1 files changed, 171 insertions, 0 deletions
diff --git a/gfx/harfbuzz/src/OT/Layout/GPOS/GPOS.hh b/gfx/harfbuzz/src/OT/Layout/GPOS/GPOS.hh
new file mode 100644
index 0000000000..9493ec987e
--- /dev/null
+++ b/gfx/harfbuzz/src/OT/Layout/GPOS/GPOS.hh
@@ -0,0 +1,171 @@
+#ifndef OT_LAYOUT_GPOS_GPOS_HH
+#define OT_LAYOUT_GPOS_GPOS_HH
+
+#include "../../../hb-ot-layout-common.hh"
+#include "../../../hb-ot-layout-gsubgpos.hh"
+#include "Common.hh"
+#include "PosLookup.hh"
+
+namespace OT {
+
+using Layout::GPOS_impl::PosLookup;
+
+namespace Layout {
+
+static void
+propagate_attachment_offsets (hb_glyph_position_t *pos,
+                              unsigned int len,
+                              unsigned int i,
+                              hb_direction_t direction,
+                              unsigned nesting_level = HB_MAX_NESTING_LEVEL);
+
+/*
+ * GPOS -- Glyph Positioning
+ * https://docs.microsoft.com/en-us/typography/opentype/spec/gpos
+ */
+
+struct GPOS : GSUBGPOS
+{
+  static constexpr hb_tag_t tableTag = HB_OT_TAG_GPOS;
+
+  using Lookup = PosLookup;
+
+  const PosLookup& get_lookup (unsigned int i) const
+  { return static_cast<const PosLookup &> (GSUBGPOS::get_lookup (i)); }
+
+  static inline void position_start (hb_font_t *font, hb_buffer_t *buffer);
+  static inline void position_finish_advances (hb_font_t *font, hb_buffer_t *buffer);
+  static inline void position_finish_offsets (hb_font_t *font, hb_buffer_t *buffer);
+
+  bool subset (hb_subset_context_t *c) const
+  {
+    hb_subset_layout_context_t l (c, tableTag);
+    return GSUBGPOS::subset<PosLookup> (&l);
+  }
+
+  bool sanitize (hb_sanitize_context_t *c) const
+  {
+    TRACE_SANITIZE (this);
+    return_trace (GSUBGPOS::sanitize<PosLookup> (c));
+  }
+
+  HB_INTERNAL bool is_blocklisted (hb_blob_t *blob,
+                                   hb_face_t *face) const;
+
+  void collect_variation_indices (hb_collect_variation_indices_context_t *c) const
+  {
+    for (unsigned i = 0; i < GSUBGPOS::get_lookup_count (); i++)
+    {
+      if (!c->gpos_lookups->has (i)) continue;
+      const PosLookup &l = get_lookup (i);
+      l.dispatch (c);
+    }
+  }
+
+  void closure_lookups (hb_face_t      *face,
+                        const hb_set_t *glyphs,
+                        hb_set_t       *lookup_indexes /* IN/OUT */) const
+  { GSUBGPOS::closure_lookups<PosLookup> (face, glyphs, lookup_indexes); }
+
+  typedef GSUBGPOS::accelerator_t<GPOS> accelerator_t;
+};
+
+
+static void
+propagate_attachment_offsets (hb_glyph_position_t *pos,
+                              unsigned int len,
+                              unsigned int i,
+                              hb_direction_t direction,
+                              unsigned nesting_level)
+{
+  /* Adjusts offsets of attached glyphs (both cursive and mark) to accumulate
+   * offset of glyph they are attached to. */
+  int chain = pos[i].attach_chain(), type = pos[i].attach_type();
+  if (likely (!chain))
+    return;
+
+  pos[i].attach_chain() = 0;
+
+  unsigned int j = (int) i + chain;
+
+  if (unlikely (j >= len))
+    return;
+
+  if (unlikely (!nesting_level))
+    return;
+
+  propagate_attachment_offsets (pos, len, j, direction, nesting_level - 1);
+
+  assert (!!(type & GPOS_impl::ATTACH_TYPE_MARK) ^ !!(type & GPOS_impl::ATTACH_TYPE_CURSIVE));
+
+  if (type & GPOS_impl::ATTACH_TYPE_CURSIVE)
+  {
+    if (HB_DIRECTION_IS_HORIZONTAL (direction))
+      pos[i].y_offset += pos[j].y_offset;
+    else
+      pos[i].x_offset += pos[j].x_offset;
+  }
+  else /*if (type & GPOS_impl::ATTACH_TYPE_MARK)*/
+  {
+    pos[i].x_offset += pos[j].x_offset;
+    pos[i].y_offset += pos[j].y_offset;
+
+    assert (j < i);
+    if (HB_DIRECTION_IS_FORWARD (direction))
+      for (unsigned int k = j; k < i; k++) {
+        pos[i].x_offset -= pos[k].x_advance;
+        pos[i].y_offset -= pos[k].y_advance;
+      }
+    else
+      for (unsigned int k = j + 1; k < i + 1; k++) {
+        pos[i].x_offset += pos[k].x_advance;
+        pos[i].y_offset += pos[k].y_advance;
+      }
+  }
+}
+
+void
+GPOS::position_start (hb_font_t *font HB_UNUSED, hb_buffer_t *buffer)
+{
+  unsigned int count = buffer->len;
+  for (unsigned int i = 0; i < count; i++)
+    buffer->pos[i].attach_chain() = buffer->pos[i].attach_type() = 0;
+}
+
+void
+GPOS::position_finish_advances (hb_font_t *font HB_UNUSED, hb_buffer_t *buffer HB_UNUSED)
+{
+  //_hb_buffer_assert_gsubgpos_vars (buffer);
+}
+
+void
+GPOS::position_finish_offsets (hb_font_t *font, hb_buffer_t *buffer)
+{
+  _hb_buffer_assert_gsubgpos_vars (buffer);
+
+  unsigned int len;
+  hb_glyph_position_t *pos = hb_buffer_get_glyph_positions (buffer, &len);
+  hb_direction_t direction = buffer->props.direction;
+
+  /* Handle attachments */
+  if (buffer->scratch_flags & HB_BUFFER_SCRATCH_FLAG_HAS_GPOS_ATTACHMENT)
+    for (unsigned i = 0; i < len; i++)
+      propagate_attachment_offsets (pos, len, i, direction);
+
+  if (unlikely (font->slant))
+  {
+    for (unsigned i = 0; i < len; i++)
+      if (unlikely (pos[i].y_offset))
+        pos[i].x_offset += _hb_roundf (font->slant_xy * pos[i].y_offset);
+  }
+}
+
+}
+
+struct GPOS_accelerator_t : Layout::GPOS::accelerator_t {
+  GPOS_accelerator_t (hb_face_t *face) : Layout::GPOS::accelerator_t (face) {}
+};
+
+}
+
+#endif  /* OT_LAYOUT_GPOS_GPOS_HH */