com.facebook.litho

Class Component

java.lang.Object

com.facebook.litho.Component

All Implemented Interfaces:

Equivalence<Component>, EventDispatcher, HasEventDispatcher, java.lang.Cloneable

Direct Known Subclasses:

Column, EmptyComponent, Row, SpecGeneratedComponent, TestComponent

public abstract class Component
extends java.lang.Object
implements java.lang.Cloneable, HasEventDispatcher, EventDispatcher, Equivalence<Component>

Represents a unique instance of a component. To create new Component instances, use the create() method in the generated subclass which returns a builder that allows you to set values for individual props. Component instances are immutable after creation.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	Component.Builder<T extends Component.Builder<T>>
static class	Component.ContainerBuilder<T extends Component.ContainerBuilder<T>>
static class	Component.MountType
static interface	Component.RenderData A per-Component-class data structure to keep track of some of the last mounted @Prop/@State params a component was rendered with.

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	Component()
protected	Component(int identityHashCode) This constructor should be called only if working with a manually crafted "special" Component.

Method Summary

Modifier and Type	Method and Description
protected boolean	canMeasure() Whether this Component is able to measure itself according to specific size constraints.
protected java.lang.Object	clone()
java.lang.Object	createMountContent(Context c)
static void	dispatchErrorEvent(ComponentContext c, ErrorEvent e) For internal use, only.
java.lang.Object	dispatchOnEvent(EventHandler eventHandler, java.lang.Object eventState)
protected java.lang.Object	dispatchOnEventImpl(EventHandler eventHandler, java.lang.Object eventState)
boolean	equals(java.lang.Object obj)
protected boolean	excludeFromIncrementalMount()
CommonProps	getCommonProps()
protected DynamicValue[]	getDynamicProps()
protected EventHandler<ErrorEvent>	getErrorHandler()
EventDispatcher	getEventDispatcher() Deprecated.
protected static EventTrigger	getEventTrigger(ComponentContext c, int id, Handle handle)
protected static EventTrigger	getEventTrigger(ComponentContext c, int id, java.lang.String key)
Handle	getHandle()
Component.MountType	getMountType() This indicates the type of the Object that will be returned by com.facebook.litho.Component#mount.
java.lang.String	getSimpleName()
static <T> T	getTreePropFromParent(TreeProps parentTreeProps, java.lang.Class<T> key)
int	getTypeId()
protected boolean	hasChildLithoViews() Whether this Component mounts views that contain component-based content that can be incrementally mounted e.g.
boolean	hasClickHandlerSet()
int	hashCode()
protected boolean	implementsShouldUpdate()
protected boolean	isEqualivalentTreeProps(ComponentContext current, ComponentContext next)
protected boolean	isEquivalentCommonProps(Component other)
boolean	isEquivalentProps(Component other, boolean shouldCompareCommonProps) Determine if this component has equivalent props to a given component.
boolean	isEquivalentTo(Component other) Compares this component to a different one to check if they are the same
boolean	isEquivalentTo(Component other, boolean shouldCompareCommonProps)
static boolean	isLayoutSpecWithSizeSpec(Component component)
protected boolean	isPureRender()
static boolean	isPureRender(Component component)
Component	makeShallowCopy()
void	measure(ComponentContext c, int widthSpec, int heightSpec, Size outputSize) Measure a component with the given SizeSpec constrain.
void	measure(ComponentContext c, int widthSpec, int heightSpec, Size outputSize, boolean shouldCacheResult)
void	measureMightNotCacheInternalNode(ComponentContext c, int widthSpec, int heightSpec, Size outputSize) Deprecated.
protected static <E> EventHandler<E>	newEventHandler(java.lang.Class<? extends Component> reference, java.lang.String className, ComponentContext c, int id, java.lang.Object[] params)
protected static <E> EventTrigger<E>	newEventTrigger(ComponentContext c, Component component, int methodId) This variant is used to create an EventTrigger used to register this component as a target in EventTriggersContainer
protected static <E> EventTrigger<E>	newEventTrigger(ComponentContext c, java.lang.String childKey, int methodId) Deprecated.
protected java.lang.Object	onCreateMountContent(Context context) Create the object that will be mounted in the LithoView.
protected Transition	onCreateTransition(ComponentContext c)
protected void	onLoadStyle(ComponentContext c)
protected void	onPopulateAccessibilityNode(ComponentContext c, View host, AccessibilityNodeInfoCompat accessibilityNode, InterStagePropsContainer interStagePropsContainer) Populate an accessibility node with information about the component.
protected void	onPopulateExtraAccessibilityNode(ComponentContext c, AccessibilityNodeInfoCompat accessibilityNode, int extraNodeIndex, int componentBoundsX, int componentBoundsY, InterStagePropsContainer interStagePropsContainer) Populate an extra accessibility node.
protected PrepareResult	prepare(RenderStateContext renderStateContext, ComponentContext c)
protected static void	registerWorkingRange(ComponentContext scopedContext, java.lang.String name, WorkingRange workingRange, Component component, java.lang.String globalKey) Store a working range information into a list for later use by LayoutState.
protected RenderResult	render(RenderStateContext renderStateContext, ComponentContext c, int widthSpec, int heightSpec) Invokes the Component-specific render implementation, returning a RenderResult.
protected LithoNode	resolve(RenderStateContext renderStateContext, ComponentContext c) Resolves the ComponentLayout for the given Component.
protected static <T> T	retrieveValue(DynamicValue<T> dynamicValue)
protected boolean	shouldUpdate(Component previous, StateContainer prevStateContainer, Component next, StateContainer nextStateContainer) Whether the component needs updating.
java.lang.String	toString()
protected void	transferState(StateContainer previousStateContainer, StateContainer nextStateContainer) Call this to transfer the State annotated values between two Component with the same global scope.
protected boolean	usesLocalStateContainer()
static boolean	willRender(ComponentContext c, Component component) Deprecated. Using willRender is regarded as an anti-pattern, since it will load all classes into memory in order to potentially decide not to use any of them.

