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/*
* 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;
/**
* A listener implemented by all two-way bindings to be notified when a triggering change happens.
* For example, when there is a two-way binding for android:text, an implementation of
* <code>InverseBindingListener</code> will be generated in the layout's binding class.
* <pre>
* private static class InverseListenerTextView implements InverseBindingListener {
* @Override
* public void onChange() {
* mObj.setTextValue(mTextView.getText());
* }
* }
* </pre>
* <p>
* A {@link BindingAdapter} should be used to assign the event listener.
* For example, <code>android:onTextChanged</code> will need to trigger the event listener
* for the <code>android:text</code> attribute.
* <pre>
* @InverseBindingAdapter(attribute = "android:text", event = "android:textAttrChanged")
* public static void captureTextValue(TextView view, ObservableField<CharSequence> value) {
* CharSequence newValue = view.getText();
* CharSequence oldValue = value.get();
* if (oldValue == null) {
* value.set(newValue);
* } else if (!contentEquals(newValue, oldValue)) {
* value.set(newValue);
* }
* }
* @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);
* }
* </pre>
*/
public interface InverseBindingListener {
/**
* Notifies the data binding system that the attribute value has changed.
*/
void onChange();
}
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