Swipe and Tap detection

'/////////////////////////////////////////////////
'TGestureControl
'/////////////////////////////////////////////////
Class TGestureControl
	Const SWIPE_NONE:Int = 0
	Const SWIPE_UP:Int = 1
	Const SWIPE_DOWN:Int = 2
	Const SWIPE_LEFT:Int = 3
	Const SWIPE_RIGHT:Int = 4
	Const SWIPE_TAP:Int = 5
	
	Field downCounter:Int = 0
	Field minDistance:Int = 100
	Field swipeType:Int = SWIPE_NONE
	Field tapMaxDistance:Int = 80 'measured diagonally
	Field tapMaxTime:Int = 30 'frames	
	Field touchStartX:Float = -1
	Field touchStartY:Float = -1
	
	Method GetSwipe:Int()
		'Return and clear the swipe type
		Local temp:Int = swipeType
		swipeType = SWIPE_NONE
		Return temp
	End Method
	
	Method Reset:Void()
		touchStartX = -1
		touchStartY = -1	
	End Method

	Method Update:Void()
		If myGame.touchDown[0] Then
			'Has the finger just been placed down?
			If touchStartX = -1 And touchStartY = -1 Then
				touchStartX = VTouchX(0)
				touchStartY = VTouchY(0)
				downCounter = 0
			Else
				downCounter += 1		
			Endif
		Else
			If touchStartX <> -1 And touchStartY <> -1 Then				
				'Has it moved far enough to be a swipe yet?
				Local newX:Float = VTouchX(0)
				Local newY:Float = VTouchY(0)
				Local diffX:Float = newX-touchStartX
				Local diffY:Float = newY-touchStartY
					
				If diffX>0 And diffX>minDistance And diffX>Abs(diffY) Then
					swipeType = SWIPE_RIGHT
					Reset()
				Elseif diffX<0 And diffX<-minDistance And Abs(diffX)>Abs(diffY) Then
					swipeType = SWIPE_LEFT
					Reset()
				Elseif diffY>0 And diffY>minDistance And diffY>Abs(diffX) Then
					swipeType = SWIPE_DOWN
					Reset()
				Elseif diffY<0 And diffY<-minDistance And Abs(diffY)>Abs(diffX) Then
					swipeType = SWIPE_UP
					Reset()
				Else
					'Is the distance small enough that we can call it a tap?
					If math.Sqrt(diffX*diffX+diffY*diffY)<=tapMaxDistance And downCounter<=tapMaxTime Then
						swipeType = SWIPE_TAP
					Else
						swipeType = SWIPE_NONE
					Endif
					Reset()
				Endif				
			Endif
		Endif	
	End Method
	
End Class

STARTS   : When TouchDown(0), and only TouchDown(0), becomes True
ENDS     : When TouchDown(0) becomes False & a touch-sequence is in progress
IS VOIDED: If TouchDown(n), where n >= 1, becomes True while a touch-sequence is in progress

touchStartX, touchStartY, touchStartTime
touchEndX, touchEndY, touchEndTime

_MAX_TAP_DELTA_TIME	'The max time allowed between start & end to be considered a SINGLE-TAP (anything longer is a HOLD event)
_MAX_TAP_DELTA_DIST	'The max distance allowed between start & end to be considered a SINGLE-TAP

_MAX_SWIPE_DELTA_TIME	'The max time allowed between start & end to still be considered a SWIPE (anything longer is a DRAG)
_MIN_SWIPE_DELTA_DIST	'The min distance required between start & end for consideration as a SWIPE (must be larger than _MAX_TAP_DELTA_DIST)

for t = 0 until 5
  if TouchDown( t ) touch-count+=1
end

select touch-count
case 1
  if TouchDown( 0 )
    if not touch-in-progress
      touch-in-progress = True

      touchStartX = TouchX
      touchStartY = TouchY
      touchStartTime = Millisecs

      ' just in case touch-sequence ends before next update
      touchEndX = TouchX
      touchEndY = TouchY
      touchEndTime = Millisecs
    else
      touchEndX = TouchX
      touchEndY = TouchY
      touchEndTime = Millisecs
    end
  else
    touch-in-progress = false
  end

case 0
  if touch-in-progress
    touch-in-progress = False

    delta-x = Abs( touchStartX - touchEndX )
    delta-y = Abs( touchStartY - touchEndY )
    delta-time = Abs( touchStartTime - touchEndTime )

    ' check for single tap
    if ((delta-x <= _MAX_TAP_DELTA_DIST) and (delta-y <= _MAX_TAP_DELTA_DIST)) and (delta-time <= _MAX_TAP_DELTA_TIME)
      ' is a single-tap

    ' check for swipe
    else if ((delta-x >= _MIN_SWIPE_DELTA_DIST) or (delta-y >= _MIN_SWIPE_DELTA_DIST)) and (delta-time <= _MAX_SWIPE_DELTA_TIME)
      if delta-x >= delta-y
        If end-x < start-x
          ' swipe left
        else
          ' swipe right
        end
      else
        if end-y < start-y
          ' swipe up
        else
          ' swipe-down
        end
      end
    end
  end
	
default
  touch-in-progress = false

end