[mutter] x11-display: Set the correct default Xcursor theme size

[Jonas Ådahl <jadahl src gnome org>]

commit e2464660bcb3740e726246532ac85c9e37ea1d73
Author: Jonas Ådahl <jadahl gmail com>
Date:   Fri Jul 6 19:22:26 2018 +0200

    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         | 12 +++++++
 src/core/prefs.c           | 85 ++++++----------------------------------------
 src/x11/meta-x11-display.c |  8 ++++-
 3 files changed, 30 insertions(+), 75 deletions(-)
---
diff --git a/src/core/display.c b/src/core/display.c
index f5cefb4e9..2e6fe3349 100644
--- a/src/core/display.c
+++ b/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);
diff --git a/src/core/prefs.c b/src/core/prefs.c
index 2f96e5633..343ca8e43 100644
--- a/src/core/prefs.c
+++ b/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::cursor-size",
-                      G_CALLBACK (wayland_settings_changed), NULL);
+  g_signal_connect (settings, "changed::" KEY_GNOME_CURSOR_SIZE,
+                    G_CALLBACK (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:
  *
diff --git a/src/x11/meta-x11-display.c b/src/x11/meta-x11-display.c
index 76433a4b5..3dd7f204d 100644
--- a/src/x11/meta-x11-display.c
+++ b/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