[hb-ot-font] Make 'glyf' table loading lazy
Apparently some clients have reference-table callbacks that copy the table.
As such, avoid loading 'glyf' table which is only needed if fallback positioning
happens.
diff --git a/src/hb-ot-font.cc b/src/hb-ot-font.cc
index 23ac41a..8b62bb1 100644
--- a/src/hb-ot-font.cc
+++ b/src/hb-ot-font.cc
@@ -300,13 +300,54 @@
}
};
+template <typename T>
+struct hb_lazy_loader_t
+{
+ inline void init (hb_face_t *face_)
+ {
+ face = face_;
+ instance = NULL;
+ }
+
+ inline void fini (void)
+ {
+ if (instance && instance != &OT::Null(T))
+ {
+ instance->fini();
+ free (instance);
+ }
+ }
+
+ inline const T* operator-> (void) const
+ {
+ retry:
+ T *p = (T *) hb_atomic_ptr_get (&instance);
+ if (unlikely (!p))
+ {
+ p = (T *) calloc (1, sizeof (T));
+ if (unlikely (!p))
+ return &OT::Null(T);
+ p->init (face);
+ if (unlikely (!hb_atomic_ptr_cmpexch (const_cast<T **>(&instance), NULL, p)))
+ {
+ p->fini ();
+ goto retry;
+ }
+ }
+ return p;
+ }
+
+ private:
+ hb_face_t *face;
+ T *instance;
+};
struct hb_ot_font_t
{
hb_ot_face_cmap_accelerator_t cmap;
hb_ot_face_metrics_accelerator_t h_metrics;
hb_ot_face_metrics_accelerator_t v_metrics;
- hb_ot_face_glyf_accelerator_t glyf;
+ hb_lazy_loader_t<hb_ot_face_glyf_accelerator_t> glyf;
};
@@ -390,7 +431,7 @@
void *user_data HB_UNUSED)
{
const hb_ot_font_t *ot_font = (const hb_ot_font_t *) font_data;
- bool ret = ot_font->glyf.get_extents (glyph, extents);
+ bool ret = ot_font->glyf->get_extents (glyph, extents);
extents->x_bearing = font->em_scale_x (extents->x_bearing);
extents->y_bearing = font->em_scale_y (extents->y_bearing);
extents->width = font->em_scale_x (extents->width);
