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 * InverseBindingAdapter is associated with a method used to retrieve the value for a View 23 * when setting values gathered from the View. This is similar to {@link BindingAdapter}s: 24 * <pre> 25 * @InverseBindingAdapter(attribute = "android:text", event = "android:textAttrChanged") 26 * public static String captureTextValue(TextView view, CharSequence originalValue) { 27 * CharSequence newValue = view.getText(); 28 * CharSequence oldValue = value.get(); 29 * if (oldValue == null) { 30 * value.set(newValue); 31 * } else if (!contentEquals(newValue, oldValue)) { 32 * value.set(newValue); 33 * } 34 * } 35 * </pre> 36 * <p> 37 * The default value for event is the attribute name suffixed with "AttrChanged". In the 38 * above example, the default value would have been <code>android:textAttrChanged</code> even 39 * if it wasn't provided. 40 * <p> 41 * The event attribute is used to notify the data binding system that the value has changed. 42 * The developer will typically create a {@link BindingAdapter} to assign the event. For example: 43 * <p> 44 * <pre> 45 * @BindingAdapter(value = {"android:beforeTextChanged", "android:onTextChanged", 46 * "android:afterTextChanged", "android:textAttrChanged"}, 47 * requireAll = false) 48 * public static void setTextWatcher(TextView view, final BeforeTextChanged before, 49 * final OnTextChanged on, final AfterTextChanged after, 50 * final InverseBindingListener textAttrChanged) { 51 * TextWatcher newValue = new TextWatcher() { 52 * ... 53 * @Override 54 * public void onTextChanged(CharSequence s, int start, int before, int count) { 55 * if (on != null) { 56 * on.onTextChanged(s, start, before, count); 57 * } 58 * if (textAttrChanged != null) { 59 * textAttrChanged.onChange(); 60 * } 61 * } 62 * } 63 * TextWatcher oldValue = ListenerUtil.trackListener(view, newValue, R.id.textWatcher); 64 * if (oldValue != null) { 65 * view.removeTextChangedListener(oldValue); 66 * } 67 * view.addTextChangedListener(newValue); 68 * } 69 * </pre> 70 * <p> 71 * Like <code>BindingAdapter</code>s, InverseBindingAdapter methods may also take 72 * {@link DataBindingComponent} as the first parameter and may be an instance method with the 73 * instance retrieved from the <code>DataBindingComponent</code>. 74 * 75 * @see DataBindingUtil#setDefaultComponent(DataBindingComponent) 76 * @see InverseBindingMethod 77 */ 78 @Target({ElementType.METHOD, ElementType.ANNOTATION_TYPE}) 79 public @interface InverseBindingAdapter { 80 81 /** 82 * The attribute that the value is to be retrieved for. 83 */ 84 String attribute(); 85 86 /** 87 * The event used to trigger changes. This is used in {@link BindingAdapter}s for the 88 * data binding system to set the event listener when two-way binding is used. 89 */ 90 String event() default ""; 91 } 92
