[embolden] Add in-place option

Adds --font-grade to hb-view and hb-shape.

src/hb-font.cc

@@ -1774,8 +1774,9 @@ DEFINE_NULL_INSTANCE (hb_font_t) =
   1000, /* y_scale */
   0.f, /* x_embolden */
   0.f, /* y_embolden */
-  0, /* x_shift */
+  true, /* embolden_in_place */
-  0, /* y_shift */
+  0, /* x_strength */
+  0, /* y_strength */
   0.f, /* slant */
   0.f, /* slant_xy; */
   1.f, /* x_multf */
@@ -1815,6 +1816,7 @@ _hb_font_create (hb_face_t *face)
   font->klass = hb_font_funcs_get_empty ();
   font->data.init0 (font);
   font->x_scale = font->y_scale = face->get_upem ();
+  font->embolden_in_place = true;
   font->x_multf = font->y_multf = 1.f;
   font->x_mult = font->y_mult = 1 << 16;
   font->instance_index = HB_FONT_NO_VAR_NAMED_INSTANCE;
@@ -1901,6 +1903,7 @@ hb_font_create_sub_font (hb_font_t *parent)
   font->y_scale = parent->y_scale;
   font->x_embolden = parent->x_embolden;
   font->y_embolden = parent->y_embolden;
+  font->embolden_in_place = parent->embolden_in_place;
   font->slant = parent->slant;
   font->x_ppem = parent->x_ppem;
   font->y_ppem = parent->y_ppem;
@@ -2453,54 +2456,67 @@ hb_font_get_ptem (hb_font_t *font)
  * @font: #hb_font_t to work upon
  * @x_embolden: the amount to embolden horizontally
  * @y_embolden: the amount to embolden vertically
+ * @in_place: whether to embolden glyphs in-place
  *
  * Sets the "synthetic boldness" of a font.
  *
- * Positive values make a font bolder, negative values
+ * Positive values for @x_embolden / @y_embolden make a font
- * thinner. Typical values are in the 0.01 to 0.05 range.
+ * bolder, negative values thinner. Typical values are in the
- * The default value is zero.
+ * 0.01 to 0.05 range. The default value is zero.
  *
  * Synthetic boldness is applied by offsetting the contour
  * points of the glyph shape.
  *
- * HarfBuzz applies synthetic boldness when rendering a glyph
+ * Synthetic boldness is applied when rendering a glyph via
- * via hb_font_draw_glyph(), and also uses the values to adjust
+ * hb_font_draw_glyph().
- * the advance width of emboldened glyphs.
+ *
+ * If @in_place is %FALSE, then glyph advance-widths are also
+ * adjusted, otherwise they are not.
  *
  * Since: REPLACEME
  **/
 void
-hb_font_set_synthetic_bold (hb_font_t *font, float x_embolden, float y_embolden)
+hb_font_set_synthetic_bold (hb_font_t *font,
+			    float x_embolden,
+			    float y_embolden,
+			    hb_bool_t in_place)
 {
   if (hb_object_is_immutable (font))
     return;
 
   if (font->x_embolden == x_embolden &&
-      font->y_embolden == y_embolden)
+      font->y_embolden == y_embolden &&
+      font->embolden_in_place == in_place)
     return;
 
   font->serial++;
 
   font->x_embolden = x_embolden;
   font->y_embolden = y_embolden;
+  font->embolden_in_place = in_place;
   font->mults_changed ();
 }
 
 /**
  * hb_font_get_synthetic_bold:
  * @font: #hb_font_t to work upon
- * @x_embolden: return location for horizontal value
+ * @x_embolden: (out): return location for horizontal value
- * @y_embolden: return location for vertical value
+ * @y_embolden: (out): return location for vertical value
+ * @in_place: (out): return location for in-place value
  *
- * Fetches the "synthetic boldness" of a font.
+ * Fetches the "synthetic boldness" parameters of a font.
  *
  * Since: REPLACEME
  **/
 void
-hb_font_get_synthetic_bold (hb_font_t *font, float *x_embolden, float *y_embolden)
+hb_font_get_synthetic_bold (hb_font_t *font,
+			    float *x_embolden,
+			    float *y_embolden,
+			    hb_bool_t *in_place)
 {
   if (x_embolden) *x_embolden = font->x_embolden;
   if (y_embolden) *y_embolden = font->y_embolden;
+  if (in_place) *in_place = font->embolden_in_place;
 }
 
