[mutter] backend: Update cursor visibility based on device availability

[Carlos Garnacho <carlosg src gnome org>]

commit 3471ef34411a00c3d19a8363b0daee1bfad0f250
Author: Carlos Garnacho <carlosg gnome org>
Date:   Wed Feb 11 17:04:13 2015 +0100

    backend: Update cursor visibility based on device availability
    
    On startup, the cursor is kept hidden if there's any touchscreen available.
    If the device that was last interacted is removed, we check on available
    pointing devices though, so we don't possibly hide the pointer if there are
    further mice/touchpads/etc.
    
    Devices being added don't update cursor visibility, we wait for the user
    interacting with those instead.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=712775

 src/backends/meta-backend.c |   81 +++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 81 insertions(+), 0 deletions(-)
---
diff --git a/src/backends/meta-backend.c b/src/backends/meta-backend.c
index 474184a..f55a4a0 100644
--- a/src/backends/meta-backend.c
+++ b/src/backends/meta-backend.c
@@ -137,6 +137,55 @@ on_device_added (ClutterDeviceManager *device_manager,
   create_device_monitor (backend, device_id);
 }
 
+static inline gboolean
+device_is_slave_touchscreen (ClutterInputDevice *device)
+{
+  return (clutter_input_device_get_device_mode (device) != CLUTTER_INPUT_MODE_MASTER &&
+          clutter_input_device_get_device_type (device) == CLUTTER_TOUCHSCREEN_DEVICE);
+}
+
+static inline gboolean
+check_has_pointing_device (ClutterDeviceManager *manager)
+{
+  const GSList *devices;
+
+  devices = clutter_device_manager_peek_devices (manager);
+
+  for (; devices; devices = devices->next)
+    {
+      ClutterInputDevice *device = devices->data;
+
+      if (clutter_input_device_get_device_mode (device) == CLUTTER_INPUT_MODE_MASTER)
+        continue;
+      if (clutter_input_device_get_device_type (device) == CLUTTER_TOUCHSCREEN_DEVICE ||
+          clutter_input_device_get_device_type (device) == CLUTTER_KEYBOARD_DEVICE)
+        continue;
+
+      return TRUE;
+    }
+
+  return FALSE;
+}
+
+static inline gboolean
+check_has_slave_touchscreen (ClutterDeviceManager *manager)
+{
+  const GSList *devices;
+
+  devices = clutter_device_manager_peek_devices (manager);
+
+  for (; devices; devices = devices->next)
+    {
+      ClutterInputDevice *device = devices->data;
+
+      if (clutter_input_device_get_device_mode (device) != CLUTTER_INPUT_MODE_MASTER &&
+          clutter_input_device_get_device_type (device) == CLUTTER_TOUCHSCREEN_DEVICE)
+        return TRUE;
+    }
+
+  return FALSE;
+}
+
 static void
 on_device_removed (ClutterDeviceManager *device_manager,
                    ClutterInputDevice   *device,
@@ -146,6 +195,32 @@ on_device_removed (ClutterDeviceManager *device_manager,
   int device_id = clutter_input_device_get_device_id (device);
 
   destroy_device_monitor (backend, device_id);
+
+  /* If the device the user last interacted goes away, check again pointer
+   * visibility.
+   */
+  if (backend->current_device_id == device_id)
+    {
+      MetaCursorTracker *cursor_tracker = meta_cursor_tracker_get_for_screen (NULL);
+      gboolean has_touchscreen, has_pointing_device;
+      ClutterInputDeviceType device_type;
+
+      device_type = clutter_input_device_get_device_type (device);
+      has_touchscreen = check_has_slave_touchscreen (device_manager);
+
+      if (device_type == CLUTTER_TOUCHSCREEN_DEVICE && has_touchscreen)
+        {
+          /* There's more touchscreens left, keep the pointer hidden */
+          meta_cursor_tracker_set_pointer_visible (cursor_tracker, FALSE);
+        }
+      else if (device_type != CLUTTER_KEYBOARD_DEVICE)
+        {
+          has_pointing_device = check_has_pointing_device (device_manager);
+          meta_cursor_tracker_set_pointer_visible (cursor_tracker,
+                                                   has_pointing_device &&
+                                                   !has_touchscreen);
+        }
+    }
 }
 
 static MetaMonitorManager *
@@ -178,7 +253,9 @@ meta_backend_real_post_init (MetaBackend *backend)
                                                     NULL, (GDestroyNotify) g_object_unref);
 
   {
+    MetaCursorTracker *cursor_tracker;
     ClutterDeviceManager *manager;
+    gboolean has_touchscreen = FALSE;
     GSList *devices, *l;
 
     /* Create the core device monitor. */
@@ -196,8 +273,12 @@ meta_backend_real_post_init (MetaBackend *backend)
       {
         ClutterInputDevice *device = l->data;
         on_device_added (manager, device, backend);
+        has_touchscreen |= device_is_slave_touchscreen (device);
       }
 
+    cursor_tracker = meta_cursor_tracker_get_for_screen (NULL);
+    meta_cursor_tracker_set_pointer_visible (cursor_tracker, !has_touchscreen);
+
     g_slist_free (devices);
   }