ChangeScroll

Artifact: androidx.transition:transition

Added in 1.0.0

Kotlin |Java

public class ChangeScroll extends Transition

java.lang.Object
↳	androidx.transition.Transition
	↳	androidx.transition.ChangeScroll

This transition captures the scroll properties of targets before and after the scene change and animates any changes.

Summary

Public constructors
`ChangeScroll()`
`ChangeScroll(@NonNull Context context, @NonNull AttributeSet attrs)`

Public methods
`void`	`captureEndValues(@NonNull TransitionValues transitionValues)` Captures the values in the end scene for the properties that this transition monitors.
`void`	`captureStartValues(@NonNull TransitionValues transitionValues)` Captures the values in the start scene for the properties that this transition monitors.
`@Nullable Animator`	`createAnimator( @NonNull ViewGroup sceneRoot, @Nullable TransitionValues startValues, @Nullable TransitionValues endValues )` 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.
`@Nullable String[]`	`getTransitionProperties()` 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.
`boolean`	`isSeekingSupported()` Returns `true` if the Transition can be used by `controlDelayedTransition`.

Inherited Constants

From androidx.transition.Transition

`static final int`	`MATCH_ID = 3` With `setMatchOrder`, chooses to match by `getId`.
`static final int`	`MATCH_INSTANCE = 1` With `setMatchOrder`, chooses to match by View instance.
`static final int`	`MATCH_ITEM_ID = 4` With `setMatchOrder`, chooses to match by the `android.widget.Adapter` item id.
`static final int`	`MATCH_NAME = 2` With `setMatchOrder`, chooses to match by `getTransitionName`.

