rtl.h revision 2a99a7e74a7f215066514fe81d2bfa6639d9eddd
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/string16.h" 13#include "build/build_config.h" 14 15namespace base { 16 17class FilePath; 18 19namespace i18n { 20 21const char16 kRightToLeftMark = 0x200F; 22const char16 kLeftToRightMark = 0x200E; 23const char16 kLeftToRightEmbeddingMark = 0x202A; 24const char16 kRightToLeftEmbeddingMark = 0x202B; 25const char16 kPopDirectionalFormatting = 0x202C; 26const char16 kLeftToRightOverride = 0x202D; 27const char16 kRightToLeftOverride = 0x202E; 28 29enum TextDirection { 30 UNKNOWN_DIRECTION, 31 RIGHT_TO_LEFT, 32 LEFT_TO_RIGHT, 33}; 34 35// Get the locale that the currently running process has been configured to use. 36// The return value is of the form language[-country] (e.g., en-US) where the 37// language is the 2 or 3 letter code from ISO-639. 38BASE_I18N_EXPORT std::string GetConfiguredLocale(); 39 40// Canonicalize a string (eg. a POSIX locale string) to a Chrome locale name. 41BASE_I18N_EXPORT std::string GetCanonicalLocale(const char* locale); 42 43// Sets the default locale of ICU. 44// Once the application locale of Chrome in GetApplicationLocale is determined, 45// the default locale of ICU need to be changed to match the application locale 46// so that ICU functions work correctly in a locale-dependent manner. 47// This is handy in that we don't have to call GetApplicationLocale() 48// everytime we call locale-dependent ICU APIs as long as we make sure 49// that this is called before any locale-dependent API is called. 50BASE_I18N_EXPORT void SetICUDefaultLocale(const std::string& locale_string); 51 52// Returns true if the application text direction is right-to-left. 53BASE_I18N_EXPORT bool IsRTL(); 54 55// Returns whether the text direction for the default ICU locale is RTL. This 56// assumes that SetICUDefaultLocale has been called to set the default locale to 57// the UI locale of Chrome. 58// NOTE: Generally, you should call IsRTL() instead of this. 59BASE_I18N_EXPORT bool ICUIsRTL(); 60 61// Returns the text direction for |locale_name|. 62BASE_I18N_EXPORT TextDirection GetTextDirectionForLocale( 63 const char* locale_name); 64 65// Given the string in |text|, returns the directionality of the first 66// character with strong directionality in the string. If no character in the 67// text has strong directionality, LEFT_TO_RIGHT is returned. The Bidi 68// character types L, LRE, LRO, R, AL, RLE, and RLO are considered as strong 69// directionality characters. Please refer to http://unicode.org/reports/tr9/ 70// for more information. 71BASE_I18N_EXPORT TextDirection GetFirstStrongCharacterDirection( 72 const string16& text); 73 74// Given the string in |text|, returns LEFT_TO_RIGHT or RIGHT_TO_LEFT if all the 75// strong directionality characters in the string are of the same 76// directionality. It returns UNKNOWN_DIRECTION if the string contains a mix of 77// LTR and RTL strong directionality characters. Defaults to LEFT_TO_RIGHT if 78// the string does not contain directionality characters. Please refer to 79// http://unicode.org/reports/tr9/ for more information. 80BASE_I18N_EXPORT TextDirection GetStringDirection(const string16& text); 81 82// Given the string in |text|, this function modifies the string in place with 83// the appropriate Unicode formatting marks that mark the string direction 84// (either left-to-right or right-to-left). The function checks both the current 85// locale and the contents of the string in order to determine the direction of 86// the returned string. The function returns true if the string in |text| was 87// properly adjusted. 88// 89// Certain LTR strings are not rendered correctly when the context is RTL. For 90// example, the string "Foo!" will appear as "!Foo" if it is rendered as is in 91// an RTL context. Calling this function will make sure the returned localized 92// string is always treated as a right-to-left string. This is done by 93// inserting certain Unicode formatting marks into the returned string. 94// 95// ** Notes about the Windows version of this function: 96// TODO(idana) bug 6806: this function adjusts the string in question only 97// if the current locale is right-to-left. The function does not take care of 98// the opposite case (an RTL string displayed in an LTR context) since 99// adjusting the string involves inserting Unicode formatting characters that 100// Windows does not handle well unless right-to-left language support is 101// installed. Since the English version of Windows doesn't have right-to-left 102// language support installed by default, inserting the direction Unicode mark 103// results in Windows displaying squares. 104BASE_I18N_EXPORT bool AdjustStringForLocaleDirection(string16* text); 105 106// Undoes the actions of the above function (AdjustStringForLocaleDirection). 107BASE_I18N_EXPORT bool UnadjustStringForLocaleDirection(string16* text); 108 109// Returns true if the string contains at least one character with strong right 110// to left directionality; that is, a character with either R or AL Unicode 111// BiDi character type. 112BASE_I18N_EXPORT bool StringContainsStrongRTLChars(const string16& text); 113 114// Wraps a string with an LRE-PDF pair which essentialy marks the string as a 115// Left-To-Right string. Doing this is useful in order to make sure LTR 116// strings are rendered properly in an RTL context. 117BASE_I18N_EXPORT void WrapStringWithLTRFormatting(string16* text); 118 119// Wraps a string with an RLE-PDF pair which essentialy marks the string as a 120// Right-To-Left string. Doing this is useful in order to make sure RTL 121// strings are rendered properly in an LTR context. 122BASE_I18N_EXPORT void WrapStringWithRTLFormatting(string16* text); 123 124// Wraps file path to get it to display correctly in RTL UI. All filepaths 125// should be passed through this function before display in UI for RTL locales. 126BASE_I18N_EXPORT void WrapPathWithLTRFormatting(const FilePath& path, 127 string16* rtl_safe_path); 128 129// Return the string in |text| wrapped with LRE (Left-To-Right Embedding) and 130// PDF (Pop Directional Formatting) marks, if needed for UI display purposes. 131BASE_I18N_EXPORT string16 GetDisplayStringInLTRDirectionality( 132 const string16& text) WARN_UNUSED_RESULT; 133 134// Strip the beginning (U+202A..U+202B, U+202D..U+202E) and/or ending (U+202C) 135// explicit bidi control characters from |text|, if there are any. Otherwise, 136// return the text itself. Explicit bidi control characters display and have 137// semantic effect. They can be deleted so they might not always appear in a 138// pair. 139BASE_I18N_EXPORT string16 StripWrappingBidiControlCharacters( 140 const string16& text) WARN_UNUSED_RESULT; 141 142} // namespace i18n 143} // namespace base 144 145#endif // BASE_I18N_RTL_H_ 146