Tossable specification
This is the engineering specification for the Tossable interaction.
Overview
The tossable interaction allows an element to be dragged and tossed to a destination.
Example use:
let tossable = Tossable(position: propertyOf(view).center,
to: propertyOf(targetView).center,
containerView: view,
springSource: popSpringSource)
MVP
Expose a Tossable type
Subclass the AttachWithSpring interaction.
public class Tossable: AttachWithSpring
Expose configurable values
All property values should be readonly, all stream values should be settable.
class Tossable {
/** A stream that emits the pan gesture's velocity when the gesture ends. */
public var initialVelocityStream: MotionObservable<CGPoint>
Expose an initializer
class Tossable {
public init(position: ReactiveProperty<CGPoint>,
to destination: ReactiveProperty<CGPoint>,
containerView: UIView,
springSource: SpringSource<CGPoint>,
panGestureRecognizer: UIPanGestureRecognizer? = nil)
}
Create a pan gesture recognizer if one was not provided
class Tossable {
init(...) {
let panGestureRecognizer = panGestureRecognizer ?? UIPanGestureRecognizer()
if panGestureRecognizer.view == nil {
containerView.addGestureRecognizer(panGestureRecognizer)
}
...
Create a translation stream
class Tossable {
init(...) {
...
let dragStream = gestureSource(panGestureRecognizer)
let translationStream = dragStream.translated(from: position, in: containerView)
...
Store the initial velocity stream
class Tossable {
init(...) {
...
self.initialVelocityStream = dragStream.onRecognitionState(.ended).velocity(in: container)
...
Call super and store the position stream
class Tossable {
init(...) {
...
super.init(position: position, to: destination, springSource: springSource)
self.positionStream = self.positionStream.toggled(with: translationStream)
}