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Android APIs
public abstract class

Transition

extends Object
implements Cloneable
java.lang.Object
   ↳ android.transition.Transition
Known Direct Subclasses
Known Indirect Subclasses

Class Overview

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 ORDERING_TOGETHER behavior to be ORDERING_SEQUENTIAL instead. Also, the Fade transition uses a fadingMode of OUT instead of the default out-in behavior. Finally, note the use of the targets sub-tag, which takes a set of 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.

Further information on XML resource descriptions for transitions can be found for Transition , TransitionSet , TransitionTarget , and Fade .

Summary

Nested Classes
interface Transition.TransitionListener A transition listener receives notifications from a transition. 
XML Attributes
Attribute Name Related Method Description
android:duration setDuration(long) Amount of time (in milliseconds) that the transition should run. 
android:interpolator setInterpolator(TimeInterpolator) Interpolator to be used in the animations spawned by this transition. 
android:startDelay setStartDelay(long) Delay in milliseconds before the transition starts. 
Public Constructors
Transition ()
Constructs a Transition object with no target objects.
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 (int targetId)
Adds the id of a target view that this Transition is interested in animating.
Transition addTarget ( View target)
Sets the target view instances 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 ()
Creates and returns a copy of this Object .
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 ( View target, boolean exclude)
Whether to add the children of given target to the list of target children 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 (int targetId, boolean exclude)
Whether to add the children of the given id to the list of targets 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.
Transition excludeTarget ( Class type, boolean exclude)
Whether to add the given type to the list of types 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.
long getDuration ()
Returns the duration set on this transition.
TimeInterpolator getInterpolator ()
Returns the interpolator set on this transition.
String getName ()
Returns the name of this Transition.
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 < 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.
Transition removeListener ( Transition.TransitionListener listener)
Removes a listener from the set listening to this animation.
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 setDuration (long duration)
Sets the duration of this transition.
Transition setInterpolator ( TimeInterpolator interpolator)
Sets the interpolator of this transition.
Transition setStartDelay (long startDelay)
Sets the startDelay of this transition.
String toString ()
Returns a string containing a concise, human-readable description of this object.
[Expand]
Inherited Methods
From class java.lang.Object

XML Attributes

android:duration

Amount of time (in milliseconds) that the transition should run.

Must be an integer value, such as " 100 ".

This may also be a reference to a resource (in the form " @[ package :] type : name ") or theme attribute (in the form " ?[ package :][ type :] name ") containing a value of this type.

This corresponds to the global attribute resource symbol duration .

Related Methods

android:interpolator

Interpolator to be used in the animations spawned by this transition.

Must be a reference to another resource, in the form " @[+][ package :] type : name " or to a theme attribute in the form " ?[ package :][ type :] name ".

This corresponds to the global attribute resource symbol interpolator .

Related Methods

android:startDelay

Delay in milliseconds before the transition starts.

Must be an integer value, such as " 100 ".

This may also be a reference to a resource (in the form " @[ package :] type : name ") or theme attribute (in the form " ?[ package :][ type :] name ") containing a value of this type.

This corresponds to the global attribute resource symbol startDelay .

Related Methods

Public Constructors

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).

Public Methods

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 the listener to be added to the current set of listeners for this animation.
Returns
  • This transition object.

public Transition addTarget (int targetId)

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 underneat the scene root.

Parameters
targetId The id of a target view, must be a positive number.
Returns
  • 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

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 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 A View on which the Transition will act, must be non-null.
Returns
  • 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

public abstract void captureEndValues ( 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(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(android.view.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 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

public abstract void captureStartValues ( 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(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(android.view.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 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

public Transition clone ()

Creates and returns a copy of this Object . The default implementation returns a so-called "shallow" copy: It creates a new instance of the same class and then copies the field values (including object references) from this instance to the new instance. A "deep" copy, in contrast, would also recursively clone nested objects. A subclass that needs to implement this kind of cloning should call super.clone() to create the new instance and then create deep copies of the nested, mutable objects.

Returns
  • a copy of this object.

public 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. 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
sceneRoot The root of the transition hierarchy.
startValues The values for a specific target in the start scene.
endValues The values for the target in the end scene.
Returns
  • 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.

public 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. 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 The target to ignore when running this transition.
exclude Whether to add the target to or remove the target from the current list of excluded targets.
Returns
  • This transition object.
See Also

public 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. 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 The type to ignore when running this transition.
exclude Whether to add the target type to or remove it from the current list of excluded target types.
Returns
  • This transition object.
See Also

public 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. 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 The id of a target whose children should be ignored when running this transition.
exclude Whether to add the target to or remove the target from the current list of excluded-child targets.
Returns
  • This transition object.
See Also

public Transition excludeTarget (int targetId, boolean exclude)

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 The id of a target to ignore when running this transition.
exclude Whether to add the target to or remove the target from the current list of excluded targets.
Returns
  • This transition object.
See Also

public Transition excludeTarget ( Class type, boolean exclude)

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 The type to ignore when running this transition.
exclude Whether to add the target type to or remove it from the current list of excluded target types.
Returns
  • This transition object.
See Also

public Transition excludeTarget ( View target, boolean exclude)

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 The target to ignore when running this transition.
exclude Whether to add the target to or remove the target from the current list of excluded targets.
Returns
  • This transition object.
See Also

public long getDuration ()

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.

Returns
  • The duration set on this transition, in milliseconds, if one has been set, otherwise returns a negative number.

public TimeInterpolator getInterpolator ()

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.

Returns
  • The interpolator set on this transition, if one has been set, otherwise returns null.

public String getName ()

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.

Returns
  • The name of this transition.

public long getStartDelay ()

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.

Returns
  • The startDelay set on this transition, in milliseconds, if one has been set, otherwise returns a negative number.

public List < Integer > getTargetIds ()

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.

Returns
  • the list of target IDs

public List < View > getTargets ()

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.

Returns
  • the list of target views

public 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. 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
  • An array of property names as described in the class documentation for TransitionValues . The default implementation returns null .

public 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. This might be necessary, for example, to query the before/after state of related views for a given transition.

public Transition removeListener ( Transition.TransitionListener listener)

Removes a listener from the set listening to this animation.

Parameters
listener the listener to be removed from the current set of listeners for this transition.
Returns
  • This transition object.

public Transition removeTarget (int targetId)

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

Parameters
targetId The id of a target view, must be a positive number.
Returns
  • 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);

public Transition removeTarget ( View target)

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

Parameters
target The target view, must be non-null.
Returns
  • 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);

public Transition setDuration (long duration)

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.

Related XML Attributes
Parameters
duration The length of the animation, in milliseconds.
Returns
  • This transition object.

public Transition setInterpolator ( TimeInterpolator interpolator)

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.

Related XML Attributes
Parameters
interpolator The time interpolator used by the transition
Returns
  • This transition object.

public Transition setStartDelay (long startDelay)

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.

Related XML Attributes
Parameters
startDelay The length of the delay, in milliseconds.
Returns
  • This transition object.

public String toString ()

Returns a string containing a concise, human-readable description of this object. Subclasses are encouraged to override this method and provide an implementation that takes into account the object's type and data. The default implementation is equivalent to the following expression: 

          getClass().getName() + '@' + Integer.toHexString(hashCode())

See Writing a useful toString method if you intend implementing your own toString method.

Returns
  • a printable representation of this object.