 /**

src/hb-font.h

@@ -1132,10 +1132,14 @@ HB_EXTERN float
 hb_font_get_ptem (hb_font_t *font);
 
 HB_EXTERN void
-hb_font_set_synthetic_bold (hb_font_t *font, float x_embolden, float y_embolden);
+hb_font_set_synthetic_bold (hb_font_t *font,
+			    float x_embolden, float y_embolden,
+			    hb_bool_t in_place);
 
 HB_EXTERN void
-hb_font_get_synthetic_bold (hb_font_t *font, float *x_embolden, float *y_embolden);
+hb_font_get_synthetic_bold (hb_font_t *font,
+			    float *x_embolden, float *y_embolden,
+			    hb_bool_t *in_place);
 
 HB_EXTERN void
 hb_font_set_synthetic_slant (hb_font_t *font, float slant);

src/hb-font.hh

@@ -116,8 +116,9 @@ struct hb_font_t
 
   float x_embolden;
   float y_embolden;
-  int32_t x_shift; /* x_embolden, in scaled units. */
+  bool embolden_in_place;
-  int32_t y_shift; /* y_embolden, in scaled units. */
+  int32_t x_strength; /* x_embolden, in scaled units. */
+  int32_t y_strength; /* y_embolden, in scaled units. */
 
   float slant;
   float slant_xy;
@@ -681,8 +682,8 @@ struct hb_font_t
     bool y_neg = y_scale < 0;
     y_mult = (y_neg ? -((int64_t) -y_scale << 16) : ((int64_t) y_scale << 16)) / upem;
 
-    x_shift = fabs (roundf (x_scale * x_embolden));
+    x_strength = fabs (roundf (x_scale * x_embolden));
-    y_shift = fabs (roundf (y_scale * y_embolden));
+    y_strength = fabs (roundf (y_scale * y_embolden));
 
     slant_xy = y_scale ? slant * x_scale / y_scale : 0.f;
 

src/hb-ft.cc

@@ -490,14 +490,14 @@ hb_ft_get_glyph_h_advances (hb_font_t* font, void* font_data,
     first_advance = &StructAtOffsetUnaligned<hb_position_t> (first_advance, advance_stride);
   }
 
-  if (font->x_shift)
+  if (font->x_strength && !font->embolden_in_place)
   {
     /* Emboldening. */
-    hb_position_t x_shift = font->x_scale >= 0 ? font->x_shift : -font->x_shift;
+    hb_position_t x_strength = font->x_scale >= 0 ? font->x_strength : -font->x_strength;
     first_advance = orig_first_advance;
     for (unsigned int i = 0; i < count; i++)
     {
-      *first_advance += *first_advance ? x_shift : 0;
+      *first_advance += *first_advance ? x_strength : 0;
       first_advance = &StructAtOffsetUnaligned<hb_position_t> (first_advance, advance_stride);
     }
   }
@@ -536,8 +536,8 @@ hb_ft_get_glyph_v_advance (hb_font_t *font,
   /* Note: FreeType's vertical metrics grows downward while other FreeType coordinates
    * have a Y growing upward.  Hence the extra negation. */
 
-  hb_position_t y_shift = font->y_scale >= 0 ? font->y_shift : -font->y_shift;
+  hb_position_t y_strength = font->y_scale >= 0 ? font->y_strength : -font->y_strength;
-  return ((-v + (1<<9)) >> 10) + y_shift;
+  return ((-v + (1<<9)) >> 10) + (font->embolden_in_place ? 0 : y_strength);
 }
 #endif
 
@@ -858,7 +858,38 @@ hb_ft_draw_glyph (hb_font_t *font,
 
   hb_draw_session_t draw_session (draw_funcs, draw_data, font->slant_xy);
 
