evdev: Implement keyboard repeat

The kernel keyboard repeat functionality isn't configurable and
libinput rightfully ignores it.

This implements keyboard repeat in userspace allowing for consumers to
set the initial delay and repeat intervals.

https://bugzilla.gnome.org/show_bug.cgi?id=725102

clutter/evdev/clutter-device-manager-evdev.c

@@ -72,6 +72,15 @@ struct _ClutterSeatEvdev
   xkb_led_index_t num_lock_led;
   xkb_led_index_t scroll_lock_led;
   uint32_t button_state;
+
+  /* keyboard repeat */
+  gboolean repeat;
+  guint32 repeat_delay;
+  guint32 repeat_interval;
+  guint32 repeat_key;
+  guint32 repeat_count;
+  guint32 repeat_timer;
+  ClutterInputDevice *repeat_device;
 };
 
 typedef struct _ClutterEventSource  ClutterEventSource;
@@ -206,6 +215,20 @@ remove_key (GArray  *keys,
     }
 }
 
+static void
+clear_repeat_timer (ClutterSeatEvdev *seat)
+{
+  if (seat->repeat_timer)
+    {
+      g_source_remove (seat->repeat_timer);
+      seat->repeat_timer = 0;
+      g_clear_object (&seat->repeat_device);
+    }
+}
+
+static gboolean
+keyboard_repeat (gpointer data);
+
 static void
 clutter_seat_evdev_sync_leds (ClutterSeatEvdev *seat);
 
@@ -227,7 +250,10 @@ notify_key_device (ClutterInputDevice *input_device,
    * associated with the device yet. */
   stage = _clutter_input_device_get_stage (input_device);
   if (!stage)
+    {
+      clear_repeat_timer (seat);
       return;
+    }
 
   event = _clutter_key_event_new_from_evdev (input_device,
 					     seat->core_keyboard,
@@ -253,12 +279,71 @@ notify_key_device (ClutterInputDevice *input_device,
 	}
     }
   else
+    {
       changed_state = 0;
+      clutter_event_set_flags (event, CLUTTER_EVENT_FLAG_SYNTHETIC);
+    }
 
   queue_event (event);
 
   if (update_keys && (changed_state & XKB_STATE_LEDS))
     clutter_seat_evdev_sync_leds (seat);
+
+  if (state == 0 ||             /* key release */
+      !seat->repeat ||
+      !xkb_keymap_key_repeats (xkb_state_get_keymap (seat->xkb), event->key.hardware_keycode))
+    {
+      clear_repeat_timer (seat);
+      return;
+    }
+
+  if (state == 1)               /* key press */
+    seat->repeat_count = 0;
+
+  seat->repeat_count += 1;
+  seat->repeat_key = key;
+
+  switch (seat->repeat_count)
+    {
+    case 1:
+    case 2:
+      {
+        guint32 interval;
+
+        clear_repeat_timer (seat);
+        seat->repeat_device = g_object_ref (input_device);
+
+        if (seat->repeat_count == 1)
+          interval = seat->repeat_delay;
+        else
+          interval = seat->repeat_interval;
+
+        seat->repeat_timer =
+          clutter_threads_add_timeout_full (CLUTTER_PRIORITY_EVENTS,
+                                            interval,
+                                            keyboard_repeat,
+                                            seat,
+                                            NULL);
+        return;
+      }
+    default:
+      return;
+    }
+}
+
+static gboolean
+keyboard_repeat (gpointer data)
+{
+  ClutterSeatEvdev *seat = data;
+  guint32 time;
+
+  g_return_val_if_fail (seat->repeat_device != NULL, G_SOURCE_REMOVE);
+
+  time = g_source_get_time (g_main_context_find_source_by_id (NULL, seat->repeat_timer)) / 1000;
+
+  notify_key_device (seat->repeat_device, time, seat->repeat_key, AUTOREPEAT_VALUE, FALSE);
+
+  return G_SOURCE_CONTINUE;
 }
 
 static void
@@ -642,6 +727,10 @@ clutter_seat_evdev_new (ClutterDeviceManagerEvdev *manager_evdev,
       xkb_keymap_unref (keymap);
     }
 
+  seat->repeat = TRUE;
+  seat->repeat_delay = 250;     /* ms */
+  seat->repeat_interval = 33;   /* ms */
+
   return seat;
 }
 
@@ -661,6 +750,8 @@ clutter_seat_evdev_free (ClutterSeatEvdev *seat)
   xkb_state_unref (seat->xkb);
   g_array_free (seat->keys, TRUE);
 
+  clear_repeat_timer (seat);
+
   libinput_seat_unref (seat->libinput_seat);
 
   g_free (seat);
@@ -773,6 +864,9 @@ clutter_device_manager_evdev_remove_device (ClutterDeviceManager *manager,
   seat->devices = g_slist_remove (seat->devices, device);
   priv->devices = g_slist_remove (priv->devices, device);
 
+  if (seat->repeat_timer && seat->repeat_device == device)
+    clear_repeat_timer (seat);
+
   g_object_unref (device);
 }
 
@@ -1480,3 +1574,34 @@ clutter_evdev_set_pointer_constrain_callback (ClutterDeviceManager            *e
   priv->constrain_data = user_data;
   priv->constrain_data_notify = user_data_notify;
 }
+
+/**
+ * clutter_evdev_set_keyboard_repeat:
+ * @evdev: the #ClutterDeviceManager created by the evdev backend
+ * @repeat: whether to enable or disable keyboard repeat events
+ * @delay: the delay in ms between the hardware key press event and
+ * the first synthetic event
+ * @interval: the period in ms between consecutive synthetic key
+ * press events
+ *
+ * Enables or disables sythetic key press events, allowing for initial
+ * delay and interval period to be specified.
+ */
+void
+clutter_evdev_set_keyboard_repeat (ClutterDeviceManager *evdev,
+                                   gboolean              repeat,
+                                   guint32               delay,
+                                   guint32               interval)
+{
+  ClutterDeviceManagerEvdev *manager_evdev;
+  ClutterSeatEvdev *seat;
+
+  g_return_if_fail (CLUTTER_IS_DEVICE_MANAGER_EVDEV (evdev));
+
+  manager_evdev = CLUTTER_DEVICE_MANAGER_EVDEV (evdev);
+  seat = manager_evdev->priv->main_seat;
+
+  seat->repeat = repeat;
+  seat->repeat_delay = delay;
+  seat->repeat_interval = interval;
+}

clutter/evdev/clutter-evdev.h

@@ -85,6 +85,10 @@ void  clutter_evdev_set_pointer_constrain_callback (ClutterDeviceManager
 void               clutter_evdev_set_keyboard_map   (ClutterDeviceManager *evdev,
 						     struct xkb_keymap    *keymap);
 
+void clutter_evdev_set_keyboard_repeat (ClutterDeviceManager *evdev,
+                                        gboolean              repeat,
+                                        guint32               delay,
+                                        guint32               interval);
 
 G_END_DECLS