GtkTextView: Add fallback and letter-spacing support

Add support for the Pango attributes controlling font fallback
and letter spacing to GtkTextTag.

https://bugzilla.gnome.org/show_bug.cgi?id=740954

5 files changed, 107 insertions, 3 deletions

diff --git a/gtk/gtktextattributes.c b/gtk/gtktextattributes.c
index 5998bd398c..b864f39bd3 100644
--- a/gtk/gtktextattributes.c
+++ b/gtk/gtktextattributes.c
@@ -378,6 +378,12 @@ G_GNUC_END_IGNORE_DEPRECATIONS
       if (tag->priv->language_set)
 	dest->language = vals->language;
 
+      if (tag->priv->fallback_set)
+        dest->no_fallback = vals->no_fallback;
+
+      if (tag->priv->letter_spacing_set)
+        dest->letter_spacing = vals->letter_spacing;
+
       ++n;
     }
 
@@ -404,7 +410,8 @@ _gtk_text_tag_affects_size (GtkTextTag *tag)
     priv->tabs_set ||
     priv->underline_set ||
     priv->wrap_mode_set ||
-    priv->invisible_set;
+    priv->invisible_set ||
+    priv->letter_spacing_set;
 }
 
 gboolean
@@ -417,5 +424,6 @@ _gtk_text_tag_affects_nonsize_appearance (GtkTextTag *tag)
     priv->fg_color_set ||
     priv->strikethrough_set ||
     priv->bg_full_height_set ||
-    priv->pg_bg_color_set;
+    priv->pg_bg_color_set ||
+    priv->fallback_set;
 }
diff --git a/gtk/gtktextattributes.h b/gtk/gtktextattributes.h
index 0e2f85b0b8..0a57c69bd4 100644
--- a/gtk/gtktextattributes.h
+++ b/gtk/gtktextattributes.h
@@ -210,11 +210,15 @@ struct _GtkTextAttributes
   /* can edit this text */
   guint editable : 1;
 
+  guint no_fallback: 1;
+
   /*< private >*/
   /* Paragraph background */
   GdkRGBA *pg_bg_rgba;
 
-  guint padding[3];
+  gint letter_spacing;
+
+  guint padding[2];
 };
 
 GDK_AVAILABLE_IN_ALL
diff --git a/gtk/gtktextlayout.c b/gtk/gtktextlayout.c
index 7dbb62e13b..44b87bbd99 100644
--- a/gtk/gtktextlayout.c
+++ b/gtk/gtktextlayout.c
@@ -1580,6 +1580,24 @@ add_text_attrs (GtkTextLayout      *layout,
       
       pango_attr_list_insert (attrs, attr);
     }
+
+  if (style->no_fallback)
+    {
+      attr = pango_attr_fallback_new (!style->no_fallback);
+      attr->start_index = start;
+      attr->end_index = start + byte_count;
+
+      pango_attr_list_insert (attrs, attr);
+    }
+
+  if (style->letter_spacing != 0)
+    {
+      attr = pango_attr_letter_spacing_new (style->letter_spacing);
+      attr->start_index = start;
+      attr->end_index = start + byte_count;
+
+      pango_attr_list_insert (attrs, attr);
+    }
 }
 
 static void
diff --git a/gtk/gtktexttag.c b/gtk/gtktexttag.c
index 6e16fd6689..f02ae45c32 100644
--- a/gtk/gtktexttag.c
+++ b/gtk/gtktexttag.c
@@ -129,6 +129,8 @@ enum {
   PROP_PARAGRAPH_BACKGROUND,
   PROP_PARAGRAPH_BACKGROUND_GDK,
   PROP_PARAGRAPH_BACKGROUND_RGBA,
+  PROP_FALLBACK,
+  PROP_LETTER_SPACING,
 
   /* Behavior args */
   PROP_ACCUMULATIVE_MARGIN,
@@ -160,6 +162,8 @@ enum {
   PROP_TABS_SET,
   PROP_INVISIBLE_SET,
   PROP_PARAGRAPH_BACKGROUND_SET,
+  PROP_FALLBACK_SET,
+  PROP_LETTER_SPACING_SET,
 
   LAST_ARG
 };
@@ -600,6 +604,38 @@ gtk_text_tag_class_init (GtkTextTagClass *klass)
                                                        GTK_PARAM_READWRITE));
 
