1 /* 2 * Copyright (C) 2015 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 android.databinding; 17 18 /** 19 * Listener set on {@link ViewDataBinding#addOnRebindCallback(OnRebindCallback)} that 20 * is called when bound values must be reevaluated in {@link 21 * ViewDataBinding#executePendingBindings()}. 22 */ 23 public abstract class OnRebindCallback<T extends ViewDataBinding> { 24 25 /** 26 * Called when values in a ViewDataBinding should be reevaluated. This does not 27 * mean that values will actually change, but only that something in the data 28 * model that affects the bindings has been perturbed. 29 * <p> 30 * Return true to allow the reevaluation to happen or false if the reevaluation 31 * should be stopped. If false is returned, it is the responsibility of the 32 * OnRebindListener implementer to explicitly call {@link 33 * ViewDataBinding#executePendingBindings()}. 34 * <p> 35 * The default implementation only returns <code>true</code>. 36 * 37 * @param binding The ViewDataBinding that is reevaluating its bound values. 38 * @return true to indicate that the reevaluation should continue or false to 39 * halt evaluation. 40 */ 41 public boolean onPreBind(T binding) { 42 return true; 43 } 44 45 /** 46 * Called after all callbacks have completed {@link #onPreBind(ViewDataBinding)} when 47 * one or more of the calls has returned <code>false</code>. 48 * <p> 49 * The default implementation does nothing. 50 * 51 * @param binding The ViewDataBinding that is reevaluating its bound values. 52 */ 53 public void onCanceled(T binding) { 54 } 55 56 /** 57 * Called after values have been reevaluated in {@link 58 * ViewDataBinding#executePendingBindings()}. This is only called if all listeners have 59 * returned true from {@link #onPreBind(ViewDataBinding)}. 60 * <p> 61 * The default implementation does nothing. 62 * 63 * @param binding The ViewDataBinding that is reevaluating its bound values. 64 */ 65 public void onBound(T binding) { 66 } 67 } 68
