ComponentLifecycle

java.lang.Object
- com.facebook.litho.ComponentLifecycle

All Implemented Interfaces:

EventDispatcher, EventTriggerTarget

Direct Known Subclasses:

Component
```
public abstract class ComponentLifecycle
extends Object
implements EventDispatcher, EventTriggerTarget
```
ComponentLifecycle is extended by the Component class and declare methods used by a Component instances to calculate their layout bounds and mount elements, among other things. This is the base class from which all new component types inherit.

Nested Class Summary

Nested Classes
Modifier and Type	Class and Description
`static class`	`ComponentLifecycle.MountType`
`static interface`	`ComponentLifecycle.RenderData` A per-Component-class data structure to keep track of some of the last mounted @Prop/@State params a component was rendered with.
`static interface`	`ComponentLifecycle.TransitionContainer` Generated component's state container could implement this interface along with `StateContainer` when componentspec specifies state update method with `OnUpdateStateWithTransition` annotation.

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`Object`	`acceptTriggerEvent(EventTrigger eventTrigger, Object eventState, Object[] params)`
`protected void`	`applyPreviousRenderData(ComponentLifecycle.RenderData previousRenderData)`
`protected boolean`	`callsShouldUpdateOnMount()`
`protected boolean`	`canMeasure()` Whether this `ComponentLifecycle` is able to measure itself according to specific size constraints.
`protected boolean`	`canPreallocate()`
`protected void`	`createInitialState(ComponentContext c)`
`Object`	`createMountContent(Context c)`
`static void`	`dispatchErrorEvent(ComponentContext c, ErrorEvent e)` For internal use, only.
`static void`	`dispatchErrorEvent(ComponentContext c, Exception e)` Reraise an error event up the hierarchy so it can be caught by another component, or reach the root and cause the application to crash.
`protected void`	`dispatchOnEnteredRange(String name)`
`Object`	`dispatchOnEvent(EventHandler eventHandler, Object eventState)`
`protected void`	`dispatchOnExitedRange(String name)`
`protected static EventTrigger`	`getEventTrigger(ComponentContext c, int id, Handle handle)`
`protected static EventTrigger`	`getEventTrigger(ComponentContext c, int id, String key)`
`protected int`	`getExtraAccessibilityNodeAt(int x, int y)` Get extra accessibility node id at a given point within the component.
`protected int`	`getExtraAccessibilityNodesCount()` The number of extra accessibility nodes that this component wishes to provides to the accessibility system.
`ComponentLifecycle.MountType`	`getMountType()` This indicates the type of the `Object` that will be returned by `mount(com.facebook.litho.ComponentContext, java.lang.Object)`.
`protected TreeProps`	`getTreePropsForChildren(ComponentContext c, TreeProps treeProps)` Updates the TreeProps map with outputs from all `OnCreateTreeProp` methods.
`protected boolean`	`hasAttachDetachCallback()`
`protected boolean`	`hasChildLithoViews()` Whether this `ComponentLifecycle` mounts views that contain component-based content that can be incrementally mounted e.g.
`protected boolean`	`hasState()`
`protected boolean`	`implementsAccessibility()` Whether this component will populate any accessibility nodes or events that are passed to it.
`protected boolean`	`implementsExtraAccessibilityNodes()` Whether this component will expose any virtual views to the accessibility framework
`protected boolean`	`isLayoutSpecWithSizeSpecCheck()`
`protected boolean`	`isMountSizeDependent()`
`protected boolean`	`isPureRender()`
`protected boolean`	`needsPreviousRenderData()`
`protected static <E> EventHandler<E>`	`newEventHandler(Class<? extends Component> reference, ComponentContext c, int id, Object[] params)`
`protected static <E> EventTrigger<E>`	`newEventTrigger(ComponentContext c, String childKey, int id, Handle handle)`
`protected void`	`onAttached(ComponentContext c)` Called when the component is attached to the `ComponentTree`.
