Add a mechanism for selective style overrides

This adds 2 new API functions:

  ass_set_selective_style_override()
  ass_set_selective_style_override_enabled()

They can be used to force dialog text to use a specific ASS_Style. It
uses a fuzzy heuristic for that, and the quality of results may vary.
It does style overriding selectively and tries not to override things
that need explicit styling. The heuristic for that isn't set in stone
either, and can change with future libass versions.

Closes libass#88.

1 files changed, 18 insertions, 0 deletions

diff --git a/libass/ass_render_api.c b/libass/ass_render_api.c
index b06fc80..072b693 100644
--- a/libass/ass_render_api.c
+++ b/libass/ass_render_api.c
@@ -151,6 +151,24 @@ void ass_set_fonts(ASS_Renderer *priv, const char *default_font,
                         default_font, fc, config, update);
 }
 
+void ass_set_selective_style_override_enabled(ASS_Renderer *priv, int enable)
+{
+    enable = !!enable;
+    if (priv->settings.selective_style_overrides != enable) {
+        priv->settings.selective_style_overrides = enable;
+        ass_reconfigure(priv);
+    }
+}
+
+void ass_set_selective_style_override(ASS_Renderer *priv, ASS_Style *style)
+{
+    ASS_Style *user_style = &priv->user_override_style;
+    free(user_style->FontName);
+    *user_style = *style;
+    user_style->FontName = strdup(user_style->FontName);
+    user_style->Name = "OverrideStyle"; // name insignificant
+}
+
 int ass_fonts_update(ASS_Renderer *render_priv)
 {
     return fontconfig_update(render_priv->fontconfig_priv);