[mutter/gnome-3-22] MetaInputSettings: fix two finger preference over edge scrolling logic

[Rui Matos <rtcm src gnome org>]

commit 374bba2d4e75a3f801f225565ed2c31f5ec2ceec
Author: Rui Matos <tiagomatos gmail com>
Date:   Thu Oct 27 19:25:16 2016 +0200

    MetaInputSettings: fix two finger preference over edge scrolling logic
    
    Enabling edge scrolling before disabling two finger would result in
    edge scrolling not actually being enabled because two finger is still
    enabled at the time and we bail out.
    
    This patch moves this logic to common code for both the native and X
    backends and fixes it by ensuring that both settings are never set at
    the same time and still re-checking if edge scrolling should be
    enabled after two finger scrolling gets disabled.
    
    We also simplify the code by not checking for supported/available
    settings since the underlying devices will just reject those values
    and there isn't anything we can do about it here. It's the UI's job to
    only show supported/available settings to users.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=771744

 src/backends/meta-input-settings.c               |   14 ++++
 src/backends/native/meta-input-settings-native.c |   51 +++-----------
 src/backends/x11/meta-input-settings-x11.c       |   78 ++++++----------------
 3 files changed, 44 insertions(+), 99 deletions(-)
---
diff --git a/src/backends/meta-input-settings.c b/src/backends/meta-input-settings.c
index 74cf30a..9fc6f60 100644
--- a/src/backends/meta-input-settings.c
+++ b/src/backends/meta-input-settings.c
@@ -483,6 +483,7 @@ update_touchpad_edge_scroll (MetaInputSettings *input_settings,
 {
   MetaInputSettingsClass *input_settings_class;
   gboolean edge_scroll_enabled;
+  gboolean two_finger_scroll_enabled;
   MetaInputSettingsPrivate *priv;
 
   if (device &&
@@ -492,6 +493,11 @@ update_touchpad_edge_scroll (MetaInputSettings *input_settings,
   priv = meta_input_settings_get_instance_private (input_settings);
   input_settings_class = META_INPUT_SETTINGS_GET_CLASS (input_settings);
   edge_scroll_enabled = g_settings_get_boolean (priv->touchpad_settings, "edge-scrolling-enabled");
+  two_finger_scroll_enabled = g_settings_get_boolean (priv->touchpad_settings, 
"two-finger-scrolling-enabled");
+
+  /* If both are enabled we prefer two finger. */
+  if (edge_scroll_enabled && two_finger_scroll_enabled)
+    edge_scroll_enabled = FALSE;
 
   if (device)
     {
@@ -523,6 +529,10 @@ update_touchpad_two_finger_scroll (MetaInputSettings *input_settings,
   input_settings_class = META_INPUT_SETTINGS_GET_CLASS (input_settings);
   two_finger_scroll_enabled = g_settings_get_boolean (priv->touchpad_settings, 
"two-finger-scrolling-enabled");
 
+  /* Disable edge since they can't both be set. */
+  if (two_finger_scroll_enabled)
+    update_touchpad_edge_scroll (input_settings, device);
+
   if (device)
     {
       settings_device_set_bool_setting (input_settings, device,
@@ -535,6 +545,10 @@ update_touchpad_two_finger_scroll (MetaInputSettings *input_settings,
                                  (ConfigBoolFunc) input_settings_class->set_two_finger_scroll,
                                  two_finger_scroll_enabled);
     }
+
+  /* Edge might have been disabled because two finger was on. */
+  if (!two_finger_scroll_enabled)
+    update_touchpad_edge_scroll (input_settings, device);
 }
 
 static void
diff --git a/src/backends/native/meta-input-settings-native.c 
b/src/backends/native/meta-input-settings-native.c
index 5a142f7..266d224 100644
--- a/src/backends/native/meta-input-settings-native.c
+++ b/src/backends/native/meta-input-settings-native.c
@@ -160,32 +160,16 @@ meta_input_settings_native_set_edge_scroll (MetaInputSettings            *settin
                                             ClutterInputDevice           *device,
                                             gboolean                      edge_scrolling_enabled)
 {
-  enum libinput_config_scroll_method scroll_method = 0;
   struct libinput_device *libinput_device;
-  enum libinput_config_scroll_method supported;
-  enum libinput_config_scroll_method current;
+  enum libinput_config_scroll_method current, method;
 
   libinput_device = clutter_evdev_input_device_get_libinput_device (device);
-  if (!libinput_device)
-    return;
-  supported = libinput_device_config_scroll_get_methods (libinput_device);
-  current = libinput_device_config_scroll_get_method (libinput_device);
 