`protected void`	`onBind(ComponentContext c, Object mountedContent)`
`protected void`	`onBoundsDefined(ComponentContext c, ComponentLayout layout)` Called after the layout calculation is finished and the given `ComponentLayout` has its bounds defined.
`protected Component`	`onCreateLayout(ComponentContext c)` Generate a tree of `ComponentLayout` representing the layout structure of the `Component` and its sub-components.
`protected Component`	`onCreateLayoutWithSizeSpec(ComponentContext c, int widthSpec, int heightSpec)`
`protected Object`	`onCreateMountContent(Context context)` Create the object that will be mounted in the `LithoView`.
`protected MountContentPool`	`onCreateMountContentPool()`
`protected Transition`	`onCreateTransition(ComponentContext c)`
`protected void`	`onDetached(ComponentContext c)` Called when the component is detached from the `ComponentTree`.
`protected void`	`onError(ComponentContext c, Exception e)` Called to provide a fallback if a supported lifecycle method throws an exception.
`protected void`	`onLoadStyle(ComponentContext c)`
`protected void`	`onMeasure(ComponentContext c, ComponentLayout layout, int widthSpec, int heightSpec, Size size)`
`protected int`	`onMeasureBaseline(ComponentContext c, int width, int height)` Called during layout calculation to determine the baseline of a component.
`protected void`	`onMount(ComponentContext c, Object convertContent)` Deploy all UI elements representing the final bounds defined in the given `ComponentLayout`.
`protected void`	`onPopulateAccessibilityNode(View host, AccessibilityNodeInfoCompat accessibilityNode)` Populate an accessibility node with information about the component.
`protected void`	`onPopulateExtraAccessibilityNode(AccessibilityNodeInfoCompat accessibilityNode, int extraNodeIndex, int componentBoundsX, int componentBoundsY)` Populate an extra accessibility node.
`protected void`	`onPrepare(ComponentContext c)`
`protected boolean`	`onShouldCreateLayoutWithNewSizeSpec(ComponentContext context, int newWidthSpec, int newHeightSpec)`
`protected void`	`onUnbind(ComponentContext c, Object mountedContent)`
`protected void`	`onUnmount(ComponentContext c, Object mountedContent)` Unload UI elements associated with this component.
`protected int`	`poolSize()`
`protected void`	`populateTreeProps(TreeProps parentTreeProps)` Retrieves all of the tree props used by this Component from the TreeProps map and sets the tree props as fields on the ComponentImpl.
`protected ComponentLifecycle.RenderData`	`recordRenderData(ComponentLifecycle.RenderData toRecycle)`
`protected ComponentLayout`	`resolve(ComponentContext c)` Resolves the `ComponentLayout` for the given `Component`.
`protected boolean`	`shouldAlwaysRemeasure()`
`protected boolean`	`shouldUpdate(Component previous, Component next)` Whether the component needs updating.
`protected boolean`	`shouldUseGlobalPool()`
`protected void`	`transferState(StateContainer previousStateContainer, StateContainer nextStateContainer)` Call this to transfer the `State` annotated values between two `Component` with the same global scope.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Method Detail
  - acceptTriggerEvent
```
public Object acceptTriggerEvent(EventTrigger eventTrigger,
                                 Object eventState,
                                 Object[] params)
```
    Specified by:
    
    acceptTriggerEvent in interface EventTriggerTarget
  - createMountContent
```
public Object createMountContent(Context c)
```
  - dispatchOnEvent
```
public Object dispatchOnEvent(EventHandler eventHandler,
                              Object eventState)
```
    Specified by:
    
    dispatchOnEvent in interface EventDispatcher
  - getMountType
```
public ComponentLifecycle.MountType getMountType()
```
    This indicates the type of the Object that will be returned by mount(com.facebook.litho.ComponentContext, java.lang.Object).
    
