| /* |
| * 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 com.android.launcher3; |
| |
| import android.content.Context; |
| import android.support.v7.widget.RecyclerView; |
| import android.util.AttributeSet; |
| import android.view.MotionEvent; |
| import com.android.launcher3.util.Thunk; |
| |
| /** |
| * A base {@link RecyclerView}, which will NOT intercept a touch sequence unless the scrolling |
| * velocity is below a predefined threshold. |
| */ |
| public class BaseRecyclerView extends RecyclerView |
| implements RecyclerView.OnItemTouchListener { |
| |
| private static final int SCROLL_DELTA_THRESHOLD_DP = 4; |
| |
| /** Keeps the last known scrolling delta/velocity along y-axis. */ |
| @Thunk int mDy = 0; |
| private float mDeltaThreshold; |
| |
| public BaseRecyclerView(Context context) { |
| this(context, null); |
| } |
| |
| public BaseRecyclerView(Context context, AttributeSet attrs) { |
| this(context, attrs, 0); |
| } |
| |
| public BaseRecyclerView(Context context, AttributeSet attrs, int defStyleAttr) { |
| super(context, attrs, defStyleAttr); |
| mDeltaThreshold = getResources().getDisplayMetrics().density * SCROLL_DELTA_THRESHOLD_DP; |
| |
| ScrollListener listener = new ScrollListener(); |
| setOnScrollListener(listener); |
| } |
| |
| private class ScrollListener extends OnScrollListener { |
| public ScrollListener() { |
| // Do nothing |
| } |
| |
| @Override |
| public void onScrolled(RecyclerView recyclerView, int dx, int dy) { |
| mDy = dy; |
| } |
| } |
| |
| @Override |
| protected void onFinishInflate() { |
| super.onFinishInflate(); |
| addOnItemTouchListener(this); |
| } |
| |
| @Override |
| public boolean onInterceptTouchEvent(RecyclerView rv, MotionEvent ev) { |
| if (shouldStopScroll(ev)) { |
| stopScroll(); |
| } |
| return false; |
| } |
| |
| @Override |
| public void onTouchEvent(RecyclerView rv, MotionEvent ev) { |
| // Do nothing. |
| } |
| |
| public void onRequestDisallowInterceptTouchEvent(boolean disallowIntercept) { |
| // DO NOT REMOVE, NEEDED IMPLEMENTATION FOR M BUILDS |
| } |
| |
| /** |
| * Returns whether this {@link MotionEvent} should trigger the scroll to be stopped. |
| */ |
| protected boolean shouldStopScroll(MotionEvent ev) { |
| if (ev.getAction() == MotionEvent.ACTION_DOWN) { |
| if ((Math.abs(mDy) < mDeltaThreshold && |
| getScrollState() != RecyclerView.SCROLL_STATE_IDLE)) { |
| // now the touch events are being passed to the {@link WidgetCell} until the |
| // touch sequence goes over the touch slop. |
| return true; |
| } |
| } |
| return false; |
| } |
| } |