GestureController: Only accept signals from the recognizing backend

Backends should usually make sure that they consume events
but just in case and while we're using touchegg and
our own pan backend at the same time for touchscreens
don't let events from other backends mess with the
current gesture.

Author: leolost2605

lib/Gestures/GestureController.vala

@@ -192,8 +192,8 @@ public class Gala.GestureController : Object {
         return recognizing;
     }
 
-    private void gesture_begin (double percentage, uint64 elapsed_time) {
-        if (!recognizing) {
+    private void gesture_begin (GestureBackend backend, double percentage, uint64 elapsed_time) {
+        if (!recognizing || backend != recognizing_backend) {
             return;
         }
 
@@ -204,8 +204,8 @@ public class Gala.GestureController : Object {
         previous_time = elapsed_time;
     }
 
-    private void gesture_update (double percentage, uint64 elapsed_time) {
-        if (!recognizing) {
+    private void gesture_update (GestureBackend backend, double percentage, uint64 elapsed_time) {
+        if (!recognizing || backend != recognizing_backend) {
             return;
         }
 
@@ -229,8 +229,8 @@ public class Gala.GestureController : Object {
         previous_delta = updated_delta;
     }
 
-    private void gesture_end (double percentage, uint64 elapsed_time) {
-        if (!recognizing) {
+    private void gesture_end (GestureBackend backend, double percentage, uint64 elapsed_time) {
+        if (!recognizing || backend != recognizing_backend) {
             return;
         }
 
@@ -325,8 +325,8 @@ public class Gala.GestureController : Object {
 
     public void cancel_gesture () {
         if (recognizing) {
+            gesture_end (recognizing_backend, previous_percentage, previous_time);
             recognizing_backend.cancel_gesture ();
-            gesture_end (previous_percentage, previous_time);
         }
     }
 }