-  FT_Outline_EmboldenXY (&ft_face->glyph->outline, font->x_shift, font->y_shift);
+  /* Embolden */
+  if (font->x_strength || font->y_strength)
+  {
+    FT_Outline_EmboldenXY (&ft_face->glyph->outline, font->x_strength, font->y_strength);
+
+    int x_shift = 0;
+    int y_shift = 0;
+    if (font->embolden_in_place)
+    {
+      /* Undo the FreeType shift. */
+      x_shift = -font->x_strength / 2;
+      y_shift = 0;
+      if (font->y_scale < 0) y_shift = -font->y_strength;
+    }
+    else
+    {
+      /* FreeType applied things in the wrong direction for negative scale; fix up. */
+      if (font->x_scale < 0) x_shift = -font->x_strength;
+      if (font->y_scale < 0) y_shift = -font->y_strength;
+    }
+    if (x_shift || y_shift)
+    {
+      auto &outline = ft_face->glyph->outline;
+      for (auto &point : hb_iter (outline.points, outline.contours[outline.n_contours - 1]))
+      {
+	point.x += x_shift;
+	point.y += y_shift;
+      }
+    }
+  }
+
+
   FT_Outline_Decompose (&ft_face->glyph->outline,
 			&outline_funcs,
 			&draw_session);

src/hb-ot-font.cc

@@ -262,14 +262,14 @@ hb_ot_get_glyph_h_advances (hb_font_t* font, void* font_data,
   OT::VariationStore::destroy_cache (varStore_cache);
 #endif
 
-  if (font->x_shift)
+  if (font->x_strength && !font->embolden_in_place)
   {
     /* Emboldening. */
-    hb_position_t x_shift = font->x_scale >= 0 ? font->x_shift : -font->x_shift;
+    hb_position_t x_strength = font->x_scale >= 0 ? font->x_strength : -font->x_strength;
     first_advance = orig_first_advance;
     for (unsigned int i = 0; i < count; i++)
     {
-      *first_advance += *first_advance ? x_shift : 0;
+      *first_advance += *first_advance ? x_strength : 0;
       first_advance = &StructAtOffsetUnaligned<hb_position_t> (first_advance, advance_stride);
     }
   }
@@ -326,14 +326,14 @@ hb_ot_get_glyph_v_advances (hb_font_t* font, void* font_data,
     }
   }
 
-  if (font->y_shift)
+  if (font->y_strength && !font->embolden_in_place)
   {
     /* Emboldening. */
-    hb_position_t y_shift = font->y_scale >= 0 ? font->y_shift : -font->y_shift;
+    hb_position_t y_strength = font->y_scale >= 0 ? font->y_strength : -font->y_strength;
     first_advance = orig_first_advance;
     for (unsigned int i = 0; i < count; i++)
     {
-      *first_advance += *first_advance ? y_shift : 0;
+      *first_advance += *first_advance ? y_strength : 0;
       first_advance = &StructAtOffsetUnaligned<hb_position_t> (first_advance, advance_stride);
     }
   }
@@ -492,7 +492,7 @@ hb_ot_draw_glyph (hb_font_t *font,
 		  hb_draw_funcs_t *draw_funcs, void *draw_data,
 		  void *user_data)
 {
-  bool embolden = font->x_shift || font->y_shift;
+  bool embolden = font->x_strength || font->y_strength;
   hb_outline_t outline;
 
   { // Need draw_session to be destructed before emboldening.
@@ -508,7 +508,13 @@ hb_ot_draw_glyph (hb_font_t *font,
 
   if (embolden)
   {
-    outline.embolden (font->x_shift, font->y_shift);
+    float x_shift = font->embolden_in_place ? 0 : font->x_strength / 2;
+    float y_shift = font->y_strength / 2;
+    if (font->x_scale < 0) x_shift = -x_shift;
+    if (font->y_scale < 0) y_shift = -y_shift;
+    outline.embolden (font->x_strength, font->y_strength,
+		      x_shift, y_shift);
+
     outline.replay (draw_funcs, draw_data);
   }
 }

src/hb-outline.cc

@@ -105,7 +105,8 @@ float hb_outline_t::area () const
   return a * .5f;
 }
 
-void hb_outline_t::embolden (float x_strength, float y_strength)
+void hb_outline_t::embolden (float x_strength, float y_strength,
+			     float x_shift, float y_shift)
 {
   /* This function is a straight port of FreeType's FT_Outline_EmboldenXY.
    * Permission has been obtained from the FreeType authors of the code
@@ -203,8 +204,8 @@ void hb_outline_t::embolden (float x_strength, float y_strength)
 	      i != j;
 	      i = i < last ? i + 1 : first )
 	{
-	  points[i].x += x_strength + shift.x;
+	  points[i].x += x_shift + shift.x;
-	  points[i].y += y_strength + shift.y;
+	  points[i].y += y_shift + shift.y;
 	}
       }
       else

