fix(study-screen): whiteboard gestures

only whiteboard gestures worked. Now, if the gestures can trigger other actions from the reviewer as well.

Author: BrayanDSO

AnkiDroid/src/main/java/com/ichi2/anki/ui/windows/reviewer/ReviewerFragment.kt

@@ -560,8 +560,12 @@ class ReviewerFragment :
             doubleBackCallback.isEnabled =
                 isEnabled && compat.isUsingSystemGestureNavigation(requireContext())
             if (whiteboardFragment == null && isEnabled) {
+                val whiteboardFragment = WhiteboardFragment()
+                whiteboardFragment.gestureFallbackListener = { gesture ->
+                    bindingMap.onGesture(gesture)
+                }
                 childFragmentManager.commit {
-                    add(R.id.whiteboard_container, WhiteboardFragment::class.java, null, WhiteboardFragment::class.jvmName)
+                    add(R.id.whiteboard_container, whiteboardFragment, WhiteboardFragment::class.jvmName)
                 }
             }
         }

AnkiDroid/src/main/java/com/ichi2/anki/ui/windows/reviewer/whiteboard/WhiteboardFragment.kt

@@ -75,6 +75,9 @@ class WhiteboardFragment :
     private var eraserPopup: PopupWindow? = null
     private var brushConfigPopup: PopupWindow? = null
 
+    /** Called when no bindings used the triggered gestures */
+    var gestureFallbackListener: ((Gesture) -> Unit)? = null
+
     override fun onViewCreated(
         view: View,
         savedInstanceState: Bundle?,
@@ -165,9 +168,12 @@ class WhiteboardFragment :
                     2 -> Gesture.TWO_FINGER_TAP
                     3 -> Gesture.THREE_FINGER_TAP
                     4 -> Gesture.FOUR_FINGER_TAP
-                    else -> null
+                    else -> return@setOnMultiTouchListener
                 }
-            gesture?.let { bindingMap.onGesture(it) }
+            val result = bindingMap.onGesture(gesture)
+            if (!result) {
+                gestureFallbackListener?.invoke(gesture)
+            }
         }
     }