[mutter] input-settings: detect trackball using udev ID_INPUT_TRACKBALL

[Jonas Ådahl <jadahl src gnome org>]

commit 8685de9607f85e51bd50abf214dffedb17d019d2
Author: Tony Novak <afn2 cornell edu>
Date:   Mon Sep 17 15:31:16 2018 -0400

    input-settings: detect trackball using udev ID_INPUT_TRACKBALL
    
    Previously, trackballs were detected based on the presence of the
    substring "trackball" in the device name. This had the downside of
    missing devices, such as the Kensington Expert Mouse, which don't have
    "trackball" in their names.
    
    Rather than depending on the device name, use the ID_INPUT_TRACKBALL
    property from udev to determine whether or not to treat a device as a
    trackball.
    
    This adds a new function, `is_trackball_device`, to MetaInputEvents, and
    eliminates the `meta_input_device_is_trackball` function.
    
    Fixes: https://gitlab.gnome.org/GNOME/mutter/issues/258

 src/backends/meta-input-settings-private.h       |  4 ++--
 src/backends/meta-input-settings.c               | 25 +++++-------------------
 src/backends/native/meta-input-settings-native.c |  8 +++++---
 src/backends/x11/meta-input-settings-x11.c       |  9 +++++----
 4 files changed, 17 insertions(+), 29 deletions(-)
---
diff --git a/src/backends/meta-input-settings-private.h b/src/backends/meta-input-settings-private.h
index 893d4ec23..8e037cb5f 100644
--- a/src/backends/meta-input-settings-private.h
+++ b/src/backends/meta-input-settings-private.h
@@ -115,6 +115,8 @@ struct _MetaInputSettingsClass
                                   GDesktopStylusButtonAction  tertiary);
   gboolean (* has_two_finger_scroll) (MetaInputSettings  *settings,
                                       ClutterInputDevice *device);
+  gboolean (* is_trackball_device) (MetaInputSettings  *settings,
+                                    ClutterInputDevice *device);
 };
 
 GSettings *           meta_input_settings_get_tablet_settings (MetaInputSettings  *settings,
@@ -141,6 +143,4 @@ WacomDevice * meta_input_settings_get_tablet_wacom_device (MetaInputSettings *se
                                                            ClutterInputDevice *device);
 #endif
 
-gboolean meta_input_device_is_trackball (ClutterInputDevice *device);
-
 #endif /* META_INPUT_SETTINGS_PRIVATE_H */
diff --git a/src/backends/meta-input-settings.c b/src/backends/meta-input-settings.c
index fd3ba3dec..48ebe59c6 100644
--- a/src/backends/meta-input-settings.c
+++ b/src/backends/meta-input-settings.c
@@ -709,22 +709,6 @@ update_touchpad_send_events (MetaInputSettings  *input_settings,
     }
 }
 
-gboolean
-meta_input_device_is_trackball (ClutterInputDevice *device)
-{
-  gboolean is_trackball;
-  char *name;
-
-  if (clutter_input_device_get_device_mode (device) == CLUTTER_INPUT_MODE_MASTER)
-    return FALSE;
-
-  name = g_ascii_strdown (clutter_input_device_get_device_name (device), -1);
-  is_trackball = strstr (name, "trackball") != NULL;
-  g_free (name);
-
-  return is_trackball;
-}
-
 static void
 update_trackball_scroll_button (MetaInputSettings  *input_settings,
                                 ClutterInputDevice *device)
@@ -733,11 +717,12 @@ update_trackball_scroll_button (MetaInputSettings  *input_settings,
   MetaInputSettingsPrivate *priv;
   guint button;
 
