Android Code Snippet Swipe left-right between activities

Sub Globals
    Dim Xprevious As Float
End sub

Sub Activity_Resume   
    Xprevious = 0
End Sub

Sub Activity_Touch (Action As Int, X As Float, Y As Float)
    
    If Action= Activity.ACTION_MOVE Then
        If Xprevious = 0 Then Xprevious = X
    End If
    If Action = Activity.ACTION_UP Then       
        If X > 0 And X - Xprevious > 400 And Xprevious > 0 Then  '400 = swipe distance
            Log("right")
            StartActivity("Right")
        Else
            If X > 0 And X - Xprevious < -400  Then        '-400 = swipe distance
                Log("left")
                StartActivity("Left")           
            End If
        End If
        Xprevious = 0       
    End If
End Sub