LayoutTransition

Kotlin |Java

open class LayoutTransition

kotlin.Any
↳	android.animation.LayoutTransition

This class enables automatic animations on layout changes in ViewGroup objects. To enable transitions for a layout container, create a LayoutTransition object and set it on any ViewGroup by calling ViewGroup.setLayoutTransition(LayoutTransition). This will cause default animations to run whenever items are added to or removed from that container. To specify custom animations, use the setAnimator() method.

One of the core concepts of these transition animations is that there are two types of changes that cause the transition and four different animations that run because of those changes. The changes that trigger the transition are items being added to a container (referred to as an "appearing" transition) or removed from a container (also known as "disappearing"). Setting the visibility of views (between GONE and VISIBLE) will trigger the same add/remove logic. The animations that run due to those events are one that animates items being added, one that animates items being removed, and two that animate the other items in the container that change due to the add/remove occurrence. Users of the transition may want different animations for the changing items depending on whether they are changing due to an appearing or disappearing event, so there is one animation for each of these variations of the changing event. Most of the API of this class is concerned with setting up the basic properties of the animations used in these four situations, or with setting up custom animations for any or all of the four.

By default, the DISAPPEARING animation begins immediately, as does the CHANGE_APPEARING animation. The other animations begin after a delay that is set to the default duration of the animations. This behavior facilitates a sequence of animations in transitions as follows: when an item is being added to a layout, the other children of that container will move first (thus creating space for the new item), then the appearing animation will run to animate the item being added. Conversely, when an item is removed from a container, the animation to remove it will run first, then the animations of the other children in the layout will run (closing the gap created in the layout when the item was removed). If this default choreography behavior is not desired, the setDuration(int,long) and setStartDelay(int,long) of any or all of the animations can be changed as appropriate. Keep in mind, however, that if you start an APPEARING animation before a DISAPPEARING animation is completed, the DISAPPEARING animation stops, and any effects from the DISAPPEARING animation are reverted. If you instead start a DISAPPEARING animation before an APPEARING animation is completed, a similar set of effects occurs for the APPEARING animation.

The animations specified for the transition, both the defaults and any custom animations set on the transition object, are templates only. That is, these animations exist to hold the basic animation properties, such as the duration, start delay, and properties being animated. But the actual target object, as well as the start and end values for those properties, are set automatically in the process of setting up the transition each time it runs. Each of the animations is cloned from the original copy and the clone is then populated with the dynamic values of the target being animated (such as one of the items in a layout container that is moving as a result of the layout event) as well as the values that are changing (such as the position and size of that object). The actual values that are pushed to each animation depends on what properties are specified for the animation. For example, the default CHANGE_APPEARING animation animates the left, top, right, bottom, scrollX, and scrollY properties. Values for these properties are updated with the pre- and post-layout values when the transition begins. Custom animations will be similarly populated with the target and values being animated, assuming they use ObjectAnimator objects with property names that are known on the target object.

This class, and the associated XML flag for containers, animateLayoutChanges="true", provides a simple utility meant for automating changes in straightforward situations. Using LayoutTransition at multiple levels of a nested view hierarchy may not work due to the interrelationship of the various levels of layout. Also, a container that is being scrolled at the same time as items are being added or removed is probably not a good candidate for this utility, because the before/after locations calculated by LayoutTransition may not match the actual locations when the animations finish due to the container being scrolled as the animations are running. You can work around that particular issue by disabling the 'changing' animations by setting the CHANGE_APPEARING and CHANGE_DISAPPEARING animations to null, and setting the startDelay of the other animations appropriately.

Summary

Nested classes
abstract	`TransitionListener` This interface is used for listening to starting and ending events for transitions.

Constants
static Int	`APPEARING` A flag indicating the animation that runs on those items that are appearing in the container.
static Int	`CHANGE_APPEARING` A flag indicating the animation that runs on those items that are changing due to a new item appearing in the container.
static Int	`CHANGE_DISAPPEARING` A flag indicating the animation that runs on those items that are changing due to an item disappearing from the container.
static Int	`CHANGING` A flag indicating the animation that runs on those items that are changing due to a layout change not caused by items being added to or removed from the container.
static Int	`DISAPPEARING` A flag indicating the animation that runs on those items that are disappearing from the container.

Public constructors
`LayoutTransition()` Constructs a LayoutTransition object.

