1 /*
2  * Copyright (C) 2016 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file
5  * except in compliance with the License. You may obtain a copy of the License at
6  *
7  *      http://www.apache.org/licenses/LICENSE-2.0
8  *
9  * Unless required by applicable law or agreed to in writing, software distributed under the
10  * License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
11  * KIND, either express or implied. See the License for the specific language governing
12  * permissions and limitations under the License.
13  */
14 
15 package com.android.systemui.qs;
16 
17 import android.annotation.Nullable;
18 import android.content.Context;
19 import android.content.res.TypedArray;
20 import android.database.DataSetObserver;
21 import android.os.Handler;
22 import android.util.AttributeSet;
23 import android.view.View;
24 import android.widget.LinearLayout;
25 import android.widget.ListAdapter;
26 import com.android.systemui.R;
27 
28 /**
29  * Similar to a ListView, but it will show only as many items as fit on screen and
30  * bind those instead of scrolling.
31  */
32 public class AutoSizingList extends LinearLayout {
33 
34     private static final String TAG = "AutoSizingList";
35     private final int mItemSize;
36     private final Handler mHandler;
37 
38     private ListAdapter mAdapter;
39     private int mCount;
40 
AutoSizingList(Context context, @Nullable AttributeSet attrs)41     public AutoSizingList(Context context, @Nullable AttributeSet attrs) {
42         super(context, attrs);
43 
44         mHandler = new Handler();
45         TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.AutoSizingList);
46         mItemSize = a.getDimensionPixelSize(R.styleable.AutoSizingList_itemHeight, 0);
47     }
48 
setAdapter(ListAdapter adapter)49     public void setAdapter(ListAdapter adapter) {
50         if (mAdapter != null) {
51             mAdapter.unregisterDataSetObserver(mDataObserver);
52         }
53         mAdapter = adapter;
54         if (adapter != null) {
55             adapter.registerDataSetObserver(mDataObserver);
56         }
57     }
58 
59     @Override
onMeasure(int widthMeasureSpec, int heightMeasureSpec)60     protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
61         int requestedHeight = MeasureSpec.getSize(heightMeasureSpec);
62         if (requestedHeight != 0) {
63             int count = Math.min(requestedHeight / mItemSize, getDesiredCount());
64             if (mCount != count) {
65                 postRebindChildren();
66                 mCount = count;
67             }
68         }
69         super.onMeasure(widthMeasureSpec, heightMeasureSpec);
70     }
71 
getDesiredCount()72     private int getDesiredCount() {
73         return mAdapter != null ? mAdapter.getCount() : 0;
74     }
75 
postRebindChildren()76     private void postRebindChildren() {
77         mHandler.post(mBindChildren);
78     }
79 
rebindChildren()80     private void rebindChildren() {
81         if (mAdapter == null) {
82             return;
83         }
84         for (int i = 0; i < mCount; i++) {
85             View v = i < getChildCount() ? getChildAt(i) : null;
86             View newView = mAdapter.getView(i, v, this);
87             if (newView != v) {
88                 if (v != null) {
89                     removeView(v);
90                 }
91                 addView(newView, i);
92             }
93         }
94         // Ditch extra views.
95         while (getChildCount() > mCount) {
96             removeViewAt(getChildCount() - 1);
97         }
98     }
99 
100     private final Runnable mBindChildren = new Runnable() {
101         @Override
102         public void run() {
103             rebindChildren();
104         }
105     };
106 
107     private final DataSetObserver mDataObserver = new DataSetObserver() {
108         @Override
109         public void onChanged() {
110             if (mCount > getDesiredCount()) {
111                 mCount = getDesiredCount();
112             }
113             postRebindChildren();
114         }
115 
116         @Override
117         public void onInvalidated() {
118             postRebindChildren();
119         }
120     };
121 }
122