parse: replace mult_alpha and change_alpha exports

They are both used only once outside of ass_parse.c
to apply fade, so instead export one function handling
VSFilter-compatible fade application.

3 files changed, 11 insertions, 8 deletions

diff --git a/libass/ass_parse.c b/libass/ass_parse.c
index db25879..242fa4c 100644
--- a/libass/ass_parse.c
+++ b/libass/ass_parse.c
@@ -153,7 +153,7 @@ static void change_color(uint32_t *var, uint32_t new, double pwr)
 }
 
 // like change_color, but for alpha component only
-inline void change_alpha(uint32_t *var, int32_t new, double pwr)
+static inline void change_alpha(uint32_t *var, int32_t new, double pwr)
 {
     *var = (*var & 0xFFFFFF00) | (uint8_t)calc_anim_int32(new, _a(*var), pwr);
 }
@@ -166,11 +166,18 @@ inline void change_alpha(uint32_t *var, int32_t new, double pwr)
  * At least one of the parameters must be less than or equal to 0xFF.
  * The result is less than or equal to max(a, b, 0xFF).
  */
-inline uint32_t mult_alpha(uint32_t a, uint32_t b)
+static inline uint32_t mult_alpha(uint32_t a, uint32_t b)
 {
     return a - ((uint64_t) a * b + 0x7F) / 0xFF + b;
 }
 
+void ass_apply_fade(uint32_t *clr, int fade)
+{
+    // VSFilter compatibility: apply fade only when it's positive
+    if (fade > 0)
+        change_alpha(clr, mult_alpha(_a(*clr), fade), 1);
+}
+
 /**
  * \brief Calculate alpha value by piecewise linear function
  * Used for \fad, \fade implementation.
diff --git a/libass/ass_parse.h b/libass/ass_parse.h
index 03d40a0..6c96e41 100644
--- a/libass/ass_parse.h
+++ b/libass/ass_parse.h
@@ -33,8 +33,7 @@ unsigned get_next_char(ASS_Renderer *render_priv, char **str);
 char *parse_tags(ASS_Renderer *render_priv, char *p, char *end, double pwr,
                  bool nested);
 int event_has_hard_overrides(char *str);
-extern void change_alpha(uint32_t *var, int32_t new, double pwr);
-extern uint32_t mult_alpha(uint32_t a, uint32_t b);
+void ass_apply_fade(uint32_t *clr, int fade);
 
 
 #endif /* LIBASS_PARSE_H */
diff --git a/libass/ass_render.c b/libass/ass_render.c
index dedd2a7..6253ecc 100644
--- a/libass/ass_render.c
+++ b/libass/ass_render.c
@@ -2103,11 +2103,8 @@ static bool parse_events(ASS_Renderer *render_priv, ASS_Event *event)
             ass_cache_inc_ref(info->font);
         for (int i = 0; i < 4; i++) {
             uint32_t clr = render_priv->state.c[i];
-            // VSFilter compatibility: apply fade only when it's positive
             info->a_pre_fade[i] = _a(clr);
-            if (render_priv->state.fade > 0)
-                change_alpha(&clr,
-                             mult_alpha(_a(clr), render_priv->state.fade), 1.);
+            ass_apply_fade(&clr, render_priv->state.fade);
             info->c[i] = clr;
         }