LibGUI: Allow override the font on a per-index basis in GListView

This should be ported to all of the GAbstractView subclasses.

Libraries/LibGUI/GAbstractView.cpp

@@ -108,3 +108,18 @@ void GAbstractView::notify_selection_changed(Badge<GModelSelection>)
         on_selection_change();
     update();
 }
+
+NonnullRefPtr<Font> GAbstractView::font_for_index(const GModelIndex& index) const
+{
+    if (!model())
+        return font();
+
+    auto font_data = model()->data(index, GModel::Role::Font);
+    if (font_data.is_font())
+        return font_data.as_font();
+
+    auto column_metadata = model()->column_metadata(index.column());
+    if (column_metadata.font)
+        return *column_metadata.font;
+    return font();
+}

Libraries/LibGUI/GAbstractView.h

@@ -45,6 +45,8 @@ public:
 
     void notify_selection_changed(Badge<GModelSelection>);
 
+    NonnullRefPtr<Font> font_for_index(const GModelIndex&) const;
+
 protected:
     virtual void did_scroll() override;
     void activate(const GModelIndex&);

Libraries/LibGUI/GListView.cpp

@@ -113,11 +113,12 @@ void GListView::paint_event(GPaintEvent& event)
         }
 
         auto column_metadata = model()->column_metadata(m_model_column);
-        const Font& font = column_metadata.font ? *column_metadata.font : this->font();
+
         Rect row_rect(0, y, content_width(), item_height());
         painter.fill_rect(row_rect, background_color);
         auto index = model()->index(row_index, m_model_column);
         auto data = model()->data(index);
+        auto font = font_for_index(index);
         if (data.is_bitmap()) {
             painter.blit(row_rect.location(), data.as_bitmap(), data.as_bitmap().rect());
         } else if (data.is_icon()) {

Libraries/LibGUI/GModel.h

@@ -34,7 +34,8 @@ public:
         Custom,
         ForegroundColor,
         BackgroundColor,
-        Icon
+        Icon,
+        Font,
     };
 
     virtual ~GModel();