src/hb-outline.hh

@@ -69,7 +69,8 @@ struct hb_outline_t
 
   HB_INTERNAL void replay (hb_draw_funcs_t *pen, void *pen_data) const;
   HB_INTERNAL float area () const;
-  HB_INTERNAL void embolden (float x_strength, float y_strength);
+  HB_INTERNAL void embolden (float x_strength, float y_strength,
+			     float x_shift, float y_shift);
 
   hb_vector_t<hb_outline_point_t> points;
   hb_vector_t<unsigned> contours;

util/font-options.hh

@@ -65,6 +65,7 @@ struct font_options_t : face_options_t
   double ptem = 0.;
   double x_embolden = 0.;
   double y_embolden = 0.;
+  hb_bool_t embolden_in_place = false;
   double slant = 0.;
   unsigned int subpixel_bits = SUBPIXEL_BITS;
   mutable double font_size_x = DEFAULT_FONT_SIZE;
@@ -103,7 +104,9 @@ font_options_t::post_parse (GError **error)
   hb_font_set_ppem (font, x_ppem, y_ppem);
   hb_font_set_ptem (font, ptem);
 
-  hb_font_set_synthetic_bold (font, (float) x_embolden, (float) y_embolden);
+  hb_font_set_synthetic_bold (font,
+			      (float) x_embolden, (float) y_embolden,
+			      embolden_in_place);
   hb_font_set_synthetic_slant (font, slant);
 
   int scale_x = (int) scalbnf (font_size_x, subpixel_bits);
@@ -249,7 +252,7 @@ parse_font_ppem (const char *name G_GNUC_UNUSED,
 }
 
 static gboolean
-parse_font_bold (const char *name G_GNUC_UNUSED,
+parse_font_embolden (const char *name G_GNUC_UNUSED,
 		     const char *arg,
 		     gpointer    data,
 		     GError    **error G_GNUC_UNUSED)
@@ -266,6 +269,28 @@ parse_font_bold (const char *name G_GNUC_UNUSED,
   }
 }
 
+static gboolean
+parse_font_bold (const char *name G_GNUC_UNUSED,
+		 const char *arg,
+		 gpointer    data,
+		 GError    **error G_GNUC_UNUSED)
+{
+  font_options_t *font_opts = (font_options_t *) data;
+  font_opts->embolden_in_place = false;
+  return parse_font_embolden ( name, arg, data, error);
+}
+
+static gboolean
+parse_font_grade (const char *name G_GNUC_UNUSED,
+		  const char *arg,
+		  gpointer    data,
+		  GError    **error G_GNUC_UNUSED)
+{
+  font_options_t *font_opts = (font_options_t *) data;
+  font_opts->embolden_in_place = true;
+  return parse_font_embolden ( name, arg, data, error);
+}
+
 void
 font_options_t::add_options (option_parser_t *parser)
 {
@@ -309,6 +334,8 @@ font_options_t::add_options (option_parser_t *parser)
 			      G_OPTION_ARG_DOUBLE,	&this->ptem,			"Set font point-size (default: 0; disabled)",	"point-size"},
     {"font-bold",	0, font_size_flags,
 			      G_OPTION_ARG_CALLBACK,	(gpointer) &parse_font_bold,	"Set synthetic bold (default: 0)",		"1/2 numbers; eg. 0.05"},
+    {"font-grade",	0, font_size_flags,
+			      G_OPTION_ARG_CALLBACK,	(gpointer) &parse_font_grade,	"Set synthetic grade (default: 0)",		"1/2 numbers; eg. 0.05"},
     {"font-slant",	0, font_size_flags,
 			      G_OPTION_ARG_DOUBLE,	&this->slant,			"Set synthetic slant (default: 0)",		 "slant ratio; eg. 0.2"},
     {"font-funcs",	0, 0, G_OPTION_ARG_STRING,	&this->font_funcs,		text,						"impl"},