rtl.h revision 7d4cd473f85ac64c3747c96c277f9e506a0d2246
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 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. 40BASE_I18N_EXPORT std::string GetConfiguredLocale(); 41 42// Canonicalize a string (eg. a POSIX locale string) to a Chrome locale name. 43BASE_I18N_EXPORT std::string GetCanonicalLocale(const char* 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. 52BASE_I18N_EXPORT void SetICUDefaultLocale(const std::string& locale_string); 53 54// Returns true if the application text direction is right-to-left. 55BASE_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. 61BASE_I18N_EXPORT bool ICUIsRTL(); 62 63// Returns the text direction for |locale_name|. 64BASE_I18N_EXPORT TextDirection GetTextDirectionForLocale( 65 const char* locale_name); 66 67// Given the string in |text|, returns the directionality of the first 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. 73BASE_I18N_EXPORT TextDirection GetFirstStrongCharacterDirection( 74 const string16& text); 75 76// Given the string in |text|, returns LEFT_TO_RIGHT or RIGHT_TO_LEFT if all the 77// strong directionality characters in the string are of the same 78// directionality. It returns UNKNOWN_DIRECTION if the string contains a mix of 79// LTR and RTL strong directionality characters. Defaults to LEFT_TO_RIGHT if 80// the string does not contain directionality characters. Please refer to 81// http://unicode.org/reports/tr9/ for more information. 82BASE_I18N_EXPORT TextDirection GetStringDirection(const string16& text); 83 84// Given the string in |text|, this function modifies the string in place with 85// the appropriate Unicode formatting marks that mark the string direction 86// (either left-to-right or right-to-left). The function checks both the current 87// locale and the contents of the string in order to determine the direction of 88// the returned string. The function returns true if the string in |text| was 89// properly adjusted. 90// 91// Certain LTR strings are not rendered correctly when the context is RTL. For 92// example, the string "Foo!" will appear as "!Foo" if it is rendered as is in 93// an RTL context. Calling this function will make sure the returned localized 94// string is always treated as a right-to-left string. This is done by 95// inserting certain Unicode formatting marks into the returned string. 96// 97// ** Notes about the Windows version of this function: 98// TODO(idana) bug 6806: this function adjusts the string in question only 99// if the current locale is right-to-left. The function does not take care of 100// the opposite case (an RTL string displayed in an LTR context) since 101// adjusting the string involves inserting Unicode formatting characters that 102// Windows does not handle well unless right-to-left language support is 103// installed. Since the English version of Windows doesn't have right-to-left 104// language support installed by default, inserting the direction Unicode mark 105// results in Windows displaying squares. 106BASE_I18N_EXPORT bool AdjustStringForLocaleDirection(string16* text); 107 108// Undoes the actions of the above function (AdjustStringForLocaleDirection). 109BASE_I18N_EXPORT bool UnadjustStringForLocaleDirection(string16* text); 110 111// Returns true if the string contains at least one character with strong right 112// to left directionality; that is, a character with either R or AL Unicode 113// BiDi character type. 114BASE_I18N_EXPORT bool StringContainsStrongRTLChars(const string16& text); 115 116// Wraps a string with an LRE-PDF pair which essentialy marks the string as a 117// Left-To-Right string. Doing this is useful in order to make sure LTR 118// strings are rendered properly in an RTL context. 119BASE_I18N_EXPORT void WrapStringWithLTRFormatting(string16* text); 120 121// Wraps a string with an RLE-PDF pair which essentialy marks the string as a 122// Right-To-Left string. Doing this is useful in order to make sure RTL 123// strings are rendered properly in an LTR context. 124BASE_I18N_EXPORT void WrapStringWithRTLFormatting(string16* text); 125 126// Wraps file path to get it to display correctly in RTL UI. All filepaths 127// should be passed through this function before display in UI for RTL locales. 128BASE_I18N_EXPORT void WrapPathWithLTRFormatting(const FilePath& path, 129 string16* rtl_safe_path); 130 131// Return the string in |text| wrapped with LRE (Left-To-Right Embedding) and 132// PDF (Pop Directional Formatting) marks, if needed for UI display purposes. 133BASE_I18N_EXPORT string16 GetDisplayStringInLTRDirectionality( 134 const string16& text) WARN_UNUSED_RESULT; 135 136// Strip the beginning (U+202A..U+202B, U+202D..U+202E) and/or ending (U+202C) 137// explicit bidi control characters from |text|, if there are any. Otherwise, 138// return the text itself. Explicit bidi control characters display and have 139// semantic effect. They can be deleted so they might not always appear in a 140// pair. 141BASE_I18N_EXPORT string16 StripWrappingBidiControlCharacters( 142 const string16& text) WARN_UNUSED_RESULT; 143 144} // namespace i18n 145} // namespace base 146 147#endif // BASE_I18N_RTL_H_ 148