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 import java.lang.annotation.ElementType; 19 import java.lang.annotation.Target; 20 21 /** 22 * BindingAdapter is applied to methods that are used to manipulate how values with expressions 23 * are set to views. The simplest example is to have a public static method that takes the view 24 * and the value to set: 25 * <p><pre> 26 *<code>@BindingAdapter("android:bufferType") 27 * public static void setBufferType(TextView view, TextView.BufferType bufferType) { 28 * view.setText(view.getText(), bufferType); 29 * }</code></pre> 30 * In the above example, when android:bufferType is used on a TextView, the method 31 * setBufferType is called. 32 * <p> 33 * It is also possible to take previously set values, if the old values are listed first: 34 * <p><pre> 35 *<code>@BindingAdapter("android:onLayoutChange") 36 * public static void setOnLayoutChangeListener(View view, View.OnLayoutChangeListener oldValue, 37 * View.OnLayoutChangeListener newValue) { 38 * if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) { 39 * if (oldValue != null) { 40 * view.removeOnLayoutChangeListener(oldValue); 41 * } 42 * if (newValue != null) { 43 * view.addOnLayoutChangeListener(newValue); 44 * } 45 * } 46 * }</code></pre> 47 * When a binding adapter may also take multiple attributes, it will only be called when all 48 * attributes associated with the binding adapter have binding expressions associated with them. 49 * This is useful when there are unusual interactions between attributes. For example: 50 * <p><pre> 51 *<code>@BindingAdapter({"android:onClick", "android:clickable"}) 52 * public static void setOnClick(View view, View.OnClickListener clickListener, 53 * boolean clickable) { 54 * view.setOnClickListener(clickListener); 55 * view.setClickable(clickable); 56 * }</code></pre> 57 * The order of the parameters must match the order of the attributes in values in the 58 * BindingAdapter. 59 * <p> 60 * A binding adapter may optionally take a class extending DataBindingComponent as the first 61 * parameter as well. If it does, it will be passed the value passed in during binding, either 62 * directly in the inflate method or indirectly, using the value from 63 * {@link DataBindingUtil#getDefaultComponent()}. 64 * <p> 65 * If a binding adapter is an instance method, the generated DataBindingComponent will have 66 * a getter to retrieve an instance of the BindingAdapter's class to use to call the method. 67 */ 68 @Target(ElementType.METHOD) 69 public @interface BindingAdapter { 70 71 /** 72 * @return The attributes associated with this binding adapter. 73 */ 74 String[] value(); 75 } 76
