[mutter] wayland: Don't pre-multiply root cursor sizes with primary monitor scale

[Jonas Ådahl <jadahl src gnome org>]

commit 130807a30803e1d691b613be074d8414c630dce9
Author: Jonas Ådahl <jadahl gmail com>
Date:   Wed Sep 16 15:47:31 2015 +0800

    wayland: Don't pre-multiply root cursor sizes with primary monitor scale
    
    We cannot use the XSETTINGS value for cursor theme size because
    gnome-settings-daemon already multiplies it by the primary monitor's
    scale.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=755099

 src/core/prefs.c |   64 ++++++++++++++++++++++++++++++++++++++++++++++-------
 1 files changed, 55 insertions(+), 9 deletions(-)
---
diff --git a/src/core/prefs.c b/src/core/prefs.c
index 2da8da3..90ad108 100644
--- a/src/core/prefs.c
+++ b/src/core/prefs.c
@@ -96,6 +96,10 @@ static gboolean bell_is_audible = TRUE;
 static gboolean gnome_accessibility = FALSE;
 static gboolean gnome_animations = TRUE;
 static char *cursor_theme = NULL;
+/* cursor_size will, when running as an X11 compositing window manager, be the
+ * actual cursor size, multiplied with the global window scaling factor. On
+ * Wayland, it will be the actual cursor size retrieved from gsettings.
+ */
 static int   cursor_size = 24;
 static int   draggable_border_width = 10;
 static int   drag_threshold;
@@ -123,6 +127,9 @@ 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);
@@ -134,9 +141,10 @@ static void shell_shows_app_menu_changed (GtkSettings *settings,
                                           GParamSpec  *pspec,
                                           gpointer     data);
 
-static void update_cursor_size (GtkSettings *settings,
-                                GParamSpec *pspec,
-                                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);
 
@@ -963,14 +971,18 @@ 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_hash_table_insert (settings_schemas, g_strdup (SCHEMA_INTERFACE), settings);
 
   g_signal_connect (gtk_settings_get_default (),
                     "notify::gtk-shell-shows-app-menu",
                     G_CALLBACK (shell_shows_app_menu_changed), NULL);
 
-  g_signal_connect (gtk_settings_get_default (), "notify::gtk-cursor-theme-size",
-                    G_CALLBACK (update_cursor_size), NULL);
+  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,
@@ -992,7 +1004,7 @@ meta_prefs_init (void)
   handle_preference_init_string_array ();
   handle_preference_init_int ();
 
-  update_cursor_size (gtk_settings_get_default (), NULL, NULL);
+  update_cursor_size ();
   shell_shows_app_menu_changed (gtk_settings_get_default (), NULL, NULL);
 
   init_bindings ();
@@ -1134,6 +1146,20 @@ 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,
                   gpointer data)
@@ -1216,9 +1242,29 @@ shell_shows_app_menu_changed (GtkSettings *settings,
 }
 
 static void
-update_cursor_size (GtkSettings *settings,
-                    GParamSpec *pspec,
-                    gpointer data)
+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;