[mutter] clutter: Add function to find out the number of modes for a pad group

[Carlos Garnacho <carlosg src gnome org>]

commit d6fc41b73e80fe7b8320254650a3bc058fa955be
Author: Carlos Garnacho <carlosg gnome org>
Date:   Wed Dec 28 11:44:27 2016 +0100

    clutter: Add function to find out the number of modes for a pad group
    
    This is obtained in backend-dependent ways in the upper layers, seems
    better to let ClutterInputDevice provide this information.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=771098

 clutter/clutter/clutter-device-manager-private.h   |    2 ++
 clutter/clutter/clutter-input-device.c             |   19 +++++++++++++++++++
 clutter/clutter/clutter-input-device.h             |    4 ++++
 clutter/clutter/evdev/clutter-input-device-evdev.c |   14 ++++++++++++++
 4 files changed, 39 insertions(+), 0 deletions(-)
---
diff --git a/clutter/clutter/clutter-device-manager-private.h 
b/clutter/clutter/clutter-device-manager-private.h
index a554467..37b2eec 100644
--- a/clutter/clutter/clutter-device-manager-private.h
+++ b/clutter/clutter/clutter-device-manager-private.h
@@ -158,6 +158,8 @@ struct _ClutterInputDeviceClass
   gboolean (* is_mode_switch_button) (ClutterInputDevice *device,
                                       guint               group,
                                       guint               button);
+  gint (* get_group_n_modes) (ClutterInputDevice *device,
+                              gint                group);
 };
 
 /* Platform-dependent interface */
diff --git a/clutter/clutter/clutter-input-device.c b/clutter/clutter/clutter-input-device.c
index 89aa09e..686e5a8 100644
--- a/clutter/clutter/clutter-input-device.c
+++ b/clutter/clutter/clutter-input-device.c
@@ -2175,6 +2175,25 @@ clutter_input_device_get_n_mode_groups (ClutterInputDevice *device)
   return device->n_mode_groups;
 }
 
+gint
+clutter_input_device_get_group_n_modes (ClutterInputDevice *device,
+                                        gint                group)
+{
+  ClutterInputDeviceClass *device_class;
+
+  g_return_val_if_fail (CLUTTER_IS_INPUT_DEVICE (device), 0);
+  g_return_val_if_fail (clutter_input_device_get_device_type (device) ==
+                        CLUTTER_PAD_DEVICE, 0);
+  g_return_val_if_fail (group >= 0, 0);
+
+  device_class = CLUTTER_INPUT_DEVICE_GET_CLASS (device);
+
+  if (device_class->get_group_n_modes)
+    return device_class->get_group_n_modes (device, group);
+
+  return 0;
+}
+
 gboolean
 clutter_input_device_is_mode_switch_button (ClutterInputDevice *device,
                                             guint               group,
diff --git a/clutter/clutter/clutter-input-device.h b/clutter/clutter/clutter-input-device.h
index f9b3edc..f80a48c 100644
--- a/clutter/clutter/clutter-input-device.h
+++ b/clutter/clutter/clutter-input-device.h
@@ -148,6 +148,10 @@ CLUTTER_AVAILABLE_IN_ALL
 gint                    clutter_input_device_get_n_mode_groups  (ClutterInputDevice *device);
 
 CLUTTER_AVAILABLE_IN_ALL
+gint                    clutter_input_device_get_group_n_modes  (ClutterInputDevice *device,
+                                                                 gint                group);
+
+CLUTTER_AVAILABLE_IN_ALL
 gboolean                clutter_input_device_is_mode_switch_button (ClutterInputDevice *device,
                                                                     guint               group,
                                                                    guint               button);
diff --git a/clutter/clutter/evdev/clutter-input-device-evdev.c 
b/clutter/clutter/evdev/clutter-input-device-evdev.c
index 9ad8935..0dc578d 100644
--- a/clutter/clutter/evdev/clutter-input-device-evdev.c
+++ b/clutter/clutter/evdev/clutter-input-device-evdev.c
@@ -180,6 +180,19 @@ clutter_input_device_evdev_is_mode_switch_button (ClutterInputDevice *device,
   return libinput_tablet_pad_mode_group_button_is_toggle (mode_group, button) != 0;
 }
 
+static gint
+clutter_input_device_evdev_get_group_n_modes (ClutterInputDevice *device,
+                                              gint                group)
+{
+  struct libinput_device *libinput_device;
+  struct libinput_tablet_pad_mode_group *mode_group;
+
+  libinput_device = clutter_evdev_input_device_get_libinput_device (device);
+  mode_group = libinput_device_tablet_pad_get_mode_group (libinput_device, group);
+
+  return libinput_tablet_pad_mode_group_get_num_modes (mode_group);
+}
+
 static void
 clutter_input_device_evdev_class_init (ClutterInputDeviceEvdevClass *klass)
 {
@@ -192,6 +205,7 @@ clutter_input_device_evdev_class_init (ClutterInputDeviceEvdevClass *klass)
   klass->keycode_to_evdev = clutter_input_device_evdev_keycode_to_evdev;
   klass->update_from_tool = clutter_input_device_evdev_update_from_tool;
   klass->is_mode_switch_button = clutter_input_device_evdev_is_mode_switch_button;
+  klass->get_group_n_modes = clutter_input_device_evdev_get_group_n_modes;
 
   obj_props[PROP_DEVICE_MATRIX] =
     g_param_spec_boxed ("device-matrix",