com.facebook.litho.widget

Class VerticalScroll

java.lang.Object

com.facebook.litho.ComponentLifecycle

com.facebook.litho.Component

com.facebook.litho.widget.VerticalScroll

All Implemented Interfaces:

Equivalence<Component>, EventDispatcher, EventTriggerTarget, HasEventDispatcher, HasEventTrigger, Cloneable

public final class VerticalScroll
extends Component

Component that wraps another component, allowing it to be vertically scrollable. It's analogous to ScrollView. TreeProps will only be set during @OnCreateInitialState once, so updating TreeProps on the parent will not reflect on the VerticalScroll.

See also: HorizontalScroll for horizontal scrollability.

See Also:

com.facebook.litho.widget.VerticalScrollSpec

Required Props

childComponent

Type:

com.facebook.litho.Component

Optional Props

fadingEdgeLength

size of the faded edge used to indicate that more content is available

Type:

int

fillViewport

Type:

boolean

incrementalMountEnabled

Type:

boolean

initialScrollOffsetPixels

Type:

int

nestedScrollingEnabled

Type:

boolean

onInterceptTouchListener

NOT THE SAME AS LITHO'S interceptTouchHandler COMMON PROP. this is a listener that handles the underlying ScrollView's onInterceptTouchEvent first, whereas the Litho prop wraps the component into another view and intercepts there.

Type:

com.facebook.litho.widget.VerticalScrollSpec.OnInterceptTouchListener

onScrollChangeListener

Type:

androidx.core.widget.NestedScrollView.OnScrollChangeListener

scrollbarEnabled

whether the vertical scrollbar should be drawn

Type:

boolean

scrollbarFadingEnabled

whether the scrollbar should fade out when the view is not scrolling @props initialScrollOffsetPixels initial vertical scroll offset, in pixels @props verticalFadingEdgeEnabled whether the vertical edges should be faded when scrolled

Type:

boolean

verticalFadingEdgeEnabled

Type:

boolean

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	VerticalScroll.Builder

Nested classes/interfaces inherited from class com.facebook.litho.Component

Component.ContainerBuilder<T extends Component.ContainerBuilder<T>>

Nested classes/interfaces inherited from class com.facebook.litho.ComponentLifecycle

ComponentLifecycle.MountType, ComponentLifecycle.RenderData, ComponentLifecycle.TransitionContainer

Method Summary

Modifier and Type	Method and Description
boolean	callsShouldUpdateOnMount()
protected boolean	canMeasure() Whether this ComponentLifecycle is able to measure itself according to specific size constraints.
protected boolean	canPreallocate()
protected void	copyInterStageImpl(Component component)
static VerticalScroll.Builder	create(ComponentContext context)
static VerticalScroll.Builder	create(ComponentContext context, int defStyleAttr, int defStyleRes)
protected void	createInitialState(ComponentContext context)
ComponentLifecycle.MountType	getMountType() This indicates the type of the Object that will be returned by ComponentLifecycle.mount(com.facebook.litho.ComponentContext, java.lang.Object).
protected StateContainer	getStateContainer()
boolean	hasChildLithoViews() Whether this ComponentLifecycle mounts views that contain component-based content that can be incrementally mounted e.g.
protected boolean	hasState()
boolean	isEquivalentTo(Component other) Compares this component to a different one to check if they are the same
boolean	isPureRender()
VerticalScroll	makeShallowCopy()
protected void	onBoundsDefined(ComponentContext c, ComponentLayout layout) Called after the layout calculation is finished and the given ComponentLayout has its bounds defined.
protected Object	onCreateMountContent(Context context) Create the object that will be mounted in the LithoView.
protected void	onMeasure(ComponentContext c, ComponentLayout layout, int widthSpec, int heightSpec, Size size)
protected void	onMount(ComponentContext context, Object lithoScrollView) Deploy all UI elements representing the final bounds defined in the given ComponentLayout.
protected void	onUnmount(ComponentContext context, Object lithoScrollView) Unload UI elements associated with this component.
protected int	poolSize()
protected boolean	shouldUpdate(Component _prevAbstractImpl, Component _nextAbstractImpl) Whether the component needs updating.
protected void	transferState(StateContainer _prevStateContainer, StateContainer _nextStateContainer) Call this to transfer the State annotated values between two Component with the same global scope.

Methods inherited from class com.facebook.litho.Component

bindDynamicProp, canResolve, clearCachedLayout, getCommonProps, getDynamicProps, getEventDispatcher, getHandle, getId, getKey, getScopedContext, getSimpleName, getSimpleNameDelegate, hasBackgroundSet, hasClickHandlerSet, measure, measureMightNotCacheInternalNode, recordEventTrigger, registerWorkingRange, retrieveValue, setScopedContext, updateInternalChildState, willRender

