Android APIs
public abstract class

Visibility

extends Transition
java.lang.Object
   ↳ android.transition.Transition
     ↳ android.transition.Visibility
Known Direct Subclasses

Class Overview

This transition tracks changes to the visibility of target views in the start and end scenes. Visibility is determined not just by the setVisibility(int) state of views, but also whether views exist in the current view hierarchy. The class is intended to be a utility for subclasses such as Fade, which use this visibility information to determine the specific animations to run when visibility changes occur. Subclasses should implement one or both of the methods onAppear(ViewGroup, TransitionValues, int, TransitionValues, int), onDisappear(ViewGroup, TransitionValues, int, TransitionValues, int),

Summary

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Inherited XML Attributes
From class android.transition.Transition
Public Constructors
Visibility()
Public Methods
void captureEndValues(TransitionValues transitionValues)
Captures the values in the end scene for the properties that this transition monitors.
void captureStartValues(TransitionValues transitionValues)
Captures the values in the start scene for the properties that this transition monitors.
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.
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.
boolean isVisible(TransitionValues values)
Returns whether the view is 'visible' according to the given values object.
Animator onAppear(ViewGroup sceneRoot, TransitionValues startValues, int startVisibility, TransitionValues endValues, int endVisibility)
The default implementation of this method does nothing.
Animator onDisappear(ViewGroup sceneRoot, TransitionValues startValues, int startVisibility, TransitionValues endValues, int endVisibility)
The default implementation of this method does nothing.
[Expand]
Inherited Methods
From class android.transition.Transition
From class java.lang.Object

Public Constructors

public Visibility ()

Added in API level 19

Public Methods

public void captureEndValues (TransitionValues transitionValues)

Added in API level 19

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.

public void captureStartValues (TransitionValues transitionValues)

Added in API level 19

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.

public Animator createAnimator (ViewGroup sceneRoot, TransitionValues startValues, TransitionValues endValues)

Added in API level 19

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 String[] getTransitionProperties ()

Added in API level 19

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 boolean isVisible (TransitionValues values)

Added in API level 19

Returns whether the view is 'visible' according to the given values object. This is determined by testing the same properties in the values object that are used to determine whether the object is appearing or disappearing in the createAnimator(ViewGroup, TransitionValues, TransitionValues) method. This method can be called by, for example, subclasses that want to know whether the object is visible in the same way that Visibility determines it for the actual animation.

Parameters
values The TransitionValues object that holds the information by which visibility is determined.
Returns
  • True if the view reference by values is visible, false otherwise.

public Animator onAppear (ViewGroup sceneRoot, TransitionValues startValues, int startVisibility, TransitionValues endValues, int endVisibility)

Added in API level 19

The default implementation of this method does nothing. Subclasses should override if they need to create an Animator when targets appear. The method should only be called by the Visibility class; it is not intended to be called from external classes.

Parameters
sceneRoot The root of the transition hierarchy
startValues The target values in the start scene
startVisibility The target visibility in the start scene
endValues The target values in the end scene
endVisibility The target visibility in the end scene
Returns
  • An 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 Animator onDisappear (ViewGroup sceneRoot, TransitionValues startValues, int startVisibility, TransitionValues endValues, int endVisibility)

Added in API level 19

The default implementation of this method does nothing. Subclasses should override if they need to create an Animator when targets disappear. The method should only be called by the Visibility class; it is not intended to be called from external classes.

Parameters
sceneRoot The root of the transition hierarchy
startValues The target values in the start scene
startVisibility The target visibility in the start scene
endValues The target values in the end scene
endVisibility The target visibility in the end scene
Returns
  • An 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.