EventRouter.java
/*
* Copyright 2017 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.core.util.Preconditions.checkArgument;
import android.view.MotionEvent;
import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;
import androidx.recyclerview.widget.RecyclerView.OnItemTouchListener;
/**
* A class responsible for routing MotionEvents to tool-type specific handlers.
* Individual tool-type specific handlers are added after the class is constructed.
*
* <p>
* EventRouter takes its name from
* {@link RecyclerView#addOnItemTouchListener(OnItemTouchListener)}. Despite "Touch"
* being in the name, it receives MotionEvents for all types of tools.
*/
final class EventRouter implements OnItemTouchListener, Resettable {
private final ToolHandlerRegistry<OnItemTouchListener> mDelegates;
private boolean mDisallowIntercept;
EventRouter() {
mDelegates = new ToolHandlerRegistry<>(new StubOnItemTouchListener());
}
/**
* @param toolType See MotionEvent for details on available types.
* @param delegate An {@link OnItemTouchListener} to receive events
* of {@code toolType}.
*/
void set(int toolType, @NonNull OnItemTouchListener delegate) {
checkArgument(delegate != null);
mDelegates.set(toolType, delegate);
}
@Override
public boolean onInterceptTouchEvent(@NonNull RecyclerView rv, @NonNull MotionEvent e) {
// Reset disallow when the event is down as advised in http://b/139141511#comment20.
if (mDisallowIntercept && MotionEvents.isActionDown(e)) {
mDisallowIntercept = false;
}
return !mDisallowIntercept && mDelegates.get(e).onInterceptTouchEvent(rv, e);
}
@Override
public void onTouchEvent(@NonNull RecyclerView rv, @NonNull MotionEvent e) {
if (!mDisallowIntercept) {
mDelegates.get(e).onTouchEvent(rv, e);
}
}
@Override
public void onRequestDisallowInterceptTouchEvent(boolean disallowIntercept) {
if (!disallowIntercept) {
return; // Ignore as advised in http://b/139141511#comment20
}
// Some types of views, such as HorizontalScrollView, may want
// to take over the input stream. In this case they'll call this method
// with disallowIntercept=true. mDisallowIntercept is reset on UP or CANCEL
// events in onInterceptTouchEvent.
mDisallowIntercept = disallowIntercept;
}
@Override
public boolean isResetRequired() {
return mDisallowIntercept;
}
@Override
public void reset() {
mDisallowIntercept = false;
}
}