Methods inherited from class java.lang.Object

finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

Component

protected Component()

Component

protected Component(int identityHashCode)

This constructor should be called only if working with a manually crafted "special" Component. This should NOT be used in general use cases. Use the standard Component() instead.

Method Detail

createMountContent

public final java.lang.Object createMountContent(Context c)

dispatchOnEvent

public final java.lang.Object dispatchOnEvent(EventHandler eventHandler,
                                              java.lang.Object eventState)

Specified by:

dispatchOnEvent in interface EventDispatcher

dispatchOnEventImpl

protected java.lang.Object dispatchOnEventImpl(EventHandler eventHandler,
                                               java.lang.Object eventState)

getMountType

public Component.MountType getMountType()

This indicates the type of the Object that will be returned by com.facebook.litho.Component#mount.

Returns:

one of Component.MountType

getTypeId

public final int getTypeId()

canMeasure

protected boolean canMeasure()

Whether this Component is able to measure itself according to specific size constraints.

excludeFromIncrementalMount

protected boolean excludeFromIncrementalMount()

Returns:

Boolean indicating whether the component skips Incremental Mount. If this is true then the Component will not be involved in Incremental Mount.

hasChildLithoViews

protected boolean hasChildLithoViews()

Whether this Component 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.

usesLocalStateContainer

protected boolean usesLocalStateContainer()

implementsShouldUpdate

protected boolean implementsShouldUpdate()

isPureRender

protected boolean isPureRender()

render

protected RenderResult render(RenderStateContext renderStateContext,
                              ComponentContext c,
                              int widthSpec,
                              int heightSpec)

Invokes the Component-specific render implementation, returning a RenderResult. The RenderResult will have the Component this Component rendered to (which will then need to be render()'ed or #resolve(LayoutStateContext, ComponentContext)'ed), as well as other metadata from that render call such as transitions that should be applied.

onCreateMountContent

protected java.lang.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.

onCreateTransition

protected Transition onCreateTransition(ComponentContext c)

Returns:

a TransitionSet specifying how to animate this component to its new layout and props.

onLoadStyle

protected void onLoadStyle(ComponentContext c)

onPopulateAccessibilityNode

protected void onPopulateAccessibilityNode(ComponentContext c,
                                           View host,
                                           AccessibilityNodeInfoCompat accessibilityNode,
                                           InterStagePropsContainer interStagePropsContainer)

Populate an accessibility node with information about the component.

Parameters:

accessibilityNode - node to populate

onPopulateExtraAccessibilityNode

protected void onPopulateExtraAccessibilityNode(ComponentContext c,
                                                AccessibilityNodeInfoCompat accessibilityNode,
                                                int extraNodeIndex,
                                                int componentBoundsX,
                                                int componentBoundsY,
                                                InterStagePropsContainer interStagePropsContainer)

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

interStagePropsContainer -

prepare

protected PrepareResult prepare(RenderStateContext renderStateContext,
                                ComponentContext c)

resolve

protected LithoNode resolve(RenderStateContext renderStateContext,
                            ComponentContext c)

Resolves the ComponentLayout for the given Component.

isEqualivalentTreeProps

protected boolean isEqualivalentTreeProps(ComponentContext current,
                                          ComponentContext next)

shouldUpdate

protected boolean shouldUpdate(Component previous,
                               StateContainer prevStateContainer,
                               Component next,
                               StateContainer nextStateContainer)

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.

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,
                                      ErrorEvent e)

For internal use, only.

getEventTrigger

protected static EventTrigger getEventTrigger(ComponentContext c,
                                              int id,
                                              java.lang.String key)

getEventTrigger

protected static EventTrigger getEventTrigger(ComponentContext c,
                                              int id,
                                              Handle handle)

newEventHandler

protected static <E> EventHandler<E> newEventHandler(java.lang.Class<? extends Component> reference,
                                                     java.lang.String className,
                                                     ComponentContext c,
                                                     int id,
                                                     java.lang.Object[] params)

newEventTrigger

protected static <E> EventTrigger<E> newEventTrigger(ComponentContext c,
                                                     Component component,
                                                     int methodId)

This variant is used to create an EventTrigger used to register this component as a target in EventTriggersContainer

newEventTrigger

@Deprecated
protected static <E> EventTrigger<E> newEventTrigger(ComponentContext c,
                                                                 java.lang.String childKey,
                                                                 int methodId)

Deprecated.

