android.databinding.InverseBindingAdapter Maven / Gradle / Ivy
/*
* Copyright (C) 2015 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 android.databinding;
import java.lang.annotation.ElementType;
import java.lang.annotation.Target;
/**
* InverseBindingAdapter is associated with a method used to retrieve the value for a View
* when setting values gathered from the View. This is similar to {@link BindingAdapter}s:
*
* @InverseBindingAdapter(attribute = "android:text", event = "android:textAttrChanged")
* public static String captureTextValue(TextView view, CharSequence originalValue) {
* CharSequence newValue = view.getText();
* CharSequence oldValue = value.get();
* if (oldValue == null) {
* value.set(newValue);
* } else if (!contentEquals(newValue, oldValue)) {
* value.set(newValue);
* }
* }
*
*
* The default value for event is the attribute name suffixed with "AttrChanged". In the
* above example, the default value would have been android:textAttrChanged even
* if it wasn't provided.
*
* The event attribute is used to notify the data binding system that the value has changed.
* The developer will typically create a {@link BindingAdapter} to assign the event. For example:
*
*
* @BindingAdapter(value = {"android:beforeTextChanged", "android:onTextChanged",
* "android:afterTextChanged", "android:textAttrChanged"},
* requireAll = false)
* public static void setTextWatcher(TextView view, final BeforeTextChanged before,
* final OnTextChanged on, final AfterTextChanged after,
* final InverseBindingListener textAttrChanged) {
* TextWatcher newValue = new TextWatcher() {
* ...
* @Override
* public void onTextChanged(CharSequence s, int start, int before, int count) {
* if (on != null) {
* on.onTextChanged(s, start, before, count);
* }
* if (textAttrChanged != null) {
* textAttrChanged.onChange();
* }
* }
* }
* TextWatcher oldValue = ListenerUtil.trackListener(view, newValue, R.id.textWatcher);
* if (oldValue != null) {
* view.removeTextChangedListener(oldValue);
* }
* view.addTextChangedListener(newValue);
* }
*
*
* Like BindingAdapters, InverseBindingAdapter methods may also take
* {@link DataBindingComponent} as the first parameter and may be an instance method with the
* instance retrieved from the DataBindingComponent.
*
* @see DataBindingUtil#setDefaultComponent(DataBindingComponent)
* @see InverseBindingMethod
*/
@Target({ElementType.METHOD, ElementType.ANNOTATION_TYPE})
public @interface InverseBindingAdapter {
/**
* The attribute that the value is to be retrieved for.
*/
String attribute();
/**
* The event used to trigger changes. This is used in {@link BindingAdapter}s for the
* data binding system to set the event listener when two-way binding is used.
*/
String event() default "";
}