public class LayoutTransition extends Object
ViewGroup.setLayoutTransition(LayoutTransition)
. This will cause
default animations to run whenever items are added to or removed from that container. To specify
custom animations, use the setAnimator()
method.
One of the core concepts of these transition animations is that there are two types of changes that cause the transition and four different animations that run because of those changes. The changes that trigger the transition are items being added to a container (referred to as an "appearing" transition) or removed from a container (also known as "disappearing"). Setting the visibility of views (between GONE and VISIBLE) will trigger the same add/remove logic. The animations that run due to those events are one that animates items being added, one that animates items being removed, and two that animate the other items in the container that change due to the add/remove occurrence. Users of the transition may want different animations for the changing items depending on whether they are changing due to an appearing or disappearing event, so there is one animation for each of these variations of the changing event. Most of the API of this class is concerned with setting up the basic properties of the animations used in these four situations, or with setting up custom animations for any or all of the four.
By default, the DISAPPEARING animation begins immediately, as does the CHANGE_APPEARING
animation. The other animations begin after a delay that is set to the default duration
of the animations. This behavior facilitates a sequence of animations in transitions as
follows: when an item is being added to a layout, the other children of that container will
move first (thus creating space for the new item), then the appearing animation will run to
animate the item being added. Conversely, when an item is removed from a container, the
animation to remove it will run first, then the animations of the other children in the
layout will run (closing the gap created in the layout when the item was removed). If this
default choreography behavior is not desired, the setDuration(int, long)
and
setStartDelay(int, long)
of any or all of the animations can be changed as
appropriate. Keep in mind, however, that if you start an APPEARING animation before a
DISAPPEARING animation is completed, the DISAPPEARING animation stops, and any effects from
the DISAPPEARING animation are reverted. If you instead start a DISAPPEARING animation
before an APPEARING animation is completed, a similar set of effects occurs for the
APPEARING animation.
The animations specified for the transition, both the defaults and any custom animations
set on the transition object, are templates only. That is, these animations exist to hold the
basic animation properties, such as the duration, start delay, and properties being animated.
But the actual target object, as well as the start and end values for those properties, are
set automatically in the process of setting up the transition each time it runs. Each of the
animations is cloned from the original copy and the clone is then populated with the dynamic
values of the target being animated (such as one of the items in a layout container that is
moving as a result of the layout event) as well as the values that are changing (such as the
position and size of that object). The actual values that are pushed to each animation
depends on what properties are specified for the animation. For example, the default
CHANGE_APPEARING animation animates the left
, top
, right
,
bottom
, scrollX
, and scrollY
properties.
Values for these properties are updated with the pre- and post-layout
values when the transition begins. Custom animations will be similarly populated with
the target and values being animated, assuming they use ObjectAnimator objects with
property names that are known on the target object.
This class, and the associated XML flag for containers, animateLayoutChanges="true", provides a simple utility meant for automating changes in straightforward situations. Using LayoutTransition at multiple levels of a nested view hierarchy may not work due to the interrelationship of the various levels of layout. Also, a container that is being scrolled at the same time as items are being added or removed is probably not a good candidate for this utility, because the before/after locations calculated by LayoutTransition may not match the actual locations when the animations finish due to the container being scrolled as the animations are running. You can work around that particular issue by disabling the 'changing' animations by setting the CHANGE_APPEARING and CHANGE_DISAPPEARING animations to null, and setting the startDelay of the other animations appropriately.
Modifier and Type | Class and Description |
---|---|
static interface |
LayoutTransition.TransitionListener
This interface is used for listening to starting and ending events for transitions.
|
Modifier and Type | Field and Description |
---|---|
static int |
APPEARING
A flag indicating the animation that runs on those items that are appearing
in the container.
|
static int |
CHANGE_APPEARING
A flag indicating the animation that runs on those items that are changing
due to a new item appearing in the container.
|
static int |
CHANGE_DISAPPEARING
A flag indicating the animation that runs on those items that are changing
due to an item disappearing from the container.
|
static int |
CHANGING
A flag indicating the animation that runs on those items that are changing
due to a layout change not caused by items being added to or removed
from the container.
|
static int |
DISAPPEARING
A flag indicating the animation that runs on those items that are disappearing
from the container.
|
Constructor and Description |
---|
LayoutTransition()
Constructs a LayoutTransition object.
|
Modifier and Type | Method and Description |
---|---|
void |
addChild(ViewGroup parent,
View child)
This method is called by ViewGroup when a child view is about to be added to the
container.
|
void |
addTransitionListener(LayoutTransition.TransitionListener listener)
Add a listener that will be called when the bounds of the view change due to
layout processing.
|
void |
cancel()
Cancels the currently running transition.
|
void |
cancel(int transitionType)
Cancels the specified type of transition.
|
void |
disableTransitionType(int transitionType)
Disables the specified transitionType for this LayoutTransition object.
|
void |
enableTransitionType(int transitionType)
Enables the specified transitionType for this LayoutTransition object.
|
void |
endChangingAnimations()
Ends the animations that are set up for a CHANGING transition.
