DelayingSuggestionsAdapter.java revision 8b2936607176720172aee068abc5631bdf77e843 
1/*
2 * Copyright (C) 2009 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.quicksearchbox.ui;
18
19import com.android.quicksearchbox.Corpora;
20import com.android.quicksearchbox.SuggestionCursor;
21import com.android.quicksearchbox.Suggestions;
22
23import android.database.DataSetObserver;
24import android.util.Log;
25
26/**
27 * A {@link SuggestionsAdapter} that doesn't expose the new suggestions
28 * until there are some results to show.
29 */
30public class DelayingSuggestionsAdapter extends SuggestionsAdapter {
31
32    private static final boolean DBG = false;
33    private static final String TAG = "QSB.DelayingSuggestionsAdapter";
34
35    private DataSetObserver mPendingDataSetObserver;
36
37    private Suggestions mPendingSuggestions;
38
39    public DelayingSuggestionsAdapter(SuggestionViewFactory fallbackFactory, Corpora corpora) {
40        super(fallbackFactory, corpora);
41    }
42
43    @Override
44    public void close() {
45        setPendingSuggestions(null);
46        super.close();
47    }
48
49    @Override
50    public void setSuggestions(Suggestions suggestions) {
51        if (suggestions == null) {
52            super.setSuggestions(null);
53            setPendingSuggestions(null);
54            return;
55        }
56        if (shouldPublish(suggestions)) {
57            if (DBG) Log.d(TAG, "Publishing suggestions immediately: " + suggestions);
58            super.setSuggestions(suggestions);
59            // Clear any old pending suggestions.
60            setPendingSuggestions(null);
61        } else {
62            if (DBG) Log.d(TAG, "Delaying suggestions publishing: " + suggestions);
63            setPendingSuggestions(suggestions);
64        }
65    }
66
67    /**
68     * Gets whether the given suggestions are non-empty for the selected source.
69     */
70    private boolean shouldPublish(Suggestions suggestions) {
71        if (suggestions.isDone()) return true;
72        SuggestionCursor cursor = getPromoted(suggestions);
73        return cursor != null && cursor.getCount() > 0;
74    }
75
76    private void setPendingSuggestions(Suggestions suggestions) {
77        if (mPendingSuggestions == suggestions) {
78            return;
79        }
80        if (isClosed()) {
81            if (suggestions != null) {
82                suggestions.release();
83            }
84            return;
85        }
86        if (mPendingDataSetObserver == null) {
87            mPendingDataSetObserver = new PendingSuggestionsObserver();
88        }
89        if (mPendingSuggestions != null) {
90            mPendingSuggestions.unregisterDataSetObserver(mPendingDataSetObserver);
91            // Close old suggestions, but only if they are not also the current
92            // suggestions.
93            if (mPendingSuggestions != getSuggestions()) {
94                mPendingSuggestions.release();
95            }
96        }
97        mPendingSuggestions = suggestions;
98        if (mPendingSuggestions != null) {
99            mPendingSuggestions.registerDataSetObserver(mPendingDataSetObserver);
100        }
101    }
102
103    protected void onPendingSuggestionsChanged() {
104        if (DBG) {
105            Log.d(TAG, "onPendingSuggestionsChanged(), mPendingSuggestions="
106                    + mPendingSuggestions);
107        }
108        if (shouldPublish(mPendingSuggestions)) {
109            if (DBG) Log.d(TAG, "Suggestions now available, publishing: " + mPendingSuggestions);
110            super.setSuggestions(mPendingSuggestions);
111            // The suggestions are no longer pending.
112            setPendingSuggestions(null);
113        }
114    }
115
116    private class PendingSuggestionsObserver extends DataSetObserver {
117        @Override
118        public void onChanged() {
119            onPendingSuggestionsChanged();
120        }
121    }
122
123}
124