| // Copyright 2018 The Feed Authors. |
| // |
| // 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.google.android.libraries.feed.basicstream.internal; |
| |
| import android.graphics.Canvas; |
| import android.support.v7.widget.RecyclerView; |
| import android.support.v7.widget.RecyclerView.ViewHolder; |
| import android.support.v7.widget.helper.ItemTouchHelper; |
| import android.view.animation.Interpolator; |
| import android.support.v4.view.animation.FastOutLinearInInterpolator; |
| import com.google.android.libraries.feed.basicstream.internal.viewholders.SwipeableViewHolder; |
| |
| /** {@link ItemTouchHelper.Callback} to allow dismissing cards via swiping. */ |
| public final class StreamItemTouchCallbacks extends ItemTouchHelper.Callback { |
| |
| private static final Interpolator DISMISS_INTERPOLATOR = new FastOutLinearInInterpolator(); |
| |
| @Override |
| public int getMovementFlags(RecyclerView recyclerView, ViewHolder viewHolder) { |
| int swipeFlags = 0; |
| if (viewHolder instanceof SwipeableViewHolder |
| && ((SwipeableViewHolder) viewHolder).canSwipe()) { |
| swipeFlags = ItemTouchHelper.START | ItemTouchHelper.END; |
| } |
| return makeMovementFlags(/* dragFlags= */ 0, swipeFlags); |
| } |
| |
| @Override |
| public boolean onMove(RecyclerView recyclerView, ViewHolder viewHolder, ViewHolder viewHolder1) { |
| throw new AssertionError( |
| "onMove not supported."); // Drag and drop not supported, the method will never be called. |
| } |
| |
| @Override |
| public void onSwiped(ViewHolder viewHolder, int i) { |
| // Only PietViewHolders support swipe to dismiss. If new ViewHolders support swipe to dismiss, |
| // this should instead use an interface. |
| ((SwipeableViewHolder) viewHolder).onSwiped(); |
| } |
| |
| @Override |
| public void onChildDraw( |
| Canvas canvas, |
| RecyclerView recyclerView, |
| ViewHolder viewHolder, |
| float dX, |
| float dY, |
| int i, |
| boolean isCurrentlyActive) { |
| float input = Math.abs(dX) / viewHolder.itemView.getMeasuredWidth(); |
| float alpha = 1 - DISMISS_INTERPOLATOR.getInterpolation(input); |
| |
| viewHolder.itemView.setTranslationX(dX); |
| viewHolder.itemView.setAlpha(alpha); |
| } |
| } |