Transition

const val MATCH_ID = 3: Int

With setMatchOrder, chooses to match by getId. Negative IDs will not be matched.

const val MATCH_INSTANCE = 1: Int

With setMatchOrder, chooses to match by View instance.

const val MATCH_ITEM_ID = 4: Int

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

const val MATCH_NAME = 2: Int

With setMatchOrder, chooses to match by getTransitionName. Null names will not be matched.

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).

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.

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.

fun addTarget(targetId: @IdRes 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.

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.

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.

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 should be used instead of addTarget. 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.

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. 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 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.

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. 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 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.

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 view field.

fun excludeChildren(targetId: @IdRes 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).

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).

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).

fun excludeTarget(targetId: @IdRes 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).

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).

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).

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).

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.

fun getEpicenter(): Rect?

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

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.

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.

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 getName, but subclasses are free to override and return something different.

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.

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.

fun getRootTransition(): Transition

If this Transition is not part of a TransitionSet, this is returned. If it is part of a TransitionSet, the parent TransitionSets are walked until a TransitionSet is found that isn't contained in another TransitionSet.

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.

fun getTargetIds(): (Mutable)List<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.

fun getTargetNames(): (Mutable)List<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.

fun getTargetTypes(): (Mutable)List<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.

fun getTargets(): (Mutable)List<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.

fun getTransitionProperties(): Array<String!>?

Returns the set of property names used stored in the TransitionValues object passed into captureStartValues 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.

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.

fun isSeekingSupported(): Boolean

Returns true if the Transition can be used by controlDelayedTransition. This means that any the state must be ready before any Animator returned by createAnimator has started and if the Animator has ended, it must be able to restore the state when starting in reverse. If a Transition must know when the entire transition has ended, a TransitionListener can be added to getRootTransition and it can listen for onTransitionEnd.

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

Returns whether or not the transition should create an Animator, based on the values captured during captureStartValues and captureEndValues. 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.

fun removeListener(listener: Transition.TransitionListener): Transition

Removes a listener from the set listening to this animation.

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

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

fun removeTarget(targetId: @IdRes Int): Transition

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

fun removeTarget(targetName: String): Transition

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

fun removeTarget(target: View): Transition

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

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.

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.

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.

fun setMatchOrder(matches: IntArray?): Unit

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

The default behavior is to match first by getTransitionName, then by View instance, then by 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.

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 getPath.

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.

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.

inline fun Transition.addListener(
    crossinline onEnd: (transition: Transition) -> Unit = {},
    crossinline onStart: (transition: Transition) -> Unit = {},
    crossinline onCancel: (transition: Transition) -> Unit = {},
    crossinline onResume: (transition: Transition) -> Unit = {},
    crossinline onPause: (transition: Transition) -> Unit = {}
): Transition.TransitionListener

Add a listener to this Transition using the provided actions.

inline fun Transition.doOnCancel(
    crossinline action: (transition: Transition) -> Unit
): Transition.TransitionListener

Add an action which will be invoked when this transition has been cancelled.

inline fun Transition.doOnEnd(crossinline action: (transition: Transition) -> Unit): Transition.TransitionListener

Add an action which will be invoked when this transition has ended.

inline fun Transition.doOnPause(crossinline action: (transition: Transition) -> Unit): Transition.TransitionListener

Add an action which will be invoked when this transition has been paused.

inline fun Transition.doOnResume(
    crossinline action: (transition: Transition) -> Unit
): Transition.TransitionListener

Add an action which will be invoked when this transition has resumed after a pause.

inline fun Transition.doOnStart(crossinline action: (transition: Transition) -> Unit): Transition.TransitionListener

Add an action which will be invoked when this transition has started.