base/i18n/rtl.h

   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
   3 // found in the LICENSE file.
   4
   5 #ifndef BASE_I18N_RTL_H_
   6 #define BASE_I18N_RTL_H_
   7
   8 #include <string>
   9
  10 #include "base/compiler_specific.h"
  11 #include "base/i18n/base_i18n_export.h"
  12 #include "base/strings/string16.h"
  13 #include "build/build_config.h"
  14
  15 namespace base {
  16
  17 class FilePath;
  18
  19 namespace i18n {
  20
  21 const char16 kRightToLeftMark = 0x200F;
  22 const char16 kLeftToRightMark = 0x200E;
  23 const char16 kLeftToRightEmbeddingMark = 0x202A;
  24 const char16 kRightToLeftEmbeddingMark = 0x202B;
  25 const char16 kPopDirectionalFormatting = 0x202C;
  26 const char16 kLeftToRightOverride = 0x202D;
  27 const char16 kRightToLeftOverride = 0x202E;
  28
  29 // Locale.java mirrored this enum TextDirection. Please keep in sync.
  30 enum TextDirection {
  31   UNKNOWN_DIRECTION = 0,
  32   RIGHT_TO_LEFT = 1,
  33   LEFT_TO_RIGHT = 2,
  34   TEXT_DIRECTION_NUM_DIRECTIONS = 3,
  35 };
  36
  37 // Get the locale that the currently running process has been configured to use.
  38 // The return value is of the form language[-country] (e.g., en-US) where the
  39 // language is the 2 or 3 letter code from ISO-639.
  40 BASE_I18N_EXPORT std::string GetConfiguredLocale();
  41
  42 // Canonicalize a string (eg. a POSIX locale string) to a Chrome locale name.
  43 BASE_I18N_EXPORT std::string GetCanonicalLocale(const std::string& locale);
  44
  45 // Sets the default locale of ICU.
  46 // Once the application locale of Chrome in GetApplicationLocale is determined,
  47 // the default locale of ICU need to be changed to match the application locale
  48 // so that ICU functions work correctly in a locale-dependent manner.
  49 // This is handy in that we don't have to call GetApplicationLocale()
  50 // everytime we call locale-dependent ICU APIs as long as we make sure
  51 // that this is called before any locale-dependent API is called.
  52 BASE_I18N_EXPORT void SetICUDefaultLocale(const std::string& locale_string);
  53
  54 // Returns true if the application text direction is right-to-left.
  55 BASE_I18N_EXPORT bool IsRTL();
  56
  57 // Returns whether the text direction for the default ICU locale is RTL.  This
  58 // assumes that SetICUDefaultLocale has been called to set the default locale to
  59 // the UI locale of Chrome.
  60 // NOTE: Generally, you should call IsRTL() instead of this.
  61 BASE_I18N_EXPORT bool ICUIsRTL();
  62
  63 // Returns the text direction for |locale_name|.
  64 // As a startup optimization, this method checks the locale against a list of
  65 // Chrome-supported RTL locales.
  66 BASE_I18N_EXPORT TextDirection
  67 GetTextDirectionForLocaleInStartUp(const char* locale_name);
  68
  69 // Returns the text direction for |locale_name|.
  70 BASE_I18N_EXPORT TextDirection GetTextDirectionForLocale(
  71     const char* locale_name);
  72
  73 // Given the string in |text|, returns the directionality of the first or last
  74 // character with strong directionality in the string. If no character in the
  75 // text has strong directionality, LEFT_TO_RIGHT is returned. The Bidi
  76 // character types L, LRE, LRO, R, AL, RLE, and RLO are considered as strong
  77 // directionality characters. Please refer to http://unicode.org/reports/tr9/
  78 // for more information.
  79 BASE_I18N_EXPORT TextDirection GetFirstStrongCharacterDirection(
  80     const string16& text);
  81 BASE_I18N_EXPORT TextDirection GetLastStrongCharacterDirection(
  82     const string16& text);
  83
  84 // Given the string in |text|, returns LEFT_TO_RIGHT or RIGHT_TO_LEFT if all the
  85 // strong directionality characters in the string are of the same
  86 // directionality. It returns UNKNOWN_DIRECTION if the string contains a mix of
  87 // LTR and RTL strong directionality characters. Defaults to LEFT_TO_RIGHT if
  88 // the string does not contain directionality characters. Please refer to
  89 // http://unicode.org/reports/tr9/ for more information.
