TimeZonePickerUtils.java revision 099b3306d12e24f8f7e76a140c69791739fe6ed0 
1/*
2 * Copyright (C) 2013 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.timezonepicker;
18
19import android.content.Context;
20import android.content.res.Resources;
21import android.os.Build;
22import android.text.format.DateUtils;
23import android.text.format.Time;
24import android.util.Log;
25
26import java.util.Locale;
27import java.util.TimeZone;
28
29public class TimeZonePickerUtils {
30    private static final String TAG = "TimeZonePickerUtils";
31
32    private Locale mDefaultLocale;
33    private String[] mOverrideIds;
34    private String[] mOverrideLabels;
35
36    /**
37     * This needs to be an instantiated class so that it doesn't need to continuously re-load the
38     * list of timezone IDs that need to be overridden.
39     * @param context
40     */
41    public TimeZonePickerUtils(Context context) {
42        // Instead of saving a reference to the context (because we might need to look up the
43        // labels every time getGmtDisplayName is called), we'll cache the lists of override IDs
44        // and labels now.
45        cacheOverrides(context);
46    }
47
48    /**
49     * Given a timezone id (e.g. America/Los_Angeles), returns the corresponding timezone
50     * display name (e.g. (GMT-7.00) Pacific Time).
51     *
52     * @param context Context in case the override labels need to be re-cached.
53     * @param id The timezone id
54     * @param millis The time (daylight savings or not)
55     * @return The display name of the timezone.
56     */
57    public String getGmtDisplayName(Context context, String id, long millis) {
58        TimeZone timezone = TimeZone.getTimeZone(id);
59        if (timezone == null) {
60            return null;
61        }
62
63        final Locale defaultLocale = Locale.getDefault();
64        if (!defaultLocale.equals(mDefaultLocale)) {
65            // If the IDs and labels haven't been set yet, or if the locale has been changed
66            // recently, we'll need to re-cache them.
67            mDefaultLocale = defaultLocale;
68            cacheOverrides(context);
69        }
70        return buildGmtDisplayName(timezone, millis);
71    }
72
73    private String buildGmtDisplayName(TimeZone tz, long timeMillis) {
74        Time time = new Time(tz.getID());
75        time.set(timeMillis);
76
77        StringBuilder sb = new StringBuilder();
78        sb.append("(GMT");
79
80        final int gmtOffset = tz.getOffset(timeMillis);
81        if (gmtOffset < 0) {
82            sb.append('-');
83        } else {
84            sb.append('+');
85        }
86
87        final int p = Math.abs(gmtOffset);
88        sb.append(p / DateUtils.HOUR_IN_MILLIS); // Hour
89
90        final int min = (p / (int) DateUtils.MINUTE_IN_MILLIS) % 60;
91        if (min != 0) { // Show minutes if non-zero
92            sb.append(':');
93            if (min < 10) {
94                sb.append('0');
95            }
96            sb.append(min);
97        }
98        sb.append(") ");
99
100        String displayName = getDisplayName(tz, time.isDst != 0);
101        sb.append(displayName);
102
103        if (tz.useDaylightTime()) {
104            String dstSymbol = getDstSymbol();
105            sb.append(" ");
106            sb.append(dstSymbol); // Sun symbol
107        }
108        return sb.toString();
109    }
110
111    public static String getDstSymbol() {
112        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN) {
113            return "\u2600"; // The Sun emoji icon.
114        } else {
115            return "*";
116        }
117    }
118
119    /**
120     * Gets the display name for the specified Timezone ID. If the ID matches the list of IDs that
121     * need to be have their default display names overriden, use the pre-set display name from
122     * R.arrays.
123     * @param id The timezone ID.
124     * @param daylightTime True for daylight time, false for standard time
125     * @return The display name of the timezone. This will just use the default display name,
126     * except that certain timezones have poor defaults, and should use the pre-set override labels
127     * from R.arrays.
128     */
129    private String getDisplayName(TimeZone tz, boolean daylightTime) {
130        if (mOverrideIds == null || mOverrideLabels == null) {
131            // Just in case they somehow didn't get loaded correctly.
132            return tz.getDisplayName(daylightTime, TimeZone.LONG, Locale.getDefault());
133        }
134
135        for (int i = 0; i < mOverrideIds.length; i++) {
136            if (tz.getID().equals(mOverrideIds[i])) {
137                if (mOverrideLabels.length > i) {
138                    return mOverrideLabels[i];
139                }
140                Log.e(TAG, "timezone_rename_ids len=" + mOverrideIds.length +
141                        " timezone_rename_labels len=" + mOverrideLabels.length);
142                break;
143            }
144        }
145
146        // If the ID doesn't need to have the display name overridden, or if the labels were
147        // malformed, just use the default.
148        return tz.getDisplayName(daylightTime, TimeZone.LONG, Locale.getDefault());
149    }
150
151    private void cacheOverrides(Context context) {
152        Resources res = context.getResources();
153        mOverrideIds = res.getStringArray(R.array.timezone_rename_ids);
154        mOverrideLabels = res.getStringArray(R.array.timezone_rename_labels);
155    }
156}
157