|
Animator |
getAnimator(int transitionType)
Gets the animation used during one of the transition types that may run.
|
long |
getDuration(int transitionType)
Gets the duration on one of the animation objects used by this transition.
|
TimeInterpolator |
getInterpolator(int transitionType)
Gets the interpolator on one of the animation objects used by this transition.
|
long |
getStagger(int transitionType)
Gets the length of time to delay between starting each animation during one of the
change animations.
|
long |
getStartDelay(int transitionType)
Gets the start delay on one of the animation objects used by this transition.
|
List<LayoutTransition.TransitionListener> |
getTransitionListeners()
Gets the current list of listeners for layout changes.
|
void |
hideChild(ViewGroup parent,
View child)
Deprecated.
|
void |
hideChild(ViewGroup parent,
View child,
int newVisibility)
This method is called by ViewGroup when a child view is about to be hidden in
container.
|
boolean |
isChangingLayout()
Returns true if animations are running which animate layout-related properties.
|
boolean |
isRunning()
Returns true if any of the animations in this transition are currently running.
|
boolean |
isTransitionTypeEnabled(int transitionType)
Returns whether the specified transitionType is enabled for this LayoutTransition object.
|
void |
layoutChange(ViewGroup parent)
This method is called by ViewGroup when there is a call to layout() on the container
with this LayoutTransition.
|
void |
removeChild(ViewGroup parent,
View child)
This method is called by ViewGroup when a child view is about to be removed from the
container.
|
void |
removeTransitionListener(LayoutTransition.TransitionListener listener)
Remove a listener for layout changes.
|
void |
setAnimateParentHierarchy(boolean animateParentHierarchy)
This flag controls whether CHANGE_APPEARING or CHANGE_DISAPPEARING animations will
cause the default changing animation to be run on the parent hierarchy as well.
|
void |
setAnimator(int transitionType,
Animator animator)
Sets the animation used during one of the transition types that may run.
|
void |
setDuration(int transitionType,
long duration)
Sets the duration on one of the animation objects used by this transition.
|
void |
setDuration(long duration)
Sets the duration to be used by all animations of this transition object.
|
void |
setInterpolator(int transitionType,
TimeInterpolator interpolator)
Sets the interpolator on one of the animation objects used by this transition.
|
void |
setStagger(int transitionType,
long duration)
Sets the length of time to delay between starting each animation during one of the
change animations.
|
void |
setStartDelay(int transitionType,
long delay)
Sets the start delay on one of the animation objects used by this transition.
|
void |
showChild(ViewGroup parent,
View child)
Deprecated.
|
void |
showChild(ViewGroup parent,
View child,
int oldVisibility)
This method is called by ViewGroup when a child view is about to be made visible in the
container.
|
void |
startChangingAnimations()
Starts the animations set up for a CHANGING transition.
|
public static final int CHANGE_APPEARING
public static final int CHANGE_DISAPPEARING
public static final int APPEARING
public static final int DISAPPEARING
public static final int CHANGING
enableTransitionType(int)
.public LayoutTransition()
public void setDuration(long duration)
setDuration(int, long)
method.duration
- The length of time, in milliseconds, that the transition animations
should last.public void enableTransitionType(int transitionType)
CHANGING
are enabled by default.
You can also enable CHANGING
animations by calling this method with the
CHANGING
transitionType.transitionType
- One of CHANGE_APPEARING
, CHANGE_DISAPPEARING
,
CHANGING
, APPEARING
, or DISAPPEARING
.public void disableTransitionType(int transitionType)
CHANGING
are enabled.transitionType
- One of CHANGE_APPEARING
, CHANGE_DISAPPEARING
,
CHANGING
, APPEARING
, or DISAPPEARING
.public boolean isTransitionTypeEnabled(int transitionType)
CHANGING
are enabled.transitionType
- One of CHANGE_APPEARING
, CHANGE_DISAPPEARING
,
CHANGING
, APPEARING
, or DISAPPEARING
.public void setStartDelay(int transitionType, long delay)
transitionType
parameter determines the animation whose start delay
is being set.transitionType
- One of CHANGE_APPEARING
, CHANGE_DISAPPEARING
,
CHANGING
, APPEARING
, or DISAPPEARING
, which determines
the animation whose start delay is being set.delay
- The length of time, in milliseconds, to delay before starting the animation.Animator.setStartDelay(long)
public long getStartDelay(int transitionType)
transitionType
parameter determines the animation whose start delay
is returned.transitionType
- One of CHANGE_APPEARING
, CHANGE_DISAPPEARING
,
CHANGING
, APPEARING
, or DISAPPEARING
, which determines
the animation whose start delay is returned.Animator.getStartDelay()
public void setDuration(int transitionType, long duration)
transitionType
parameter determines the animation whose duration
is being set.transitionType
- One of CHANGE_APPEARING
, CHANGE_DISAPPEARING
,
CHANGING
, APPEARING
, or DISAPPEARING
, which determines
the animation whose duration is being set.duration
- The length of time, in milliseconds, that the specified animation should run.Animator.setDuration(long)
public long getDuration(int transitionType)
transitionType
parameter determines the animation whose duration
