1 /*
2  * Copyright (C) 2018 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 package androidx.constraintlayout.widget;
17 
18 /**
19  * <b>Added in 2.0</b>
20  * <p>
21  * Callbacks on state change
22  * </p>
23  */
24 public abstract class ConstraintsChangedListener {
25 
26     /**
27      * called before layout happens
28      * @param stateId -1 if state unknown, otherwise the state we will transition to
29      * @param constraintId the constraintSet id that we will transition to
30      */
preLayoutChange(int stateId, int constraintId)31     public void preLayoutChange(int stateId, int constraintId){
32         // nothing
33     }
34 
35     /**
36      * called after layout happens
37      * @param stateId -1 if state unknown, otherwise the current state
38      * @param constraintId the current constraintSet id we transitioned to
39      */
postLayoutChange(int stateId, int constraintId)40     public void postLayoutChange(int stateId, int constraintId) {
41         // nothing
42     }
43 }
44