Add OnLayoutCalculated component lifecycle method

litho-annotations/src/main/java/com/facebook/litho/annotations/OnLayoutCalculated.java

@@ -0,0 +1,23 @@
+/*
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.facebook.litho.annotations;
+
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+
+@Retention(RetentionPolicy.RUNTIME)
+public @interface OnLayoutCalculated {}

litho-core/src/main/java/com/facebook/litho/ComponentLifecycle.java

@@ -394,6 +394,13 @@ protected void onBind(ComponentContext c, Object mountedContent) {
    */
   protected void onBoundsDefined(ComponentContext c, ComponentLayout layout) {}
 
+  /**
+   * Called after the layout calculation is finished.
+   *
+   * @param c The {@link Context} used by this component.
+   */
+  protected void onLayoutCalculated(ComponentContext c) {}
+
   /**
    * Generate a tree of {@link ComponentLayout} representing the layout structure of the {@link
    * Component} and its sub-components.

litho-core/src/main/java/com/facebook/litho/DefaultInternalNode.java

@@ -411,6 +411,10 @@ && isLayoutDirectionRTL(c.getAndroidContext())) {
 
     mYogaNode.calculateLayout(width, height);
 
+    for (Component component : mComponents) {
+      component.onLayoutCalculated(mComponentContext);
+    }
+
     return this;
   }
 

litho-it/src/main/java/com/facebook/litho/LifecycleStep.java

@@ -26,6 +26,7 @@ public enum LifecycleStep {
   ON_PREPARE,
   ON_MEASURE,
   ON_BOUNDS_DEFINED,
+  ON_LAYOUT_CALCULATED,
   ON_CREATE_MOUNT_CONTENT,
   ON_MOUNT,
   ON_UNMOUNT,

litho-it/src/main/java/com/facebook/litho/widget/LayoutSpecLifecycleTesterSpec.java

@@ -42,6 +42,7 @@
 import com.facebook.litho.annotations.OnCreateTreeProp;
 import com.facebook.litho.annotations.OnDetached;
 import com.facebook.litho.annotations.OnEvent;
+import com.facebook.litho.annotations.OnLayoutCalculated;
 import com.facebook.litho.annotations.OnUpdateState;
 import com.facebook.litho.annotations.OnUpdateStateWithTransition;
 import com.facebook.litho.annotations.Param;
@@ -113,6 +114,11 @@ static void onDetached(ComponentContext c, @Prop List<LifecycleStep.StepInfo> st
     steps.add(new StepInfo(LifecycleStep.ON_DETACHED));
   }
 
+  @OnLayoutCalculated
+  static void onLayoutCalculated(ComponentContext c, @Prop List<LifecycleStep.StepInfo> steps) {
+    steps.add(new StepInfo(LifecycleStep.ON_LAYOUT_CALCULATED));
+  }
+
   @OnUpdateState
   static void updateState(@Param List<LifecycleStep.StepInfo> stepsAsParam) {
     stepsAsParam.add(new StepInfo(LifecycleStep.ON_UPDATE_STATE));

litho-it/src/test/java/com/facebook/litho/LayoutSpecLifecycleTest.java

@@ -69,6 +69,7 @@ public void lifecycle_onSetRootWithLayout_shouldCallLifecycleMethods() {
             LifecycleStep.ON_CALCULATE_CACHED_VALUE,
             LifecycleStep.ON_CREATE_LAYOUT,
             LifecycleStep.ON_CREATE_TRANSITION,
+            LifecycleStep.ON_LAYOUT_CALCULATED,
             LifecycleStep.ON_ATTACHED);
     ComponentsConfiguration.isAnimationDisabled = true;
   }
@@ -108,7 +109,8 @@ public void lifecycle_subsequentSetRoot_shouldCallLifecycleMethod() {
         .containsExactly(
             LifecycleStep.ON_CREATE_TREE_PROP,
             LifecycleStep.ON_CALCULATE_CACHED_VALUE,
-            LifecycleStep.ON_CREATE_LAYOUT);
+            LifecycleStep.ON_CREATE_LAYOUT,
+            LifecycleStep.ON_LAYOUT_CALCULATED);
   }
 
