Transition

abstract class Transition : Cloneable
kotlin.Any
   ↳ androidx.transition.Transition

A Transition holds information about animations that will be run on its targets during a scene change. Subclasses of this abstract class may choreograph several child transitions (TransitionSet or they may perform custom animations themselves. Any Transition has two main jobs: (1) capture property values, and (2) play animations based on changes to captured property values. A custom transition knows what property values on View objects are of interest to it, and also knows how to animate changes to those values. For example, the Fade transition tracks changes to visibility-related properties and is able to construct and run animations that fade items in or out based on changes to those properties.

Note: Transitions may not work correctly with either SurfaceView or TextureView, due to the way that these views are displayed on the screen. For SurfaceView, the problem is that the view is updated from a non-UI thread, so changes to the view due to transitions (such as moving and resizing the view) may be out of sync with the display inside those bounds. TextureView is more compatible with transitions in general, but some specific transitions (such as Fade) may not be compatible with TextureView because they rely on android.view.ViewOverlay functionality, which does not currently work with TextureView.

Transitions can be declared in XML resource files inside the res/transition directory. Transition resources consist of a tag name for one of the Transition subclasses along with attributes to define some of the attributes of that transition. For example, here is a minimal resource file that declares a ChangeBounds transition:

 <changeBounds/>

Note that attributes for the transition are not required, just as they are optional when declared in code; Transitions created from XML resources will use the same defaults as their code-created equivalents. Here is a slightly more elaborate example which declares a TransitionSet transition with ChangeBounds and Fade child transitions:

 <transitionSet xmlns:android="http://schemas.android.com/apk/res/android" android:transitionOrdering="sequential"> <changeBounds/> <fade android:fadingMode="fade_out"> <targets> <target android:targetId="@id/grayscaleContainer"/> </targets> </fade> </transitionSet>

In this example, the transitionOrdering attribute is used on the TransitionSet object to change from the default TransitionSet#ORDERING_TOGETHER behavior to be TransitionSet#ORDERING_SEQUENTIAL instead. Also, the Fade transition uses a fadingMode of Fade#OUT instead of the default out-in behavior. Finally, note the use of the targets sub-tag, which takes a set of {code target} tags, each of which lists a specific targetId which this transition acts upon. Use of targets is optional, but can be used to either limit the time spent checking attributes on unchanging views, or limiting the types of animations run on specific views. In this case, we know that only the grayscaleContainer will be disappearing, so we choose to limit the Fade transition to only that view.

Summary

Nested classes
abstract

Class to get the epicenter of Transition.
abstract

A transition listener receives notifications from a transition.
Constants
static Int

With #setMatchOrder(int...), chooses to match by android.view.View#getId().
static Int

With #setMatchOrder(int...), chooses to match by View instance.
static Int

With #setMatchOrder(int...), chooses to match by the android.widget.Adapter item id.
static Int

With #setMatchOrder(int...), chooses to match by android.view.View#getTransitionName().
Public constructors

Constructs a Transition object with no target objects.
<init>(context: Context!, attrs: AttributeSet!)

Perform inflation from XML and apply a class-specific base style from a theme attribute or style resource.
Public methods
open Transition.EpicenterCallback?

Returns the callback used to find the epicenter of the Transition.
open Long

Returns the duration set on this transition.
open Long

Returns the startDelay set on this transition.
open String

Returns the name of this Transition.
open Unit
setMatchOrder(vararg matches: Int)

Sets the order in which Transition matches View start and end values.
open Transition

Adds a listener to the set of listeners that are sent events through the life of an animation, such as start, repeat, and end.
open Animator?
createAnimator(sceneRoot: ViewGroup, startValues: TransitionValues?, endValues: TransitionValues?)

This method creates an animation that will be run for this transition given the information in the startValues and endValues structures captured earlier for the start and end scenes.
open Transition
setStartDelay(startDelay: Long)

Sets the startDelay of this transition.
open Rect?

