[mutter] backends: Trigger MetaCursorTracker::cursor-changed on texture changes

[Carlos Garnacho <carlosg src gnome org>]

commit f45df4265d089dc4df22a411161db53e5a06bff7
Author: Carlos Garnacho <carlosg gnome org>
Date:   Thu Nov 16 19:26:41 2017 +0100

    backends: Trigger MetaCursorTracker::cursor-changed on texture changes
    
    So we allow gnome-shell's magnifier to update fake cursors while it's
    turned on.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=754806

 src/backends/meta-cursor-tracker.c |   12 ++++++++++++
 1 files changed, 12 insertions(+), 0 deletions(-)
---
diff --git a/src/backends/meta-cursor-tracker.c b/src/backends/meta-cursor-tracker.c
index 3cdab83..f1562a2 100644
--- a/src/backends/meta-cursor-tracker.c
+++ b/src/backends/meta-cursor-tracker.c
@@ -53,6 +53,13 @@ enum {
 
 static guint signals[LAST_SIGNAL];
 
+static void
+cursor_texture_updated (MetaCursorSprite  *cursor,
+                        MetaCursorTracker *tracker)
+{
+  g_signal_emit (tracker, signals[CURSOR_CHANGED], 0);
+}
+
 static gboolean
 update_displayed_cursor (MetaCursorTracker *tracker)
 {
@@ -71,7 +78,12 @@ update_displayed_cursor (MetaCursorTracker *tracker)
   if (tracker->displayed_cursor == cursor)
     return FALSE;
 
+  g_signal_handlers_disconnect_by_func (tracker->displayed_cursor,
+                                        cursor_texture_updated,
+                                        tracker);
   g_set_object (&tracker->displayed_cursor, cursor);
+  g_signal_connect (tracker->displayed_cursor, "texture-changed",
+                    G_CALLBACK (cursor_texture_updated), tracker);
   return TRUE;
 }