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