Returns the epicenter as specified by the android.transition.Transition.EpicenterCallback or null if no callback exists.
open Transition
excludeTarget(target: View, exclude: Boolean)

Whether to add the given target to the list of targets to exclude from this transition.
open Transition
excludeTarget(targetId: Int, exclude: Boolean)

Whether to add the given id to the list of target ids to exclude from this transition.
open Transition
excludeTarget(targetName: String, exclude: Boolean)

Whether to add the given transitionName to the list of target transitionNames to exclude from this transition.
open Transition
excludeTarget(type: Class<Any!>, exclude: Boolean)

Whether to add the given type to the list of types to exclude from this transition.
open Transition

Removes a listener from the set listening to this animation.
open MutableList<Int!>

Returns the array of target IDs that this transition limits itself to tracking and animating.
open Unit
setPropagation(transitionPropagation: TransitionPropagation?)

Sets the method for determining Animator start delays.
open TimeInterpolator?

Returns the interpolator set on this transition.
open Transition

open Transition

Sets the interpolator of this transition.
open PathMotion

Returns the algorithm object used to interpolate along two dimensions.
open Unit

Sets the callback to use to find the epicenter of a Transition.
open Array<String!>?

Returns the set of property names used stored in the TransitionValues object passed into #captureStartValues(TransitionValues) that this transition cares about for the purposes of canceling overlapping animations.
open Transition
excludeChildren(target: View, exclude: Boolean)

Whether to add the children of given target to the list of target children to exclude from this transition.
open Transition
excludeChildren(targetId: Int, exclude: Boolean)

Whether to add the children of the given id to the list of targets to exclude from this transition.
open Transition
excludeChildren(type: Class<Any!>, exclude: Boolean)

Whether to add the given type to the list of types whose children should be excluded from this transition.
open Transition
addTarget(target: View)

Sets the target view instances that this Transition is interested in animating.
open Transition
addTarget(targetId: Int)

Adds the id of a target view that this Transition is interested in animating.
open Transition
addTarget(targetName: String)

Adds the transitionName of a target view that this Transition is interested in animating.
open Transition
addTarget(targetType: Class<Any!>)

Adds the Class of a target view that this Transition is interested in animating.
abstract Unit

Captures the values in the start scene for the properties that this transition monitors.
open String

open Transition
setDuration(duration: Long)

Sets the duration of this transition.
open TransitionValues?

This method can be called by transitions to get the TransitionValues for any particular view during the transition-playing process.
abstract Unit

Captures the values in the end scene for the properties that this transition monitors.
open TransitionPropagation?

Returns the android.transition.TransitionPropagation used to calculate Animator start delays.
open MutableList<View!>

Returns the array of target views that this transition limits itself to tracking and animating.
open Boolean

Returns whether or not the transition should create an Animator, based on the values captured during #captureStartValues(TransitionValues) and #captureEndValues(TransitionValues).
open Transition
removeTarget(target: View)

Removes the given target from the list of targets that this Transition is interested in animating.
open Transition
removeTarget(targetId: Int)

Removes the given targetId from the list of ids that this Transition is interested in animating.
open Transition
removeTarget(targetName: String)

Removes the given targetName from the list of transitionNames that this Transition is interested in animating.
open Transition
removeTarget(target: Class<Any!>)

Removes the given target from the list of targets that this Transition is interested in animating.
open MutableList<Class<Any!>!>?

Returns the list of target transitionNames that this transition limits itself to tracking and animating.
open Unit
setPathMotion(pathMotion: PathMotion?)

Sets the algorithm used to calculate two-dimensional interpolation.
open MutableList<String!>?

Returns the list of target transitionNames that this transition limits itself to tracking and animating.

Constants

MATCH_ID

static val MATCH_ID: Int

With #setMatchOrder(int...), chooses to match by android.view.View#getId(). Negative IDs will not be matched.

Value: 3

MATCH_INSTANCE

static val MATCH_INSTANCE: Int

With #setMatchOrder(int...), chooses to match by View instance.

Value: 1

MATCH_ITEM_ID

static val MATCH_ITEM_ID: Int

With #setMatchOrder(int...), chooses to match by the android.widget.Adapter item id. When android.widget.Adapter#hasStableIds() returns false, no match will be made for items.

