visualize specification
This is the engineering specification for the MotionObservable operator: visualize.
Overview
visualize writes any upstream value to a visible label and emits the value without modification.
Example usage:
stream.visualize(in: runtime.visualizationElement)
upstream | downstream | label.text
20 | 20 | 20
40 | 40 | 40
80 | 80 | 80
stream.visualize(prefix: "The value is: ", in: runtime.visualizationElement)
upstream | downstream | label.text
20 | 20 | The value is: 20
40 | 40 | The value is: 40
80 | 80 | The value is: 80
MVP
Expose a visualize operator API
Use MotionObservable to implement the operator. Accept an optional prefix string and an element to which the visualization label will be added.
class MotionObservable {
public func visualize(prefix: String? = nil, in: Element) -> MotionObservable<T>
Create a new label and add it to the visualization element
Create a new label on each connection and append it to the visualization element.
Subscribe to the stream and write values to the label
Create a new label and subscribe to the upstream, writing emitted values to the label as they’re received. Flash the label with a background color in order to draw attention to the fact that the value changed.
class MotionObservable {
public func visualize(prefix: String? = nil, in: Element) -> MotionObservable<T>
let visualizationSubscription = self.asStream().toString().dedupe().subscribeToValue { value in
label.text = (prefix ?? "") + stringValue
highlight.alpha = 1
UIView.animate(withDuration: 0.3) {
highlight.alpha = 0
}
}
let subscription = self.asStream().subscribeAndForward(to: observer)
return {
visualizationSubscription.unsubscribe()
subscription.unsubscribe()
}
}
}