-  if (device && !meta_input_device_is_trackball (device))
-    return;
-
   priv = meta_input_settings_get_instance_private (input_settings);
   input_settings_class = META_INPUT_SETTINGS_GET_CLASS (input_settings);
+
+  if (device && !input_settings_class->is_trackball_device (input_settings, device))
+    return;
+
   /* This key is 'i' in the schema but it also specifies a minimum
    * range of 0 so the cast here is safe. */
   button = (guint) g_settings_get_int (priv->trackball_settings, "scroll-wheel-emulation-button");
@@ -756,7 +741,7 @@ update_trackball_scroll_button (MetaInputSettings  *input_settings,
         {
           device = devices->data;
 
-          if (meta_input_device_is_trackball (device))
+          if (input_settings_class->is_trackball_device (input_settings, device))
             input_settings_class->set_scroll_button (input_settings, device, button);
 
           devices = devices->next;
diff --git a/src/backends/native/meta-input-settings-native.c 
b/src/backends/native/meta-input-settings-native.c
index 7450725f1..7ff94e2db 100644
--- a/src/backends/native/meta-input-settings-native.c
+++ b/src/backends/native/meta-input-settings-native.c
@@ -398,9 +398,10 @@ is_mouse_device (ClutterInputDevice *device)
 }
 
 static gboolean
-is_trackball_device (ClutterInputDevice *device)
+meta_input_settings_native_is_trackball_device (MetaInputSettings  *settings,
+                                                ClutterInputDevice *device)
 {
-  return meta_input_device_is_trackball (device);
+  return has_udev_property (device, "ID_INPUT_TRACKBALL");
 }
 
 static void
@@ -419,7 +420,7 @@ meta_input_settings_native_set_trackball_accel_profile (MetaInputSettings
                                                         ClutterInputDevice         *device,
                                                         GDesktopPointerAccelProfile profile)
 {
-  if (!is_trackball_device (device))
+  if (!meta_input_settings_native_is_trackball_device (settings, device))
     return;
 
   set_device_accel_profile (device, profile);
@@ -588,6 +589,7 @@ meta_input_settings_native_class_init (MetaInputSettingsNativeClass *klass)
   input_settings_class->set_stylus_button_map = meta_input_settings_native_set_stylus_button_map;
 
   input_settings_class->has_two_finger_scroll = meta_input_settings_native_has_two_finger_scroll;
+  input_settings_class->is_trackball_device = meta_input_settings_native_is_trackball_device;
 }
 
 static void
diff --git a/src/backends/x11/meta-input-settings-x11.c b/src/backends/x11/meta-input-settings-x11.c
index cfcdf2ece..7e1f03520 100644
--- a/src/backends/x11/meta-input-settings-x11.c
+++ b/src/backends/x11/meta-input-settings-x11.c
@@ -500,10 +500,10 @@ is_mouse (MetaInputSettings  *settings,
 }
 
 static gboolean
-is_trackball (MetaInputSettings  *settings,
-              ClutterInputDevice *device)
+meta_input_settings_x11_is_trackball_device (MetaInputSettings  *settings,
+                                             ClutterInputDevice *device)
 {
-  return meta_input_device_is_trackball (device);
+  return has_udev_property (settings, device, "ID_INPUT_TRACKBALL");
 }
 
 static void
@@ -566,7 +566,7 @@ meta_input_settings_x11_set_trackball_accel_profile (MetaInputSettings
                                                      ClutterInputDevice         *device,
                                                      GDesktopPointerAccelProfile profile)
 {
-  if (!is_trackball (settings, device))
+  if (!meta_input_settings_x11_is_trackball_device (settings, device))
     return;
 
   set_device_accel_profile (device, profile);
@@ -852,6 +852,7 @@ meta_input_settings_x11_class_init (MetaInputSettingsX11Class *klass)
   input_settings_class->set_stylus_button_map = meta_input_settings_x11_set_stylus_button_map;
 
   input_settings_class->has_two_finger_scroll = meta_input_settings_x11_has_two_finger_scroll;
+  input_settings_class->is_trackball_device = meta_input_settings_x11_is_trackball_device;
 }
 
 static void