   /**
+   * GtkTextTag:fallback:
+   *
+   * Whether font fallback is enabled.
+   *
+   * When set to %TRUE, other fonts will be substituted
+   * where the current font is missing glyphs.
+   *
+   * Since: 3.16
+   */
+  g_object_class_install_property (object_class,
+                                   PROP_FALLBACK,
+                                   g_param_spec_boolean ("fallback",
+                                                         P_("Fallback"),
+                                                         P_("Whether font fallback is enabled."),
+                                                         TRUE,
+                                                         GTK_PARAM_READWRITE));
+
+  /**
+   * GtkTextTag:letter-spacing:
+   *
+   * Extra spacing between graphemes, in Pango units.
+   *
+   * Since: 3.16
+   */
+  g_object_class_install_property (object_class,
+                                   PROP_LETTER_SPACING,
+                                   g_param_spec_int ("letter-spacing",
+                                                     P_("Letter Spacing"),
+                                                     P_("Extra spacing between graphemes"),
+                                                     0, G_MAXINT, 0,
+                                                     GTK_PARAM_READWRITE));
+  /**
    * GtkTextTag:accumulative-margin:
    *
    * Whether the margins accumulate or override each other.
@@ -726,6 +762,14 @@ gtk_text_tag_class_init (GtkTextTagClass *klass)
                 P_("Paragraph background set"),
                 P_("Whether this tag affects the paragraph background color"));
 
+  ADD_SET_PROP ("fallback-set", PROP_FALLBACK_SET,
+                P_("Fallback set"),
+                P_("Whether this tag affects font fallback"));
+
+  ADD_SET_PROP ("letter-spacing-set", PROP_LETTER_SPACING_SET,
+                P_("Letter spacing set"),
+                P_("Whether this tag affects letter spacing"));
+
   /**
    * GtkTextTag::event:
    * @tag: the #GtkTextTag on which the signal is emitted
@@ -1450,6 +1494,18 @@ gtk_text_tag_set_property (GObject      *object,
       }
       break;
 
+    case PROP_FALLBACK:
+      priv->fallback_set = TRUE;
+      priv->values->no_fallback = !g_value_get_boolean (value);
+      g_object_notify (object, "fallback-set");
+      break;
+
+    case PROP_LETTER_SPACING:
+      priv->letter_spacing_set = TRUE;
+      priv->values->letter_spacing = g_value_get_int (value);
+      g_object_notify (object, "letter-spacing-set");
+      break;
+
     case PROP_ACCUMULATIVE_MARGIN:
       priv->accumulative_margin = g_value_get_boolean (value);
       g_object_notify (object, "accumulative-margin");
@@ -1763,6 +1819,14 @@ gtk_text_tag_get_property (GObject      *object,
       g_value_set_boxed (value, priv->values->pg_bg_rgba);
       break;
 
+    case PROP_FALLBACK:
+      g_value_set_boolean (value, !priv->values->no_fallback);
+      break;
+
+    case PROP_LETTER_SPACING:
+      g_value_set_int (value, priv->values->letter_spacing);
+      break;
+
     case PROP_ACCUMULATIVE_MARGIN:
       g_value_set_boolean (value, priv->accumulative_margin);
       break;
@@ -1861,6 +1925,14 @@ gtk_text_tag_get_property (GObject      *object,
       g_value_set_boolean (value, priv->pg_bg_color_set);
       break;
 
+    case PROP_FALLBACK_SET:
+      g_value_set_boolean (value, priv->fallback_set);
+      break;
+
+    case PROP_LETTER_SPACING_SET:
+      g_value_set_boolean (value, priv->letter_spacing_set);
+      break;
+
     case PROP_BACKGROUND:
     case PROP_FOREGROUND:
     case PROP_PARAGRAPH_BACKGROUND:
diff --git a/gtk/gtktexttagprivate.h b/gtk/gtktexttagprivate.h
index 4942b27890..cd31b7cb2c 100644
--- a/gtk/gtktexttagprivate.h
+++ b/gtk/gtktexttagprivate.h
@@ -75,6 +75,8 @@ struct _GtkTextTagPrivate
   guint editable_set : 1;
   guint language_set : 1;
   guint pg_bg_color_set : 1;
+  guint fallback_set : 1;
+  guint letter_spacing_set : 1;
 
   /* Whether these margins accumulate or override */
   guint accumulative_margin : 1;