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Diffstat (limited to 'src/com/android/launcher3/BaseRecyclerView.java')
-rw-r--r-- | src/com/android/launcher3/BaseRecyclerView.java | 102 |
1 files changed, 102 insertions, 0 deletions
diff --git a/src/com/android/launcher3/BaseRecyclerView.java b/src/com/android/launcher3/BaseRecyclerView.java new file mode 100644 index 000000000..b63ef788a --- /dev/null +++ b/src/com/android/launcher3/BaseRecyclerView.java @@ -0,0 +1,102 @@ +/* + * 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; + } +}
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