    Returns:
    
    one of ComponentLifecycle.MountType
  - applyPreviousRenderData
```
protected void applyPreviousRenderData(ComponentLifecycle.RenderData previousRenderData)
```
  - callsShouldUpdateOnMount
```
protected boolean callsShouldUpdateOnMount()
```
  - canMeasure
```
protected boolean canMeasure()
```
    Whether this ComponentLifecycle is able to measure itself according to specific size constraints.
  - canPreallocate
```
protected boolean canPreallocate()
```
    Returns:
    
    true if this component can be preallocated.
  - createInitialState
```
protected void createInitialState(ComponentContext c)
```
  - dispatchOnEnteredRange
```
protected void dispatchOnEnteredRange(String name)
```
  - dispatchOnExitedRange
```
protected void dispatchOnExitedRange(String name)
```
  - getExtraAccessibilityNodeAt
```
protected int getExtraAccessibilityNodeAt(int x,
                                          int y)
```
    Get extra accessibility node id at a given point within the component.
    
    Parameters:
    
    x - x co-ordinate within the mounted component
    
    y - y co-ordinate within the mounted component
    
    Returns:
    
    the extra virtual view id if one is found, otherwise ExploreByTouchHelper#INVALID_ID
  - getExtraAccessibilityNodesCount
```
protected int getExtraAccessibilityNodesCount()
```
    The number of extra accessibility nodes that this component wishes to provides to the accessibility system.
    
    Returns:
    
    the number of extra nodes
  - getTreePropsForChildren
```
protected TreeProps getTreePropsForChildren(ComponentContext c,
                                            TreeProps treeProps)
```
    Updates the TreeProps map with outputs from all OnCreateTreeProp methods.
  - hasAttachDetachCallback
```
protected boolean hasAttachDetachCallback()
```
    Returns:
    
    true if the component implements OnAttached or OnDetached delegate methods.
  - hasChildLithoViews
```
protected boolean hasChildLithoViews()
```
    Whether this ComponentLifecycle mounts views that contain component-based content that can be incrementally mounted e.g. if the mounted view has a LithoView with incremental mount enabled.
  - hasState
```
protected boolean hasState()
```
    Returns:
    
    true if the Component is using state, false otherwise.
  - implementsAccessibility
```
protected boolean implementsAccessibility()
```
    Whether this component will populate any accessibility nodes or events that are passed to it.
    
    Returns:
    
    true if the component implements accessibility info
  - implementsExtraAccessibilityNodes
```
protected boolean implementsExtraAccessibilityNodes()
```
    Whether this component will expose any virtual views to the accessibility framework
    
    Returns:
    
    true if the component exposes extra accessibility nodes
  - isLayoutSpecWithSizeSpecCheck
```
protected boolean isLayoutSpecWithSizeSpecCheck()
```
    Returns:
    
    true iff the LayoutSpec implements OnShouldCreateLayoutWithNewSizeSpec to true.
  - isMountSizeDependent
```
protected boolean isMountSizeDependent()
```
    Returns:
    
    true if Mount uses @FromMeasure or @FromOnBoundsDefined parameters.
  - isPureRender
```
protected boolean isPureRender()
```
  - needsPreviousRenderData
```
protected boolean needsPreviousRenderData()
```
  - onAttached
```
protected void onAttached(ComponentContext c)
```
    Called when the component is attached to the ComponentTree.
    
    Parameters:
    
    c - The ComponentContext the Component was constructed with.
  - onBind
```
protected void onBind(ComponentContext c,
                      Object mountedContent)
```
  - onBoundsDefined
```
protected void onBoundsDefined(ComponentContext c,
                               ComponentLayout layout)
```
    Called after the layout calculation is finished and the given ComponentLayout has its bounds defined. You can use ComponentLayout.getX(), ComponentLayout.getY(), ComponentLayout.getWidth(), and ComponentLayout.getHeight() to get the size and position of the component in the layout tree.
    
    Parameters:
    
    c - The Context used by this component.
    
    layout - The ComponentLayout with defined position and size.
  - onCreateLayout
```
protected Component onCreateLayout(ComponentContext c)
```
    Generate a tree of ComponentLayout representing the layout structure of the Component and its sub-components.
    
