IMContext

open class IMContext : GLibObject.Object, IMContextProtocol

GtkIMContext defines the interface for GTK+ input methods. An input method is used by GTK+ text input widgets like GtkEntry to map from key events to Unicode character strings.

The default input method can be set programmatically via the GtkSettings:gtk-im-module GtkSettings property. Alternatively, you may set the GTK_IM_MODULE environment variable as documented in Running GTK+ Applications.

The GtkEntry GtkEntry:im-module and GtkTextView GtkTextView:im-module properties may also be used to set input methods for specific widget instances. For instance, a certain entry widget might be expected to contain certain characters which would be easier to input with a certain input method.

An input method may consume multiple key events in sequence and finally output the composed result. This is called preediting, and an input method may provide feedback about this process by displaying the intermediate composition states as preedit text. For instance, the default GTK+ input method implements the input of arbitrary Unicode code points by holding down the Control and Shift keys and then typing “U” followed by the hexadecimal digits of the code point. When releasing the Control and Shift keys, preediting ends and the character is inserted as text. Ctrl+Shift+u20AC for example results in the € sign.

Additional input methods can be made available for use by GTK+ widgets as loadable modules. An input method module is a small shared library which implements a subclass of GtkIMContext or GtkIMContextSimple and exports these four functions:

(C Language Example):

void im_module_init(GTypeModule *module);

This function should register the GType of the GtkIMContext subclass which implements the input method by means of g_type_module_register_type(). Note that g_type_register_static() cannot be used as the type needs to be registered dynamically.

(C Language Example):

void im_module_exit(void);

Here goes any cleanup code your input method might require on module unload.

(C Language Example):

void im_module_list(const GtkIMContextInfo ***contexts, int *n_contexts)
{
  *contexts = info_list;
  *n_contexts = G_N_ELEMENTS (info_list);
}

This function returns the list of input methods provided by the module. The example implementation above shows a common solution and simply returns a pointer to statically defined array of GtkIMContextInfo items for each provided input method.

(C Language Example):

GtkIMContext * im_module_create(const gchar *context_id);

This function should return a pointer to a newly created instance of the GtkIMContext subclass identified by context_id. The context ID is the same as specified in the GtkIMContextInfo array returned by im_module_list().

After a new loadable input method module has been installed on the system, the configuration file gtk.immodules needs to be regenerated by gtk-query-immodules-3.0, in order for the new input method to become available to GTK+ applications.

The IMContext type acts as a reference-counted owner of an underlying GtkIMContext instance. It provides the methods that can operate on this data type through IMContextProtocol conformance. Use IMContext as a strong reference or owner of a GtkIMContext instance.