xref: /haiku/docs/user/locale/Catalog.dox (revision 7e8daebe3464f9137ded3201665515b349bba9c8)
1/*!
2\class BCatalog
3\ingroup locale
4\brief Class handling string localization.
5
6BCatalog is the class that allows you to perform string localization. This means
7you give it a string in english, and it automatically returns the translation of
8this string in the user's specified language, if available.
9
10Most of the time, you don't have to deal with BCatalog directly. You use the
11translation macros instead. However, there are some cases where you will have to
12use catalogs directly. These include :
13	\li Tools for managing catalogs : if you want to add, remove or edit
14entries in a catalog, you need to do it using the BCatalog class.
15	\li Accessing catalogs other than your own : the macros only grant you
16access to the catalog linked with your application. To access other catalogs
17(for example if you create a script interpreter and want to localize the
18scripts), you will have to open a catalog associated with your script.
19
20\section macros Using the macros
21You don't have to do much in your program to handle catalogs. You must first
22set the B_TRANSLATE_CONTEXT define to a string that identifies which part of the
23application the strings you will translate are in. This allows the translators
24to keep track of the strings in the catalog more easily, and find where they are
25visible in the application. then, all you have to do, is enclose any string you
26want to make translatable in the B_TRANSLATE() macro. This macro has two uses,
27it will allow your text to be replaced at run-time by the proper localized one,
28but it will also allow to build the base catalog, the one that you will send to
29the translator team, from your sourcecode.
30
31\section chaining Chaining of catalogs
32The catalogs you get from the locale kit are designed to use a fallback system
33so that the user get strings in the language he's the most fluent with,
34depending on what catalogs are available.
35
36For example, if the user sets his language preferences as french(France),
37spanish, english, when an application loads a catalog, the following rules are
38used :
39	\li Try to load a french(France) catalog. If it is found, this catalog
40		will automatically include strings from the generic french catalog.
41	\li Try to load a generic french catalog.
42	\li Try to load a generic spanish catalog.
43	\li Try to load a generic english catalog.
44	\li If all of them failed, use the strings that are in the source code.
45
46Note that french(France) will failback to french, but then directly to the
47language in the source code. This avoids mixing 3 or more languages in the same
48application if the catalogs are incomplete and avoids confusion.
49
50*/
51
52/*!
53\fn BCatalog::BCatalog(const char* signature, const char* language = NULL, uint32 fingerprint = 0)
54\brief Construct a catalog for the given application.
55
56This constructor builds a catalog for the application with the given mime
57signature. In Haiku, the mime signature is used as a way to uniquely identify a
58catalog and match it with the corresponding application.
59
60If you don't specify a language, the system default list will be used.
61The language is passed here as a 2 letter ISO code.
62
63The fingerprint is a way to check that the catalog that will be loaded matches
64the current version of the application. A catalog made for a different version
65of the application can be loaded if you set the fingerprint to 0. This is
66usually not a problem, it only means that some strings may not be translated
67properly. But if you want to provide different versions of your application, it
68may be useful to separate their catalogs.
69
70\param signature Mime-signature of the application for which to load a catalog.
71\param language The language of the catalog to load. If NULL, the user settings
72will be used.
73\param fingerprint The fingerprint version-info for the catalog to load. If 0,
74the fingerprint will not be checked,and any version of the catalog will be
75loaded.
76*/
77
78/*!
79\fn const char* BCatalog::GetString(const char* string, const char* context = NULL, const char* comment = NULL)
80\brief Get a string from the catalog.
81
82This method access the data of the catalog and reeturns you the translated
83version of the string. You must pass it the context where the string is, as
84the same string may appear somewhere else and need a differnet translation.
85The comment is optional. It is meant as an help to translators, when the string
86alone is not helpful enough or there are special things to note. The comment is
87also used as a way to uniquely identify a string, so if two identical strings
88share the same context, it is still possible to provide different translations.
89
90\returns The translated string, or the one passed as a parameter if no
91translation was found.
92\param string The string to translate.
93\param context The context where the string is located.
