break;
+               }
+       }
+
        return subs;
 }
 
@@ -477,9 +488,14 @@ SSAReader::read (function<optional<string> ()> get_line)
                                                sub.effect = style.effect;
                                                sub.horizontal_position.reference = style.horizontal_reference;
                                                sub.vertical_position.reference = style.vertical_reference;
-                                               sub.vertical_position.proportional = float(style.vertical_margin) / play_res_y;
+                                               if (sub.vertical_position.reference != sub::VERTICAL_CENTRE_OF_SCREEN) {
+                                                       sub.vertical_position.proportional = float(style.vertical_margin) / play_res_y;
+                                               }
                                        } else if (event_format[i] == "MarginV") {
-                                               sub.vertical_position.proportional = raw_convert<float>(event[i]) / play_res_y;
+                                               if (event[i] != "0" && sub.vertical_position.reference != sub::VERTICAL_CENTRE_OF_SCREEN) {
+                                                       /* Override the style if its non-zero */
+                                                       sub.vertical_position.proportional = raw_convert<float>(event[i]) / play_res_y;
+                                               }
                                        } else if (event_format[i] == "Text") {
                                                for (auto j: parse_line (sub, event[i], play_res_x, play_res_y)) {
                                                        _subs.push_back (j);