ResetManager.java
/*
* Copyright 2019 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 androidx.recyclerview.selection;
import static androidx.recyclerview.selection.Shared.DEBUG;
import android.util.Log;
import android.view.MotionEvent;
import androidx.annotation.NonNull;
import androidx.recyclerview.selection.SelectionTracker.SelectionObserver;
import androidx.recyclerview.widget.RecyclerView;
import androidx.recyclerview.widget.RecyclerView.OnItemTouchListener;
import java.util.ArrayList;
import java.util.List;
/**
* Class managing resetting of library state in response to specific
* events like clearing of selection and MotionEvent.ACTION_CANCEL
* events.
*
* @param <K> Selection key type. @see {@link StorageStrategy} for supported types.
*/
final class ResetManager<K> {
private static final String TAG = "ResetManager";
private final List<Resettable> mResetHandlers = new ArrayList<>();
private final OnItemTouchListener mInputListener = new OnItemTouchListener() {
@Override
public boolean onInterceptTouchEvent(@NonNull RecyclerView unused,
@NonNull MotionEvent e) {
if (MotionEvents.isActionCancel(e)) {
if (DEBUG) Log.d(TAG, "Received CANCEL event.");
callResetHandlers();
}
return false;
}
@Override
public void onTouchEvent(@NonNull RecyclerView rv, @NonNull MotionEvent e) {
}
@Override
public void onRequestDisallowInterceptTouchEvent(boolean disallowIntercept) {
}
};
// Resettable interface has a #requiresReset method because DefaultSelectionTracker
// (owner of the state we observe with our SelectionObserver) is, itself,
// a Resettable. Such an arrangement introduces the real possibility of infinite recursion.
// When we call reset on DefaultSelectionTracker it'll eventually call back to
// notify us of the change via onSelectionCleared. We avoid recursion by
// checking #requiresReset before calling reset again.
private final SelectionObserver<K> mSelectionObserver = new SelectionObserver<K>() {
@Override
protected void onSelectionCleared() {
if (DEBUG) Log.d(TAG, "Received onSelectionCleared event.");
callResetHandlers();
}
};
SelectionObserver<K> getSelectionObserver() {
return mSelectionObserver;
}
OnItemTouchListener getInputListener() {
return mInputListener;
}
/**
* Registers a new Resettable.
*/
void addResetHandler(@NonNull Resettable handler) {
mResetHandlers.add(handler);
}
void callResetHandlers() {
for (Resettable handler : mResetHandlers) {
if (handler.isResetRequired()) {
handler.reset();
}
}
}
}