94\param comment Supplementary comment for translators.
95*/
96
97/*!
98\fn const char* BCatalog::GetString(uint32 id)
99\brief Get a string by id from the catalog.
100
101The id based version of this method is slightly faster, as it doesn't have to
102compute the hash from the 3 parameters. However, it will fail if there is an
103hash collision, so you should still fallback to the first one in case of
104problems. Also note that the hash value may be different from one catalog to
105another, depending on the file format they are stored in, so you shouldn't rely
106on this method unless you are sure you can keep all the catalog files under
107control.
108
109\returns The translated string if found, or an empty string.
110\param id The identifier of the string.
111*/
112
113/*!
114\fn const char* BCatalog::GetStringNoAutoCollate(const char* string, const char* context = NULL, const char* comment = NULL)
115\fn const char* GetStringNoAutoCollate(uint32 id)
116\brief Get a string from the catalog, without registering it for collectcatkeys.
117
118This function does exactly the same thing as GetString, except it will not be
119parsed by the collectcatkeys tool. This allows you, for example, to translate a
120string constant that you declared at another place, without getting a warning
121message from collectcatkeys.
122
123\returns The translated string, or the one passed as a parameter if no
124translation was found.
125\param string The string to translate.
126\param context The context where the string is located.
127\param comment Supplementary comment for translators.
128*/
129
130
131/*!
132\fn status_t BCatalog::GetData(const char* name, BMessage* msg)
133\brief Get custom data from the catalog.
134
135This function allows you to localize something else than raw text. This may
136include pictures, sounds, videos, or anything else. Note there is no support for
137generatinga catalog with such data inside, and the current format may not
138support it. If you need to localize data that is not text, it is advised to
139handle it by yourself.
140
141\returns An error code.
142\param name The name of the data to retrieve.
143\param msg The BMessage to fill in with the data.
144*/
145
146/*!
147\fn status_t BCatalog::GetData(uint32 id, BMessage* msg)
148\brief Get custom data from the catalog.
149
150As for GetString, the id-based version may be subject to hash-collisions, but is
151faster.
152
153Note the current catalog format doesn't allow storing custom data in catalogs,
154so the only way to use this function is providing your own catalog add-on for
155storing the data.
156*/
157
158/*!
159\fn status_t BCatalog::GetSignature(BString* sig)
160\brief Get the catalog mime-signature.
161
162This function fills the sig string with the mime-signature associated to the
163catalog.
164
165\param sig The string where to copy the signature.
166\returns An error code.
167*/
168
169/*!
170\fn status_t BCatalog::GetLanguage(BString* lang)
171\brief Get the catalog language.
172
173This function fills the lang string with the language name for the catalog.
174
175\param sig The string where to copy the language.
176\returns An error code.
177*/
178
179/*!
180\fn status_t BCatalog::GetFingerprint(uint32* fp)
181\brief Get the catalog fingerprint.
182
183This function setsfp to the fingerprint of the catalog. This allows you to check
184which version of the sourcecode this catalog was generated from.
185
186\returns An error code.
187\param fp The integer to set to the fingerprint value.
188*/
189
190/*!
191\fn status_t BCatalog::SetCatalog(const char* signature, uint32 fingerprint)
192\brief Reload the string data.
193
194This function reloads the data for the given signature and fingerprint.
195
196\returns An error code.
197\param signature The signature of the catalog youwant to load
198\param fingerprint The fingerprint of the catalog you want to load.
199*/
200
201/*!
202\fn status_t BCatalog::InitCheck() const
203\brief Check if the catalog is in an useable state.
204
205This function returns B_OK if the catalog is initialized properly.
206*/
207
208/*!
209\fn int32 BCatalog::CountItems()
210\brief Returns the number of items in the catalog.
211
212This function returns the number of strings in the catalog.
213*/
214
215/*!
216\fn BCatalogaddOn* BCatalog::CatalogAddOn()
217\brief Returns the internal storage for this catalog.
218
219This function returns the internal storage class used by this catalog.
220You should not have to use it.
221*/
222