-  /* Don't set edge scrolling if two-finger scrolling is enabled and available */
-  if (current == LIBINPUT_CONFIG_SCROLL_2FG)
-    return;
-
-  if (supported & LIBINPUT_CONFIG_SCROLL_EDGE &&
-      edge_scrolling_enabled)
-    {
-      scroll_method = LIBINPUT_CONFIG_SCROLL_EDGE;
-    }
-  else
-    {
-      scroll_method = LIBINPUT_CONFIG_SCROLL_NO_SCROLL;
-    }
+  method = edge_scrolling_enabled ? LIBINPUT_CONFIG_SCROLL_EDGE : LIBINPUT_CONFIG_SCROLL_NO_SCROLL;
+  current = libinput_device_config_scroll_get_method (libinput_device);
+  current &= ~LIBINPUT_CONFIG_SCROLL_EDGE;
 
-  device_set_scroll_method (libinput_device, scroll_method);
+  device_set_scroll_method (libinput_device, current | method);
 }
 
 static void
@@ -193,31 +177,16 @@ meta_input_settings_native_set_two_finger_scroll (MetaInputSettings            *
                                                   ClutterInputDevice           *device,
                                                   gboolean                      two_finger_scroll_enabled)
 {
-  enum libinput_config_scroll_method scroll_method = 0;
   struct libinput_device *libinput_device;
-  enum libinput_config_scroll_method supported;
-  enum libinput_config_scroll_method current;
+  enum libinput_config_scroll_method current, method;
 
   libinput_device = clutter_evdev_input_device_get_libinput_device (device);
-  supported = libinput_device_config_scroll_get_methods (libinput_device);
-  current = libinput_device_config_scroll_get_method (libinput_device);
-
-  if (two_finger_scroll_enabled &&
-      !(supported & LIBINPUT_CONFIG_SCROLL_2FG))
-    return;
 
-  if (two_finger_scroll_enabled)
-    {
-      scroll_method = LIBINPUT_CONFIG_SCROLL_2FG;
-    }
-  else if (current != LIBINPUT_CONFIG_SCROLL_EDGE)
-    {
-      scroll_method = LIBINPUT_CONFIG_SCROLL_NO_SCROLL;
-    }
-  else
-    return;
+  method = two_finger_scroll_enabled ? LIBINPUT_CONFIG_SCROLL_2FG : LIBINPUT_CONFIG_SCROLL_NO_SCROLL;
+  current = libinput_device_config_scroll_get_method (libinput_device);
+  current &= ~LIBINPUT_CONFIG_SCROLL_2FG;
 
-  device_set_scroll_method (libinput_device, scroll_method);
+  device_set_scroll_method (libinput_device, current | method);
 }
 
 static void
diff --git a/src/backends/x11/meta-input-settings-x11.c b/src/backends/x11/meta-input-settings-x11.c
index f595d42..332997b 100644
--- a/src/backends/x11/meta-input-settings-x11.c
+++ b/src/backends/x11/meta-input-settings-x11.c
@@ -222,32 +222,19 @@ meta_input_settings_x11_set_edge_scroll (MetaInputSettings            *settings,
                                          gboolean                      edge_scroll_enabled)
 {
   guchar values[SCROLL_METHOD_NUM_FIELDS] = { 0 }; /* 2fg, edge, button. The last value is unused */
-  guchar *defaults;
-  guchar *available;
-
-  available = get_property (device, "libinput Scroll Methods Available",
-                            XA_INTEGER, 8, SCROLL_METHOD_NUM_FIELDS);
-  defaults = get_property (device, "libinput Scroll Method Enabled",
-                           XA_INTEGER, 8, SCROLL_METHOD_NUM_FIELDS);
-  if (!available || !defaults)
-    goto out;
+  guchar *current;
 
