x11-display: Set the correct default Xcursor theme size

Under Xorg the cursor size preference was pre-scaled originating from
gtk, while with Wayland it came directly from GSettings remaining
unscaled. Under Xwayland this caused the X11 display code to set the
wrong size with HiDPI configurations, which was often later overridden
by the equivalent code in gtk, but not always.

Fix this by always having the cursor size preference unscaled, scaling
the size correctly where it's used, depending on how it's used.

https://bugzilla.gnome.org/show_bug.cgi?id=759538

src/core/display.c

@@ -676,6 +676,13 @@ on_startup_notification_changed (MetaStartupNotification *sn,
   g_signal_emit_by_name (display, "startup-sequence-changed", sequence);
 }
 
+static void
+on_ui_scaling_factor_changed (MetaSettings *settings,
+                              MetaDisplay  *display)
+{
+  meta_display_reload_cursor (display);
+}
+
 /**
  * meta_display_open:
  *
@@ -697,6 +704,7 @@ meta_display_open (void)
   Window old_active_xwindow = None;
   MetaBackend *backend = meta_get_backend ();
   MetaMonitorManager *monitor_manager;
+  MetaSettings *settings;
 
   g_assert (the_display == NULL);
   display = the_display = g_object_new (META_TYPE_DISPLAY, NULL);
@@ -755,6 +763,10 @@ meta_display_open (void)
   g_signal_connect (monitor_manager, "monitors-changed-internal",
                     G_CALLBACK (on_monitors_changed_internal), display);
 
+  settings = meta_backend_get_settings (backend);
+  g_signal_connect (settings, "ui-scaling-factor-changed",
+                    G_CALLBACK (on_ui_scaling_factor_changed), display);
+
   meta_display_set_cursor (display, META_CURSOR_DEFAULT);
 
   display->stack = meta_stack_new (display);

src/core/prefs.c

@@ -36,6 +36,7 @@
 #include <stdlib.h>
 #include "keybindings-private.h"
 #include "meta-accel-parse.h"
+#include "x11/meta-x11-display-private.h"
 
 /* If you add a key, it needs updating in init() and in the gsettings
  * notify listener and of course in the .schemas file.
@@ -52,6 +53,7 @@
 #define KEY_GNOME_ACCESSIBILITY "toolkit-accessibility"
 #define KEY_GNOME_ANIMATIONS "enable-animations"
 #define KEY_GNOME_CURSOR_THEME "cursor-theme"
+#define KEY_GNOME_CURSOR_SIZE "cursor-size"
 #define KEY_XKB_OPTIONS "xkb-options"
 
 #define KEY_OVERLAY_KEY "overlay-key"
@@ -127,9 +129,6 @@ static gboolean update_binding         (MetaKeyPref *binding,
 static gboolean update_key_binding     (const char  *key,
                                         gchar      **strokes);
 
-static void wayland_settings_changed (GSettings      *settings,
-                                      gchar          *key,
-                                      gpointer        data);
 static void settings_changed (GSettings      *settings,
                               gchar          *key,
                               gpointer        data);
@@ -137,11 +136,6 @@ static void bindings_changed (GSettings      *settings,
                               gchar          *key,
                               gpointer        data);
 
-static void update_cursor_size_from_gtk (GtkSettings *settings,
-                                         GParamSpec *pspec,
-                                         gpointer data);
-static void update_cursor_size (void);
-
 static void queue_changed (MetaPreference  pref);
 
 static void maybe_give_disable_workarounds_warning (void);
@@ -156,7 +150,6 @@ static void     do_override               (char *key, char *schema);
 
 static void     init_bindings             (void);
 
-
 typedef struct
 {
   MetaPrefsChangedFunc func;
@@ -489,6 +482,13 @@ static MetaIntPreference preferences_int[] =
       },
       &drag_threshold
     },
+    {
+      { "cursor-size",
+        SCHEMA_INTERFACE,
+        META_PREF_CURSOR_SIZE,
+      },
+      &cursor_size
+    },
     { { NULL, 0, 0 }, NULL },
   };
 
@@ -965,15 +965,10 @@ meta_prefs_init (void)
                     G_CALLBACK (settings_changed), NULL);
   g_signal_connect (settings, "changed::" KEY_GNOME_CURSOR_THEME,
                     G_CALLBACK (settings_changed), NULL);
-  if (meta_is_wayland_compositor ())
+  g_signal_connect (settings, "changed::" KEY_GNOME_CURSOR_SIZE,
-    g_signal_connect (settings, "changed::cursor-size",
+                    G_CALLBACK (settings_changed), NULL);
-                      G_CALLBACK (wayland_settings_changed), NULL);
   g_hash_table_insert (settings_schemas, g_strdup (SCHEMA_INTERFACE), settings);
 