Value: 4

MATCH_NAME

static val MATCH_NAME: Int

With #setMatchOrder(int...), chooses to match by android.view.View#getTransitionName(). Null names will not be matched.

Value: 2

Public constructors

<init>

Transition()

Constructs a Transition object with no target objects. A transition with no targets defaults to running on all target objects in the scene hierarchy (if the transition is not contained in a TransitionSet), or all target objects passed down from its parent (if it is in a TransitionSet).

<init>

Transition(context: Context!, attrs: AttributeSet!)

Perform inflation from XML and apply a class-specific base style from a theme attribute or style resource. This constructor of Transition allows subclasses to use their own base style when they are inflating.

Parameters
context Context!: The Context the transition is running in, through which it can access the current theme, resources, etc.
attrs Context!: The attributes of the XML tag that is inflating the transition.

Public methods

getEpicenterCallback

open fun getEpicenterCallback(): Transition.EpicenterCallback?

Returns the callback used to find the epicenter of the Transition. Transitions like android.transition.Explode use a point or Rect to orient the direction of travel. This is called the epicenter of the Transition and is typically centered on a touched View. The android.transition.Transition.EpicenterCallback allows a Transition to dynamically retrieve the epicenter during a Transition.

Return
Transition.EpicenterCallback?: the callback used to find the epicenter of the Transition.

getDuration

open fun getDuration(): Long

Returns the duration set on this transition. If no duration has been set, the returned value will be negative, indicating that resulting animators will retain their own durations.

Return
Long: The duration set on this transition, in milliseconds, if one has been set, otherwise returns a negative number.

getStartDelay

open fun getStartDelay(): Long

Returns the startDelay set on this transition. If no startDelay has been set, the returned value will be negative, indicating that resulting animators will retain their own startDelays.

Return
Long: The startDelay set on this transition, in milliseconds, if one has been set, otherwise returns a negative number.

getName

open fun getName(): String

Returns the name of this Transition. This name is used internally to distinguish between different transitions to determine when interrupting transitions overlap. For example, a ChangeBounds running on the same target view as another ChangeBounds should determine whether the old transition is animating to different end values and should be canceled in favor of the new transition.

By default, a Transition's name is simply the value of Class#getName(), but subclasses are free to override and return something different.

Return
String: The name of this transition.

setMatchOrder

open fun setMatchOrder(vararg matches: Int): Unit

Sets the order in which Transition matches View start and end values.

The default behavior is to match first by android.view.View#getTransitionName(), then by View instance, then by android.view.View#getId() and finally by its item ID if it is in a direct child of ListView. The caller can choose to have only some or all of the values of #MATCH_INSTANCE, #MATCH_NAME, #MATCH_ITEM_ID, and #MATCH_ID. Only the match algorithms supplied will be used to determine whether Views are the the same in both the start and end Scene. Views that do not match will be considered as entering or leaving the Scene.

Parameters
matches Int: A list of zero or more of #MATCH_INSTANCE, #MATCH_NAME, #MATCH_ITEM_ID, and #MATCH_ID. If none are provided, then the default match order will be set.

addListener

open fun addListener(listener: Transition.TransitionListener): Transition

Adds a listener to the set of listeners that are sent events through the life of an animation, such as start, repeat, and end.

Parameters
listener Transition.TransitionListener: the listener to be added to the current set of listeners for this animation.
Return
Transition: This transition object.

createAnimator

open fun createAnimator(sceneRoot: ViewGroup, startValues: TransitionValues?, endValues: TransitionValues?): Animator?

This method creates an animation that will be run for this transition given the information in the startValues and endValues structures captured earlier for the start and end scenes. Subclasses of Transition should override this method. The method should only be called by the transition system; it is not intended to be called from external classes.