is returned.transitionType
- One of CHANGE_APPEARING
, CHANGE_DISAPPEARING
,
CHANGING
, APPEARING
, or DISAPPEARING
, which determines
the animation whose duration is returned.Animator.getDuration()
public void setStagger(int transitionType, long duration)
transitionType
- A value of CHANGE_APPEARING
, CHANGE_DISAPPEARING
, or
CHANGING
.duration
- The length of time, in milliseconds, to delay before launching the next
animation in the sequence.public long getStagger(int transitionType)
transitionType
- A value of CHANGE_APPEARING
, CHANGE_DISAPPEARING
, or
CHANGING
.public void setInterpolator(int transitionType, TimeInterpolator interpolator)
transitionType
parameter determines the animation whose interpolator
is being set.transitionType
- One of CHANGE_APPEARING
, CHANGE_DISAPPEARING
,
CHANGING
, APPEARING
, or DISAPPEARING
, which determines
the animation whose interpolator is being set.interpolator
- The interpolator that the specified animation should use.Animator.setInterpolator(TimeInterpolator)
public TimeInterpolator getInterpolator(int transitionType)
transitionType
parameter determines the animation whose interpolator
is returned.transitionType
- One of CHANGE_APPEARING
, CHANGE_DISAPPEARING
,
CHANGING
, APPEARING
, or DISAPPEARING
, which determines
the animation whose interpolator is being returned.Animator.setInterpolator(TimeInterpolator)
public void setAnimator(int transitionType, Animator animator)
left
property from the View objects being animated by the layout
transition. The transition works by setting target objects and properties
dynamically, according to the pre- and post-layoout values of those objects, so
having animations that can handle those properties appropriately will work best
for custom animation. The dynamic setting of values is only the case for the
CHANGE animations; the APPEARING and DISAPPEARING animations are simply run with
the values they have.
It is also worth noting that any and all animations (and their underlying PropertyValuesHolder objects) will have their start and end values set according to the pre- and post-layout values. So, for example, a custom animation on "alpha" as the CHANGE_APPEARING animation will inherit the real value of alpha on the target object (presumably 1) as its starting and ending value when the animation begins. Animations which need to use values at the beginning and end that may not match the values queried when the transition begins may need to use a different mechanism than a standard ObjectAnimator object.
transitionType
- One of CHANGE_APPEARING
, CHANGE_DISAPPEARING
,
CHANGING
, APPEARING
, or DISAPPEARING
, which determines the
animation whose animator is being set.animator
- The animation being assigned. A value of null
means that no
animation will be run for the specified transitionType.public Animator getAnimator(int transitionType)
transitionType
- One of CHANGE_APPEARING
, CHANGE_DISAPPEARING
,
CHANGING
, APPEARING
, or DISAPPEARING
, which determines
the animation whose animator is being returned.setAnimator(int, Animator)
public void setAnimateParentHierarchy(boolean animateParentHierarchy)
The default changing transitions animate the bounds and scroll positions of the target views. These are the animations that will run on the parent hierarchy, not the custom animations that happen to be set on the transition. This allows custom behavior for the children of the transitioning container, but uses standard behavior of resizing/rescrolling on any changing parents.
animateParentHierarchy
- A boolean value indicating whether the parents of
transitioning views should also be animated during the transition. Default value is true.public void startChangingAnimations()
public void endChangingAnimations()
public boolean isChangingLayout()
public boolean isRunning()
public void cancel()
public void cancel(int transitionType)
public void layoutChange(ViewGroup parent)
parent
- The ViewGroup whose layout() method has been called.public void addChild(ViewGroup parent, View child)
parent
- The ViewGroup to which the View is being added.child
- The View being added to the ViewGroup.@Deprecated public void showChild(ViewGroup parent, View child)
showChild(android.view.ViewGroup, android.view.View, int)
.public void showChild(ViewGroup parent, View child, int oldVisibility)
parent
- The ViewGroup in which the View is being made visible.child
- The View being made visible.oldVisibility
- The previous visibility value of the child View, either
View.GONE
or View.INVISIBLE
.public void removeChild(ViewGroup parent, View child)
parent
- The ViewGroup from which the View is being removed.child
- The View being removed from the ViewGroup.@Deprecated public void hideChild(ViewGroup parent, View child)
hideChild(android.view.ViewGroup, android.view.View, int)
.public void hideChild(ViewGroup parent, View child, int newVisibility)
parent
- The parent ViewGroup of the View being hidden.child
- The View being hidden.newVisibility
- The new visibility value of the child View, either
View.GONE
or View.INVISIBLE
.public void addTransitionListener(LayoutTransition.TransitionListener listener)
listener
- The listener that will be called when layout bounds change.public void removeTransitionListener(LayoutTransition.TransitionListener listener)
listener
- The listener for layout bounds change.public List<LayoutTransition.TransitionListener> getTransitionListeners()