-  if (!meta_is_wayland_compositor ())
-    g_signal_connect (gtk_settings_get_default (), "notify::gtk-cursor-theme-size",
-                      G_CALLBACK (update_cursor_size_from_gtk), NULL);
-
   settings = g_settings_new (SCHEMA_INPUT_SOURCES);
   g_signal_connect (settings, "changed::" KEY_XKB_OPTIONS,
                     G_CALLBACK (settings_changed), NULL);
@@ -994,8 +989,6 @@ meta_prefs_init (void)
   handle_preference_init_string_array ();
   handle_preference_init_int ();
 
-  update_cursor_size ();
-
   init_bindings ();
 }
 
@@ -1134,20 +1127,6 @@ meta_prefs_override_preference_schema (const char *key, const char *schema)
 /****************************************************************************/
 
 
-static void
-wayland_settings_changed (GSettings      *settings,
-                          gchar          *key,
-                          gpointer        data)
-{
-  GVariant *value = g_settings_get_value (settings, key);
-  const GVariantType *type = g_variant_get_type (value);
-
-  g_return_if_fail (g_variant_type_equal (type, G_VARIANT_TYPE_INT32));
-  g_return_if_fail (g_str_equal (key, "cursor-size"));
-
-  update_cursor_size ();
-}
-
 static void
 settings_changed (GSettings *settings,
                   gchar *key,
@@ -1209,48 +1188,6 @@ bindings_changed (GSettings *settings,
   g_strfreev (strokes);
 }
 
-static void
-update_cursor_size (void)
-{
-  if (meta_is_wayland_compositor ())
-    {
-      /* When running as a Wayland compositor, since we size of the cursor
-       * depends on what output it is on, we cannot use the GTK+
-       * "gtk-cursor-theme-size" setting because it has already been multiplied
-       * by the primary monitor scale. So, instead get the non-premultiplied
-       * cursor size value directly from gsettings instead.
-       */
-      cursor_size =
-        g_settings_get_int (SETTINGS (SCHEMA_INTERFACE), "cursor-size");
-    }
-  else
-    {
-      update_cursor_size_from_gtk (gtk_settings_get_default (), NULL, NULL);
-    }
-}
-
-static void
-update_cursor_size_from_gtk (GtkSettings *settings,
-                             GParamSpec *pspec,
-                             gpointer data)
-{
-  GdkScreen *screen = gdk_screen_get_default ();
-  GValue value = G_VALUE_INIT;
-  int xsettings_cursor_size = 24;
-
-  g_value_init (&value, G_TYPE_INT);
-  if (gdk_screen_get_setting (screen, "gtk-cursor-theme-size", &value))
-    {
-      xsettings_cursor_size = g_value_get_int (&value);
-    }
-
-  if (xsettings_cursor_size != cursor_size)
-    {
-      cursor_size = xsettings_cursor_size;
-      queue_changed (META_PREF_CURSOR_SIZE);
-    }
-}
-
 /**
  * maybe_give_disable_workaround_warning:
  *

src/x11/meta-x11-display.c

@@ -53,6 +53,7 @@
 
 #include "backends/meta-backend-private.h"
 #include "backends/meta-logical-monitor.h"
+#include "backends/meta-settings-private.h"
 #include "backends/x11/meta-backend-x11.h"
 #include "core/frame.h"
 #include "core/meta-workspace-manager-private.h"
@@ -1462,8 +1463,13 @@ meta_x11_display_reload_cursor (MetaX11Display *x11_display)
 static void
 set_cursor_theme (Display *xdisplay)
 {
+  MetaBackend *backend = meta_get_backend ();
+  MetaSettings *settings = meta_backend_get_settings (backend);
+  int scale;
+
+  scale = meta_settings_get_ui_scaling_factor (settings);
   XcursorSetTheme (xdisplay, meta_prefs_get_cursor_theme ());
-  XcursorSetDefaultSize (xdisplay, meta_prefs_get_cursor_size ());
+  XcursorSetDefaultSize (xdisplay, meta_prefs_get_cursor_size () * scale);
 }
 
 static void