This method is called by the transition's parent (all the way up to the topmost Transition in the hierarchy) with the sceneRoot and start/end values that the transition may need to set up initial target values and construct an appropriate animation. For example, if an overall Transition is a TransitionSet consisting of several child transitions in sequence, then some of the child transitions may want to set initial values on target views prior to the overall Transition commencing, to put them in an appropriate state for the delay between that start and the child Transition start time. For example, a transition that fades an item in may wish to set the starting alpha value to 0, to avoid it blinking in prior to the transition actually starting the animation. This is necessary because the scene change that triggers the Transition will automatically set the end-scene on all target views, so a Transition that wants to animate from a different value should set that value prior to returning from this method.

Additionally, a Transition can perform logic to determine whether the transition needs to run on the given target and start/end values. For example, a transition that resizes objects on the screen may wish to avoid running for views which are not present in either the start or end scenes.

If there is an animator created and returned from this method, the transition mechanism will apply any applicable duration, startDelay, and interpolator to that animation and start it. A return value of null indicates that no animation should run. The default implementation returns null.

The method is called for every applicable target object, which is stored in the TransitionValues#view field.

Parameters
sceneRoot ViewGroup: The root of the transition hierarchy.
startValues ViewGroup: The values for a specific target in the start scene.
endValues ViewGroup: The values for the target in the end scene.
Return
Animator?: A Animator to be started at the appropriate time in the overall transition for this scene change. A null value means no animation should be run.

setStartDelay

open fun setStartDelay(startDelay: Long): Transition

Sets the startDelay of this transition. By default, there is no delay (indicated by a negative number), which means that the Animator created by the transition will have its own specified startDelay. If the delay of a Transition is set, that delay will override the Animator delay.

Parameters
startDelay Long: The length of the delay, in milliseconds.
Return
Transition: This transition object.

getEpicenter

open fun getEpicenter(): Rect?

Returns the epicenter as specified by the android.transition.Transition.EpicenterCallback or null if no callback exists.

Return
Rect?: the epicenter as specified by the android.transition.Transition.EpicenterCallback or null if no callback exists.

excludeTarget

open fun excludeTarget(target: View, exclude: Boolean): Transition

Whether to add the given target to the list of targets to exclude from this transition. The exclude parameter specifies whether the target should be added to or removed from the excluded list.

Excluding targets is a general mechanism for allowing transitions to run on a view hierarchy while skipping target views that should not be part of the transition. For example, you may want to avoid animating children of a specific ListView or Spinner. Views can be excluded either by their id, or by their instance reference, or by the Class of that view (eg, Spinner).

Parameters
target View: The target to ignore when running this transition.
exclude View: Whether to add the target to or remove the target from the current list of excluded targets.
Return
Transition: This transition object.

excludeTarget

open fun excludeTarget(targetId: Int, exclude: Boolean): Transition

Whether to add the given id to the list of target ids to exclude from this transition. The exclude parameter specifies whether the target should be added to or removed from the excluded list.

Excluding targets is a general mechanism for allowing transitions to run on a view hierarchy while skipping target views that should not be part of the transition. For example, you may want to avoid animating children of a specific ListView or Spinner. Views can be excluded either by their id, or by their instance reference, or by the Class of that view (eg, Spinner).

Parameters
targetId Int: The id of a target to ignore when running this transition.
exclude Int: Whether to add the target to or remove the target from the current list of excluded targets.
Return
Transition: This transition object.

excludeTarget

open fun excludeTarget(targetName: String, exclude: Boolean): Transition

Whether to add the given transitionName to the list of target transitionNames to exclude from this transition. The exclude parameter specifies whether the target should be added to or removed from the excluded list.

Excluding targets is a general mechanism for allowing transitions to run on a view hierarchy while skipping target views that should not be part of the transition. For example, you may want to avoid animating children of a specific ListView or Spinner. Views can be excluded by their id, their instance reference, their transitionName, or by the Class of that view (eg, Spinner).

Parameters
targetName String: The name of a target to ignore when running this transition.
exclude String: Whether to add the target to or remove the target from the current list of excluded targets.
Return
Transition: This transition object.

excludeTarget

open fun excludeTarget(type: Class<Any!>, exclude: Boolean): Transition

Whether to add the given type to the list of types to exclude from this transition. The exclude parameter specifies whether the target type should be added to or removed from the excluded list.

