Transition

public abstract class Transition
extends Object implements Cloneable

java.lang.Object
   ↳ 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 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

class Transition.EpicenterCallback

Class to get the epicenter of Transition. 

interface Transition.TransitionListener

A transition listener receives notifications from a transition. 

Constants

int MATCH_ID

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

int MATCH_INSTANCE

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

int MATCH_ITEM_ID

With setMatchOrder(int), chooses to match by the Adapter item id.

int MATCH_NAME

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

Public constructors

Transition()

Constructs a Transition object with no target objects.

Transition(Context context, AttributeSet attrs)

Perform inflation from XML and apply a class-specific base style from a theme attribute or style resource.

Public methods

Transition addListener(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.

Transition addTarget(View target)

Sets the target view instances that this Transition is interested in animating.

Transition addTarget(int targetId)

Adds the id of a target view that this Transition is interested in animating.

Transition addTarget(String targetName)

Adds the transitionName of a target view that this Transition is interested in animating.

Transition addTarget(Class<?> targetType)

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

abstract void captureEndValues(TransitionValues transitionValues)

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

abstract void captureStartValues(TransitionValues transitionValues)

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

Transition clone()
Animator createAnimator(ViewGroup sceneRoot, TransitionValues startValues, 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.

Transition excludeChildren(int targetId, boolean exclude)

Whether to add the children of the given id to the list of targets to exclude from this transition.

Transition excludeChildren(Class<?> type, boolean exclude)

Whether to add the given type to the list of types whose children should be excluded from this transition.

Transition excludeChildren(View target, boolean exclude)

Whether to add the children of given target to the list of target children to exclude from this transition.

Transition excludeTarget(View target, boolean exclude)

Whether to add the given target to the list of targets to exclude from this transition.

Transition excludeTarget(Class<?> type, boolean exclude)

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

Transition excludeTarget(String targetName, boolean exclude)

Whether to add the given transitionName to the list of target transitionNames to exclude from this transition.

Transition excludeTarget(int targetId, boolean exclude)

Whether to add the given id to the list of target ids to exclude from this transition.

long getDuration()

Returns the duration set on this transition.

Rect getEpicenter()

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

Transition.EpicenterCallback getEpicenterCallback()

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

TimeInterpolator getInterpolator()

Returns the interpolator set on this transition.

String getName()

Returns the name of this Transition.

PathMotion getPathMotion()

Returns the algorithm object used to interpolate along two dimensions.

TransitionPropagation getPropagation()

Returns the TransitionPropagation used to calculate Animator start delays.

long getStartDelay()

Returns the startDelay set on this transition.

List<Integer> getTargetIds()

Returns the array of target IDs that this transition limits itself to tracking and animating.

List<String> getTargetNames()

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

List<Class<?>> getTargetTypes()

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

List<View> getTargets()

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

String[] getTransitionProperties()

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.

TransitionValues getTransitionValues(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(TransitionValues startValues, TransitionValues endValues)

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

Transition removeListener(Transition.TransitionListener listener)

Removes a listener from the set listening to this animation.

Transition removeTarget(Class<?> target)

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

Transition removeTarget(int targetId)

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

Transition removeTarget(View target)

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

Transition removeTarget(String targetName)

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

Transition setDuration(long duration)

Sets the duration of this transition.

void setEpicenterCallback(Transition.EpicenterCallback epicenterCallback)

Sets the callback to use to find the epicenter of a Transition.

Transition setInterpolator(TimeInterpolator interpolator)

Sets the interpolator of this transition.

void setMatchOrder(int... matches)

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

void setPathMotion(PathMotion pathMotion)

Sets the algorithm used to calculate two-dimensional interpolation.

void setPropagation(TransitionPropagation transitionPropagation)

Sets the method for determining Animator start delays.

Transition setStartDelay(long startDelay)

Sets the startDelay of this transition.

String toString()

Inherited methods

Constants

MATCH_ID

public static final int MATCH_ID

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

Constant Value: 3 (0x00000003)

MATCH_INSTANCE

public static final int MATCH_INSTANCE

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

Constant Value: 1 (0x00000001)

MATCH_ITEM_ID

public static final int MATCH_ITEM_ID

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

Constant Value: 4 (0x00000004)

MATCH_NAME

public static final int MATCH_NAME

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

Constant Value: 2 (0x00000002)

Public constructors

Transition

public 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

public Transition (Context context, 
                AttributeSet attrs)

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 AttributeSet: The attributes of the XML tag that is inflating the transition.

Public methods

addListener

public Transition addListener (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.

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

Returns
Transition This transition object.

addTarget

public Transition addTarget (View target)

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 dis