Reduce number of glyph copies

Do not copy glyphs when it isn't really needed.
Profiling with valgrind's callgrind showed that FT_Glyph_Copy takes a
big fraction of the rendering time (~40%) for "simple styled softsubs"
cases. It turned out that glyphs are duplicated much more often than
is necessary. Reducing the number of copies cuts down the rendering
time for the "simple styled softsubs" case by about 70%!

diff --git a/libass/ass_render.c b/libass/ass_render.c
index 89a1365d561086d6e5ea7f5826a3de9416632cc6..6596e888f1ad45c0f52415a5adc1e1822f699e1b 100644 (file)
--- a/libass/ass_render.c
+++ b/libass/ass_render.c
@@ -1040,9 +1040,9 @@ get_outline_glyph(ASS_Renderer *render_priv, int symbol, GlyphInfo *info,
 
     val = cache_find_glyph(render_priv->cache.glyph_cache, &key);
     if (val) {
-        FT_Glyph_Copy(val->glyph, &info->glyph);
+        info->glyph = val->glyph;
         if (val->outline_glyph)
-            FT_Glyph_Copy(val->outline_glyph, &info->outline_glyph);
+            info->outline_glyph = val->outline_glyph;
         info->bbox = val->bbox_scaled;
         info->advance.x = val->advance.x;
         info->advance.y = val->advance.y;
@@ -1055,7 +1055,7 @@ get_outline_glyph(ASS_Renderer *render_priv, int symbol, GlyphInfo *info,
         if (drawing->hash) {
             if(!ass_drawing_parse(drawing, 0))
                 return;
-            FT_Glyph_Copy((FT_Glyph) drawing->glyph, &info->glyph);
+            info->glyph = (FT_Glyph) drawing->glyph;
         } else {
             info->glyph =
                 ass_font_get_glyph(render_priv->fontconfig_priv,
@@ -1092,9 +1092,9 @@ get_outline_glyph(ASS_Renderer *render_priv, int symbol, GlyphInfo *info,
         }
 
         memset(&v, 0, sizeof(v));
-        FT_Glyph_Copy(info->glyph, &v.glyph);
+        v.glyph = info->glyph;
         if (info->outline_glyph)
-            FT_Glyph_Copy(info->outline_glyph, &v.outline_glyph);
+            v.outline_glyph = info->outline_glyph;
         v.advance = info->advance;
         v.bbox_scaled = info->bbox;
         if (drawing->hash) {
@@ -1138,6 +1138,10 @@ get_bitmap_glyph(ASS_Renderer *render_priv, GlyphInfo *info)
         info->bm = info->bm_o = info->bm_s = 0;
         if (info->glyph && info->symbol != '\n' && info->symbol != 0
             && !info->skip) {
+            FT_Glyph glyph = info->glyph;
+            FT_Glyph outline = info->outline_glyph;
+            FT_Glyph_Copy(info->glyph, &glyph);
+            FT_Glyph_Copy(info->outline_glyph, &outline);
             // calculating rotation shift vector (from rotation origin to the glyph basepoint)
             shift.x = info->hash_key.shift_x;
             shift.y = info->hash_key.shift_y;
@@ -1145,26 +1149,26 @@ get_bitmap_glyph(ASS_Renderer *render_priv, GlyphInfo *info)
                          render_priv->state.scale_x;
             fay_scaled = info->fay * render_priv->state.scale_y;
             // apply rotation
-            transform_3d(shift, &info->glyph, &info->outline_glyph,
+            transform_3d(shift, &glyph, &outline,
                          info->frx, info->fry, info->frz, fax_scaled,
                          fay_scaled, render_priv->font_scale, info->asc);
 
             // subpixel shift
-            if (info->glyph)
+            if (glyph)
                 FT_Outline_Translate(
-                    &((FT_OutlineGlyph) info->glyph)->outline,
+                    &((FT_OutlineGlyph) glyph)->outline,
                     info->hash_key.advance.x,
                     -info->hash_key.advance.y);
-            if (info->outline_glyph)
+            if (outline)
                 FT_Outline_Translate(
-                    &((FT_OutlineGlyph) info->outline_glyph)->outline,
+                    &((FT_OutlineGlyph) outline)->outline,
                     info->hash_key.advance.x,
                     -info->hash_key.advance.y);
 
             // render glyph
             error = glyph_to_bitmap(render_priv->library,
                                     render_priv->synth_priv,
-                                    info->glyph, info->outline_glyph,
+                                    glyph, outline,
                                     &info->bm, &info->bm_o,
                                     &info->bm_s, info->be,
                                     info->blur * render_priv->border_scale,
@@ -1179,13 +1183,11 @@ get_bitmap_glyph(ASS_Renderer *render_priv, GlyphInfo *info)
             hash_val.bm_s = info->bm_s;
             cache_add_bitmap(render_priv->cache.bitmap_cache,
                              &(info->hash_key), &hash_val);
+
+            FT_Done_Glyph(glyph);
+            FT_Done_Glyph(outline);
         }
     }
-    // deallocate glyphs
-    if (info->glyph)
-        FT_Done_Glyph(info->glyph);
-    if (info->outline_glyph)
-        FT_Done_Glyph(info->outline_glyph);
 }
 
 /**