Input Method (basic)(3m17n)

NAME
m17nInputMethod - Input Method (basic): API for Input method.

  Data Structures
struct MInputDriver
Structure of input method driver.
struct MInputMethod
Structure of input method.
struct MInputContext
Structure of input context.

  Variables: Predefined symbols for callback commands.
These are the predefined symbols that are used as the COMMAND argument of callback functions of an input method driver (see MInputDriver::callback_list).

Most of them do not require extra argument nor return any value; exceptions are these:

Minput_get_surrounding_text: When a callback function assigned for this command is called, the first element of MInputContext::plist has key Minteger and the value specifies which portion of the surrounding text should be retrieved. If the value is positive, it specifies the number of characters following the current cursor position. If the value is negative, the absolute value specifies the number of characters preceding the current cursor position. If the value is zero, it means that the caller just wants to know if the surrounding text is currently supported or not.

If the surrounding text is currently supported, the callback function must set the key of this element to Mtext and the value to the retrieved M-text. The length of the M-text may be shorter than the requested number of characters, if the available text is not that long. The length can be zero in the worst case. Or, the length may be longer if an application thinks it is more efficient to return that length.

If the surrounding text is not currently supported, the callback function should return without changing the first element of MInputContext::plist.

Minput_delete_surrounding_text: When a callback function assigned for this command is called, the first element of MInputContext::plist has key Minteger and the value specifies which portion of the surrounding text should be deleted in the same way as the case of Minput_get_surrounding_text. The callback function must delete the specified text. It should not alter MInputContext::plist.
MSymbol Minput_preedit_start
MSymbol Minput_preedit_done
MSymbol Minput_preedit_draw
MSymbol Minput_status_start
MSymbol Minput_status_done
MSymbol Minput_status_draw
MSymbol Minput_candidates_start
MSymbol Minput_candidates_done
MSymbol Minput_candidates_draw
MSymbol Minput_set_spot
MSymbol Minput_toggle
MSymbol Minput_reset
MSymbol Minput_get_surrounding_text
MSymbol Minput_delete_surrounding_text

  Variables: Predefined symbols for special input events.
These are the predefined symbols that are used as the KEY argument of minput_filter().
MSymbol Minput_focus_out
MSymbol Minput_focus_in
MSymbol Minput_focus_move

  Variables: Predefined symbols used in input method information.
These are the predefined symbols describing status of input method command and variable, and are used in a return value of minput_get_command() and minput_get_variable().
MSymbol Minherited
MSymbol Mcustomized
MSymbol Mconfigured

  Functions
MInputMethod * minput_open_im (MSymbol language, MSymbol name, void *arg)
Open an input method.
void minput_close_im (MInputMethod *im)
Close an input method.
MInputContext * minput_create_ic (MInputMethod *im, void *arg)
Create an input context.
void minput_destroy_ic (MInputContext *ic)
Destroy an input context.
int minput_filter (MInputContext *ic, MSymbol key, void *arg)
Filter an input key.
int minput_lookup (MInputContext *ic, MSymbol key, void *arg, MText *mt)
Look up a text produced in the input context.
void minput_set_spot (MInputContext *ic, int x, int y, int ascent, int descent, int fontsize, MText *mt, int pos)
Set the spot of the input context.
void minput_toggle (MInputContext *ic)
Toggle input method.
void minput_reset_ic (MInputContext *ic)
Reset an input context.
MText * minput_get_description (MSymbol language, MSymbol name)
Get description text of an input method.
MPlist * minput_get_title_icon (MSymbol language, MSymbol name)
Get title and icon filename of an input method.
MPlist * minput_get_command (MSymbol language, MSymbol name, MSymbol command)
Get information about input method command(s).
int minput_config_command (MSymbol language, MSymbol name, MSymbol command, MPlist *keyseqlist)
Configure the key sequence of an input method command.
MPlist * minput_get_variable (MSymbol language, MSymbol name, MSymbol variable)
Get information about input method variable(s).
int minput_config_variable (MSymbol language, MSymbol name, MSymbol variable, MPlist *value)
Configure the value of an input method variable.
char * minput_config_file ()
Get the name of per-user customization file.
int minput_save_config (void)
Save configurations in per-user customization file.

