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wxWidgets/interface/wx/translation.h
Scott Talbert c68e5d0617 Fix some spelling/grammar errors in documentation 
Mostly replace ungrammatical "allows to do" with correct "allows doing".

Closes https://github.com/wxWidgets/wxWidgets/pull/1183
2019-01-26 03:50:47 +01:00

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/////////////////////////////////////////////////////////////////////////////
// Name: translation.h
// Purpose: wxTranslation class
// Author: wxWidgets team
// Licence: wxWindows licence
/////////////////////////////////////////////////////////////////////////////
/**
This class allows getting translations for strings.
In wxWidgets this class manages message catalogs which contain the
translations of the strings used to the current language. Unlike wxLocale,
it isn't bound to locale. It can be used either independently of, or in
conjunction with wxLocale. In the latter case, you should initialize
wxLocale (which creates wxTranslations instance) first; in the former, you
need to create a wxTranslations object and Set() it manually.
Only one wxTranslations instance is active at a time; it is set with the
Set() method and obtained using Get().
Unlike wxLocale, wxTranslations' primary mean of identifying language
is by its "canonical name", i.e. ISO 639 code, possibly combined with
ISO 3166 country code and additional modifiers (examples include
"fr", "en_GB" or "ca@valencia"; see wxLocale::GetCanonicalName() for
more information). This allows apps using wxTranslations API to use even
languages not recognized by the operating system or not listed in
wxLanguage enum.
@since 2.9.1
@see wxLocale, wxTranslationsLoader, wxFileTranslationsLoader
*/
class wxTranslations
{
public:
/// Constructor
wxTranslations();
/**
Returns current translations object, may return NULL.
You must either call this early in app initialization code, or let
wxLocale do it for you.
*/
static wxTranslations *Get();
/**
Sets current translations object.
Deletes previous translation object and takes ownership of @a t.
*/
static void Set(wxTranslations *t);
/**
Changes loader use to read catalogs to a non-default one.
Deletes previous loader and takes ownership of @a loader.
@see wxTranslationsLoader, wxFileTranslationsLoader, wxResourceTranslationsLoader
*/
void SetLoader(wxTranslationsLoader *loader);
/**
Sets translations language to use.
wxLANGUAGE_DEFAULT has special meaning: best suitable translation,
given user's preference and available translations, will be used.
*/
void SetLanguage(wxLanguage lang);
/**
Sets translations language to use.
Empty @a lang string has the same meaning as wxLANGUAGE_DEFAULT in
SetLanguage(wxLanguage): best suitable translation, given user's
preference and available translations, will be used.
*/
void SetLanguage(const wxString& lang);
/**
Returns list of all translations of @a domain that were found.
This method can be used e.g. to populate list of application's
translations offered to the user. To do this, pass the app's main
catalog as @a domain.
@see GetBestTranslation()
*/
wxArrayString GetAvailableTranslations(const wxString& domain) const;
/**
Returns the best UI language for the @a domain.
The language is determined from the preferred UI language or languages
list the user configured in the OS. Notice that this may or may not
correspond to the default @em locale as obtained from
wxLocale::GetSystemLanguage(); modern operation systems (Windows
Vista+, OS X) have separate language and regional (= locale) settings.
@param domain
The catalog domain to look for.
@param msgIdLanguage
Specifies the language of "msgid" strings in source code
(i.e. arguments to GetString(), wxGetTranslation() and the _() macro).
@return Language code if a suitable match was found, empty string
otherwise.
@since 2.9.5
*/
wxString GetBestTranslation(const wxString& domain, wxLanguage msgIdLanguage);
/**
Returns the best UI language for the @a domain.
The language is determined from the preferred UI language or languages
list the user configured in the OS. Notice that this may or may not
correspond to the default @em locale as obtained from
wxLocale::GetSystemLanguage(); modern operation systems (Windows
Vista+, OS X) have separate language and regional (= locale) settings.
@param domain
The catalog domain to look for.
@param msgIdLanguage
Specifies the language of "msgid" strings in source code
(i.e. arguments to GetString(), wxGetTranslation() and the _() macro).
@return Language code if a suitable match was found, empty string
otherwise.
@since 2.9.5
*/
wxString GetBestTranslation(const wxString& domain,
const wxString& msgIdLanguage = "en");
/**
Add standard wxWidgets catalogs ("wxstd" and possible port-specific
catalogs).