Inherited methods

From androidx.transition.Transition

`@NonNull Transition`	`addListener(@NonNull Transition.TransitionListener listener)` Adds a listener to the set of listeners that are sent events through the life of an animation, such as start, repeat, and end.
`@NonNull Transition`	`addTarget(@IdRes int targetId)` Adds the id of a target view that this Transition is interested in animating.
`@NonNull Transition`	`addTarget(@NonNull String targetName)` Adds the transitionName of a target view that this Transition is interested in animating.
`@NonNull Transition`	`addTarget(@NonNull Class<Object> targetType)` Adds the Class of a target view that this Transition is interested in animating.
`@NonNull Transition`	`addTarget(@NonNull View target)` Sets the target view instances that this Transition is interested in animating.
`@NonNull Transition`	`clone()`
`@NonNull Transition`	`excludeChildren(@IdRes int targetId, boolean exclude)` Whether to add the children of the given id to the list of targets to exclude from this transition.
`@NonNull Transition`	`excludeChildren(@NonNull View target, boolean exclude)` Whether to add the children of given target to the list of target children to exclude from this transition.
`@NonNull Transition`	`excludeChildren(@NonNull Class<Object> type, boolean exclude)` Whether to add the given type to the list of types whose children should be excluded from this transition.
`@NonNull Transition`	`excludeTarget(@IdRes int targetId, boolean exclude)` Whether to add the given id to the list of target ids to exclude from this transition.
`@NonNull Transition`	`excludeTarget(@NonNull String targetName, boolean exclude)` Whether to add the given transitionName to the list of target transitionNames to exclude from this transition.
`@NonNull Transition`	`excludeTarget(@NonNull View target, boolean exclude)` Whether to add the given target to the list of targets to exclude from this transition.
`@NonNull Transition`	`excludeTarget(@NonNull Class<Object> type, boolean exclude)` Whether to add the given type to the list of types to exclude from this transition.
`long`	`getDuration()` Returns the duration set on this transition.
`@Nullable Rect`	`getEpicenter()` Returns the epicenter as specified by the `android.transition.Transition.EpicenterCallback` or null if no callback exists.
`@Nullable Transition.EpicenterCallback`	`getEpicenterCallback()` Returns the callback used to find the epicenter of the Transition.
`@Nullable TimeInterpolator`	`getInterpolator()` Returns the interpolator set on this transition.
`@NonNull String`	`getName()` Returns the name of this Transition.
`@NonNull PathMotion`	`getPathMotion()` Returns the algorithm object used to interpolate along two dimensions.
`@Nullable TransitionPropagation`	`getPropagation()` Returns the `android.transition.TransitionPropagation` used to calculate Animator start delays.
`final @NonNull Transition`	`getRootTransition()` If this Transition is not part of a TransitionSet, this is returned.
`long`	`getStartDelay()` Returns the startDelay set on this transition.
`@NonNull List<Integer>`	`getTargetIds()` Returns the array of target IDs that this transition limits itself to tracking and animating.
`@Nullable List<String>`	`getTargetNames()` Returns the list of target transitionNames that this transition limits itself to tracking and animating.
`@Nullable List<Class<Object>>`	`getTargetTypes()` Returns the list of target transitionNames that this transition limits itself to tracking and animating.
`@NonNull List<View>`	`getTargets()` Returns the array of target views that this transition limits itself to tracking and animating.
`@Nullable TransitionValues`	`getTransitionValues(@NonNull View view, boolean start)` This method can be called by transitions to get the TransitionValues for any particular view during the transition-playing process.
`boolean`	`isTransitionRequired( @Nullable TransitionValues startValues, @Nullable TransitionValues endValues )` Returns whether or not the transition should create an Animator, based on the values captured during `captureStartValues` and `captureEndValues`.
`@NonNull Transition`	`removeListener(@NonNull Transition.TransitionListener listener)` Removes a listener from the set listening to this animation.
`@NonNull Transition`	`removeTarget(@NonNull Class<Object> target)` Removes the given target from the list of targets that this Transition is interested in animating.
`@NonNull Transition`	`removeTarget(@IdRes int targetId)` Removes the given targetId from the list of ids that this Transition is interested in animating.
`@NonNull Transition`	`removeTarget(@NonNull String targetName)` Removes the given targetName from the list of transitionNames that this Transition is interested in animating.
`@NonNull Transition`	`removeTarget(@NonNull View target)` Removes the given target from the list of targets that this Transition is interested in animating.
`@NonNull Transition`	`setDuration(long duration)` Sets the duration of this transition.
`void`	`setEpicenterCallback( @Nullable Transition.EpicenterCallback epicenterCallback )` Sets the callback to use to find the epicenter of a Transition.
`@NonNull Transition`	`setInterpolator(@Nullable TimeInterpolator interpolator)` Sets the interpolator of this transition.
`void`	`setMatchOrder(@Nullable int[] matches)` Sets the order in which Transition matches View start and end values.
`void`	`setPathMotion(@Nullable PathMotion pathMotion)` Sets the algorithm used to calculate two-dimensional interpolation.
`void`	`setPropagation(@Nullable TransitionPropagation transitionPropagation)` Sets the method for determining Animator start delays.
`@NonNull Transition`	`setStartDelay(long startDelay)` Sets the startDelay of this transition.
`@NonNull String`	`toString()`

Public constructors

ChangeScroll

Added in 1.0.0

public ChangeScroll()

ChangeScroll

Added in 1.0.0

public ChangeScroll(@NonNull Context context, @NonNull AttributeSet attrs)

Public methods

captureEndValues

Added in 1.5.1

public void captureEndValues(@NonNull TransitionValues transitionValues)

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.

Parameters

Parameters
`@NonNull 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.

@NonNull 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.

See also
`captureStartValues`
`createAnimator`

captureStartValues

Added in 1.5.1

public void captureStartValues(@NonNull TransitionValues transitionValues)

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.

Parameters

Parameters
`@NonNull 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.

@NonNull TransitionValues transitionValues

See also
`captureEndValues`
`createAnimator`

createAnimator

public @Nullable Animator createAnimator(
    @NonNull ViewGroup sceneRoot,
    @Nullable TransitionValues startValues,
    @Nullable TransitionValues endValues
)

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.

Parameters
`@NonNull ViewGroup sceneRoot`	The root of the transition hierarchy.
`@Nullable TransitionValues startValues`	The values for a specific target in the start scene.
`@Nullable TransitionValues endValues`	The values for the target in the end scene.

Returns
`@Nullable 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.

getTransitionProperties

public @Nullable String[] getTransitionProperties()

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.

Returns
`@Nullable String[]`	An array of property names as described in the class documentation for `TransitionValues`. The default implementation returns `null`.

isSeekingSupported

public boolean isSeekingSupported()

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.