  Obsolete functions
int minput_callback (MInputContext *ic, MSymbol command)
Call a callback function.
MPlist * minput_get_commands (MSymbol language, MSymbol name)
Get information about input method commands.
int minput_assign_command_keys (MSymbol language, MSymbol name, MSymbol command, MPlist *keyseq)
Assign a key sequence to an input method command (obsolete).
MPlist * minput_get_variables (MSymbol language, MSymbol name)
Get a list of variables of an input method (obsolete).
int minput_set_variable (MSymbol language, MSymbol name, MSymbol variable, void *value)
Set the initial value of an input method variable.

  Typedefs
typedef struct MInputMethod MInputMethod
typedef struct MInputContext MInputContext
typedef void(* MInputCallbackFunc )(MInputContext *ic, MSymbol command)
Type of input method callback functions.

  Enumerations
enum MInputCandidatesChanged { MINPUT_CANDIDATES_LIST_CHANGED = 1, MINPUT_CANDIDATES_INDEX_CHANGED = 2, MINPUT_CANDIDATES_SHOW_CHANGED = 4, MINPUT_CANDIDATES_CHANGED_MAX }
Bit-masks to specify how candidates of input method is changed.

  Variables
MInputDriver minput_default_driver
The default driver for internal input methods.
MSymbol Minput_driver
MInputDriver * minput_driver
The driver for internal input methods.
MSymbol Minput_preedit_start
MSymbol Minput_preedit_draw
MSymbol Minput_preedit_done
MSymbol Minput_status_start
MSymbol Minput_status_draw
MSymbol Minput_status_done
MSymbol Minput_candidates_start
MSymbol Minput_candidates_draw
MSymbol Minput_candidates_done
MSymbol Minput_set_spot
MSymbol Minput_toggle
MSymbol Minput_reset
MSymbol Minput_get_surrounding_text
MSymbol Minput_delete_surrounding_text
MSymbol Minput_focus_move
MSymbol Minput_focus_in
MSymbol Minput_focus_out
MSymbol Minherited
MSymbol Mcustomized
MSymbol Mconfigured
MInputDriver minput_default_driver
The default driver for internal input methods.
MInputDriver * minput_driver
The driver for internal input methods.
MSymbol Minput_driver

Detailed Description

API for Input method.

An input method is an object to enable inputting various characters. An input method is identified by a pair of symbols, LANGUAGE and NAME. This pair decides an input method driver of the input method. An input method driver is a set of functions for handling the input method. There are two kinds of input methods; internal one and foreign one.

•   Internal Input Method
An internal input method has non Mnil LANGUAGE, and its body is defined in the m17n database by the tag <Minput_method, LANGUAGE, NAME>. For this kind of input methods, the m17n library uses two predefined input method drivers, one for CUI use and the other for GUI use. Those drivers utilize the input processing engine provided by the m17n library itself. The m17n database may provide input methods that are not limited to a specific language. The database uses Mt as LANGUAGE of those input methods.
An internal input method accepts an input key which is a symbol associated with an input event. As there is no way for the m17n library to know how input events are represented in an application program, an application programmer has to convert an input event to an input key by himself. See the documentation of the function minput_event_to_key() for the detail.
•   Foreign Input Method
A foreign input method has Mnil LANGUAGE, and its body is defined in an external resource (e.g. XIM of X Window System). For this kind of input methods, the symbol NAME must have a property of key Minput_driver, and the value must be a pointer to an input method driver. Therefore, by preparing a proper driver, any kind of input method can be treated in the framework of the m17n library.
For convenience, the m17n-X library provides an input method driver that enables the input style of OverTheSpot for XIM, and stores Minput_driver property of the symbol Mxim with a pointer to the driver. See the documentation of m17n GUI API for the detail.
PROCESSING FLOW
The typical processing flow of handling an input method is:
•   open an input method
•   create an input context for the input method
•   filter an input key
•   look up a produced text in the input context

