protected internal override void update(EventLayer eventLayer, bool allowProcessing, Clock clock)
{
var touches = eventLayer.EventManager.Touches;
var fingers = touches.Fingers;
if (fingers.Count == 2)
{
Finger finger1 = fingers[0];
Finger finger2 = fingers[1];
Vector2 finger1Vec = new Vector2(finger1.NrmlDeltaX, finger1.NrmlDeltaY);
Vector2 finger2Vec = new Vector2(finger2.NrmlDeltaX, finger2.NrmlDeltaY);
float finger1Len = finger1Vec.length2();
float finger2Len = finger2Vec.length2();
if (finger1Len > 0 || finger2Len > 0)
{
if (finger1Len > 0 && finger2Len > 0)
{
float cosTheta = finger1Vec.dot(ref finger2Vec) / (finger1Vec.length() * finger2Vec.length());
if (cosTheta < -0.5f && Zoom != null)
{
computeZoom(eventLayer, ref didGesture, finger1, finger2, ref finger1Vec, ref finger2Vec);
}
}
else if (finger1Len == 0 && finger2Len > 0)
{
computeZoom(eventLayer, ref didGesture, finger1, finger2, ref finger1Vec, ref finger2Vec);
}
else if (finger2Len == 0 && finger1Len > 0)
{
computeZoom(eventLayer, ref didGesture, finger1, finger2, ref finger1Vec, ref finger2Vec);
}
}
}
//Momentum
if (!didGesture)
{
if (momentum > 0.0f)
{
zoomDelta = momentum * momentumDirection;
if (!momentumStarted)
{
momentumStarted = true;
if (MomentumStarted != null)
{
MomentumStarted.Invoke(eventLayer, this);
}
}
momentum -= deceleration * clock.DeltaSeconds;
if (momentum < 0.0f)
{
momentum = 0.0f;
}
if (Zoom != null)
{
Zoom.Invoke(eventLayer, this);
}
}
else if (momentumStarted)
{
zoomDelta = 0.0f;
momentumStarted = false;
gestureStarted = false;
if (MomentumEnded != null)
{
MomentumEnded.Invoke(eventLayer, this);
}
}
}
didGesture = false;
}
private void computeZoom(EventLayer eventLayer, ref bool didGesture, Finger finger1, Finger finger2, ref Vector2 finger1Vec, ref Vector2 finger2Vec)
{
Vector2 finger1Pos = new Vector2(finger1.NrmlX, finger1.NrmlY);
Vector2 finger2Pos = new Vector2(finger2.NrmlX, finger2.NrmlY);
float currentPinchDistance = (finger1Pos - finger2Pos).length2();
Vector2 vectorSum = finger1Vec - finger2Vec;
momentumDirection = 1.0f;
zoomDelta = vectorSum.length();
momentum = zoomDelta;
deceleration = momentum / decelerationTime;
if (currentPinchDistance > lastPinchDistance)
{
zoomDelta = -zoomDelta;
momentumDirection = -1.0f;
}
didGesture = true;
lastPinchDistance = currentPinchDistance;
if (!gestureStarted)
{
gestureStarted = true;
if (GestureStarted != null)
{
GestureStarted.Invoke(eventLayer, this);
}
}
if (Zoom != null)
{
Zoom.Invoke(eventLayer, this);
}
}