   @Test
@@ -132,7 +134,8 @@ public void lifecycle_updateState_shouldCallLifecycleMethod() {
             LifecycleStep.ON_UPDATE_STATE,
             LifecycleStep.ON_CREATE_TREE_PROP,
             LifecycleStep.ON_CALCULATE_CACHED_VALUE,
-            LifecycleStep.ON_CREATE_LAYOUT);
+            LifecycleStep.ON_CREATE_LAYOUT,
+            LifecycleStep.ON_LAYOUT_CALCULATED);
     ComponentsConfiguration.isReconciliationEnabled = true;
   }
 
@@ -158,7 +161,8 @@ public void lifecycle_updateStateWithTransition_shouldCallLifecycleMethod() {
             LifecycleStep.ON_UPDATE_STATE_WITH_TRANSITION,
             LifecycleStep.ON_CREATE_TREE_PROP,
             LifecycleStep.ON_CALCULATE_CACHED_VALUE,
-            LifecycleStep.ON_CREATE_LAYOUT);
+            LifecycleStep.ON_CREATE_LAYOUT,
+            LifecycleStep.ON_LAYOUT_CALCULATED);
     ComponentsConfiguration.isReconciliationEnabled = true;
   }
 

litho-processor/src/main/java/com/facebook/litho/specmodels/model/DelegateMethodDescriptions.java

@@ -46,6 +46,7 @@
 import com.facebook.litho.annotations.OnCreateMountContentPool;
 import com.facebook.litho.annotations.OnCreateTransition;
 import com.facebook.litho.annotations.OnDetached;
+import com.facebook.litho.annotations.OnLayoutCalculated;
 import com.facebook.litho.annotations.OnError;
 import com.facebook.litho.annotations.OnLoadStyle;
 import com.facebook.litho.annotations.OnMeasure;
@@ -162,6 +163,18 @@ public final class DelegateMethodDescriptions {
                       .build()))
           .build();
 
+  public static final DelegateMethodDescription ON_LAYOUT_CALCULATED =
+      DelegateMethodDescription.newBuilder()
+          .annotations(ImmutableList.of(AnnotationSpec.builder(Override.class).build()))
+          .accessType(Modifier.PROTECTED)
+          .returnType(TypeName.VOID)
+          .name("onLayoutCalculated")
+          .definedParameterTypes(
+              ImmutableList.<TypeName>of(ClassNames.COMPONENT_CONTEXT))
+          .optionalParameterTypes(
+              ImmutableList.of(PROP, TREE_PROP, STATE, INJECT_PROP, CACHED_VALUE))
+          .build();
+
   public static final DelegateMethodDescription ON_CREATE_INITIAL_STATE =
       DelegateMethodDescription.newBuilder()
           .annotations(ImmutableList.of(AnnotationSpec.builder(Override.class).build()))
@@ -521,6 +534,7 @@ public int compare(Class<? extends Annotation> lhs, Class<? extends Annotation>
     layoutSpecDelegateMethodsMap.put(ShouldUpdate.class, SHOULD_UPDATE);
     layoutSpecDelegateMethodsMap.put(OnAttached.class, ON_ATTACHED);
     layoutSpecDelegateMethodsMap.put(OnDetached.class, ON_DETACHED);
+    layoutSpecDelegateMethodsMap.put(OnLayoutCalculated.class, ON_LAYOUT_CALCULATED);
     LAYOUT_SPEC_DELEGATE_METHODS_MAP = Collections.unmodifiableMap(layoutSpecDelegateMethodsMap);
 
     Map<Class<? extends Annotation>, DelegateMethodDescription> mountSpecDelegateMethodsMap =