Excluding targets is a general mechanism for allowing transitions to run on a view hierarchy while skipping target views that should not be part of the transition. For example, you may want to avoid animating children of a specific ListView or Spinner. Views can be excluded either by their id, or by their instance reference, or by the Class of that view (eg, Spinner).

Parameters
type Class<Any!>: The type to ignore when running this transition.
exclude Class<Any!>: Whether to add the target type to or remove it from the current list of excluded target types.
Return
Transition: This transition object.

removeListener

open fun removeListener(listener: Transition.TransitionListener): Transition

Removes a listener from the set listening to this animation.

Parameters
listener Transition.TransitionListener: the listener to be removed from the current set of listeners for this transition.
Return
Transition: This transition object.

getTargetIds

open fun getTargetIds(): MutableList<Int!>

Returns the array of target IDs that this transition limits itself to tracking and animating. If the array is null for both this method and #getTargets(), then this transition is not limited to specific views, and will handle changes to any views in the hierarchy of a scene change.

Return
MutableList<Int!>: the list of target IDs

setPropagation

open fun setPropagation(transitionPropagation: TransitionPropagation?): Unit

Sets the method for determining Animator start delays. When a Transition affects several Views like android.transition.Explode or android.transition.Slide, there may be a desire to have a "wave-front" effect such that the Animator start delay depends on position of the View. The TransitionPropagation specifies how the start delays are calculated.

Parameters
transitionPropagation TransitionPropagation?: The class used to determine the start delay of Animators created by this Transition. A null value indicates that no delay should be used.

getInterpolator

open fun getInterpolator(): TimeInterpolator?

Returns the interpolator set on this transition. If no interpolator has been set, the returned value will be null, indicating that resulting animators will retain their own interpolators.

Return
TimeInterpolator?: The interpolator set on this transition, if one has been set, otherwise returns null.

clone

open fun clone(): Transition

setInterpolator

open fun setInterpolator(interpolator: TimeInterpolator?): Transition

Sets the interpolator of this transition. By default, the interpolator is null, which means that the Animator created by the transition will have its own specified interpolator. If the interpolator of a Transition is set, that interpolator will override the Animator interpolator.

Parameters
interpolator TimeInterpolator?: The time interpolator used by the transition
Return
Transition: This transition object.

getPathMotion

open fun getPathMotion(): PathMotion

Returns the algorithm object used to interpolate along two dimensions. This is typically used to determine the View motion between two points.

Return
PathMotion: The algorithm object used to interpolate along two dimensions.

setEpicenterCallback

open fun setEpicenterCallback(epicenterCallback: Transition.EpicenterCallback?): Unit

Sets the callback to use to find the epicenter of a Transition. A null value indicates that there is no epicenter in the Transition and onGetEpicenter() will return null. Transitions like android.transition.Explode use a point or Rect to orient the direction of travel. This is called the epicenter of the Transition and is typically centered on a touched View. The android.transition.Transition.EpicenterCallback allows a Transition to dynamically retrieve the epicenter during a Transition.

Parameters
epicenterCallback Transition.EpicenterCallback?: The callback to use to find the epicenter of the Transition.

getTransitionProperties

open fun getTransitionProperties(): Array<String!>?

Returns the set of property names used stored in the TransitionValues object passed into #captureStartValues(TransitionValues) that this transition cares about for the purposes of canceling overlapping animations. When any transition is started on a given scene root, all transitions currently running on that same scene root are checked to see whether the properties on which they based their animations agree with the end values of the same properties in the new transition. If the end values are not equal, then the old animation is canceled since the new transition will start a new animation to these new values. If the values are equal, the old animation is allowed to continue and no new animation is started for that transition.

A transition does not need to override this method. However, not doing so will mean that the cancellation logic outlined in the previous paragraph will be skipped for that transition, possibly leading to artifacts as old transitions and new transitions on the same targets run in parallel, animating views toward potentially different end values.

