[gtk+] font chooser: Manage tweak button sensitivity

[Matthias Clasen <matthiasc src gnome org>]

commit a79f950dfe94d5556df7f1e2b000f831a11fe314
Author: Matthias Clasen <mclasen redhat com>
Date:   Wed Jan 3 14:06:00 2018 -0500

    font chooser: Manage tweak button sensitivity
    
    When we don't have any font features or variation axes,
    there is no point in going to the tweak page, so disable
    the action in this case.

 gtk/gtkfontchooserwidget.c |   33 +++++++++++++++++++++++++--------
 1 files changed, 25 insertions(+), 8 deletions(-)
---
diff --git a/gtk/gtkfontchooserwidget.c b/gtk/gtkfontchooserwidget.c
index ba7c19d..d021da4 100644
--- a/gtk/gtkfontchooserwidget.c
+++ b/gtk/gtkfontchooserwidget.c
@@ -1547,7 +1547,7 @@ static struct {
   { FT_MAKE_TAG ('o', 'p', 's', 'z'), N_("Optical Size") },
 };
 
-static void
+static gboolean
 add_axis (GtkFontChooserWidget *fontchooser,
           FT_Face               face,
           FT_Var_Axis          *ax,
@@ -1601,10 +1601,14 @@ add_axis (GtkFontChooserWidget *fontchooser,
       gtk_widget_hide (axis->label);
       gtk_widget_hide (axis->scale);
       gtk_widget_hide (axis->spin);
+
+      return FALSE;
     }
+
+  return TRUE;
 }
 
-static void
+static gboolean
 gtk_font_chooser_widget_update_font_variations (GtkFontChooserWidget *fontchooser)
 {
   GtkFontChooserWidgetPrivate *priv = fontchooser->priv;
@@ -1612,9 +1616,10 @@ gtk_font_chooser_widget_update_font_variations (GtkFontChooserWidget *fontchoose
   FT_Face ft_face;
   FT_MM_Var *ft_mm_var;
   FT_Error ret;
+  gboolean has_axis = FALSE;
 
   if (priv->updating_variations)
-    return;
+    return FALSE;
 
   g_hash_table_foreach (priv->axes, axis_remove, NULL);
   g_hash_table_remove_all (priv->axes);
@@ -1644,7 +1649,10 @@ gtk_font_chooser_widget_update_font_variations (GtkFontChooserWidget *fontchoose
         }
 
       for (i = 0; i < ft_mm_var->num_axis; i++)
-        add_axis (fontchooser, ft_face, &ft_mm_var->axis[i], coords[i], i + 4);
+        {
+          if (add_axis (fontchooser, ft_face, &ft_mm_var->axis[i], coords[i], i + 4))
+            has_axis = TRUE;
+        }
 
       g_free (coords);
       free (ft_mm_var);
@@ -1652,6 +1660,8 @@ gtk_font_chooser_widget_update_font_variations (GtkFontChooserWidget *fontchoose
 
   pango_fc_font_unlock_face (PANGO_FC_FONT (pango_font));
   g_object_unref (pango_font);
+
+  return has_axis;
 }
 
 /* OpenType features */
@@ -1993,7 +2003,7 @@ gtk_font_chooser_widget_populate_features (GtkFontChooserWidget *fontchooser)
   update_font_features (fontchooser);
 }
 
-static void
+static gboolean
 gtk_font_chooser_widget_update_font_features (GtkFontChooserWidget *fontchooser)
 {
   GtkFontChooserWidgetPrivate *priv = fontchooser->priv;
@@ -2006,6 +2016,7 @@ gtk_font_chooser_widget_update_font_features (GtkFontChooserWidget *fontchooser)
   guint lang_index = 0;
   int i, j;
   GList *l;
+  gboolean has_feature = FALSE;
 
   gtk_widget_hide (priv->feature_language_combo);
 
@@ -2057,6 +2068,7 @@ gtk_font_chooser_widget_update_font_features (GtkFontChooserWidget *fontchooser)
               if (item->tag != features[j])
                 continue;
 
+              has_feature = TRUE;
               gtk_widget_show (item->feat);
               gtk_widget_show (gtk_widget_get_parent (item->feat));
               gtk_widget_show (priv->feature_language_combo);
@@ -2078,6 +2090,8 @@ gtk_font_chooser_widget_update_font_features (GtkFontChooserWidget *fontchooser)
 
   pango_fc_font_unlock_face (PANGO_FC_FONT (pango_font));
   g_object_unref (pango_font);
+
+  return has_feature;
 }
 
 static void
@@ -2196,22 +2210,25 @@ gtk_font_chooser_widget_merge_font_desc (GtkFontChooserWidget       *fontchooser
   if (mask & (PANGO_FONT_MASK_FAMILY | PANGO_FONT_MASK_STYLE | PANGO_FONT_MASK_VARIANT |
               PANGO_FONT_MASK_WEIGHT | PANGO_FONT_MASK_STRETCH))
     {
+      gboolean has_tweak = FALSE;
+
       if (&priv->font_iter != iter)
         {
           if (iter == NULL)
             memset (&priv->font_iter, 0, sizeof (GtkTreeIter));
           else
             memcpy (&priv->font_iter, iter, sizeof (GtkTreeIter));
-          
+
           gtk_font_chooser_widget_ensure_selection (fontchooser);
         }
 
       gtk_font_chooser_widget_update_marks (fontchooser);
 
 #if defined(HAVE_HARFBUZZ) && defined(HAVE_PANGOFT)
-      gtk_font_chooser_widget_update_font_variations (fontchooser);
-      gtk_font_chooser_widget_update_font_features (fontchooser);
+      has_tweak = gtk_font_chooser_widget_update_font_variations (fontchooser) ||
+                  gtk_font_chooser_widget_update_font_features (fontchooser);
 #endif
+      g_simple_action_set_enabled (G_SIMPLE_ACTION (priv->tweak_action), has_tweak);
     }
 
   gtk_font_chooser_widget_update_preview_attributes (fontchooser);