refactor: move karaoke effect parsing into event parser

1 files changed, 71 insertions, 0 deletions

diff --git a/libass/ass_parse.c b/libass/ass_parse.c
index 55e8fd1..7a6dd25 100644
--- a/libass/ass_parse.c
+++ b/libass/ass_parse.c
@@ -890,6 +890,77 @@ void apply_transition_effects(ASS_Renderer *render_priv, ASS_Event *event)
 }
 
 /**
+ * \brief determine karaoke effects
+ * Karaoke effects cannot be calculated during parse stage (get_next_char()),
+ * so they are done in a separate step.
+ * Parse stage: when karaoke style override is found, its parameters are stored in the next glyph's
+ * (the first glyph of the karaoke word)'s effect_type and effect_timing.
+ * This function:
+ * 1. sets effect_type for all glyphs in the word (_karaoke_ word)
+ * 2. sets effect_timing for all glyphs to x coordinate of the border line between the left and right karaoke parts
+ * (left part is filled with PrimaryColour, right one - with SecondaryColour).
+ */
+void process_karaoke_effects(ASS_Renderer *render_priv)
+{
+    GlyphInfo *cur, *cur2;
+    GlyphInfo *s1, *e1;      // start and end of the current word
+    GlyphInfo *s2;           // start of the next word
+    int i;
+    int timing;                 // current timing
+    int tm_start, tm_end;       // timings at start and end of the current word
+    int tm_current;
+    double dt;
+    int x;
+    int x_start, x_end;
+
+    tm_current = render_priv->time - render_priv->state.event->Start;
+    timing = 0;
+    s1 = s2 = 0;
+    for (i = 0; i <= render_priv->text_info.length; ++i) {
+        cur = render_priv->text_info.glyphs + i;
+        if ((i == render_priv->text_info.length)
+            || (cur->effect_type != EF_NONE)) {
+            s1 = s2;
+            s2 = cur;
+            if (s1) {
+                e1 = s2 - 1;
+                tm_start = timing + s1->effect_skip_timing;
+                tm_end = tm_start + s1->effect_timing;
+                timing = tm_end;
+                x_start = 1000000;
+                x_end = -1000000;
+                for (cur2 = s1; cur2 <= e1; ++cur2) {
+                    x_start = FFMIN(x_start, d6_to_int(cur2->bbox.xMin + cur2->pos.x));
+                    x_end = FFMAX(x_end, d6_to_int(cur2->bbox.xMax + cur2->pos.x));
+                }
+
+                dt = (tm_current - tm_start);
+                if ((s1->effect_type == EF_KARAOKE)
+                    || (s1->effect_type == EF_KARAOKE_KO)) {
+                    if (dt > 0)
+                        x = x_end + 1;
+                    else
+                        x = x_start;
+                } else if (s1->effect_type == EF_KARAOKE_KF) {
+                    dt /= (tm_end - tm_start);
+                    x = x_start + (x_end - x_start) * dt;
+                } else {
+                    ass_msg(render_priv->library, MSGL_ERR,
+                            "Unknown effect type");
+                    continue;
+                }
+
+                for (cur2 = s1; cur2 <= e1; ++cur2) {
+                    cur2->effect_type = s1->effect_type;
+                    cur2->effect_timing = x - d6_to_int(cur2->pos.x);
+                }
+            }
+        }
+    }
+}
+
+
+/**
  * \brief Get next ucs4 char from string, parsing and executing style overrides
  * \param str string pointer
  * \return ucs4 code of the next char