Add option to buffer serialization to not output glyph advances

When advances are not printed, glyph offsets reflect absolute glyph
positions.

New API:
HB_BUFFER_SERIALIZE_FLAG_NO_ADVANCES
hb-shape --no-advances

5 files changed, 38 insertions, 11 deletions

diff --git a/src/hb-buffer-serialize.cc b/src/hb-buffer-serialize.cc
index ea62e9ff..6a19c43c 100644
--- a/src/hb-buffer-serialize.cc
+++ b/src/hb-buffer-serialize.cc
@@ -109,6 +109,7 @@ _hb_buffer_serialize_glyphs_json (hb_buffer_t *buffer,
 			     nullptr : hb_buffer_get_glyph_positions (buffer, nullptr);
 
   *buf_consumed = 0;
+  hb_position_t x = 0, y = 0;
   for (unsigned int i = start; i < end; i++)
   {
     char b[1024];
@@ -146,9 +147,10 @@ _hb_buffer_serialize_glyphs_json (hb_buffer_t *buffer,
     if (!(flags & HB_BUFFER_SERIALIZE_FLAG_NO_POSITIONS))
     {
       p += MAX (0, snprintf (p, ARRAY_LENGTH (b) - (p - b), ",\"dx\":%d,\"dy\":%d",
-			     pos[i].x_offset, pos[i].y_offset));
-      p += MAX (0, snprintf (p, ARRAY_LENGTH (b) - (p - b), ",\"ax\":%d,\"ay\":%d",
-			     pos[i].x_advance, pos[i].y_advance));
+			     x+pos[i].x_offset, y+pos[i].y_offset));
+      if (!(flags & HB_BUFFER_SERIALIZE_FLAG_NO_ADVANCES))
+	p += MAX (0, snprintf (p, ARRAY_LENGTH (b) - (p - b), ",\"ax\":%d,\"ay\":%d",
+			       pos[i].x_advance, pos[i].y_advance));
     }
 
     if (flags & HB_BUFFER_SERIALIZE_FLAG_GLYPH_FLAGS)
@@ -179,6 +181,12 @@ _hb_buffer_serialize_glyphs_json (hb_buffer_t *buffer,
       *buf = '\0';
     } else
       return i - start;
+
+    if (flags & HB_BUFFER_SERIALIZE_FLAG_NO_ADVANCES)
+    {
+      x += pos[i].x_advance;
+      y += pos[i].y_advance;
+    }
   }
 
   return end - start;
@@ -199,6 +207,7 @@ _hb_buffer_serialize_glyphs_text (hb_buffer_t *buffer,
 			     nullptr : hb_buffer_get_glyph_positions (buffer, nullptr);
 
   *buf_consumed = 0;
+  hb_position_t x = 0, y = 0;
   for (unsigned int i = start; i < end; i++)
   {
     char b[1024];
@@ -223,13 +232,16 @@ _hb_buffer_serialize_glyphs_text (hb_buffer_t *buffer,
 
     if (!(flags & HB_BUFFER_SERIALIZE_FLAG_NO_POSITIONS))
     {
-      if (pos[i].x_offset || pos[i].y_offset)
-	p += MAX (0, snprintf (p, ARRAY_LENGTH (b) - (p - b), "@%d,%d", pos[i].x_offset, pos[i].y_offset));
-
-      *p++ = '+';
-      p += MAX (0, snprintf (p, ARRAY_LENGTH (b) - (p - b), "%d", pos[i].x_advance));
-      if (pos[i].y_advance)
-	p += MAX (0, snprintf (p, ARRAY_LENGTH (b) - (p - b), ",%d", pos[i].y_advance));
+      if (x+pos[i].x_offset || y+pos[i].y_offset)
+	p += MAX (0, snprintf (p, ARRAY_LENGTH (b) - (p - b), "@%d,%d", x+pos[i].x_offset, y+pos[i].y_offset));
+
+      if (!(flags & HB_BUFFER_SERIALIZE_FLAG_NO_ADVANCES))
+      {
+	*p++ = '+';
+	p += MAX (0, snprintf (p, ARRAY_LENGTH (b) - (p - b), "%d", pos[i].x_advance));
+	if (pos[i].y_advance)
+	  p += MAX (0, snprintf (p, ARRAY_LENGTH (b) - (p - b), ",%d", pos[i].y_advance));
+      }
     }
 
     if (flags & HB_BUFFER_SERIALIZE_FLAG_GLYPH_FLAGS)
@@ -255,6 +267,12 @@ _hb_buffer_serialize_glyphs_text (hb_buffer_t *buffer,
       *buf = '\0';
     } else
       return i - start;
+
+    if (flags & HB_BUFFER_SERIALIZE_FLAG_NO_ADVANCES)
+    {
+      x += pos[i].x_advance;
+      y += pos[i].y_advance;
+    }
   }
 