-  memcpy (values, defaults, SCROLL_METHOD_NUM_FIELDS);
+  current = get_property (device, "libinput Scroll Method Enabled",
+                          XA_INTEGER, 8, SCROLL_METHOD_NUM_FIELDS);
+  if (!current)
+    return;
 
-  /* Don't set edge scrolling if two-finger scrolling is enabled and available */
-  if (available[SCROLL_METHOD_FIELD_EDGE] &&
-      !(available[SCROLL_METHOD_FIELD_2FG] && values[SCROLL_METHOD_FIELD_2FG]))
-    {
-      values[1] = !!edge_scroll_enabled;
-      change_property (device, "libinput Scroll Method Enabled",
-                       XA_INTEGER, 8, &values, SCROLL_METHOD_NUM_FIELDS);
-    }
+  memcpy (values, current, SCROLL_METHOD_NUM_FIELDS);
 
-out:
-  if (available)
-    meta_XFree (available);
-  if (defaults)
-    meta_XFree (defaults);
+  values[SCROLL_METHOD_FIELD_EDGE] = !!edge_scroll_enabled;
+  change_property (device, "libinput Scroll Method Enabled",
+                   XA_INTEGER, 8, &values, SCROLL_METHOD_NUM_FIELDS);
+  meta_XFree (current);
 }
 
 static void
@@ -256,44 +243,19 @@ meta_input_settings_x11_set_two_finger_scroll (MetaInputSettings            *set
                                                gboolean                      two_finger_scroll_enabled)
 {
   guchar values[SCROLL_METHOD_NUM_FIELDS] = { 0 }; /* 2fg, edge, button. The last value is unused */
-  guchar *defaults;
-  guchar *available;
-  gboolean changed;
-
-  available = get_property (device, "libinput Scroll Methods Available",
-                            XA_INTEGER, 8, SCROLL_METHOD_NUM_FIELDS);
-  defaults = get_property (device, "libinput Scroll Method Enabled",
-                           XA_INTEGER, 8, SCROLL_METHOD_NUM_FIELDS);
-  if (!available || !defaults)
-    goto out;
-
-  memcpy (values, defaults, SCROLL_METHOD_NUM_FIELDS);
-  changed = FALSE;
+  guchar *current;
 
-  if (available[SCROLL_METHOD_FIELD_2FG])
-    {
-      values[SCROLL_METHOD_FIELD_2FG] = !!two_finger_scroll_enabled;
-      changed = TRUE;
-    }
-
-  /* Disable edge scrolling when two-finger scrolling is enabled */
-  if (values[SCROLL_METHOD_FIELD_2FG] && values[SCROLL_METHOD_FIELD_EDGE])
-    {
-      values[SCROLL_METHOD_FIELD_EDGE] = 0;
-      changed = TRUE;
-    }
+  current = get_property (device, "libinput Scroll Method Enabled",
+                          XA_INTEGER, 8, SCROLL_METHOD_NUM_FIELDS);
+  if (!current)
+    return;
 
-  if (changed)
-    {
-      change_property (device, "libinput Scroll Method Enabled",
-                       XA_INTEGER, 8, &values, SCROLL_METHOD_NUM_FIELDS);
-    }
+  memcpy (values, current, SCROLL_METHOD_NUM_FIELDS);
 
-out:
-  if (available)
-    meta_XFree (available);
-  if (defaults)
-    meta_XFree (defaults);
+  values[SCROLL_METHOD_FIELD_2FG] = !!two_finger_scroll_enabled;
+  change_property (device, "libinput Scroll Method Enabled",
+                   XA_INTEGER, 8, &values, SCROLL_METHOD_NUM_FIELDS);
+  meta_XFree (current);
 }
 
 static void