Data Structure Documentation

  MInputDriver
Structure of input method driver.
FIELD DOCUMENTATION:
int(* MInputDriver::open_im)(MInputMethod *im)
Open an input method.
This function opens the input method im. It is called from the function minput_open_im() after all member of im but <info> set. If opening im succeeds, it returns 0. Otherwise, it returns -1. The function can setup im->info to keep various information that is referred by the other driver functions.
void(* MInputDriver::close_im)(MInputMethod *im)
Close an input method.
This function closes the input method im. It is called from the function minput_close_im(). It frees all memory allocated for im->info (if any) after finishing all the tasks of closing the input method. But, the other members of im should not be touched.
int(* MInputDriver::create_ic)(MInputContext *ic)
Create an input context.
This function creates the input context ic. It is called from the function minput_create_ic() after all members of ic but <info> are set. If creating ic succeeds, it returns 0. Otherwise, it returns -1. The function can setup ic->info to keep various information that is referred by the other driver functions.
void(* MInputDriver::destroy_ic)(MInputContext *ic)
Destroy an input context.
This function is called from the function minput_destroy_ic() and destroys the input context ic. It frees all memory allocated for ic->info (if any) after finishing all the tasks of destroying the input method. But, the other members of ic should not be touched.
int(* MInputDriver::filter)(MInputContext *ic, MSymbol key, void *arg)
Filter an input key.
This function is called from the function minput_filter() and filters an input key. key and arg are the same as what given to minput_filter().
The task of the function is to handle key, update the internal state of ic. If key is absorbed by the input method and no text is produced, it returns 1. Otherwise, it returns 0.
It may update ic->status, ic->preedit, ic->cursor_pos, ic->ncandidates, ic->candidates, and ic->produced if that is necessary for the member <callback>.
The meaning of arg depends on the input method river. See the documentation of minput_default_driver and minput_gui_driver for instance.
int(* MInputDriver::lookup)(MInputContext *ic, MSymbol key, void *arg, MText *mt)
Lookup a produced text in an input context.
It is called from the function minput_lookup() and looks up a produced text in the input context ic. This function concatenate a text produced by the input key key (if any) to M-text mt. If key was correctly handled by the input method of ic, it returns 0. Otherwise, it returns 1.
The meaning of arg depends on the input method driver. See the documentation of minput_default_driver and minput_gui_driver for instance.
MPlist* MInputDriver::callback_list
List of callback functions.
List of callback functions. Keys are one of Minput_preedit_start, Minput_preedit_draw, Minput_preedit_done, Minput_status_start, Minput_status_draw, Minput_status_done, Minput_candidates_start, Minput_candidates_draw, Minput_candidates_done, Minput_set_spot, Minput_toggle, Minput_reset, Minput_get_surrounding_text, Minput_delete_surrounding_text. Values are functions of type MInputCallbackFunc.

  MInputMethod
Structure of input method.
FIELD DOCUMENTATION:
MSymbol MInputMethod::language
Which language this input method is for. The value is Mnil if the input method is foreign.
MSymbol MInputMethod::name
Name of the input method. If the input method is foreign, it must has a property of key Minput_driver and the value must be a pointer to a proper input method driver.
MInputDriver MInputMethod::driver
Input method driver of the input method.
void* MInputMethod::arg
The argument given to minput_open_im().
void* MInputMethod::info
Pointer to extra information that <driver>.open_im() setups.

