Add TimeFormatTimeOfDayWithHourClockType() and GetHourClockType().

These functions will be used to implement 12/24 hour clock switching
on Chrome OS.

BUG=chromium-os:10534
TEST=with another patch, confirmed that the 12/24 hour clock switching worked

Review URL: http://codereview.chromium.org/6835018

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@81532 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 88 insertions, 1 deletions

diff --git a/base/i18n/time_formatting.cc b/base/i18n/time_formatting.cc
index 823f7a6..e52bd22 100644
--- a/base/i18n/time_formatting.cc
+++ b/base/i18n/time_formatting.cc
@@ -9,6 +9,8 @@
 #include "base/utf_string_conversions.h"
 #include "base/time.h"
 #include "unicode/datefmt.h"
+#include "unicode/dtptngen.h"
+#include "unicode/smpdtfmt.h"
 
 using base::Time;
 
@@ -36,6 +38,34 @@ string16 TimeFormatTimeOfDay(const Time& time) {
   return TimeFormat(formatter.get(), time);
 }
 
+string16 TimeFormatTimeOfDayWithHourClockType(const Time& time,
+                                              HourClockType type) {
+  // Just redirect to the normal function if the default type matches the
+  // given type.
+  HourClockType default_type = GetHourClockType();
+  if (default_type == type) {
+    return TimeFormatTimeOfDay(time);
+  }
+
+  // Generate a locale-dependent format pattern. The generator will take
+  // care of locale-dependent formatting issues like which separator to
+  // use (some locales use '.' instead of ':'), and where to put the am/pm
+  // marker.
+  UErrorCode status = U_ZERO_ERROR;
+  icu::DateTimePatternGenerator *generator =
+      icu::DateTimePatternGenerator::createInstance(status);
+  CHECK(U_SUCCESS(status));
+  const char* base_pattern = (type == k12HourClock ? "ahm" : "Hm");
+  icu::UnicodeString generated_pattern =
+      generator->getBestPattern(icu::UnicodeString(base_pattern), status);
+  CHECK(U_SUCCESS(status));
+
+  // Then, format the time using the generated pattern.
+  icu::SimpleDateFormat formatter(generated_pattern, status);
+  CHECK(U_SUCCESS(status));
+  return TimeFormat(&formatter, time);
+}
+
 string16 TimeFormatShortDate(const Time& time) {
   scoped_ptr<icu::DateFormat> formatter(
       icu::DateFormat::createDateInstance(icu::DateFormat::kMedium));
@@ -66,4 +96,44 @@ string16 TimeFormatFriendlyDate(const Time& time) {
   return TimeFormat(formatter.get(), time);
 }
 
+HourClockType GetHourClockType() {
+  // TODO(satorux,jshin): Rework this with ures_getByKeyWithFallback()
+  // once it becomes public. The short time format can be found at
+  // "calendar/gregorian/DateTimePatterns/3" in the resources.
+  scoped_ptr<icu::SimpleDateFormat> formatter(
+      static_cast<icu::SimpleDateFormat*>(
+          icu::DateFormat::createTimeInstance(icu::DateFormat::kShort)));
+  // Retrieve the short time format.
+  icu::UnicodeString pattern_unicode;
+  formatter->toPattern(pattern_unicode);
+
+  // Determine what hour clock type the current locale uses, by checking
+  // "a" (am/pm marker) in the short time format. This is reliable as "a"
+  // is used by all of 12-hour clock formats, but not any of 24-hour clock
+  // formats, as shown below.
+  //
+  // % grep -A4 DateTimePatterns third_party/icu/source/data/locales/*.txt |
+  //   grep -B1 -- -- |grep -v -- '--' |
+  //   perl -nle 'print $1 if /^\S+\s+"(.*)"/' |sort -u
+  //
+  // H.mm
+  // H:mm
+  // HH.mm
+  // HH:mm
+  // a h:mm
+  // ah:mm
+  // ahh:mm
+  // h-mm a
+  // h:mm a
+  // hh:mm a
+  //
+  // See http://userguide.icu-project.org/formatparse/datetime for details
+  // about the date/time format syntax.
+  if (pattern_unicode.indexOf('a') == -1) {
+    return k24HourClock;
+  } else {
+    return k12HourClock;
+  }
+}
+
 }  // namespace base
diff --git a/base/i18n/time_formatting.h b/base/i18n/time_formatting.h
index e70ad3d..99d1911 100644
--- a/base/i18n/time_formatting.h
+++ b/base/i18n/time_formatting.h
@@ -1,4 +1,4 @@
-// Copyright (c) 2009 The Chromium Authors. All rights reserved.
+// Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
@@ -15,9 +15,21 @@ namespace base {
 
 class Time;
 
+// Argument type used to specify the hour clock type.
+enum HourClockType {
+  k12HourClock,  // Uses 1-12. e.g., "3:07 PM"
+  k24HourClock,  // Uses 0-23. e.g., "15:07"
+};
+
 // Returns the time of day, e.g., "3:07 PM".
 string16 TimeFormatTimeOfDay(const Time& time);
 
+// Returns the time of day in the specified hour clock type. e.g.
+// "3:07 PM" (type == k12HourClock).
+// "15:07"   (type == k24HourClock).
+string16 TimeFormatTimeOfDayWithHourClockType(const Time& time,
+                                              HourClockType type);
+
 // Returns a shortened date, e.g. "Nov 7, 2007"
 string16 TimeFormatShortDate(const Time& time);
 
@@ -36,6 +48,11 @@ string16 TimeFormatFriendlyDateAndTime(const Time& time);
 // "Monday, March 6, 2008".
 string16 TimeFormatFriendlyDate(const Time& time);
 
+// Gets the hour clock type of the current locale. e.g.
+// k12HourClock (en-US).
+// k24HourClock (en-GB).
+HourClockType GetHourClockType();
+
 }  // namespace base
 
 #endif  // BASE_I18N_TIME_FORMATTING_H_