Return
Array<String!>?: An array of property names as described in the class documentation for TransitionValues. The default implementation returns null.

excludeChildren

open fun excludeChildren(target: View, exclude: Boolean): Transition

Whether to add the children of given target to the list of target children to exclude from this transition. The exclude parameter specifies whether the target should be added to or removed from the excluded list.

Excluding targets is a general mechanism for allowing transitions to run on a view hierarchy while skipping target views that should not be part of the transition. For example, you may want to avoid animating children of a specific ListView or Spinner. Views can be excluded either by their id, or by their instance reference, or by the Class of that view (eg, Spinner).

Parameters
target View: The target to ignore when running this transition.
exclude View: Whether to add the target to or remove the target from the current list of excluded targets.
Return
Transition: This transition object.

excludeChildren

open fun excludeChildren(targetId: Int, exclude: Boolean): Transition

Whether to add the children of the given id to the list of targets to exclude from this transition. The exclude parameter specifies whether the children of the target should be added to or removed from the excluded list. Excluding children in this way provides a simple mechanism for excluding all children of specific targets, rather than individually excluding each child individually.

Excluding targets is a general mechanism for allowing transitions to run on a view hierarchy while skipping target views that should not be part of the transition. For example, you may want to avoid animating children of a specific ListView or Spinner. Views can be excluded either by their id, or by their instance reference, or by the Class of that view (eg, Spinner).

Parameters
targetId Int: The id of a target whose children should be ignored when running this transition.
exclude Int: Whether to add the target to or remove the target from the current list of excluded-child targets.
Return
Transition: This transition object.

excludeChildren

open fun excludeChildren(type: Class<Any!>, exclude: Boolean): Transition

Whether to add the given type to the list of types whose children should be excluded from this transition. The exclude parameter specifies whether the target type should be added to or removed from the excluded list.

Excluding targets is a general mechanism for allowing transitions to run on a view hierarchy while skipping target views that should not be part of the transition. For example, you may want to avoid animating children of a specific ListView or Spinner. Views can be excluded either by their id, or by their instance reference, or by the Class of that view (eg, Spinner).

Parameters
type Class<Any!>: The type to ignore when running this transition.
exclude Class<Any!>: Whether to add the target type to or remove it from the current list of excluded target types.
Return
Transition: This transition object.

addTarget

open fun addTarget(target: View): Transition

Sets the target view instances that this Transition is interested in animating. By default, there are no targets, and a Transition will listen for changes on every view in the hierarchy below the sceneRoot of the Scene being transitioned into. Setting targets constrains the Transition to only listen for, and act on, these views. All other views will be ignored.

The target list is like the targetId list except this list specifies the actual View instances, not the ids of the views. This is an important distinction when scene changes involve view hierarchies which have been inflated separately; different views may share the same id but not actually be the same instance. If the transition should treat those views as the same, then #addTarget(int) should be used instead of #addTarget(View). If, on the other hand, scene changes involve changes all within the same view hierarchy, among views which do not necessarily have ids set on them, then the target list of views may be more convenient.

Parameters
target View: A View on which the Transition will act, must be non-null.
Return
Transition: The Transition to which the target is added. Returning the same object makes it easier to chain calls during construction, such as transitionSet.addTransitions(new Fade()).addTarget(someView);

See Also

addTarget

open fun addTarget(targetId: Int): Transition

Adds the id of a target view that this Transition is interested in animating. By default, there are no targetIds, and a Transition will listen for changes on every view in the hierarchy below the sceneRoot of the Scene being transitioned into. Setting targetIds constrains the Transition to only listen for, and act on, views with these IDs. Views with different IDs, or no IDs whatsoever, will be ignored.

Note that using ids to specify targets implies that ids should be unique within the view hierarchy underneath the scene root.

Parameters
targetId Int: The id of a target view, must be a positive number.
Return
Transition: The Transition to which the targetId is added. Returning the same object makes it easier to chain calls during construction, such as transitionSet.addTransitions(new Fade()).addTarget(someId);

See Also

addTarget

open fun addTarget(targetName: String): Transition

Adds the transitionName of a target view that this Transition is interested in animating. By default, there are no targetNames, and a Transition will listen for changes on every view in the hierarchy below the sceneRoot of the Scene being transitioned into. Setting targetNames constrains the Transition to only listen for, and act on, views with these transitionNames. Views with different transitionNames, or no transitionName whatsoever, will be ignored.

