From 9628ad303ad924255a224fdcc113ff8264172fc7 Mon Sep 17 00:00:00 2001
From: Jan Grulich <jgrulich@redhat.com>
Date: Thu, 27 Jul 2023 12:44:11 +0200
Subject: [PATCH 14/15] QGtk3Theme: Improve fixed font delivery

The gtk_fixed widget was used as a reference to obtain a fixed font
and HeaderViewFont.

This is a mistake, because the gtk_fixed widget is a container for
other widgets with fixed geometries and no layouting.

This patch makes the default style being used for a fixed font and, as
a drive-by, the combo box as a reference for a header view font.
A monospace based css provider as explicitly added to the style
context, in case a fixed font is requested. The provider is removed
afterwards.
---
 .../platformthemes/gtk3/qgtk3interface.cpp    | 24 +++++++++++++++++--
 1 file changed, 22 insertions(+), 2 deletions(-)

diff --git a/src/plugins/platformthemes/gtk3/qgtk3interface.cpp b/src/plugins/platformthemes/gtk3/qgtk3interface.cpp
index 0fab1220b4..21abea81cf 100644
--- a/src/plugins/platformthemes/gtk3/qgtk3interface.cpp
+++ b/src/plugins/platformthemes/gtk3/qgtk3interface.cpp
@@ -18,6 +18,7 @@
 #include <QtCore/QMetaEnum>
 #include <QtCore/QSettings>
 #include <QtCore/QFileInfo>
+#include <QtCore/QScopeGuard>
 #include <QtGui/QFontDatabase>
 #include <QtGui/QIcon>
 
@@ -538,13 +539,13 @@ inline constexpr QGtk3Interface::QGtkWidget QGtk3Interface::toWidgetType(QPlatfo
     case QPlatformTheme::ToolButtonFont: return QGtkWidget::gtk_button;
     case QPlatformTheme::ItemViewFont: return QGtkWidget::gtk_entry;
     case QPlatformTheme::ListViewFont: return QGtkWidget::gtk_tree_view;
-    case QPlatformTheme::HeaderViewFont: return QGtkWidget::gtk_fixed;
+    case QPlatformTheme::HeaderViewFont: return QGtkWidget::gtk_combo_box;
     case QPlatformTheme::ListBoxFont: return QGtkWidget::gtk_Default;
     case QPlatformTheme::ComboMenuItemFont: return QGtkWidget::gtk_combo_box;
     case QPlatformTheme::ComboLineEditFont: return QGtkWidget::gtk_combo_box_text;
     case QPlatformTheme::SmallFont: return QGtkWidget::gtk_Default;
     case QPlatformTheme::MiniFont: return QGtkWidget::gtk_Default;
-    case QPlatformTheme::FixedFont: return QGtkWidget::gtk_fixed;
+    case QPlatformTheme::FixedFont: return QGtkWidget::gtk_Default;
     case QPlatformTheme::GroupBoxTitleFont: return QGtkWidget::gtk_Default;
     case QPlatformTheme::TabButtonFont: return QGtkWidget::gtk_button;
     case QPlatformTheme::EditorFont: return QGtkWidget::gtk_entry;
@@ -624,6 +625,24 @@ QFont QGtk3Interface::font(QPlatformTheme::Font type) const
     if (!con)
         return QFont();
 
+    // explicitly add provider for fixed font
+    GtkCssProvider *cssProvider = nullptr;
+    if (type == QPlatformTheme::FixedFont) {
+        cssProvider = gtk_css_provider_new();
+        const char *fontSpec = "{font-family: monospace;}";
+        gtk_css_provider_load_from_data(cssProvider, fontSpec, -1, NULL);
+        gtk_style_context_add_provider(con, GTK_STYLE_PROVIDER(cssProvider),
+                                       GTK_STYLE_PROVIDER_PRIORITY_USER);
+    }
+
+    // remove monospace provider from style context and unref it
+    QScopeGuard guard([&](){
+        if (cssProvider) {
+            gtk_style_context_remove_provider(con, GTK_STYLE_PROVIDER(cssProvider));
+            g_object_unref(cssProvider);
+        }
+    });
+
     const PangoFontDescription *gtkFont = gtk_style_context_get_font(con, GTK_STATE_FLAG_NORMAL);
     if (!gtkFont)
         return QFont();
@@ -650,6 +669,7 @@ QFont QGtk3Interface::font(QPlatformTheme::Font type) const
             font.setFamily("monospace");
         }
     }
+
     return font;
 }
 
-- 
2.41.0