  90 BASE_I18N_EXPORT TextDirection GetStringDirection(const string16& text);
  91
  92 // Given the string in |text|, this function modifies the string in place with
  93 // the appropriate Unicode formatting marks that mark the string direction
  94 // (either left-to-right or right-to-left). The function checks both the current
  95 // locale and the contents of the string in order to determine the direction of
  96 // the returned string. The function returns true if the string in |text| was
  97 // properly adjusted.
  98 //
  99 // Certain LTR strings are not rendered correctly when the context is RTL. For
 100 // example, the string "Foo!" will appear as "!Foo" if it is rendered as is in
 101 // an RTL context. Calling this function will make sure the returned localized
 102 // string is always treated as a right-to-left string. This is done by
 103 // inserting certain Unicode formatting marks into the returned string.
 104 //
 105 // ** Notes about the Windows version of this function:
 106 // TODO(idana) bug 6806: this function adjusts the string in question only
 107 // if the current locale is right-to-left. The function does not take care of
 108 // the opposite case (an RTL string displayed in an LTR context) since
 109 // adjusting the string involves inserting Unicode formatting characters that
 110 // Windows does not handle well unless right-to-left language support is
 111 // installed. Since the English version of Windows doesn't have right-to-left
 112 // language support installed by default, inserting the direction Unicode mark
 113 // results in Windows displaying squares.
 114 BASE_I18N_EXPORT bool AdjustStringForLocaleDirection(string16* text);
 115
 116 // Undoes the actions of the above function (AdjustStringForLocaleDirection).
 117 BASE_I18N_EXPORT bool UnadjustStringForLocaleDirection(string16* text);
 118
 119 // Returns true if the string contains at least one character with strong right
 120 // to left directionality; that is, a character with either R or AL Unicode
 121 // BiDi character type.
 122 BASE_I18N_EXPORT bool StringContainsStrongRTLChars(const string16& text);
 123
 124 // Wraps a string with an LRE-PDF pair which essentialy marks the string as a
 125 // Left-To-Right string. Doing this is useful in order to make sure LTR
 126 // strings are rendered properly in an RTL context.
 127 BASE_I18N_EXPORT void WrapStringWithLTRFormatting(string16* text);
 128
 129 // Wraps a string with an RLE-PDF pair which essentialy marks the string as a
 130 // Right-To-Left string. Doing this is useful in order to make sure RTL
 131 // strings are rendered properly in an LTR context.
 132 BASE_I18N_EXPORT void WrapStringWithRTLFormatting(string16* text);
 133
 134 // Wraps file path to get it to display correctly in RTL UI. All filepaths
 135 // should be passed through this function before display in UI for RTL locales.
 136 BASE_I18N_EXPORT void WrapPathWithLTRFormatting(const FilePath& path,
 137                                                 string16* rtl_safe_path);
 138
 139 // Return the string in |text| wrapped with LRE (Left-To-Right Embedding) and
 140 // PDF (Pop Directional Formatting) marks, if needed for UI display purposes.
 141 BASE_I18N_EXPORT string16 GetDisplayStringInLTRDirectionality(
 142     const string16& text) WARN_UNUSED_RESULT;
 143
 144 // Strip the beginning (U+202A..U+202B, U+202D..U+202E) and/or ending (U+202C)
 145 // explicit bidi control characters from |text|, if there are any. Otherwise,
 146 // return the text itself. Explicit bidi control characters display and have
 147 // semantic effect. They can be deleted so they might not always appear in a
 148 // pair.
 149 BASE_I18N_EXPORT string16 StripWrappingBidiControlCharacters(
 150     const string16& text) WARN_UNUSED_RESULT;
 151
 152 }  // namespace i18n
 153 }  // namespace base
 154
 155 #endif  // BASE_I18N_RTL_H_