| /* |
| * 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.graphics.Canvas; |
| import android.support.v7.widget.RecyclerView; |
| import android.util.AttributeSet; |
| import android.view.MotionEvent; |
| import android.view.View; |
| import android.view.ViewGroup; |
| import android.widget.TextView; |
| |
| import com.android.launcher3.views.RecyclerViewFastScroller; |
| |
| |
| /** |
| * A base {@link RecyclerView}, which does the following: |
| * <ul> |
| * <li> NOT intercept a touch unless the scrolling velocity is below a predefined threshold. |
| * <li> Enable fast scroller. |
| * </ul> |
| */ |
| public abstract class BaseRecyclerView extends RecyclerView |
| implements RecyclerView.OnItemTouchListener { |
| |
| protected RecyclerViewFastScroller mScrollbar; |
| |
| 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); |
| } |
| |
| @Override |
| protected void onFinishInflate() { |
| super.onFinishInflate(); |
| addOnItemTouchListener(this); |
| } |
| |
| @Override |
| protected void onAttachedToWindow() { |
| super.onAttachedToWindow(); |
| ViewGroup parent = (ViewGroup) getParent(); |
| mScrollbar = parent.findViewById(R.id.fast_scroller); |
| mScrollbar.setRecyclerView(this, (TextView) parent.findViewById(R.id.fast_scroller_popup)); |
| } |
| |
| /** |
| * We intercept the touch handling only to support fast scrolling when initiated from the |
| * scroll bar. Otherwise, we fall back to the default RecyclerView touch handling. |
| */ |
| @Override |
| public boolean onInterceptTouchEvent(RecyclerView rv, MotionEvent ev) { |
| return handleTouchEvent(ev); |
| } |
| |
| @Override |
| public void onTouchEvent(RecyclerView rv, MotionEvent ev) { |
| handleTouchEvent(ev); |
| } |
| |
| /** |
| * Handles the touch event and determines whether to show the fast scroller (or updates it if |
| * it is already showing). |
| */ |
| private boolean handleTouchEvent(MotionEvent ev) { |
| // Move to mScrollbar's coordinate system. |
| int left = getLeft() - mScrollbar.getLeft(); |
| int top = getTop() - mScrollbar.getTop(); |
| ev.offsetLocation(left, top); |
| try { |
| return mScrollbar.handleTouchEvent(ev); |
| } finally { |
| ev.offsetLocation(-left, -top); |
| } |
| } |
| |
| public void onRequestDisallowInterceptTouchEvent(boolean disallowIntercept) { |
| // DO NOT REMOVE, NEEDED IMPLEMENTATION FOR M BUILDS |
| } |
| |
| public int getScrollBarTop() { |
| return getPaddingTop(); |
| } |
| |
| /** |
| * Returns the height of the fast scroll bar |
| */ |
| public int getScrollbarTrackHeight() { |
| return getHeight() - getScrollBarTop() - getPaddingBottom(); |
| } |
| |
| /** |
| * Returns the available scroll height: |
| * AvailableScrollHeight = Total height of the all items - last page height |
| */ |
| protected abstract int getAvailableScrollHeight(); |
| |
| /** |
| * Returns the available scroll bar height: |
| * AvailableScrollBarHeight = Total height of the visible view - thumb height |
| */ |
| protected int getAvailableScrollBarHeight() { |
| int availableScrollBarHeight = getScrollbarTrackHeight() - mScrollbar.getThumbHeight(); |
| return availableScrollBarHeight; |
| } |
| |
| @Override |
| protected void dispatchDraw(Canvas canvas) { |
| onUpdateScrollbar(0); |
| super.dispatchDraw(canvas); |
| } |
| |
| /** |
| * Updates the scrollbar thumb offset to match the visible scroll of the recycler view. It does |
| * this by mapping the available scroll area of the recycler view to the available space for the |
| * scroll bar. |
| * |
| * @param scrollY the current scroll y |
| */ |
| protected void synchronizeScrollBarThumbOffsetToViewScroll(int scrollY, |
| int availableScrollHeight) { |
| // Only show the scrollbar if there is height to be scrolled |
| if (availableScrollHeight <= 0) { |
| mScrollbar.setThumbOffsetY(-1); |
| return; |
| } |
| |
| // Calculate the current scroll position, the scrollY of the recycler view accounts for the |
| // view padding, while the scrollBarY is drawn right up to the background padding (ignoring |
| // padding) |
| int scrollBarY = |
| (int) (((float) scrollY / availableScrollHeight) * getAvailableScrollBarHeight()); |
| |
| // Calculate the position and size of the scroll bar |
| mScrollbar.setThumbOffsetY(scrollBarY); |
| } |
| |
| /** |
| * Returns whether the view itself will handle the touch event or not. |
| * @param ev MotionEvent in {@param eventSource} |
| */ |
| public boolean shouldContainerScroll(MotionEvent ev, View eventSource) { |
| int[] point = new int[2]; |
| point[0] = (int) ev.getX(); |
| point[1] = (int) ev.getY(); |
| Utilities.mapCoordInSelfToDescendant(mScrollbar, eventSource, point); |
| // IF the MotionEvent is inside the thumb, container should not be pulled down. |
| if (mScrollbar.shouldBlockIntercept(point[0], point[1])) { |
| return false; |
| } |
| |
| // IF scroller is at the very top OR there is no scroll bar because there is probably not |
| // enough items to scroll, THEN it's okay for the container to be pulled down. |
| if (getCurrentScrollY() == 0) { |
| return true; |
| } |
| return false; |
| } |
| |
| /** |
| * @return whether fast scrolling is supported in the current state. |
| */ |
| public boolean supportsFastScrolling() { |
| return true; |
| } |
| |
| /** |
| * Maps the touch (from 0..1) to the adapter position that should be visible. |
| * <p>Override in each subclass of this base class. |
| * |
| * @return the scroll top of this recycler view. |
| */ |
| public abstract int getCurrentScrollY(); |
| |
| /** |
| * Maps the touch (from 0..1) to the adapter position that should be visible. |
| * <p>Override in each subclass of this base class. |
| */ |
| public abstract String scrollToPositionAtProgress(float touchFraction); |
| |
| /** |
| * Updates the bounds for the scrollbar. |
| * <p>Override in each subclass of this base class. |
| */ |
| public abstract void onUpdateScrollbar(int dy); |
| |
| /** |
| * <p>Override in each subclass of this base class. |
| */ |
| public void onFastScrollCompleted() {} |
| } |