Note that transitionNames should be unique within the view hierarchy.

Parameters
targetName String: The transitionName of a target view, must be non-null.
Return
Transition: The Transition to which the target transitionName is added. Returning the same object makes it easier to chain calls during construction, such as transitionSet.addTransitions(new Fade()).addTarget(someName);

See Also

  • ViewCompat#getTransitionName(View)

addTarget

open fun addTarget(targetType: Class<Any!>): Transition

Adds the Class of a target view that this Transition is interested in animating. By default, there are no targetTypes, and a Transition will listen for changes on every view in the hierarchy below the sceneRoot of the Scene being transitioned into. Setting targetTypes constrains the Transition to only listen for, and act on, views with these classes. Views with different classes will be ignored.

Note that any View that can be cast to targetType will be included, so if targetType is View.class, all Views will be included.

Parameters
targetType Class<Any!>: The type to include when running this transition.
Return
Transition: The Transition to which the target class was added. Returning the same object makes it easier to chain calls during construction, such as transitionSet.addTransitions(new Fade()).addTarget(ImageView.class);

captureStartValues

abstract fun captureStartValues(transitionValues: TransitionValues): Unit

Captures the values in the start scene for the properties that this transition monitors. These values are then passed as the startValues structure in a later call to #createAnimator(ViewGroup, TransitionValues, TransitionValues). The main concern for an implementation is what the properties are that the transition cares about and what the values are for all of those properties. The start and end values will be compared later during the #createAnimator(ViewGroup, TransitionValues, TransitionValues) method to determine what, if any, animations, should be run.

Subclasses must implement this method. The method should only be called by the transition system; it is not intended to be called from external classes.

Parameters
transitionValues TransitionValues: The holder for any values that the Transition wishes to store. Values are stored in the values field of this TransitionValues object and are keyed from a String value. For example, to store a view's rotation value, a transition might call transitionValues.values.put("appname:transitionname:rotation", view.getRotation()). The target view will already be stored in the transitionValues structure when this method is called.

toString

open fun toString(): String

setDuration

open fun setDuration(duration: Long): Transition

Sets the duration of this transition. By default, there is no duration (indicated by a negative number), which means that the Animator created by the transition will have its own specified duration. If the duration of a Transition is set, that duration will override the Animator duration.

Parameters
duration Long: The length of the animation, in milliseconds.
Return
Transition: This transition object.

getTransitionValues

open fun getTransitionValues(view: View, start: Boolean): TransitionValues?

This method can be called by transitions to get the TransitionValues for any particular view during the transition-playing process. This might be necessary, for example, to query the before/after state of related views for a given transition.

captureEndValues

abstract fun captureEndValues(transitionValues: TransitionValues): Unit

Captures the values in the end scene for the properties that this transition monitors. These values are then passed as the endValues structure in a later call to #createAnimator(ViewGroup, TransitionValues, TransitionValues). The main concern for an implementation is what the properties are that the transition cares about and what the values are for all of those properties. The start and end values will be compared later during the #createAnimator(ViewGroup, TransitionValues, TransitionValues) method to determine what, if any, animations, should be run.

Subclasses must implement this method. The method should only be called by the transition system; it is not intended to be called from external classes.

Parameters
transitionValues TransitionValues: The holder for any values that the Transition wishes to store. Values are stored in the values field of this TransitionValues object and are keyed from a String value. For example, to store a view's rotation value, a transition might call transitionValues.values.put("appname:transitionname:rotation", view.getRotation()). The target view will already be stored in the transitionValues structure when this method is called.

getPropagation

open fun getPropagation(): TransitionPropagation?

Returns the android.transition.TransitionPropagation used to calculate Animator start delays. When a Transition affects several Views like android.transition.Explode or android.transition.Slide, there may be a desire to have a "wave-front" effect such that the Animator start delay depends on position of the View. The TransitionPropagation specifies how the start delays are calculated.

