com.facebook.litho.annotations

Annotation Type FromMeasure

@Retention(value=RUNTIME)
public @interface FromMeasure

Annotates that the argument's value should be set to the named inter-stage output from the OnMeasure lifecycle method. The name and type of the argument must match with the inter-stage output requested.

This can be used in:

• OnBoundsDefined
• OnMount
• OnBind
• OnUnbind
• OnUnmount
• OnPopulateAccessibilityNode
• OnPopulateExtraAccessibilityNode
• GetExtraAccessibilityNodeAt
• GetExtraAccessibilityNodesCount

The annotation processor will validate this and other invariants in the API at build time.

For example:

 @MountSpec
 public class SubtitleSpec {

   @OnMeasure
   static void onMeasure(
       ComponentContext componentContext,
       ComponentLayout layout,
       int widthSpec,
       int heightSpec,
       Size size,
       @Prop String text,
       Output<Layout> measuredLayout) {

     Layout textLayout = createTextLayout(text, widthSpec, heightSpec);

     size.width = SizeSpec.resolveSize(widthSpec, textLayout.getWidth());
     size.height = SizeSpec.resolveSize(heightSpec, LayoutMeasureUtil.getHeight(textLayout));

     if (size.width < 0 || size.height < 0) {
       size.width = Math.max(size.width, 0);
       size.height = Math.max(size.height, 0);
     }

     measuredLayout.set(textLayout);  // Set the value of output.
   }

   @OnMount
   static void onMount(ComponentContext c,
     TextDrawable textDrawable,
     @Prop String text,
     // Get measured layout from the output set in OnMeasure.
     @FromMeasure Layout measuredLayout) {

       textDrawable.mount(
         text,
         textLayout,
         0,
         null,
         Color.BLANK,
         Color.GREEN,
         null);
   }
 }