@return @true if a suitable catalog was found, @false otherwise
@see AddCatalog()
*/
bool AddStdCatalog();
/**
Add a catalog for use with the current locale.
By default, it is searched for in standard places (see
wxFileTranslationsLoader), but you may also prepend additional
directories to the search path with
wxFileTranslationsLoader::AddCatalogLookupPathPrefix().
All loaded catalogs will be used for message lookup by GetString() for
the current locale.
Bu default, i.e. if @a msgIdLanguage is not given, @c msgid strings are assumed
to be in English and written only using 7-bit ASCII characters.
If you have to deal with non-English strings or 8-bit characters in the
source code, see the instructions in @ref overview_nonenglish.
@param domain
The catalog domain to add.
@param msgIdLanguage
Specifies the language of "msgid" strings in source code
(i.e. arguments to GetString(), wxGetTranslation() and the _() macro).
It is used if AddCatalog() cannot find any catalog for current language:
if the language is same as source code language, then strings from source
code are used instead.
@return
@true if catalog was successfully loaded, @false otherwise (which might
mean that the catalog is not found or that it isn't in the correct format).
*/
bool AddCatalog(const wxString& domain,
wxLanguage msgIdLanguage = wxLANGUAGE_ENGLISH_US);
/**
Same as AddCatalog(const wxString&, wxLanguage), but takes two
additional arguments, @a msgIdLanguage and @a msgIdCharset.
This overload is only available in non-Unicode build.
@param domain
The catalog domain to add.
@param msgIdLanguage
Specifies the language of "msgid" strings in source code
(i.e. arguments to GetString(), wxGetTranslation() and the _() macro).
It is used if AddCatalog() cannot find any catalog for current language:
if the language is same as source code language, then strings from source
code are used instead.
@param msgIdCharset
Lets you specify the charset used for msgids in sources
in case they use 8-bit characters (e.g. German or French strings).
@return
@true if catalog was successfully loaded, @false otherwise (which might
mean that the catalog is not found or that it isn't in the correct format).
*/
bool AddCatalog(const wxString& domain,
wxLanguage msgIdLanguage,
const wxString& msgIdCharset);
/**
Check if the given catalog is loaded, and returns @true if it is.
According to GNU gettext tradition, each catalog normally corresponds to
'domain' which is more or less the application name.
@see AddCatalog()
*/
bool IsLoaded(const wxString& domain) const;
/**
Retrieves the translation for a string in all loaded domains unless the @a domain
parameter is specified (and then only this catalog/domain is searched).
Returns @NULL if translation is not available.
This function is thread-safe.
@remarks Domains are searched in the last to first order, i.e. catalogs
added later override those added before.
@since 3.0
*/
const wxString *GetTranslatedString(const wxString& origString,
const wxString& domain = wxEmptyString) const;
/**
Retrieves the translation for a string in all loaded domains unless the @a domain
parameter is specified (and then only this catalog/domain is searched).
Returns @NULL if translation is not available.
This form is used when retrieving translation of string that has different
singular and plural form in English or different plural forms in some
other language.
@param origString The singular form of the string to be converted.
@param n The number on which the plural form choice depends on.
(In some languages, there are different plural forms
for e.g. n=2 and n=3 etc., in addition to the singular
form (n=1) being different.)
@param domain The only domain (i.e. message catalog) to search if
specified. By default this parameter is empty,
indicating that all loaded catalogs should be
searched.
See GNU gettext manual for additional information on plural forms handling.
This method is called by the wxGetTranslation() function and _() macro.
This function is thread-safe.
@remarks Domains are searched in the last to first order, i.e. catalogs
added later override those added before.
@since 3.0
*/
const wxString *GetTranslatedString(const wxString& origString,
unsigned n,
const wxString& domain = wxEmptyString) const;
/**
Returns the header value for header @a header.
The search for @a header is case sensitive. If an @a domain is passed,
this domain is searched. Else all domains will be searched until a
header has been found.
The return value is the value of the header if found. Else this will be empty.
*/
wxString GetHeaderValue(const wxString& header,
const wxString& domain = wxEmptyString) const;
};
/**
Abstraction of translations discovery and loading.
This interface makes it possible to override wxWidgets' default catalogs
loading mechanism and load MO files from locations other than the
filesystem (e.g. embed them in executable).
Implementations must implement the LoadCatalog() method.
