Runtime shaper selection

Add an API call, ass_set_shaper, and infrastructure to make shapers
selectable at runtime. Currently, this allows to switch between two
shapers: a SIMPLE shaper that maps to FriBidi and a COMPLEX shaper that
maps to HarfBuzz.

1 files changed, 20 insertions, 0 deletions

diff --git a/libass/ass.h b/libass/ass.h
index 57faf7d..4986437 100644
--- a/libass/ass.h
+++ b/libass/ass.h
@@ -61,6 +61,19 @@ typedef enum {
 } ASS_Hinting;
 
 /**
+ * \brief Text shaping levels.
+ *
+ * SIMPLE is a fast, font-agnostic shaper that can do only substitutions.
+ * COMPLEX is a slower shaper using OpenType for substitutions and positioning.
+ *
+ * libass uses the best shaper available by default.
+ */
+typedef enum {
+    ASS_SHAPING_SIMPLE = 0,
+    ASS_SHAPING_COMPLEX
+} ASS_ShapingLevel;
+
+/**
  * \brief Initialize the library.
  * \return library handle or NULL if failed
  */
@@ -147,6 +160,13 @@ void ass_renderer_done(ASS_Renderer *priv);
 void ass_set_frame_size(ASS_Renderer *priv, int w, int h);
 
 /**
+ * \brief Set shaping level. This is merely a hint, the renderer will use
+ * whatever is available if the request cannot be fulfilled.
+ * \param level shaping level
+ */
+void ass_set_shaper(ASS_Renderer *priv, ASS_ShapingLevel level);
+
+/**
  * \brief Set frame margins.  These values may be negative if pan-and-scan
  * is used.
  * \param priv renderer handle