Parallax

Kotlin |Java

abstract class Parallax<PropertyT : Property<Any!, Any!>!>

kotlin.Any
↳	androidx.leanback.widget.Parallax

Known Direct Subclasses RecyclerViewParallax RecyclerViewParallax Implementation of Parallax class for RecyclerView.

Known Indirect Subclasses DetailsParallax DetailsParallax Subclass of Parallax object that tracks overview row's top and bottom edge in DetailsFragment or DetailsSupportFragment.

Parallax tracks a list of dynamic Propertys typically representing foreground UI element positions on screen. Parallax keeps a list of ParallaxEffect objects which define rules to mapping property values to ParallaxTarget.

Example: // when Property "var1" changes from 15 to max value, perform parallax effect to // change myView's translationY from 0 to 100. Parallax parallax = new Parallax() {...}; p1 = parallax.addProperty("var1"); parallax.addEffect(p1.at(15), p1.atMax()) .target(myView, PropertyValuesHolder.ofFloat("translationY", 0, 100));

To create a ParallaxEffect, user calls addEffect(PropertyMarkerValue[]) with a list of PropertyMarkerValue which defines the range of Parallax.IntProperty or Parallax.FloatProperty. Then user adds ParallaxTarget into ParallaxEffect.

App may subclass Parallax.IntProperty or Parallax.FloatProperty to supply additional information about how to retrieve Property value. RecyclerViewParallax is a great example of Parallax implementation tracking child view positions on screen.

Restrictions of properties
• FloatProperty and IntProperty cannot be mixed in one Parallax
• Values must be in ascending order.
• If the UI element is unknown above screen, use UNKNOWN_BEFORE.
• if the UI element is unknown below screen, use UNKNOWN_AFTER.
• UNKNOWN_BEFORE and UNKNOWN_AFTER are not allowed to be next to each other.

These rules will be verified at runtime.

Subclass must override updateValues() to update property values and perform ParallaxEffects. Subclass may call updateValues() automatically e.g. RecyclerViewParallax calls updateValues() in RecyclerView scrolling. App might call updateValues() manually when Parallax is unaware of the value change. For example, when a slide transition is running, RecyclerViewParallax is unaware of translation value changes; it's the app's responsibility to call updateValues() in every frame of animation.

Summary

Nested classes
open	FloatProperty FloatProperty provide access to an index based integer type property inside Parallax.
open	IntProperty IntProperty provide access to an index based integer type property inside Parallax.
open	PropertyMarkerValue Class holding a fixed value for a Property in Parallax.

Public constructors
<init>() Parallax tracks a list of dynamic Propertys typically representing foreground UI element positions on screen.

Public methods
open ParallaxEffect!	addEffect(vararg ranges: Parallax.PropertyMarkerValue<Any!>!) Create a ParallaxEffect object that will track source variable changes within a provided set of ranges.
PropertyT	addProperty(name: String!) Add a new IntProperty in the Parallax object.
abstract PropertyT	createProperty(name: String!, index: Int) Create a new Property object.
open MutableList<ParallaxEffect!>!	getEffects() Returns a list of ParallaxEffect object which defines rules to perform mapping to multiple ParallaxTargets.
abstract Float	getMaxValue() Return the max value which is typically size of parent visible area, e.
MutableList<PropertyT>!	getProperties()
open Unit	removeAllEffects() Remove all ParallaxEffect objects.
open Unit	removeEffect(effect: ParallaxEffect!) Remove the ParallaxEffect object.
open Unit	updateValues() Update property values and perform ParallaxEffects.

Public constructors

<init>

Parallax()

Parallax tracks a list of dynamic Propertys typically representing foreground UI element positions on screen. Parallax keeps a list of ParallaxEffect objects which define rules to mapping property values to ParallaxTarget.

Example: // when Property "var1" changes from 15 to max value, perform parallax effect to // change myView's translationY from 0 to 100. Parallax parallax = new Parallax() {...}; p1 = parallax.addProperty("var1"); parallax.addEffect(p1.at(15), p1.atMax()) .target(myView, PropertyValuesHolder.ofFloat("translationY", 0, 100));

To create a ParallaxEffect, user calls addEffect(PropertyMarkerValue[]) with a list of PropertyMarkerValue which defines the range of Parallax.IntProperty or Parallax.FloatProperty. Then user adds ParallaxTarget into ParallaxEffect.

App may subclass Parallax.IntProperty or Parallax.FloatProperty to supply additional information about how to retrieve Property value. RecyclerViewParallax is a great example of Parallax implementation tracking child view positions on screen.

Restrictions of properties
• FloatProperty and IntProperty cannot be mixed in one Parallax
• Values must be in ascending order.
• If the UI element is