@see wxFileTranslationsLoader, wxResourceTranslationsLoader
@since 2.9.1
*/
class wxTranslationsLoader
{
public:
/// Trivial default constructor.
wxTranslationsLoader();
/**
Called to load requested catalog.
If the catalog is found, LoadCatalog() should create wxMsgCatalog
instance with its data and return it. The caller will take ownership
of the catalog.
@param domain Domain to load.
@param lang Language to look for. This is "canonical name"
(see wxLocale::GetCanonicalName()), i.e. ISO 639
code, possibly combined with country code or
additional modifiers (e.g. "fr", "en_GB" or
"ca@valencia").
@return Loaded catalog or NULL on failure.
*/
virtual wxMsgCatalog *LoadCatalog(const wxString& domain,
const wxString& lang) = 0;
/**
Implements wxTranslations::GetAvailableTranslations().
*/
virtual wxArrayString GetAvailableTranslations(const wxString& domain) const = 0;
};
/**
Standard wxTranslationsLoader implementation.
This finds catalogs in the filesystem, using the standard Unix layout.
This is the default unless you change the loader with
wxTranslations::SetLoader().
Catalogs are searched for in standard places (system locales directory,
`LC_PATH` on Unix systems, Resources subdirectory of the application bundle
on OS X, executable's directory on Windows), but you may also prepend
additional directories to the search path with
AddCatalogLookupPathPrefix().
@since 2.9.1
*/
class wxFileTranslationsLoader : public wxTranslationsLoader
{
public:
/**
Add a prefix to the catalog lookup path: the message catalog files will
be looked up under prefix/lang/LC_MESSAGES and prefix/lang directories
(in this order).
This only applies to subsequent invocations of
wxTranslations::AddCatalog().
*/
static void AddCatalogLookupPathPrefix(const wxString& prefix);
};
/**
This loader makes it possible to load translations from Windows
resources.
If you wish to store translation MO files in resources, you have to
enable this loader before calling wxTranslations::AddCatalog() or
wxLocale::AddCatalog():
@code
wxTranslations::Get()->SetLoader(new wxResourceTranslationsLoader);
@endcode
Translations are stored in resources as compiled MO files, with type
set to "MOFILE" (unless you override GetResourceType()) and name
consisting of the domain, followed by underscore, followed by language
identification. For example, the relevant part of .rc file would look
like this:
@code
myapp_de MOFILE "catalogs/de/myapp.mo"
myapp_fr MOFILE "catalogs/fr/myapp.mo"
myapp_en_GB MOFILE "catalogs/en_GB/myapp.mo"
@endcode
This class is only available on Windows.
@since 2.9.1
*/
class wxResourceTranslationsLoader : public wxTranslationsLoader
{
protected:
/**
Returns resource type to use for translations.
Default type is "MOFILE".
*/
virtual wxString GetResourceType() const;
/**
Returns handle of the module to load resources from.
By default, the main executable is used.
*/
virtual WXHINSTANCE GetModule() const;
};
/**
Represents a loaded translations message catalog.
This class should only be used directly by wxTranslationsLoader
implementations.
@since 2.9.1
*/
class wxMsgCatalog
{
public:
/**
Creates catalog loaded from a MO file.
@param filename Path to the MO file to load.
@param domain Catalog's domain. This typically matches
the @a filename.
@return Successfully loaded catalog or NULL on failure.
*/
static wxMsgCatalog *CreateFromFile(const wxString& filename,
const wxString& domain);
/**
Creates catalog from MO file data in memory buffer.
@param data Data in MO file format.
@param domain Catalog's domain. This typically matches
the @a filename.
@return Successfully loaded catalog or NULL on failure.
*/
static wxMsgCatalog *CreateFromData(const wxScopedCharBuffer& data,
const wxString& domain);
};
// ============================================================================
// Global functions/macros
// ============================================================================
/** @addtogroup group_funcmacro_string */
//@{
/**
This macro is identical to _() but for the plural variant of
wxGetTranslation().
@return A const wxString.
@header{wx/intl.h}
*/
#define wxPLURAL(string, plural, n)
/**
Similar to _() but translates the string in the given context.
See the description of @c context argument of wxGetTranslation().
@see wxGETTEXT_IN_CONTEXT_PLURAL()
@since 3.1.1
*/
#define wxGETTEXT_IN_CONTEXT(context, string)
/**
Similar to wxPLURAL() but translates the string in the given context.
See the description of @c context argument of wxGetTranslation().