   return end - start;
diff --git a/src/hb-buffer.h b/src/hb-buffer.h
index a8a4b84e..1341be52 100644
--- a/src/hb-buffer.h
+++ b/src/hb-buffer.h
@@ -412,6 +412,8 @@ hb_buffer_normalize_glyphs (hb_buffer_t *buffer);
  * @HB_BUFFER_SERIALIZE_FLAG_NO_POSITIONS: do not serialize glyph position information.
  * @HB_BUFFER_SERIALIZE_FLAG_NO_GLYPH_NAMES: do no serialize glyph name.
  * @HB_BUFFER_SERIALIZE_FLAG_GLYPH_EXTENTS: serialize glyph extents.
+ * @HB_BUFFER_SERIALIZE_FLAG_GLYPH_FLAGS: serialize glyph flags. Since: 1.5.0
+ * @HB_BUFFER_SERIALIZE_FLAG_NO_ADVANCES: do not serialize glyph advances. Since: 1.8.0
  *
  * Flags that control what glyph information are serialized in hb_buffer_serialize_glyphs().
  *
@@ -423,7 +425,8 @@ typedef enum { /*< flags >*/
   HB_BUFFER_SERIALIZE_FLAG_NO_POSITIONS		= 0x00000002u,
   HB_BUFFER_SERIALIZE_FLAG_NO_GLYPH_NAMES	= 0x00000004u,
   HB_BUFFER_SERIALIZE_FLAG_GLYPH_EXTENTS	= 0x00000008u,
-  HB_BUFFER_SERIALIZE_FLAG_GLYPH_FLAGS		= 0x00000010u
+  HB_BUFFER_SERIALIZE_FLAG_GLYPH_FLAGS		= 0x00000010u,
+  HB_BUFFER_SERIALIZE_FLAG_NO_ADVANCES		= 0x00000020u
 } hb_buffer_serialize_flags_t;
 
 /**
diff --git a/util/hb-shape.cc b/util/hb-shape.cc
index dc9f446b..337cd431 100644
--- a/util/hb-shape.cc
+++ b/util/hb-shape.cc
@@ -72,6 +72,8 @@ struct output_buffer_t
       flags |= HB_BUFFER_SERIALIZE_FLAG_NO_CLUSTERS;
     if (!format.show_positions)
       flags |= HB_BUFFER_SERIALIZE_FLAG_NO_POSITIONS;
+    if (!format.show_advances)
+      flags |= HB_BUFFER_SERIALIZE_FLAG_NO_ADVANCES;
     if (format.show_extents)
       flags |= HB_BUFFER_SERIALIZE_FLAG_GLYPH_EXTENTS;
     if (format.show_flags)
diff --git a/util/options.cc b/util/options.cc
index 5434b156..dc95b71f 100644
--- a/util/options.cc
+++ b/util/options.cc
@@ -844,6 +844,8 @@ format_options_t::add_options (option_parser_t *parser)
 			      G_OPTION_ARG_NONE,	&this->show_glyph_names,	"Output glyph indices instead of names",				nullptr},
     {"no-positions",	0, G_OPTION_FLAG_REVERSE,
 			      G_OPTION_ARG_NONE,	&this->show_positions,		"Do not output glyph positions",					nullptr},
+    {"no-advances",	0, G_OPTION_FLAG_REVERSE,
+			      G_OPTION_ARG_NONE,	&this->show_advances,		"Do not output glyph advances",						nullptr},
     {"no-clusters",	0, G_OPTION_FLAG_REVERSE,
 			      G_OPTION_ARG_NONE,	&this->show_clusters,		"Do not output cluster indices",					nullptr},
     {"show-extents",	0, 0, G_OPTION_ARG_NONE,	&this->show_extents,		"Output glyph extents",							nullptr},
diff --git a/util/options.hh b/util/options.hh
index 4f9d85e5..103cd0d7 100644
--- a/util/options.hh
+++ b/util/options.hh
@@ -584,6 +584,7 @@ struct format_options_t : option_group_t
   format_options_t (option_parser_t *parser) {
     show_glyph_names = true;
     show_positions = true;
+    show_advances = true;
     show_clusters = true;
     show_text = false;
     show_unicode = false;
@@ -628,6 +629,7 @@ struct format_options_t : option_group_t
 
   hb_bool_t show_glyph_names;
   hb_bool_t show_positions;
+  hb_bool_t show_advances;
   hb_bool_t show_clusters;
   hb_bool_t show_text;
   hb_bool_t show_unicode;