com.facebook.litho.sections.common

Class DataDiffSection<T>

java.lang.Object

com.facebook.litho.sections.SectionLifecycle

com.facebook.litho.sections.Section

com.facebook.litho.sections.common.DataDiffSection<T>

All Implemented Interfaces:

Equivalence<Section>, EventDispatcher, EventTriggerTarget, HasEventDispatcher, HasEventTrigger, java.lang.Cloneable

public final class DataDiffSection<T>
extends Section

A DiffSectionSpec that creates a changeSet diffing a generic List of data. This Section emits the following events:

RenderEvent whenever it needs a Component to render a model T from the List<? extends T> data. Providing a handler for this OnEvent is mandatory.

OnCheckIsSameItemEvent whenever during a diffing it wants to check whether two items represent the same piece of data.

OnCheckIsSameContentEvent whenever during a diffing it wants to check whether two items that represent the same piece of data have exactly the same content.

Diffing happens when the new List<? extends T> data is provided. Changes in State alone will not trigger diffing.

• If OnCheckIsSameItemEvent returns false RenderEvent is triggered. Otherwise OnCheckIsSameContentEvent is called.
• If OnCheckIsSameContentEvent returns false RenderEvent is triggered.

If OnCheckIsSameItemEvent is not implemented, new List<? extends T> data is considered to be completely different and relayout will happen on every data update.

Example usage:

 '@'GroupSectionSpec
 public class MyGroupSectionSpec {
   '@'OnCreateChildren
   static Children onCreateChildren(
     SectionContext c,
     '@'Prop List modelList) {
     return Children.create()
         .child(
             DataDiffSection.create(c)
                 .data(modelList)
                 .renderEventHandler(MyGroupSection.onRender(c))
                 .onCheckIsSameItemEventHandler(MyGroupSection.onCheckIsSameItem(c))
                 .onCheckIsSameContentEventHandler(...))
        .build();
   }
   '@'OnEvent(OnCheckIsSameItemEvent.class)
   static boolean onCheckIsSameItem(SectionContext c, @FromEvent Model previousItem, @FromEvent Model nextItem) {
     return previousItem.getId() == nextItem.getId();
   }
   '@'OnEvent(RenderEvent.class)
   static RenderInfo onRender(SectionContext c, @FromEvent Model model) {
     return ComponentRenderInfo.create()
         .component(MyComponent.create(c).model(model).build())
         .build();
   }
 }
 

See Also:

com.facebook.litho.sections.common.DataDiffSectionSpec

Required Props

data

extends T>

Type:

java.util.List

Optional Props

alwaysDetectDuplicates

Type:

java.lang.Boolean

detectMoves

Type:

java.lang.Boolean

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	DataDiffSection.Builder<T>

Method Summary

Modifier and Type	Method and Description
static <T> DataDiffSection.Builder<T>	create(SectionContext context)
protected void	generateChangeSet(SectionContext c, ChangeSet changeSet, SectionContext _prevScopedContext, Section _prevAbstractImpl, SectionContext _nextScopedContext, Section _nextAbstractImpl) This method will delegate to the DiffSectionSpec method annotated with OnDiff
static <T> EventHandler<OnCheckIsSameContentEvent<T>>	getOnCheckIsSameContentEventHandler(SectionContext context)
static <T> EventHandler<OnCheckIsSameItemEvent<T>>	getOnCheckIsSameItemEventHandler(SectionContext context)
static <T> EventHandler<RenderEvent<T>>	getRenderEventHandler(SectionContext context)
boolean	isDiffSectionSpec()
boolean	isEquivalentProps(Section other, boolean shouldCompareCommonProps)
protected java.lang.String	verifyChangeSet(SectionContext context)

Methods inherited from class com.facebook.litho.sections.Section

createStateContainer, generateUniqueGlobalKeyForChild, getChildren, getEventDispatcher, getGlobalKey, getLogTag, getParent, getScopedContext, getSimpleName, getStateContainer, getStateContainer, isEquivalentTo, makeShallowCopy, makeShallowCopy, recordEventTrigger, setChildren, setCount, setGlobalKey, setKey, setScopedContext, setStateContainer

Methods inherited from class com.facebook.litho.sections.SectionLifecycle

acceptTriggerEvent, acceptTriggerEventImpl, bindService, createChildren, createInitialState, createService, dataBound, dataRendered, dispatchLoadingEvent, dispatchOnEvent, dispatchOnEventImpl, getEventTrigger, getEventTrigger, getLoadingEventHandler, getService, getTreePropsForChildren, isSectionIndexValid, newEventHandler, newEventTrigger, newEventTrigger, populateTreeProps, refresh, requestFocus, requestFocus, requestFocus, requestFocusWithOffset, requestFocusWithOffset, requestFocusWithOffset, requestSmoothFocus, requestSmoothFocus, requestSmoothFocus, shouldUpdate, transferService, transferState, unbindService, viewportChanged

Methods inherited from class java.lang.Object

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

Method Detail

isEquivalentProps

public boolean isEquivalentProps(Section other,
                                 boolean shouldCompareCommonProps)

Overrides:

isEquivalentProps in class Section

create

public static <T> DataDiffSection.Builder<T> create(SectionContext context)

getOnCheckIsSameContentEventHandler

public static <T> EventHandler<OnCheckIsSameContentEvent<T>> getOnCheckIsSameContentEventHandler(SectionContext context)

getOnCheckIsSameItemEventHandler

public static <T> EventHandler<OnCheckIsSameItemEvent<T>> getOnCheckIsSameItemEventHandler(SectionContext context)

getRenderEventHandler

public static <T> EventHandler<RenderEvent<T>> getRenderEventHandler(SectionContext context)

generateChangeSet

protected void generateChangeSet(SectionContext c,
                                 ChangeSet changeSet,
                                 SectionContext _prevScopedContext,
                                 Section _prevAbstractImpl,
                                 SectionContext _nextScopedContext,
                                 Section _nextAbstractImpl)

Description copied from class: SectionLifecycle

This method will delegate to the DiffSectionSpec method annotated with OnDiff

Overrides:

generateChangeSet in class SectionLifecycle

isDiffSectionSpec

public boolean isDiffSectionSpec()

Overrides:

isDiffSectionSpec in class SectionLifecycle

Returns:

true if this lifecycle will generate a changeSet. If false this lifecycle will instead implement createChildren.

verifyChangeSet

protected java.lang.String verifyChangeSet(SectionContext context)

Overrides:

verifyChangeSet in class SectionLifecycle