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Side by Side Diff: ui/base/l10n/time_format.h

Issue 147443007: Add support for localized time strings with two units, eg. "2 hours 17 minutes" (Closed) Base URL: https://chromium.googlesource.com/chromium/src.git@master
Patch Set: Address Bartosz' comments Created 6 years, 10 months ago
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1 // Copyright (c) 2011 The Chromium Authors. All rights reserved. 1 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be 2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file. 3 // found in the LICENSE file.
4 4
5 #ifndef UI_BASE_L10N_TIME_FORMAT_H_ 5 #ifndef UI_BASE_L10N_TIME_FORMAT_H_
6 #define UI_BASE_L10N_TIME_FORMAT_H_ 6 #define UI_BASE_L10N_TIME_FORMAT_H_
7 7
8 #include "base/basictypes.h" 8 #include "base/basictypes.h"
9 #include "base/strings/string16.h" 9 #include "base/strings/string16.h"
10 #include "ui/base/ui_base_export.h" 10 #include "ui/base/ui_base_export.h"
11 11
12 namespace base { 12 namespace base {
13 class Time; 13 class Time;
14 class TimeDelta; 14 class TimeDelta;
15 } 15 }
16 16
17 namespace ui { 17 namespace ui {
18 18
19 // Methods to format time values as strings. 19 // Methods to format time values as strings.
20 class UI_BASE_EXPORT TimeFormat { 20 class UI_BASE_EXPORT TimeFormat {
21 public: 21 public:
22 // TimeElapsed, TimeRemaining* and TimeDuration*: 22 enum Format {
23 // These functions return a localized string of approximate time duration. 23 FORMAT_DURATION, // Plain duration, e.g. in English: "2 minutes".
24 FORMAT_REMAINING, // Remaining time, e.g. in English: "2 minutes left".
25 FORMAT_ELAPSED, // Elapsed time, e.g. in English: "2 minutes ago".
26 FORMAT_COUNT // Enum size counter, not a format. Must be last.
27 };
24 28
25 // Returns times in elapsed-format: "3 mins ago", "2 days ago". 29 enum Length {
26 static base::string16 TimeElapsed(const base::TimeDelta& delta); 30 LENGTH_SHORT, // Short format, e.g. in English: sec/min/hour/day.
31 LENGTH_LONG, // Long format, e.g. in English: second/minute/hour/day.
32 LENGTH_COUNT // Enum size counter, not a length. Must be last.
33 };
27 34
28 // Returns times in remaining-format: "3 mins left", "2 days left". 35 // Return a localized string of approximate time duration, formatted as a
29 static base::string16 TimeRemaining(const base::TimeDelta& delta); 36 // single number, e.g. in English "2 hours ago". Currently, all combinations
37 // of format and length except (FORMAT_ELAPSED, LENGTH_LONG) are implemented
38 // but it's easy to add this, if required.
39 static base::string16 Simple(Format format,
40 Length length,
41 const base::TimeDelta& delta);
30 42
31 // Returns times in remaining-long-format: "3 minutes left", "2 days left". 43 // Return a localized string of more precise time duration, either formatted
32 static base::string16 TimeRemainingLong(const base::TimeDelta& delta); 44 // as a single number or as two numbers: for a time delta of e.g. 2h19m either
33 45 // "2 hours" or "2 hours and 19 minutes" could be returned in English.
34 // Returns times in short-format: "3 mins", "2 days". 46 // Two-number output can be forced by setting |cutoff| to -1. Single-number
35 static base::string16 TimeDurationShort(const base::TimeDelta& delta); 47 // output can be forced by using Simple() or setting |cutoff| to 0.
36 48 // Otherwise, choice of format happens automatically and the value of |cutoff|
37 // Return times in long-format: "2 hours", "25 minutes". 49 // determines the largest numeric value that may appear in a single-valued
38 static base::string16 TimeDurationLong(const base::TimeDelta& delta); 50 // format -- for lower numeric values, a second unit is added to increase
51 // precision. (Applied to the examples above, a |cutoff| of 2 or smaller
52 // would yield the first string and a |cutoff| of 3 or larger would return the
53 // second string.)
54 //
55 // The aim of this logic is to reduce rounding errors (that can amount up to
56 // 50% in single-valued representation) while at the same time avoiding
57 // over-precise time outputs such as e.g. "56 minutes 29 seconds". The
58 // relative rounding error is guaranteed to be less than approximately 0.5 /
bartfab (slow) 2014/02/20 16:31:23 I like the combination of "guaranteed to" and "app
Thiemo Nagel 2014/02/22 21:44:10 It was tempting to write it that way, but I've cha
59 // |cutoff| (e.g. 5% for a |cutoff| of 10) and a second unit is only used when
60 // necessary to achieve the precision guarantee.
61 //
62 // Currently, the only combination of format and length that is implemented is
63 // (FORMAT_DURATION, LENGTH_LONG), but it's easy to add others if required.
64 //
65 // Note: This is implemented with two translation strings (IDS_TIME_*_1ST and
66 // IDS_TIME_*_2ND) per [plurality x pair of units] which are concatenated
67 // after having been formatted individually. The separator between first unit
68 // and second unit (a blank in English) is included in IDS_TIME_*_1ST.
bartfab (slow) 2014/02/20 16:31:23 Nit: The comment is excellent. It may make sense t
Thiemo Nagel 2014/02/22 21:44:10 Done.
69 static base::string16 Detailed(Format format,
70 Length length,
71 int cutoff,
72 const base::TimeDelta& delta);
39 73
40 // For displaying a relative time in the past. This method returns either 74 // For displaying a relative time in the past. This method returns either
41 // "Today", "Yesterday", or an empty string if it's older than that. Returns 75 // "Today", "Yesterday", or an empty string if it's older than that. Returns
42 // the empty string for days in the future. 76 // the empty string for days in the future.
43 // 77 //
44 // TODO(brettw): This should be able to handle days in the future like 78 // TODO(brettw): This should be able to handle days in the future like
45 // "Tomorrow". 79 // "Tomorrow".
46 // TODO(tc): This should be able to do things like "Last week". This 80 // TODO(tc): This should be able to do things like "Last week". This
47 // requires handling singluar/plural for all languages. 81 // requires handling singluar/plural for all languages.
48 // 82 //
49 // The second parameter is optional, it is midnight of "Now" for relative day 83 // The second parameter is optional, it is midnight of "Now" for relative day
50 // computations: Time::Now().LocalMidnight() 84 // computations: Time::Now().LocalMidnight()
51 // If NULL, the current day's midnight will be retrieved, which can be 85 // If NULL, the current day's midnight will be retrieved, which can be
52 // slow. If many items are being processed, it is best to get the current 86 // slow. If many items are being processed, it is best to get the current
53 // time once at the beginning and pass it for each computation. 87 // time once at the beginning and pass it for each computation.
54 static base::string16 RelativeDate(const base::Time& time, 88 static base::string16 RelativeDate(const base::Time& time,
55 const base::Time* optional_midnight_today); 89 const base::Time* optional_midnight_today);
56 90
57 private: 91 private:
58 DISALLOW_IMPLICIT_CONSTRUCTORS(TimeFormat); 92 DISALLOW_IMPLICIT_CONSTRUCTORS(TimeFormat);
59 }; 93 };
60 94
61 } // namespace ui 95 } // namespace ui
62 96
63 #endif // UI_BASE_L10N_TIME_FORMAT_H_ 97 #endif // UI_BASE_L10N_TIME_FORMAT_H_
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