velocity specification
This is the engineering specification for the MotionObservable operator velocity that operates
on GestureRecognizer value types.
Overview
Calculate the velocity of pointer events. If element is provided, the output units are relative to that element.
Example usage:
gestureSource(gesture).velocity(in: element?)
MVP
Expose drag velocity API
Should delegate to _map. This API should only be available for streams emitting
TranslationGestureRecognizer values.
extension MotionObservable where T: TranslationGestureRecognizer {
public func velocity(in element: Element) -> MotionObservable<Point> {
return _map { gestureRecognizer in
return gestureRecognizer.velocity(in: element)
}
}
}
Expose rotation velocity API
Should delegate to _map. This API should only be available for streams emitting
RotationGestureRecognizer values.
extension MotionObservable where T: RotationGestureRecognizer {
public func velocity() -> MotionObservable<Float> {
return _map { gestureRecognizer in
return gestureRecognizer.velocity()
}
}
}
Expose scale velocity API
Should delegate to _map. This API should only be available for streams emitting
ScaleGestureRecognizer values.
extension MotionObservable where T: ScaleGestureRecognizer {
public func velocity() -> MotionObservable<Float> {
return _map { gestureRecognizer in
return gestureRecognizer.velocity()
}
}
}