Public methods
open Unit	`addChild(parent: ViewGroup!, child: View!)` This method is called by ViewGroup when a child view is about to be added to the container.
open Unit	`addTransitionListener(listener: LayoutTransition.TransitionListener!)` Add a listener that will be called when the bounds of the view change due to layout processing.
open Unit	`disableTransitionType(transitionType: Int)` Disables the specified transitionType for this LayoutTransition object.
open Unit	`enableTransitionType(transitionType: Int)` Enables the specified transitionType for this LayoutTransition object.
open Animator!	`getAnimator(transitionType: Int)` Gets the animation used during one of the transition types that may run.
open Long	`getDuration(transitionType: Int)` Gets the duration on one of the animation objects used by this transition.
open TimeInterpolator!	`getInterpolator(transitionType: Int)` Gets the interpolator on one of the animation objects used by this transition.
open Long	`getStagger(transitionType: Int)` Gets the length of time to delay between starting each animation during one of the change animations.
open Long	`getStartDelay(transitionType: Int)` Gets the start delay on one of the animation objects used by this transition.
open MutableList<LayoutTransition.TransitionListener!>!	`getTransitionListeners()` Gets the current list of listeners for layout changes.
open Unit	`hideChild(parent: ViewGroup!, child: View!)`
open Unit	`hideChild(parent: ViewGroup!, child: View!, newVisibility: Int)` This method is called by ViewGroup when a child view is about to be hidden in container.
open Boolean	`isChangingLayout()` Returns true if animations are running which animate layout-related properties.
open Boolean	`isRunning()` Returns true if any of the animations in this transition are currently running.
open Boolean	`isTransitionTypeEnabled(transitionType: Int)` Returns whether the specified transitionType is enabled for this LayoutTransition object.
open Unit	`removeChild(parent: ViewGroup!, child: View!)` This method is called by ViewGroup when a child view is about to be removed from the container.
open Unit	`removeTransitionListener(listener: LayoutTransition.TransitionListener!)` Remove a listener for layout changes.
open Unit	`setAnimateParentHierarchy(animateParentHierarchy: Boolean)` This flag controls whether CHANGE_APPEARING or CHANGE_DISAPPEARING animations will cause the default changing animation to be run on the parent hierarchy as well.
open Unit	`setAnimator(transitionType: Int, animator: Animator!)` Sets the animation used during one of the transition types that may run.
open Unit	`setDuration(transitionType: Int, duration: Long)` Sets the duration on one of the animation objects used by this transition.
open Unit	`setDuration(duration: Long)` Sets the duration to be used by all animations of this transition object.
open Unit	`setInterpolator(transitionType: Int, interpolator: TimeInterpolator!)` Sets the interpolator on one of the animation objects used by this transition.
open Unit	`setStagger(transitionType: Int, duration: Long)` Sets the length of time to delay between starting each animation during one of the change animations.
open Unit	`setStartDelay(transitionType: Int, delay: Long)` Sets the start delay on one of the animation objects used by this transition.
open Unit	`showChild(parent: ViewGroup!, child: View!)`
open Unit	`showChild(parent: ViewGroup!, child: View!, oldVisibility: Int)` This method is called by ViewGroup when a child view is about to be made visible in the container.

Parameters
`parent`	ViewGroup!: The ViewGroup to which the View is being added.
`child`	View!: The View being added to the ViewGroup.

Parameters
`parent`	ViewGroup!: The parent ViewGroup of the View being hidden.
`child`	View!: The View being hidden.
`newVisibility`	Int: The new visibility value of the child View, either `View.GONE` or `View.INVISIBLE`.

Parameters
`parent`	ViewGroup!: The ViewGroup from which the View is being removed.
`child`	View!: The View being removed from the ViewGroup.

Parameters
`transitionType`	Int: One of `CHANGE_APPEARING`, `CHANGE_DISAPPEARING`, `CHANGING`, `APPEARING`, or `DISAPPEARING`, which determines the animation whose animator is being set.
`animator`	Animator!: The animation being assigned. A value of `null` means that no animation will be run for the specified transitionType.

Parameters
`transitionType`	Int: One of `CHANGE_APPEARING`, `CHANGE_DISAPPEARING`, `CHANGING`, `APPEARING`, or `DISAPPEARING`, which determines the animation whose duration is being set.
`duration`	Long: The length of time, in milliseconds, that the specified animation should run.

Parameters
`transitionType`	Int: One of `CHANGE_APPEARING`, `CHANGE_DISAPPEARING`, `CHANGING`, `APPEARING`, or `DISAPPEARING`, which determines the animation whose interpolator is being set.
`interpolator`	TimeInterpolator!: The interpolator that the specified animation should use.

Parameters
`transitionType`	Int: A value of `CHANGE_APPEARING`, `CHANGE_DISAPPEARING`, or `CHANGING`.
`duration`	Long: The length of time, in milliseconds, to delay before launching the next animation in the sequence.

Parameters
`transitionType`	Int: One of `CHANGE_APPEARING`, `CHANGE_DISAPPEARING`, `CHANGING`, `APPEARING`, or `DISAPPEARING`, which determines the animation whose start delay is being set.
`delay`	Long: The length of time, in milliseconds, to delay before starting the animation.

Parameters
`parent`	ViewGroup!: The ViewGroup in which the View is being made visible.
`child`	View!: The View being made visible.
`oldVisibility`	Int: The previous visibility value of the child View, either `View.GONE` or `View.INVISIBLE`.

LayoutTransition

Summary

Constants

APPEARING

CHANGE_APPEARING

CHANGE_DISAPPEARING

CHANGING

DISAPPEARING

Public constructors

LayoutTransition

Public methods

addChild

addTransitionListener

disableTransitionType

enableTransitionType

getAnimator

getDuration

getInterpolator

getStagger

getStartDelay

getTransitionListeners

hideChild

hideChild

isChangingLayout

isRunning

isTransitionTypeEnabled

removeChild

removeTransitionListener

setAnimateParentHierarchy

setAnimator

setDuration

setDuration

setInterpolator

setStagger

setStartDelay

showChild

showChild