controls/io.nacular.doodle.controls.carousel/CarouselBehavior/Presenter

Presenter

Presenters own the core logic that determines what a Carousel shows at any given moment. They control which items from a Carousel's internal data are visible, how they are positioned, sized, transformed, etc. based on the Carousel's current state. Presenters can also add supplemental Views to a Carousel that aid in the presentation they provide.

Inheritors

ConstraintBasedPresenter

Constructors

Presenter

constructor()

Types

Distance

class Distance(val direction: Vector2D, val magnitude: Double)

Position

abstract class Position : Comparable<CarouselBehavior.Presenter.Position>

Provides an abstract current position of the Carousel that lets the manager "iterate" back and forward.

Presentation

data class Presentation(val items: List<Carousel.PresentedItem>, val supplementalViews: List<View> = emptyList())

Defines the list of data items to display in a Carousel as well as a list of supplemental Views the Carousel should present.

Functions

distanceToNext

abstract fun distanceToNext(carousel: Carousel<T, *>, position: CarouselBehavior.Presenter.Position, offset: Vector2D, items: (CarouselBehavior.Presenter.Position) -> Carousel.PresentedItem?): CarouselBehavior.Presenter.Distance

A Carousel will call this method when trying to do manual movement. This is a fundamentally different problem than it needs to solve when skipping through items (interpolate between indexes). This requires mapping pixel offsets to indexes. Only a Carousel's Presenter knows how items are laid out and can provide any information about "distance" between them. Hence, this API.

present

abstract fun present(carousel: Carousel<T, *>, position: CarouselBehavior.Presenter.Position, progressToNext: Float, supplementalViews: List<View>, items: (at: CarouselBehavior.Presenter.Position) -> Carousel.PresentedItem?): CarouselBehavior.Presenter.Presentation

Called by Carousel to update the Presentation it should display.

update

fun Carousel<T, *>.update()

Indicate that the stage is outdated and suggest the Carousel invoke present.