content: /*
   * Copyright (C) 2018 The Android Open Source Project
   *
   * 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 androidx.constraintlayout.widget;
  
  /**
   * <b>Added in 2.0</b>
   * <p>
   * Callbacks on state change
   * </p>
   */
  public abstract class ConstraintsChangedListener {
  
      /**
       * called before layout happens
       * @param stateId -1 if state unknown, otherwise the state we will transition to
       * @param constraintId the constraintSet id that we will transition to
       */
      public void preLayoutChange(int stateId, int constraintId){
          // nothing
      }
  
      /**
       * called after layout happens
       * @param stateId -1 if state unknown, otherwise the current state
       * @param constraintId the current constraintSet id we transitioned to
       */
      public void postLayoutChange(int stateId, int constraintId) {
          // nothing
      }
  }
  