@see wxGETTEXT_IN_CONTEXT()
@since 3.1.1
*/
#define wxGETTEXT_IN_CONTEXT_PLURAL(context, string, plural, n)
/**
This macro doesn't do anything in the program code -- it simply expands to
the value of its argument.
However it does have a purpose which is to mark the literal strings for the
extraction into the message catalog created by @c xgettext program. Usually
this is achieved using _() but that macro not only marks the string for
extraction but also expands into a wxGetTranslation() call which means that
it cannot be used in some situations, notably for static array
initialization.
Here is an example which should make it more clear: suppose that you have a
static array of strings containing the names of chemical elements, which
have to be translated. If you write:
@code
static const char * const elements[] = { _("Hydrogen"), _("Helium"), ... };
...
// use elements[n] as usual
@endcode
The code would compile and run, but there would be no translations for the
strings because static variables are initialized at a very early stage of
program execution; that is, before the locale and paths to message catalog
files have been set up.
So instead you should do this:
@code
static const char * const elements[] = { wxTRANSLATE("Hydrogen"),
wxTRANSLATE("Helium"), ... };
...
// use wxGetTranslation(elements[n])
@endcode
Note that if you simply omit wxTRANSLATE() above, those strings would not
be marked for translation, and would therefore not be included in the
message catalog. Consequently, wxGetTranslation() would not find
translations for them.
@return A const wxChar*.
@header{wx/intl.h}
*/
#define wxTRANSLATE(string)
/**
This function returns the translation of @a string in the current
@c locale().
If the string is not found in any of the loaded message catalogs (see @ref
overview_i18n), the original string is returned. If you enable logging of
trace messages with "i18n" mask (using wxLog::AddTraceMask()) and debug
logging is enabled (see @ref overview_debugging), a message is also logged
in this case -- which helps to find the strings which were not yet
translated.
If @a domain is specified then only that domain/catalog is searched for a
matching string. As this function is used very often, an alternative (and
also common in Unix world) syntax is provided: the _() macro is defined to
do the same thing as wxGetTranslation().
If @a context is not empty (notice that this argument is only available
starting from wxWidgets 3.1.1), item translation is looked up in the
specified context. This allows having different translations for the same
string appearing in different contexts, e.g. it may be necessary to
translate the same English "Open" verb differently depending on the object
it applies to. To do this, you need to use @c msgctxt in the source message
catalog and specify different contexts for the different occurrences of the
string and then use the same contexts in the calls to this function (or
wxGETTEXT_IN_CONTEXT() or wxGETTEXT_IN_CONTEXT_PLURAL() macros).
This function is thread-safe.
@note This function is not suitable for literal strings using wxT() macro
since this macro is not recognised by @c xgettext, and so such
strings are not extracted to the message catalog. Instead, use the
_() and wxPLURAL() macro for all literal strings.
@see wxGetTranslation(const wxString&, const wxString&, unsigned, const wxString&)
@header{wx/intl.h}
*/
const wxString& wxGetTranslation(const wxString& string,
const wxString& domain = wxEmptyString,
const wxString& context = wxEmptyString);
/**
This is an overloaded version of
wxGetTranslation(const wxString&, const wxString&), please see its
documentation for general information.
This version is used when retrieving translation of string that has
different singular and plural forms in English or different plural forms in
some other language. Like wxGetTranslation(const wxString&,const wxString&),
the @a string parameter must contain the singular form of the string to be
converted and is used as the key for the search in the catalog. The
@a plural parameter is the plural form (in English). The parameter @a n is
used to determine the plural form. If no message catalog is found,
@a string is returned if "n == 1", otherwise @a plural is returned.
See GNU gettext Manual for additional information on plural forms handling:
<http://www.gnu.org/software/gettext/manual/gettext.html#Plural-forms>
For a shorter alternative see the wxPLURAL() macro.
This function is thread-safe.
@header{wx/intl.h}
*/
const wxString& wxGetTranslation(const wxString& string,
const wxString& plural, unsigned n,
const wxString& domain = wxEmptyString,
const wxString& context = wxEmptyString);
/**
Macro to be used around all literal strings that should be translated.
This macro expands into a call to wxGetTranslation(), so it marks the
message for the extraction by @c xgettext just as wxTRANSLATE() does, but
also returns the translation of the string for the current locale during
execution.
This macro is thread-safe.
@header{wx/intl.h}
*/
const wxString& _(const wxString& string);
//@}
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