  MInputContext
Structure of input context.
FIELD DOCUMENTATION:
MInputMethod* MInputContext::im
Backward pointer to the input method. It is set up be the function minput_create_ic().
MText* MInputContext::produced
M-text produced by the input method. It is set up by the function minput_lookup() .
void* MInputContext::arg
Argument given to the function minput_create_im().
int MInputContext::active
Flag telling whether the input context is currently active or inactive. The value is set to 1 (active) when the input context is created. It is toggled by the function minput_toggle().
int MInputContext::x
X and Y coordinate of the spot.
int MInputContext::ascent
Ascent and descent pixels of the line of the spot.
int MInputContext::fontsize
Font size for preedit text in 1/10 point.
MText* MInputContext::mt
M-text at the spot, or NULL.
int MInputContext::pos
Character position in <mt> at the spot.
void* MInputContext::info
The usage of the following members depends on the input method driver. The descriptions below are for the driver of an internal input method. They are set by the function <im>->driver.filter(). Pointer to extra information that <im>->driver.create_ic() setups. It is used to record the internal state of the input context.
MText* MInputContext::status
M-text describing the current status of the input context.
int MInputContext::status_changed
The function <im>->driver.filter() sets the value to 1 when it changes <status>.
MText* MInputContext::preedit
M-text containing the current preedit text. The function <im>->driver.filter() sets the value.
int MInputContext::preedit_changed
The function <im>->driver.filter() sets the value to 1 when it changes <preedit>.
int MInputContext::cursor_pos
Cursor position of <preedit>.
int MInputContext::cursor_pos_changed
The function <im>->driver.filter() sets the value to 1 when it changes <cursor_pos>.
MPlist* MInputContext::candidate_list
Plist of the current candidate groups. Each element is an M-text or a plist. If an element is an M-text (i.e. the key is Mtext), candidates in that group are characters in the M-text. If it is a plist (i.e. the key is Mplist), each element is an M-text, and candidates in that group are those M-texts.
int MInputContext::candidate_index
Index number of the currently selected candidate in all the candidates. The index of the first candidate is 0. If the number is 8, and the first candidate group contains 7 candidates, the currently selected candidate is the second element of the second candidate group.
int MInputContext::candidate_from
Start and the end positions of the preedit text where <candidate_list> corresponds to.
int MInputContext::candidate_show
Flag telling whether the current candidate group must be shown or not. The function <im>->driver.filter() sets the value to 1 when an input method required to show candidates, and sets the value to 0 otherwise.
int MInputContext::candidates_changed
The function <im>->driver.filter() sets the value to bitwise OR of enum MInputCandidatesChanged when it changed any of the above members (<candidate_XXX>), and sets the value to 0 otherwise.
MPlist* MInputContext::plist
Plist that can be freely used by <im>->driver functions. The driver of internal input method uses it to exchange extra arguments and result for callback functions. The function <im>->driver.create_ic() sets this to an empty plist, and the function <im>->driver.destroy_ic() frees it by using m17n_object_unref().

Typedef Documentation

  typedef void(* MInputCallbackFunc)(MInputContext *ic, MSymbol command)
Type of input method callback functions.
This is the type of callback functions called from input method drivers. IC is a pointer to an input context, COMMAND is a name of callback for which the function is called.

Variable Documentation

  MInputDriver minput_default_driver
The default driver for internal input methods.
The variable minput_default_driver is the default driver for internal input methods.
The member MInputDriver::open_im() searches the m17n database for an input method that matches the tag < Minput_method, language, name> and loads it.
The member MInputDriver::callback_list() is NULL. Thus, it is programmers responsibility to set it to a plist of proper callback functions. Otherwise, no feedback information (e.g. preedit text) can be shown to users.
The macro M17N_INIT() sets the variable minput_driver to the pointer to this driver so that all internal input methods use it.
Therefore, unless minput_driver is set differently, the driver dependent arguments arg of the functions whose name begins with 'minput_' are all ignored.

  MInputDriver minput_default_driver
The default driver for internal input methods.
The variable minput_default_driver is the default driver for internal input methods.
The member MInputDriver::open_im() searches the m17n database for an input method that matches the tag < Minput_method, language, name> and loads it.
The member MInputDriver::callback_list() is NULL. Thus, it is programmers responsibility to set it to a plist of proper callback functions. Otherwise, no feedback information (e.g. preedit text) can be shown to users.
The macro M17N_INIT() sets the variable minput_driver to the pointer to this driver so that all internal input methods use it.
Therefore, unless minput_driver is set differently, the driver dependent arguments arg of the functions whose name begins with 'minput_' are all ignored.

  MInputDriver* minput_driver
The driver for internal input methods.
The variable minput_driver is a pointer to the input method driver that is used by internal input methods. The macro M17N_INIT() initializes it to a pointer to minput_default_driver if <m17n.h> is included.

  MInputDriver* minput_driver
The driver for internal input methods.
The variable minput_driver is a pointer to the input method driver that is used by internal input methods. The macro M17N_INIT() initializes it to a pointer to minput_default_driver if <m17n.h> is included.

