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

The user may change the current input method via a context menu, unless the "gtk-show-input-method-menu" GtkSettings property is set to FALSE. The default input method can be set programmatically via the "gtk-im-module" GtkSettings property. Alternatively, you may set the GTK_IM_MODULE environment variable as documented in gtk-running.

The Gtk.Gtk.Entry.T "im-module" and Gtk.Gtk.TextView.T "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 T or Gtk.Gtk.IMContextSimple.T and exports these four functions:

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void im_module_init(<GTKDOCLINK HREF="GTypeModule">GTypeModule</GTKDOCLINK> *module);

This function should register the GType of the T 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.

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void im_module_exit(void);

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

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void im_module_list(const <a class="link" href="GtkIMContext.html#GtkIMContextInfo" title="struct GtkIMContextInfo">GtkIMContextInfo</a> ***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 Gtk.Gtk.IMContextInfo.T items for each provided input method.

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<a class="link" href="GtkIMContext.html" title="GtkIMContext">GtkIMContext</a> * im_module_create(const <GTKDOCLINK HREF="gchar">gchar</GTKDOCLINK> *context_id);

This function should return a pointer to a newly created instance of the T subclass identified by context_id. The context ID is the same as specified in the Gtk.Gtk.IMContextInfo.T 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-2.0, in order for the new input method to become available to GTK+ applications.

Asks the widget that the input context is attached to to delete characters around the cursor position by emitting the GtkIMContext::delete_surrounding signal. Note that offset and n_chars are in characters not in bytes which differs from the usage other places in T.

In order to use this function, you should first call GetSurrounding to get the current context, and call this function immediately afterwards to make sure that you know what you are deleting. You should also account for the fact that even if the signal was handled, the input context might not have deleted all the characters that were requested to be deleted.

This function is used by an input method that wants to make subsitutions in the existing text in response to new input. It is not useful for applications.

Allow an input method to internally handle key press and release events. If this function returns TRUE, then no further processing should be done for this key event.

Notify the input method that the widget to which this input context corresponds has gained focus. The input method may, for example, change the displayed feedback to reflect this change.

Notify the input method that the widget to which this input context corresponds has lost focus. The input method may, for example, change the displayed feedback or reset the contexts state to reflect this change.

Retrieve the current preedit string for the input context, and a list of attributes to apply to the string. This string should be displayed inserted at the insertion point.

Retrieves context around the insertion point. Input methods typically want context in order to constrain input text based on existing text; this is important for languages such as Thai where only some sequences of characters are allowed.

This function is implemented by emitting the GtkIMContext::retrieve_surrounding signal on the input method; in response to this signal, a widget should provide as much context as is available, up to an entire paragraph, by calling SetSurrounding. Note that there is no obligation for a widget to respond to the ::retrieve_surrounding signal, so input methods must be prepared to function without context.

Notify the input method that a change such as a change in cursor position has been made. This will typically cause the input method to clear the preedit state.

Set the client window for the input context; this is the Gtk.Gdk.Window.T in which the input appears. This window is used in order to correctly position status windows, and may also be used for purposes internal to the input method.

Notify the input method that a change in cursor position has been made. The location is relative to the client window.

Sets surrounding context around the insertion point and preedit string. This function is expected to be called in response to the GtkIMContext::retrieve_surrounding signal, and will likely have no effect if called at other times.

Sets whether the IM context should use the preedit string to display feedback. If use_preedit is FALSE (default is TRUE), then the IM context may use some other method to display feedback, such as displaying it in a child of the root window.