litho-annotations/com.facebook.litho.annotations/LayoutSpec

LayoutSpec

@Retention(value = RetentionPolicy.RUNTIME)

annotation class ~~LayoutSpec~~

Deprecated

A class that is annotated with this annotation will be used to create a composite component that is made up of other components. A layout spec is the logical equivalent of a composite view in Android.

The class annotated with LayoutSpec must implement a method with the or OnCreateLayoutWithSizeSpec annotation. It may also implement methods with the following annotations:

Example:

@LayoutSpec
public class CounterSpec {

 @OnCreateLayout
  static Component onCreateLayout(
    ComponentContext c,
   @Prop int id,
   @State int count) {

    return Row.create(c)
      .backgroundColor(Color.WHITE)
      .heightDip(64)
      .paddingDip(YogaEdge.ALL, 8)
      .child(
        Text.create(c)
          .text(" + ")
          .clickHandler(Counter.onClick(c))
      )
      .child(
        Text.create(c)
          .text(String.valueOf(count))
      )
      .build();
  }

 @OnCreateInitialState
  static void onCreateInitialState(
      ComponentContext c,
      StateValue<Integer> count) {
    count.set(0);
  }

 @OnEvent(ClickEvent.class)
  static void onClick(ComponentContext c, @Prop int id) {
    Counter.increment(c, id);
  }

 @OnUpdateState
  static void increment(StateValue<Integer> count, @Param int counterId) {
    count.set(count.get() + 1);
  }
}