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      1 /*
      2  * Copyright (C) 2015 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package com.android.launcher3.widget;
     18 
     19 import android.content.Context;
     20 import android.graphics.Canvas;
     21 import android.graphics.Color;
     22 import android.support.v7.widget.LinearLayoutManager;
     23 import android.util.AttributeSet;
     24 import android.view.View;
     25 import com.android.launcher3.BaseRecyclerView;
     26 import com.android.launcher3.R;
     27 import com.android.launcher3.model.PackageItemInfo;
     28 import com.android.launcher3.model.WidgetsModel;
     29 
     30 /**
     31  * The widgets recycler view.
     32  */
     33 public class WidgetsRecyclerView extends BaseRecyclerView {
     34 
     35     private static final String TAG = "WidgetsRecyclerView";
     36     private WidgetsModel mWidgets;
     37     private ScrollPositionState mScrollPosState = new ScrollPositionState();
     38 
     39     public WidgetsRecyclerView(Context context) {
     40         this(context, null);
     41     }
     42 
     43     public WidgetsRecyclerView(Context context, AttributeSet attrs) {
     44         this(context, attrs, 0);
     45     }
     46 
     47     public WidgetsRecyclerView(Context context, AttributeSet attrs, int defStyleAttr) {
     48         // API 21 and below only support 3 parameter ctor.
     49         super(context, attrs, defStyleAttr);
     50     }
     51 
     52     public WidgetsRecyclerView(Context context, AttributeSet attrs, int defStyleAttr,
     53             int defStyleRes) {
     54         this(context, attrs, defStyleAttr);
     55     }
     56 
     57     @Override
     58     protected void onFinishInflate() {
     59         super.onFinishInflate();
     60         addOnItemTouchListener(this);
     61     }
     62 
     63     public int getFastScrollerTrackColor(int defaultTrackColor) {
     64         return Color.WHITE;
     65     }
     66 
     67     /**
     68      * Sets the widget model in this view, used to determine the fast scroll position.
     69      */
     70     public void setWidgets(WidgetsModel widgets) {
     71         mWidgets = widgets;
     72     }
     73 
     74     /**
     75      * We need to override the draw to ensure that we don't draw the overscroll effect beyond the
     76      * background bounds.
     77      */
     78     @Override
     79     protected void dispatchDraw(Canvas canvas) {
     80         canvas.clipRect(mBackgroundPadding.left, mBackgroundPadding.top,
     81                 getWidth() - mBackgroundPadding.right,
     82                 getHeight() - mBackgroundPadding.bottom);
     83         super.dispatchDraw(canvas);
     84     }
     85 
     86     /**
     87      * Maps the touch (from 0..1) to the adapter position that should be visible.
     88      */
     89     @Override
     90     public String scrollToPositionAtProgress(float touchFraction) {
     91         // Skip early if widgets are not bound.
     92         if (mWidgets == null) {
     93             return "";
     94         }
     95 
     96         // Skip early if there are no widgets.
     97         int rowCount = mWidgets.getPackageSize();
     98         if (rowCount == 0) {
     99             return "";
    100         }
    101 
    102         // Stop the scroller if it is scrolling
    103         stopScroll();
    104 
    105         getCurScrollState(mScrollPosState, -1);
    106         float pos = rowCount * touchFraction;
    107         int availableScrollHeight = getAvailableScrollHeight(rowCount);
    108         LinearLayoutManager layoutManager = ((LinearLayoutManager) getLayoutManager());
    109         layoutManager.scrollToPositionWithOffset(0, (int) -(availableScrollHeight * touchFraction));
    110 
    111         int posInt = (int) ((touchFraction == 1)? pos -1 : pos);
    112         PackageItemInfo p = mWidgets.getPackageItemInfo(posInt);
    113         return p.titleSectionName;
    114     }
    115 
    116     /**
    117      * Updates the bounds for the scrollbar.
    118      */
    119     @Override
    120     public void onUpdateScrollbar(int dy) {
    121         // Skip early if widgets are not bound.
    122         if (mWidgets == null) {
    123             return;
    124         }
    125 
    126         // Skip early if there are no widgets.
    127         int rowCount = mWidgets.getPackageSize();
    128         if (rowCount == 0) {
    129             mScrollbar.setThumbOffset(-1, -1);
    130             return;
    131         }
    132 
    133         // Skip early if, there no child laid out in the container.
    134         getCurScrollState(mScrollPosState, -1);
    135         if (mScrollPosState.rowIndex < 0) {
    136             mScrollbar.setThumbOffset(-1, -1);
    137             return;
    138         }
    139 
    140         synchronizeScrollBarThumbOffsetToViewScroll(mScrollPosState, rowCount);
    141     }
    142 
    143     /**
    144      * Returns the current scroll state.
    145      */
    146     protected void getCurScrollState(ScrollPositionState stateOut, int viewTypeMask) {
    147         stateOut.rowIndex = -1;
    148         stateOut.rowTopOffset = -1;
    149         stateOut.itemPos = -1;
    150 
    151         // Skip early if widgets are not bound.
    152         if (mWidgets == null) {
    153             return;
    154         }
    155 
    156         // Return early if there are no items
    157         int rowCount = mWidgets.getPackageSize();
    158         if (rowCount == 0) {
    159             return;
    160         }
    161         View child = getChildAt(0);
    162         int position = getChildPosition(child);
    163 
    164         stateOut.rowIndex = position;
    165         stateOut.rowTopOffset = getLayoutManager().getDecoratedTop(child);
    166         stateOut.itemPos = position;
    167     }
    168 
    169     @Override
    170     protected int getTop(int rowIndex) {
    171         if (getChildCount() == 0) {
    172             return 0;
    173         }
    174 
    175         // All the rows are the same height, return any child height
    176         View child = getChildAt(0);
    177         return child.getMeasuredHeight() * rowIndex;
    178     }
    179 }