This is used to create a Trigger to be invoked later, e.g. in the context of the deprecated trigger API TextInput.requestFocusTrigger(c, "my_key").

getCommonProps

public final CommonProps getCommonProps()

getEventDispatcher

@Deprecated
public final EventDispatcher getEventDispatcher()

Deprecated.

Specified by:

getEventDispatcher in interface HasEventDispatcher

getSimpleName

public java.lang.String getSimpleName()

hasClickHandlerSet

public final boolean hasClickHandlerSet()

isEquivalentProps

public boolean isEquivalentProps(Component other,
                                 boolean shouldCompareCommonProps)

Determine if this component has equivalent props to a given component. This method does not compare common props.

Parameters:

other - the component to compare to

Returns:

true if the components have equivalent props

isEquivalentCommonProps

protected final boolean isEquivalentCommonProps(Component other)

isEquivalentTo

public final boolean isEquivalentTo(Component other)

Compares this component to a different one to check if they are the same

This is used to be able to skip rendering a component again. We avoid using the Object.equals(Object) so we can optimize the code better over time since we don't have to adhere to the contract required for a equals method.

Specified by:

isEquivalentTo in interface Equivalence<Component>

Parameters:

other - the component to compare to

Returns:

true if the components are of the same type and have the same props

isEquivalentTo

public final boolean isEquivalentTo(Component other,
                                    boolean shouldCompareCommonProps)

makeShallowCopy

public Component makeShallowCopy()

measure

public final void measure(ComponentContext c,
                          int widthSpec,
                          int heightSpec,
                          Size outputSize)

Measure a component with the given SizeSpec constrain.

Parameters:

c - ComponentContext.

widthSpec - Width SizeSpec constrain.

heightSpec - Height SizeSpec constrain.

outputSize - Size object that will be set with the measured dimensions.

measure

public final void measure(ComponentContext c,
                          int widthSpec,
                          int heightSpec,
                          Size outputSize,
                          boolean shouldCacheResult)

measureMightNotCacheInternalNode

@Deprecated
public final void measureMightNotCacheInternalNode(ComponentContext c,
                                                               int widthSpec,
                                                               int heightSpec,
                                                               Size outputSize)

Deprecated.

Should not be used! Components should be manually measured only as part of a LayoutState calculation. This will measure a component and set the size in the outputSize object but the measurement result will not be cached and reused for future measurements of this component.

This is very inefficient because it throws away the InternalNode from measuring here and will have to remeasure when the component needs to be measured as part of a LayoutState. This will lead to suboptimal performance.

You probably don't need to use this. If you really need to measure your Component outside of a LayoutState calculation reach out to the Litho team to discuss an alternative solution.

If this is called during a LayoutState calculation, it will delegate to SpecGeneratedComponent.onMeasure(ComponentContext, ComponentLayout, int, int, Size, InterStagePropsContainer), which does cache the measurement result for the duration of this LayoutState.

getErrorHandler

protected final EventHandler<ErrorEvent> getErrorHandler()

getHandle

public final Handle getHandle()

Returns:

a handle that is unique to this component.

getDynamicProps

protected DynamicValue[] getDynamicProps()

toString

public final java.lang.String toString()

Overrides:

toString in class java.lang.Object

willRender

@Deprecated
public static boolean willRender(ComponentContext c,
                                             Component component)

Deprecated. Using willRender is regarded as an anti-pattern, since it will load all classes into memory in order to potentially decide not to use any of them.

Returns:

whether the given component will render because it returns non-null from its resolved onCreateLayout, based on its current props and state. Returns true if the resolved layout is non-null, otherwise false.

isLayoutSpecWithSizeSpec

public static boolean isLayoutSpecWithSizeSpec(Component component)

isPureRender

public static boolean isPureRender(Component component)

Returns:

whether the given component is a pure render component.

registerWorkingRange

protected static void registerWorkingRange(ComponentContext scopedContext,
                                           java.lang.String name,
                                           WorkingRange workingRange,
                                           Component component,
                                           java.lang.String globalKey)

Store a working range information into a list for later use by LayoutState.

retrieveValue

protected static <T> T retrieveValue(DynamicValue<T> dynamicValue)

hashCode

public final int hashCode()

Overrides:

hashCode in class java.lang.Object

equals

public final boolean equals(java.lang.Object obj)

Overrides:

equals in class java.lang.Object

clone

protected final java.lang.Object clone()
                                throws java.lang.CloneNotSupportedException

Overrides:

clone in class java.lang.Object

Throws:

java.lang.CloneNotSupportedException

getTreePropFromParent

public static <T> T getTreePropFromParent(TreeProps parentTreeProps,
                                          java.lang.Class<T> key)