Return
TransitionPropagation?: the android.transition.TransitionPropagation used to calculate Animator start delays. This is null by default.

getTargets

open fun getTargets(): MutableList<View!>

Returns the array of target views that this transition limits itself to tracking and animating. If the array is null for both this method and #getTargetIds(), then this transition is not limited to specific views, and will handle changes to any views in the hierarchy of a scene change.

Return
MutableList<View!>: the list of target views

isTransitionRequired

open fun isTransitionRequired(startValues: TransitionValues?, endValues: TransitionValues?): Boolean

Returns whether or not the transition should create an Animator, based on the values captured during #captureStartValues(TransitionValues) and #captureEndValues(TransitionValues). The default implementation compares the property values returned from #getTransitionProperties(), or all property values if getTransitionProperties() returns null. Subclasses may override this method to provide logic more specific to the transition implementation.

Parameters
startValues TransitionValues?: the values from captureStartValues, This may be null if the View did not exist in the start state.
endValues TransitionValues?: the values from captureEndValues. This may be null if the View did not exist in the end state.

removeTarget

open fun removeTarget(target: View): Transition

Removes the given target from the list of targets that this Transition is interested in animating.

Parameters
target View: The target view, must be non-null.
Return
Transition: Transition The Transition from which the target is removed. Returning the same object makes it easier to chain calls during construction, such as transitionSet.addTransitions(new Fade()).removeTarget(someView);

removeTarget

open fun removeTarget(targetId: Int): Transition

Removes the given targetId from the list of ids that this Transition is interested in animating.

Parameters
targetId Int: The id of a target view, must be a positive number.
Return
Transition: The Transition from which the targetId is removed. Returning the same object makes it easier to chain calls during construction, such as transitionSet.addTransitions(new Fade()).removeTargetId(someId);

removeTarget

open fun removeTarget(targetName: String): Transition

Removes the given targetName from the list of transitionNames that this Transition is interested in animating.

Parameters
targetName String: The transitionName of a target view, must not be null.
Return
Transition: The Transition from which the targetName is removed. Returning the same object makes it easier to chain calls during construction, such as transitionSet.addTransitions(new Fade()).removeTargetName(someName);

removeTarget

open fun removeTarget(target: Class<Any!>): Transition

Removes the given target from the list of targets that this Transition is interested in animating.

Parameters
target Class<Any!>: The type of the target view, must be non-null.
Return
Transition: Transition The Transition from which the target is removed. Returning the same object makes it easier to chain calls during construction, such as transitionSet.addTransitions(new Fade()).removeTarget(someType);

getTargetTypes

open fun getTargetTypes(): MutableList<Class<Any!>!>?

Returns the list of target transitionNames that this transition limits itself to tracking and animating. If the list is null or empty for #getTargetIds(), #getTargets(), #getTargetNames(), and #getTargetTypes() then this transition is not limited to specific views, and will handle changes to any views in the hierarchy of a scene change.

Return
MutableList<Class<Any!>!>?: the list of target Types

setPathMotion

open fun setPathMotion(pathMotion: PathMotion?): Unit

Sets the algorithm used to calculate two-dimensional interpolation.

Transitions such as android.transition.ChangeBounds move Views, typically in a straight path between the start and end positions. Applications that desire to have these motions move in a curve can change how Views interpolate in two dimensions by extending PathMotion and implementing android.transition.PathMotion#getPath(float, float, float, float).

Parameters
pathMotion PathMotion?: Algorithm object to use for determining how to interpolate in two dimensions. If null, a straight-path algorithm will be used.

getTargetNames

open fun getTargetNames(): MutableList<String!>?

Returns the list of target transitionNames that this transition limits itself to tracking and animating. If the list is null or empty for #getTargetIds(), #getTargets(), #getTargetNames(), and #getTargetTypes() then this transition is not limited to specific views, and will handle changes to any views in the hierarchy of a scene change.

Return
MutableList<String!>?: the list of target transitionNames