custom-transitions.md

Custom transitions

The TransitionHandler interface defines a single operation to be implemented:

interface TransitionHandler<C> {

    fun onTransition(elements: List<TransitionElement<out C>>): TransitionPair

The list of TransitionElements contain all the information about the transition:

open class TransitionElement<C>(
    val configuration: C,
    val direction: TransitionDirection,
    val addedOrRemoved: Boolean,
    val identifier: Rib.Identifier,
    val view: View,
    val progressEvaluator: MultiProgressEvaluator = MultiProgressEvaluator()
)

Not how here you get access to the view being transitioned on or out.

The expected return type of TransitionPair is just:

data class TransitionPair(
    val exiting: Transition?,
    val entering: Transition?
)

Where Transition is:

interface Transition {

    fun start()

    fun end()

    fun reverse()

This practically means you are free to implement your transitions however you see fit.

You can check the framework provided implementations of TransitionHandler in the com.badoo.ribs.routing.transition.handler package to get some ideas:

• CrossFader
• Slider
• TabSwitcher

These implementations mostly add some logic over simple effect elements defined in the com.badoo.ribs.routing.transition.effect package. Feel free to use them too!