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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>(@NonNull context: Context, @NonNull attrs: AttributeSet)

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

Public methods
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 Transition
addTarget(@NonNull target: View)

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

open Transition
addTarget(@IdRes targetId: Int)

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

open Transition