1/*
2 * Copyright (C) 2014 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
17package com.android.systemui.recents.views;
18
19import android.content.Context;
20
21import java.util.Iterator;
22import java.util.LinkedList;
23
24
25/* A view pool to manage more views than we can visibly handle */
26public class ViewPool<V, T> {
27
28    /* An interface to the consumer of a view pool */
29    public interface ViewPoolConsumer<V, T> {
30        public V createView(Context context);
31        public void prepareViewToEnterPool(V v);
32        public void prepareViewToLeavePool(V v, T prepareData, boolean isNewView);
33        public boolean hasPreferredData(V v, T preferredData);
34    }
35
36    Context mContext;
37    ViewPoolConsumer<V, T> mViewCreator;
38    LinkedList<V> mPool = new LinkedList<V>();
39
40    /** Initializes the pool with a fixed predetermined pool size */
41    public ViewPool(Context context, ViewPoolConsumer<V, T> viewCreator) {
42        mContext = context;
43        mViewCreator = viewCreator;
44    }
45
46    /** Returns a view into the pool */
47    void returnViewToPool(V v) {
48        mViewCreator.prepareViewToEnterPool(v);
49        mPool.push(v);
50    }
51
52    /** Gets a view from the pool and prepares it */
53    V pickUpViewFromPool(T preferredData, T prepareData) {
54        V v = null;
55        boolean isNewView = false;
56        if (mPool.isEmpty()) {
57            v = mViewCreator.createView(mContext);
58            isNewView = true;
59        } else {
60            // Try and find a preferred view
61            Iterator<V> iter = mPool.iterator();
62            while (iter.hasNext()) {
63                V vpv = iter.next();
64                if (mViewCreator.hasPreferredData(vpv, preferredData)) {
65                    v = vpv;
66                    iter.remove();
67                    break;
68                }
69            }
70            // Otherwise, just grab the first view
71            if (v == null) {
72                v = mPool.pop();
73            }
74        }
75        mViewCreator.prepareViewToLeavePool(v, prepareData, isNewView);
76        return v;
77    }
78
79    /** Returns an iterator to the list of the views in the pool. */
80    Iterator<V> poolViewIterator() {
81        if (mPool != null) {
82            return mPool.iterator();
83        }
84        return null;
85    }
86}
87