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);
}
}
protected internal override void update(EventLayer eventLayer, bool allowProcessing, Clock clock)
{
var touches = eventLayer.EventManager.Touches;
var fingers = touches.Fingers;
if (fingers.Count == fingerCount)
{
Vector2 primaryFingerVec = new Vector2(fingers[0].PixelDeltaX, fingers[0].PixelDeltaY);
float primaryFingerLen = primaryFingerVec.length();
Vector2 longestLengthVec = primaryFingerVec;
float longestLength = primaryFingerLen;
if (primaryFingerLen > 0)
{
bool allVectorsSameDirection = true;
for (int i = 1; i < fingerCount && allVectorsSameDirection; ++i)
{
Vector2 testFingerVec = new Vector2(fingers[i].PixelDeltaX, fingers[i].PixelDeltaY);
float testFingerLen = testFingerVec.length();
if (testFingerLen > 0)
{
float cosTheta = primaryFingerVec.dot(ref testFingerVec) / (primaryFingerLen * testFingerLen);
if (cosTheta > 0.5f)
{
if (testFingerLen > longestLength)
{
longestLengthVec = testFingerVec;
longestLength = testFingerLen;
}
}
else
{
allVectorsSameDirection = false;
}
}
}
if (allVectorsSameDirection)
{
DeltaX = longestLengthVec.x;
DeltaY = longestLengthVec.y;
AbsoluteX = fingers[0].PixelX;
AbsoluteY = fingers[0].PixelY;
if (!gestureStarted)
{
cancelMomentum();
gestureStarted = true;
if (GestureStarted != null)
{
GestureStarted.Invoke(eventLayer, this);
}
}
didGesture = true;
averageSpeed[averageSpeedCursor] = longestLengthVec;
averageSpeedCursor++;
averageSpeedCursor %= averageSpeed.Length;
//Make sure to fire event last so momentum can be canceled if needed
if (Dragged != null)
{
Dragged.Invoke(eventLayer, this);
}
}
}
else if (gestureStarted)
{
//If we have done the gesture once and the correct number of fingers are down, keep reporting that we did the gesture
didGesture = true;
}
}
if (!didGesture)
{
if (gestureStarted)
{
momentumStarted = true;
momentum = new IntVector2(0, 0);
for (int i = 0; i < averageSpeed.Length; ++i)
{
momentum += averageSpeed[i];
}
momentum /= averageSpeed.Length;
momentumDirection = new Vector2(1.0f, 1.0f);
if (momentum.x < 0.0f)
{
momentum.x = -momentum.x;
momentumDirection.x = -1.0f;
}
if (momentum.y < 0.0f)
{
momentum.y = -momentum.y;
momentumDirection.y = -1.0f;
}
if (momentum.x < minimumMomentum)
{
momentum.x = 0.0f;
}
if (momentum.y < minimumMomentum)
{
momentum.y = 0.0f;
}
deceleration = momentum / decelerationTime;
//Important to fire event last so momentum can be canceled if needed
if (MomentumStarted != null)
{
MomentumStarted(eventLayer, this);
}
}
gestureStarted = false;
if (momentum.length2() != 0.0f)
{
momentum -= deceleration * clock.DeltaSeconds;
if (momentum.x < 0.0f)
{
momentum.x = 0.0f;
}
if (momentum.y <= 0.0f)
{
momentum.y = 0.0f;
}
Vector2 finalMomentum = momentum * momentumDirection;
DeltaX = finalMomentum.x;
DeltaY = finalMomentum.y;
if (Dragged != null)
{
Dragged.Invoke(eventLayer, this);
}
}
else if (momentumStarted)
{
momentumStarted = false;
if (MomentumEnded != null)
{
MomentumEnded.Invoke(eventLayer, this);
}
}
}
didGesture = false;
}
protected virtual void OnGestureStarted(SKGestureEventArgs e) => GestureStarted?.Invoke(this, e);