    Parameters:
    
    c - The ComponentContext to build a ComponentLayout tree.
  - onCreateLayoutWithSizeSpec
```
protected Component onCreateLayoutWithSizeSpec(ComponentContext c,
                                               int widthSpec,
                                               int heightSpec)
```
  - onCreateMountContent
```
protected Object onCreateMountContent(Context context)
```
    Create the object that will be mounted in the LithoView.
    
    Parameters:
    
    context - The Context to be used to create the content.
    
    Returns:
    
    an Object that can be mounted for this component.
  - onCreateMountContentPool
```
protected MountContentPool onCreateMountContentPool()
```
    Returns:
    
    the MountContentPool that should be used to recycle mount content for this mount spec.
  - onCreateTransition
```
protected Transition onCreateTransition(ComponentContext c)
```
    Returns:
    
    a TransitionSet specifying how to animate this component to its new layout and props.
  - onDetached
```
protected void onDetached(ComponentContext c)
```
    Called when the component is detached from the ComponentTree.
    
    Parameters:
    
    c - The ComponentContext the Component was constructed with.
  - onError
```
protected void onError(ComponentContext c,
                       Exception e)
```
    Called to provide a fallback if a supported lifecycle method throws an exception. It is possible to either recover from the error here or reraise the exception to catch it at a higher level or crash the application.
    
    Parameters:
    
    c - The ComponentContext the Component was constructed with.
    
    e - The exception caught.
    
    See Also:
    
    OnError
  - onLoadStyle
```
protected void onLoadStyle(ComponentContext c)
```
  - onMeasure
```
protected void onMeasure(ComponentContext c,
                         ComponentLayout layout,
                         int widthSpec,
                         int heightSpec,
                         Size size)
```
  - onMeasureBaseline
```
protected int onMeasureBaseline(ComponentContext c,
                                int width,
                                int height)
```
    Called during layout calculation to determine the baseline of a component.
    
    Parameters:
    
    c - The Context used by this component.
    
    width - The width of this component.
    
    height - The height of this component.
  - onMount
```
protected void onMount(ComponentContext c,
                       Object convertContent)
```
    Deploy all UI elements representing the final bounds defined in the given ComponentLayout. Return either a Drawable or a View or null to be mounted.
    
    Parameters:
    
    c - The ComponentContext to mount the component into.
  - onPopulateAccessibilityNode
```
protected void onPopulateAccessibilityNode(View host,
                                           AccessibilityNodeInfoCompat accessibilityNode)
```
    Populate an accessibility node with information about the component.
    
    Parameters:
    
    accessibilityNode - node to populate
  - onPopulateExtraAccessibilityNode
```
protected void onPopulateExtraAccessibilityNode(AccessibilityNodeInfoCompat accessibilityNode,
                                                int extraNodeIndex,
                                                int componentBoundsX,
                                                int componentBoundsY)
```
    Populate an extra accessibility node.
    
    Parameters:
    
    accessibilityNode - node to populate
    
    extraNodeIndex - index of extra node
    
    componentBoundsX - left bound of the mounted component
    
    componentBoundsY - top bound of the mounted component
  - onPrepare
```
protected void onPrepare(ComponentContext c)
```
  - onShouldCreateLayoutWithNewSizeSpec
```
protected boolean onShouldCreateLayoutWithNewSizeSpec(ComponentContext context,
                                                      int newWidthSpec,
                                                      int newHeightSpec)
```
  - onUnbind
```
protected void onUnbind(ComponentContext c,
                        Object mountedContent)
```
  - onUnmount
```
protected void onUnmount(ComponentContext c,
                         Object mountedContent)
```
    Unload UI elements associated with this component.
    
