builder: parse tab arrays and font descriptions

We have widgets with properties that have these types, so parsing
them is useful.

Tests included.

gtk/gtkbuilder.c

@@ -153,16 +153,20 @@
  * - booleans (strings like “TRUE”, “t”, “yes”, “y”, “1” are interpreted
  *   as true values, strings like “FALSE”, “f”, “no”, “n”, “0” are interpreted
  *   as false values)
+ * - string lists (separated by newlines)
  * - enumeration types (can be specified by their full C identifier their short
  *   name used when registering the enumeration type, or their integer value)
  * - flag types (can be specified by their C identifier or short name,
  *   optionally combined with “|” for bitwise OR, or a single integer value
  *   e.g., “GTK_INPUT_HINT_EMOJI|GTK_INPUT_HINT_LOWERCASE”, or “emoji|lowercase” or 520).
- * - colors (in a format understood by [method@Gdk.RGBA.parse])
- * - `GVariant` (can be specified in the format understood by
- *    [func@GLib.Variant.parse])
- * - pixbufs (can be specified as an object id, a resource path or a filename of an image file to load relative to the Builder file or the CWD if [method@Gtk.Builder.add_from_string] was used)
- * - GFile (like pixbufs, can be specified as an object id, a URI or a filename of a file to load relative to the Builder file or the CWD if [method@Gtk.Builder.add_from_string] was used)
+ * - colors (in the format understood by [method@Gdk.RGBA.parse])
+ * - transforms (in the format understood by [func@Gsk.Transform.parse])
+ * - Pango attribute lists (in the format understood by [method@Pango.AttrList.to_string])
+ * - Pango tab arrays (in the format understood by [method@Pango.TabArray.to_string])
+ * - Pango font descriptions (in the format understood by [func@Pango.FontDescription.from_string])
+ * - `GVariant` (in the format understood by [func@GLib.Variant.parse])
+ * - textures (can be specified as an object id, a resource path or a filename of an image file to load relative to the Builder file or the CWD if [method@Gtk.Builder.add_from_string] was used)
+ * - GFile (like textures, can be specified as an object id, a URI or a filename of a file to load relative to the Builder file or the CWD if [method@Gtk.Builder.add_from_string] was used)
  *
  * Objects can be referred to by their name and by default refer to
  * objects declared in the local XML fragment and objects exposed via
@@ -2500,7 +2504,9 @@ gtk_builder_value_from_string_type (GtkBuilder   *builder,
 
           attrs = pango_attr_list_from_string (string);
           if (attrs)
-            g_value_take_boxed (value, attrs);
+            {
+              g_value_take_boxed (value, attrs);
+            }
           else
             {
               g_set_error (error,
@@ -2511,6 +2517,44 @@ gtk_builder_value_from_string_type (GtkBuilder   *builder,
               ret = FALSE;
             }
         }
+      else if (G_VALUE_HOLDS (value, PANGO_TYPE_TAB_ARRAY))
+        {
+          PangoTabArray *tabs;
+
+          tabs = pango_tab_array_from_string (string);
+          if (tabs)
+            {
+              g_value_take_boxed (value, tabs);
+            }
+          else
+            {
+              g_set_error (error,
+                           GTK_BUILDER_ERROR,
+                           GTK_BUILDER_ERROR_INVALID_VALUE,
+                           "Could not parse PangoTabArray '%s'",
+                           string);
+              ret = FALSE;
+            }
+        }
+      else if (G_VALUE_HOLDS (value, PANGO_TYPE_FONT_DESCRIPTION))
+        {
+          PangoFontDescription *desc;
+
+          desc = pango_font_description_from_string (string);
+          if (desc)
+            {
+              g_value_take_boxed (value, desc);
+            }
+          else
+            {
+              g_set_error (error,
+                           GTK_BUILDER_ERROR,
+                           GTK_BUILDER_ERROR_INVALID_VALUE,
+                           "Could not parse PangoFontDescription '%s'",
+                           string);
+              ret = FALSE;
+            }
+        }
       else if (G_VALUE_HOLDS (value, G_TYPE_DATE_TIME))
         {
           GDateTime *date_time;

testsuite/gtk/ui/fontbutton.expected

@@ -0,0 +1 @@
+SUCCESS

testsuite/gtk/ui/fontbutton.ui

@@ -0,0 +1,5 @@
+<interface>
+  <object class="GtkFontDialogButton">
+    <property name="font-desc">Cantarell Bold 11px</property>
+  </object>
+</interface>

testsuite/gtk/ui/label7.expected

@@ -0,0 +1 @@
+SUCCESS

testsuite/gtk/ui/label7.ui

@@ -0,0 +1,7 @@
+<!-- test all valid label attributes -->
+<interface>
+  <object class="GtkLabel">
+    <property name="attributes">0 -1 weight 666, 0 -1 family Cantarell</property>
+    <property name="tabs">left:10px right:20px center:30px decimal:40px</property>
+  </object>
+</interface>