ChangeScroll
public
class
ChangeScroll
extends Transition
java.lang.Object | ||
↳ | android.transition.Transition | |
↳ | android.transition.ChangeScroll |
This transition captures the scroll properties of targets before and after the scene change and animates any changes.
Summary
Inherited XML attributes | |
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Inherited constants |
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Public constructors | |
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ChangeScroll()
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ChangeScroll(Context context, AttributeSet attrs)
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Public methods | |
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void
|
captureEndValues(TransitionValues transitionValues)
Captures the values in the end scene for the properties that this transition monitors. |
void
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captureStartValues(TransitionValues transitionValues)
Captures the values in the start scene for the properties that this transition monitors. |
Animator
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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[]
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getTransitionProperties()
Returns the set of property names used stored in the |
Inherited methods | |
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Public constructors
ChangeScroll
public ChangeScroll (Context context, AttributeSet attrs)
Parameters | |
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context |
Context |
attrs |
AttributeSet |
Public methods
captureEndValues
public 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(android.view.ViewGroup, android.transition.TransitionValues, android.transition.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, android.transition.TransitionValues, android.transition.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 | |
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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. |
captureStartValues
public 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(android.view.ViewGroup, android.transition.TransitionValues, android.transition.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, android.transition.TransitionValues, android.transition.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 | |
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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. |
createAnimator
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 TransitionValues.view
field.
Parameters | |
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sceneRoot |
ViewGroup : This value cannot be null . |
startValues |
TransitionValues : This value may be null . |
endValues |
TransitionValues : This value may be null . |
Returns | |
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Animator |
This value may be null . |
getTransitionProperties
public String[] getTransitionProperties ()
Returns the set of property names used stored in the TransitionValues
object passed into captureStartValues(android.transition.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 | |
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String[] |
An array of property names as described in the class documentation for
TransitionValues . The default implementation returns null . |