Methods inherited from class com.facebook.litho.ComponentLifecycle

acceptTriggerEvent, applyPreviousRenderData, createMountContent, dispatchErrorEvent, dispatchErrorEvent, dispatchOnEnteredRange, dispatchOnEvent, dispatchOnExitedRange, getEventTrigger, getEventTrigger, getExtraAccessibilityNodeAt, getExtraAccessibilityNodesCount, getTreePropsForChildren, hasAttachDetachCallback, implementsAccessibility, implementsExtraAccessibilityNodes, isLayoutSpecWithSizeSpecCheck, isMountSizeDependent, needsPreviousRenderData, newEventHandler, newEventTrigger, onAttached, onBind, onCreateLayout, onCreateLayoutWithSizeSpec, onCreateMountContentPool, onCreateTransition, onDetached, onError, onLoadStyle, onMeasureBaseline, onPopulateAccessibilityNode, onPopulateExtraAccessibilityNode, onPrepare, onShouldCreateLayoutWithNewSizeSpec, onUnbind, populateTreeProps, recordRenderData, resolve, shouldAlwaysRemeasure, shouldUseGlobalPool

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

getStateContainer

protected StateContainer getStateContainer()

Overrides:

getStateContainer in class Component

isEquivalentTo

public boolean isEquivalentTo(Component other)

Description copied from class: Component

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>

Overrides:

isEquivalentTo in class Component

Parameters:

other - the component to compare to

Returns:

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

copyInterStageImpl

protected void copyInterStageImpl(Component component)

Overrides:

copyInterStageImpl in class Component

makeShallowCopy

public VerticalScroll makeShallowCopy()

Overrides:

makeShallowCopy in class Component

createInitialState

protected void createInitialState(ComponentContext context)

Overrides:

createInitialState in class ComponentLifecycle

onMeasure

protected void onMeasure(ComponentContext c,
                         ComponentLayout layout,
                         int widthSpec,
                         int heightSpec,
                         Size size)

Overrides:

onMeasure in class ComponentLifecycle

canMeasure

protected boolean canMeasure()

Description copied from class: ComponentLifecycle

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

Overrides:

canMeasure in class ComponentLifecycle

onBoundsDefined

protected void onBoundsDefined(ComponentContext c,
                               ComponentLayout layout)

Description copied from class: ComponentLifecycle

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.

Overrides:

onBoundsDefined in class ComponentLifecycle

Parameters:

c - The Context used by this component.

layout - The ComponentLayout with defined position and size.

onCreateMountContent

protected Object onCreateMountContent(Context context)

Description copied from class: ComponentLifecycle

Create the object that will be mounted in the LithoView.

Overrides:

onCreateMountContent in class ComponentLifecycle

Parameters:

context - The Context to be used to create the content.

Returns:

an Object that can be mounted for this component.

onMount

protected void onMount(ComponentContext context,
                       Object lithoScrollView)

Description copied from class: ComponentLifecycle

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.

Overrides:

onMount in class ComponentLifecycle

Parameters:

context - The ComponentContext to mount the component into.

onUnmount

protected void onUnmount(ComponentContext context,
                         Object lithoScrollView)

Description copied from class: ComponentLifecycle

Unload UI elements associated with this component.

Overrides:

onUnmount in class ComponentLifecycle

Parameters:

context - The Context for this mount operation.

lithoScrollView - The Drawable or View mounted by this component.

shouldUpdate

protected boolean shouldUpdate(Component _prevAbstractImpl,
                               Component _nextAbstractImpl)

Description copied from class: ComponentLifecycle

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.

Overrides:

shouldUpdate in class ComponentLifecycle

Parameters:

_prevAbstractImpl - the previous component to compare against.

_nextAbstractImpl - the component that is now in use.

Returns:

true if the component needs an update, false otherwise.

getMountType

public ComponentLifecycle.MountType getMountType()

Description copied from class: ComponentLifecycle

This indicates the type of the Object that will be returned by ComponentLifecycle.mount(com.facebook.litho.ComponentContext, java.lang.Object).

Overrides:

getMountType in class ComponentLifecycle

Returns:

one of ComponentLifecycle.MountType

poolSize

protected int poolSize()

Overrides:

poolSize in class ComponentLifecycle

canPreallocate

protected boolean canPreallocate()

Overrides:

canPreallocate in class ComponentLifecycle

Returns:

true if this component can be preallocated.

hasChildLithoViews

public boolean hasChildLithoViews()

Description copied from class: ComponentLifecycle

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.

Overrides:

hasChildLithoViews in class ComponentLifecycle

callsShouldUpdateOnMount

public boolean callsShouldUpdateOnMount()

Overrides:

callsShouldUpdateOnMount in class ComponentLifecycle

isPureRender

public boolean isPureRender()

Overrides:

isPureRender in class ComponentLifecycle

hasState

protected boolean hasState()

Overrides:

hasState in class ComponentLifecycle

Returns:

true if the Component is using state, false otherwise.

transferState

protected void transferState(StateContainer _prevStateContainer,
                             StateContainer _nextStateContainer)

Description copied from class: ComponentLifecycle

Call this to transfer the State annotated values between two Component with the same global scope.

Overrides:

transferState in class ComponentLifecycle

create

public static VerticalScroll.Builder create(ComponentContext context)

create

public static VerticalScroll.Builder create(ComponentContext context,
                                            int defStyleAttr,
                                            int defStyleRes)