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 BASE_I18N_EXPORT TextDirection GetTextDirectionForLocale(
  65     const char* locale_name);
  66
  67 // Given the string in |text|, returns the directionality of the first or last
  68 // character with strong directionality in the string. If no character in the
  69 // text has strong directionality, LEFT_TO_RIGHT is returned. The Bidi
  70 // character types L, LRE, LRO, R, AL, RLE, and RLO are considered as strong
  71 // directionality characters. Please refer to http://unicode.org/reports/tr9/
  72 // for more information.
  73 BASE_I18N_EXPORT TextDirection GetFirstStrongCharacterDirection(
  74     const string16& text);
  75 BASE_I18N_EXPORT TextDirection GetLastStrongCharacterDirection(
  76     const string16& text);
  77
  78 // Given the string in |text|, returns LEFT_TO_RIGHT or RIGHT_TO_LEFT if all the
  79 // strong directionality characters in the string are of the same
  80 // directionality. It returns UNKNOWN_DIRECTION if the string contains a mix of
  81 // LTR and RTL strong directionality characters. Defaults to LEFT_TO_RIGHT if
  82 // the string does not contain directionality characters. Please refer to
  83 // http://unicode.org/reports/tr9/ for more information.
  84 BASE_I18N_EXPORT TextDirection GetStringDirection(const string16& text);
  85
  86 // Given the string in |text|, this function modifies the string in place with
  87 // the appropriate Unicode formatting marks that mark the string direction
  88 // (either left-to-right or right-to-left). The function checks both the current
  89 // locale and the contents of the string in order to determine the direction of
  90 // the returned string. The function returns true if the string in |text| was
  91 // properly adjusted.
  92 //
  93 // Certain LTR strings are not rendered correctly when the context is RTL. For
  94 // example, the string "Foo!" will appear as "!Foo" if it is rendered as is in
  95 // an RTL context. Calling this function will make sure the returned localized
  96 // string is always treated as a right-to-left string. This is done by
  97 // inserting certain Unicode formatting marks into the returned string.
  98 //
  99 // ** Notes about the Windows version of this function:
 100 // TODO(idana) bug 6806: this function adjusts the string in question only
 101 // if the current locale is right-to-left. The function does not take care of
 102 // the opposite case (an RTL string displayed in an LTR context) since
 103 // adjusting the string involves inserting Unicode formatting characters that
 104 // Windows does not handle well unless right-to-left language support is
 105 // installed. Since the English version of Windows doesn't have right-to-left
 106 // language support installed by default, inserting the direction Unicode mark
 107 // results in Windows displaying squares.
 108 BASE_I18N_EXPORT bool AdjustStringForLocaleDirection(string16* text);
 109
 110 // Undoes the actions of the above function (AdjustStringForLocaleDirection).
 111 BASE_I18N_EXPORT bool UnadjustStringForLocaleDirection(string16* text);
 112
 113 // Returns true if the string contains at least one character with strong right
 114 // to left directionality; that is, a character with either R or AL Unicode
 115 // BiDi character type.
 116 BASE_I18N_EXPORT bool StringContainsStrongRTLChars(const string16& text);
 117
 118 // Wraps a string with an LRE-PDF pair which essentialy marks the string as a
 119 // Left-To-Right string. Doing this is useful in order to make sure LTR
 120 // strings are rendered properly in an RTL context.
 121 BASE_I18N_EXPORT void WrapStringWithLTRFormatting(string16* text);
 122
 123 // Wraps a string with an RLE-PDF pair which essentialy marks the string as a
 124 // Right-To-Left string. Doing this is useful in order to make sure RTL
 125 // strings are rendered properly in an LTR context.
 126 BASE_I18N_EXPORT void WrapStringWithRTLFormatting(string16* text);
 127
 128 // Wraps file path to get it to display correctly in RTL UI. All filepaths
 129 // should be passed through this function before display in UI for RTL locales.
 130 BASE_I18N_EXPORT void WrapPathWithLTRFormatting(const FilePath& path,
 131                                                 string16* rtl_safe_path);
 132
 133 // Return the string in |text| wrapped with LRE (Left-To-Right Embedding) and
 134 // PDF (Pop Directional Formatting) marks, if needed for UI display purposes.
 135 BASE_I18N_EXPORT string16 GetDisplayStringInLTRDirectionality(
 136     const string16& text) WARN_UNUSED_RESULT;
 137
 138 // Strip the beginning (U+202A..U+202B, U+202D..U+202E) and/or ending (U+202C)
 139 // explicit bidi control characters from |text|, if there are any. Otherwise,
 140 // return the text itself. Explicit bidi control characters display and have
 141 // semantic effect. They can be deleted so they might not always appear in a
 142 // pair.
 143 BASE_I18N_EXPORT string16 StripWrappingBidiControlCharacters(
 144     const string16& text) WARN_UNUSED_RESULT;
 145
 146 }  // namespace i18n
 147 }  // namespace base
 148
 149 #endif  // BASE_I18N_RTL_H_