rtl.h revision 868fa2fe829687343ffae624259930155e16dbd8
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 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 29// Locale.java mirrored this enum TextDirection. Please keep in sync. 30enum TextDirection { 31 UNKNOWN_DIRECTION = 0, 32 RIGHT_TO_LEFT = 1, 33 LEFT_TO_RIGHT = 2, 34}; 35 36// Get the locale that the currently running process has been configured to use. 37// The return value is of the form language[-country] (e.g., en-US) where the 38// language is the 2 or 3 letter code from ISO-639. 39BASE_I18N_EXPORT std::string GetConfiguredLocale(); 40 41// Canonicalize a string (eg. a POSIX locale string) to a Chrome locale name. 42BASE_I18N_EXPORT std::string GetCanonicalLocale(const char* locale); 43 44// Sets the default locale of ICU. 45// Once the application locale of Chrome in GetApplicationLocale is determined, 46// the default locale of ICU need to be changed to match the application locale 47// so that ICU functions work correctly in a locale-dependent manner. 48// This is handy in that we don't have to call GetApplicationLocale() 49// everytime we call locale-dependent ICU APIs as long as we make sure 50// that this is called before any locale-dependent API is called. 51BASE_I18N_EXPORT void SetICUDefaultLocale(const std::string& locale_string); 52 53// Returns true if the application text direction is right-to-left. 54BASE_I18N_EXPORT bool IsRTL(); 55 56// Returns whether the text direction for the default ICU locale is RTL. This 57// assumes that SetICUDefaultLocale has been called to set the default locale to 58// the UI locale of Chrome. 59// NOTE: Generally, you should call IsRTL() instead of this. 60BASE_I18N_EXPORT bool ICUIsRTL(); 61 62// Returns the text direction for |locale_name|. 63BASE_I18N_EXPORT TextDirection GetTextDirectionForLocale( 64 const char* locale_name); 65 66// Given the string in |text|, returns the directionality of the first 67// character with strong directionality in the string. If no character in the 68// text has strong directionality, LEFT_TO_RIGHT is returned. The Bidi 69// character types L, LRE, LRO, R, AL, RLE, and RLO are considered as strong 70// directionality characters. Please refer to http://unicode.org/reports/tr9/ 71// for more information. 72BASE_I18N_EXPORT TextDirection GetFirstStrongCharacterDirection( 73 const string16& text); 74 75// Given the string in |text|, returns LEFT_TO_RIGHT or RIGHT_TO_LEFT if all the 76// strong directionality characters in the string are of the same 77// directionality. It returns UNKNOWN_DIRECTION if the string contains a mix of 78// LTR and RTL strong directionality characters. Defaults to LEFT_TO_RIGHT if 79// the string does not contain directionality characters. Please refer to 80// http://unicode.org/reports/tr9/ for more information. 81BASE_I18N_EXPORT TextDirection GetStringDirection(const string16& text); 82 83// Given the string in |text|, this function modifies the string in place with 84// the appropriate Unicode formatting marks that mark the string direction 85// (either left-to-right or right-to-left). The function checks both the current 86// locale and the contents of the string in order to determine the direction of 87// the returned string. The function returns true if the string in |text| was 88// properly adjusted. 89// 90// Certain LTR strings are not rendered correctly when the context is RTL. For 91// example, the string "Foo!" will appear as "!Foo" if it is rendered as is in 92// an RTL context. Calling this function will make sure the returned localized 93// string is always treated as a right-to-left string. This is done by 94// inserting certain Unicode formatting marks into the returned string. 95// 96// ** Notes about the Windows version of this function: 97// TODO(idana) bug 6806: this function adjusts the string in question only 98// if the current locale is right-to-left. The function does not take care of 99// the opposite case (an RTL string displayed in an LTR context) since 100// adjusting the string involves inserting Unicode formatting characters that 101// Windows does not handle well unless right-to-left language support is 102// installed. Since the English version of Windows doesn't have right-to-left 103// language support installed by default, inserting the direction Unicode mark 104// results in Windows displaying squares. 105BASE_I18N_EXPORT bool AdjustStringForLocaleDirection(string16* text); 106 107// Undoes the actions of the above function (AdjustStringForLocaleDirection). 108BASE_I18N_EXPORT bool UnadjustStringForLocaleDirection(string16* text); 109 110// Returns true if the string contains at least one character with strong right 111// to left directionality; that is, a character with either R or AL Unicode 112// BiDi character type. 113BASE_I18N_EXPORT bool StringContainsStrongRTLChars(const string16& text); 114 115// Wraps a string with an LRE-PDF pair which essentialy marks the string as a 116// Left-To-Right string. Doing this is useful in order to make sure LTR 117// strings are rendered properly in an RTL context. 118BASE_I18N_EXPORT void WrapStringWithLTRFormatting(string16* text); 119 120// Wraps a string with an RLE-PDF pair which essentialy marks the string as a 121// Right-To-Left string. Doing this is useful in order to make sure RTL 122// strings are rendered properly in an LTR context. 123BASE_I18N_EXPORT void WrapStringWithRTLFormatting(string16* text); 124 125// Wraps file path to get it to display correctly in RTL UI. All filepaths 126// should be passed through this function before display in UI for RTL locales. 127BASE_I18N_EXPORT void WrapPathWithLTRFormatting(const FilePath& path, 128 string16* rtl_safe_path); 129 130// Return the string in |text| wrapped with LRE (Left-To-Right Embedding) and 131// PDF (Pop Directional Formatting) marks, if needed for UI display purposes. 132BASE_I18N_EXPORT string16 GetDisplayStringInLTRDirectionality( 133 const string16& text) WARN_UNUSED_RESULT; 134 135// Strip the beginning (U+202A..U+202B, U+202D..U+202E) and/or ending (U+202C) 136// explicit bidi control characters from |text|, if there are any. Otherwise, 137// return the text itself. Explicit bidi control characters display and have 138// semantic effect. They can be deleted so they might not always appear in a 139// pair. 140BASE_I18N_EXPORT string16 StripWrappingBidiControlCharacters( 141 const string16& text) WARN_UNUSED_RESULT; 142 143} // namespace i18n 144} // namespace base 145 146#endif // BASE_I18N_RTL_H_ 147