Function Documentation

  int minput_assign_command_keys (MSymbol language, MSymbol name, MSymbol command, MPlist * keyseq)
Assign a key sequence to an input method command (obsolete).
This function is obsolete. Use minput_config_command() instead.
The minput_assign_command_keys() function assigns input key sequence keyseq to input method command command for the input method specified by language and name. If name is Mnil, the key sequence is assigned globally no matter what language is. Otherwise the key sequence is assigned locally.
Each element of keyseq must have the key msymbol and the value must be a symbol representing an input key.
keyseq may be NULL, in which case, all assignments are deleted globally or locally.
This assignment gets effective in a newly opened input method.
RETURN VALUE
    If the operation was successful, 0 is returned. Otherwise -1 is returned, and merror_code is set to MERROR_IM.

  int minput_callback (MInputContext * ic, MSymbol command)
Call a callback function.
The minput_callback() functions calls a callback function command assigned for the input context ic. The caller must set specific elements in ic->plist if the callback function requires.
RETURN VALUE
    If there exists a specified callback function, 0 is returned. Otherwise -1 is returned. By side effects, ic->plist may be modified.

  MPlist * minput_get_commands (MSymbol language, MSymbol name)
Get information about input method commands.
The minput_get_commands() function returns information about input method commands of the input method specified by language and name. An input method command is a pseudo key event to which one or more actual input key sequences are assigned.
There are two kinds of commands, global and local. Global commands are used by multiple input methods for the same purpose, and have global key assignments. Local commands are used only by a specific input method, and have only local key assignments.
Each input method may locally change key assignments for global commands. The global key assignment for a global command is effective only when the current input method does not have local key assignments for that command.
If name is Mnil, information about global commands is returned. In this case language is ignored.
If name is not Mnil, information about those commands that have local key assignments in the input method specified by language and name is returned.
RETURN VALUE
    If no input method commands are found, this function returns NULL.
Otherwise, a pointer to a plist is returned. The key of each element in the plist is a symbol representing a command, and the value is a plist of the form COMMAND-INFO described below.
The first element of COMMAND-INFO has the key Mtext, and the value is an M-text describing the command.
If there are no more elements, that means no key sequences are assigned to the command. Otherwise, each of the remaining elements has the key Mplist, and the value is a plist whose keys are Msymbol and values are symbols representing input keys, which are currently assigned to the command.
As the returned plist is kept in the library, the caller must not modify nor free it.

  MPlist * minput_get_variables (MSymbol language, MSymbol name)
Get a list of variables of an input method (obsolete).
This function is obsolete. Use minput_get_variable() instead.
The minput_get_variables() function returns a plist (MPlist) of variables used to control the behavior of the input method specified by language and name. The plist is well-formed (Property List) of the following format:
    (VARNAME (DOC-MTEXT DEFAULT-VALUE [ VALUE ... ] )
     VARNAME (DOC-MTEXT DEFAULT-VALUE [ VALUE ... ] )
     ...)
VARNAME is a symbol representing the variable name.
DOC-MTEXT is an M-text describing the variable.
DEFAULT-VALUE is the default value of the variable. It is a symbol, integer, or M-text.
VALUEs (if any) specifies the possible values of the variable. If DEFAULT-VALUE is an integer, VALUE may be a plist (FROM TO), where FROM and TO specifies a range of possible values.
For instance, suppose an input method has the variables:
•   name:intvar, description:'value is an integer', initial value:0, value-range:0..3,10,20
•   name:symvar, description:'value is a symbol', initial value:nil, value-range:a, b, c, nil
•   name:txtvar, description:'value is an M-text', initial value:empty text, no value-range (i.e. any text)
Then, the returned plist is as follows.
    (intvar ("value is an integer" 0 (0 3) 10 20)
     symvar ("value is a symbol" nil a b c nil)
     txtvar ("value is an M-text" ""))
RETURN VALUE
    If the input method uses any variables, a pointer to MPlist is returned. As the plist is kept in the library, the caller must not modify nor free it. If the input method does not use any variable, NULL is returned.

  int minput_set_variable (MSymbol language, MSymbol name, MSymbol variable, void * value)
Set the initial value of an input method variable.
The minput_set_variable() function sets the initial value of input method variable variable to value for the input method specified by language and name.
By default, the initial value is 0.
This setting gets effective in a newly opened input method.
RETURN VALUE
    If the operation was successful, 0 is returned. Otherwise -1 is returned, and merror_code is set to MERROR_IM.

COPYRIGHT
Copyright (C) 2001 Information-technology Promotion Agency (IPA)
Copyright (C) 2001-2008 National Institute of Advanced Industrial Science and Technology (AIST)
Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License <http://www.gnu.org/licenses/fdl.html>.