    Parameters:
    
    c - The Context for this mount operation.
    
    mountedContent - The Drawable or View mounted by this component.
  - poolSize
```
protected int poolSize()
```
  - populateTreeProps
```
protected void populateTreeProps(TreeProps parentTreeProps)
```
    Retrieves all of the tree props used by this Component from the TreeProps map and sets the tree props as fields on the ComponentImpl.
  - recordRenderData
```
protected ComponentLifecycle.RenderData recordRenderData(ComponentLifecycle.RenderData toRecycle)
```
  - resolve
```
protected ComponentLayout resolve(ComponentContext c)
```
    Resolves the ComponentLayout for the given Component.
  - shouldAlwaysRemeasure
```
protected boolean shouldAlwaysRemeasure()
```
    Returns:
    
    true if the Component should always be measured when receiving a remeasure event, false otherwise.
  - shouldUpdate
```
protected boolean shouldUpdate(Component previous,
                               Component next)
```
    Whether the component needs updating.
    For layout components, the framework will verify that none of the children of the component need updating, and that both components have the same number of children. Therefore this method just needs to determine any changes to the top-level component that would cause it to need to be updated (for example, a click handler was added).
    For mount specs, the framework does nothing extra and this method alone determines whether the component is updated or not.
    
    Parameters:
    
    previous - the previous component to compare against.
    
    next - the component that is now in use.
    
    Returns:
    
    true if the component needs an update, false otherwise.
  - shouldUseGlobalPool
```
protected boolean shouldUseGlobalPool()
```
    Returns:
    
    true this component may be allocated with application context and placed in the global component pool.
  - transferState
```
protected void transferState(StateContainer previousStateContainer,
                             StateContainer nextStateContainer)
```
    Call this to transfer the State annotated values between two Component with the same global scope.
  - dispatchErrorEvent
```
public static void dispatchErrorEvent(ComponentContext c,
                                      Exception e)
```
    Reraise an error event up the hierarchy so it can be caught by another component, or reach the root and cause the application to crash.
    
    Parameters:
    
    c - The component context the error event was caught in.
    
    e - The original exception.
  - dispatchErrorEvent
```
public static void dispatchErrorEvent(ComponentContext c,
                                      ErrorEvent e)
```
    For internal use, only. Use dispatchErrorEvent(ComponentContext, Exception) instead.
  - getEventTrigger
```
protected static EventTrigger getEventTrigger(ComponentContext c,
                                              int id,
                                              String key)
```
  - getEventTrigger
```
protected static EventTrigger getEventTrigger(ComponentContext c,
                                              int id,
                                              Handle handle)
```
  - newEventHandler
```
protected static <E> EventHandler<E> newEventHandler(Class<? extends Component> reference,
                                                     ComponentContext c,
                                                     int id,
                                                     Object[] params)
```
  - newEventTrigger
```
protected static <E> EventTrigger<E> newEventTrigger(ComponentContext c,
                                                     String childKey,
                                                     int id,
                                                     Handle handle)
```

Class ComponentLifecycle

Nested Class Summary

Method Summary

Methods inherited from class java.lang.Object

Method Detail

acceptTriggerEvent

createMountContent

dispatchOnEvent

getMountType

applyPreviousRenderData

callsShouldUpdateOnMount

canMeasure

canPreallocate

createInitialState

dispatchOnEnteredRange

dispatchOnExitedRange

getExtraAccessibilityNodeAt

getExtraAccessibilityNodesCount

getTreePropsForChildren

hasAttachDetachCallback

hasChildLithoViews

hasState

implementsAccessibility

implementsExtraAccessibilityNodes

isLayoutSpecWithSizeSpecCheck

isMountSizeDependent

isPureRender

needsPreviousRenderData

onAttached

onBind

onBoundsDefined

onCreateLayout

onCreateLayoutWithSizeSpec

onCreateMountContent

onCreateMountContentPool

onCreateTransition

onDetached

onError

onLoadStyle

onMeasure

onMeasureBaseline

onMount

onPopulateAccessibilityNode

onPopulateExtraAccessibilityNode

onPrepare

onShouldCreateLayoutWithNewSizeSpec

onUnbind

onUnmount

poolSize

populateTreeProps

recordRenderData

resolve

shouldAlwaysRemeasure

shouldUpdate

shouldUseGlobalPool

transferState

dispatchErrorEvent

dispatchErrorEvent

getEventTrigger

getEventTrigger

newEventHandler

newEventTrigger