[libchamplain] Don't think that left+right mouse buttons pressed mean multitouch

[Jiří Techet <jiritechet src gnome org>]

commit 99b6263cb91c51d00d04f274e9304de75b706ea3
Author: Jiří Techet <techet gmail com>
Date:   Sat Apr 9 00:17:57 2016 +0200

    Don't think that left+right mouse buttons pressed mean multitouch
    
    At the moment when both left and right mouse buttons are pressed, they
    are regarded as multitouch and start of gesture-based zoom which leads
    to strange zooming in/out while holding both mouse buttons and moving the
    cursor.
    
    Don't start gesture event when using mouse. (Maybe some of the other
    devices might make sense here too but I don't have them to test.
    Anyway, mouse is the most common one so this should be OK.)

 champlain/champlain-view.c |    7 +++++--
 1 files changed, 5 insertions(+), 2 deletions(-)
---
diff --git a/champlain/champlain-view.c b/champlain/champlain-view.c
index 62c4aa7..f7af4fc 100644
--- a/champlain/champlain-view.c
+++ b/champlain/champlain-view.c
@@ -1267,8 +1267,11 @@ zoom_gesture_begin_cb (ClutterGestureAction *gesture,
     G_GNUC_UNUSED ClutterActor *actor,
     G_GNUC_UNUSED gpointer user_data)
 {
-  /* Give up on >2 finger input */
-  return clutter_gesture_action_get_n_current_points (gesture) == 2;
+  ClutterInputDevice *device = clutter_gesture_action_get_device (gesture, 0);
+
+  /* Give up on >2 finger input and when using mouse */
+  return clutter_gesture_action_get_n_current_points (gesture) == 2 &&
+    clutter_input_device_get_device_type (device) != CLUTTER_POINTER_DEVICE;
 }