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.
5#ifndef BASE_I18N_RTL_H_
6#define BASE_I18N_RTL_H_
8#include <string>
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"
15namespace base {
17class FilePath;
19namespace i18n {
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;
29// Locale.java mirrored this enum TextDirection. Please keep in sync.
30enum TextDirection {
32  RIGHT_TO_LEFT = 1,
33  LEFT_TO_RIGHT = 2,
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();
42// Canonicalize a string (eg. a POSIX locale string) to a Chrome locale name.
43BASE_I18N_EXPORT std::string GetCanonicalLocale(const char* locale);
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);
54// Returns true if the application text direction is right-to-left.
55BASE_I18N_EXPORT bool IsRTL();
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.
63// Returns the text direction for |locale_name|.
64BASE_I18N_EXPORT TextDirection GetTextDirectionForLocale(
65    const char* locale_name);
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.
73BASE_I18N_EXPORT TextDirection GetFirstStrongCharacterDirection(
74    const string16& text);
75BASE_I18N_EXPORT TextDirection GetLastStrongCharacterDirection(
76    const string16& text);
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.
84BASE_I18N_EXPORT TextDirection GetStringDirection(const string16& text);
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.
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.
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.
108BASE_I18N_EXPORT bool AdjustStringForLocaleDirection(string16* text);
110// Undoes the actions of the above function (AdjustStringForLocaleDirection).
111BASE_I18N_EXPORT bool UnadjustStringForLocaleDirection(string16* text);
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.
116BASE_I18N_EXPORT bool StringContainsStrongRTLChars(const string16& text);
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.
121BASE_I18N_EXPORT void WrapStringWithLTRFormatting(string16* text);
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.
126BASE_I18N_EXPORT void WrapStringWithRTLFormatting(string16* text);
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.
130BASE_I18N_EXPORT void WrapPathWithLTRFormatting(const FilePath& path,
131                                                string16* rtl_safe_path);
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.
135BASE_I18N_EXPORT string16 GetDisplayStringInLTRDirectionality(
136    const string16& text) WARN_UNUSED_RESULT;
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.
143BASE_I18N_EXPORT string16 StripWrappingBidiControlCharacters(
144    const string16& text) WARN_UNUSED_RESULT;
146}  // namespace i18n
147}  // namespace base
149#endif  // BASE_I18N_RTL_H_