### Class

# Gtk IMContext

#### Description [src]

    abstract class Gtk.IMContext : GObject.Object
    {
      /* No available fields */
    }

The interface for GTK input methods.

`GtkIMContext` is used by GTK text input widgets like `GtkText` to map from key events to Unicode character strings.

An input method may consume multiple key events in sequence before finally outputting 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. To do so, the `GtkIMContext` will emit `GtkIMContext::preedit-start`, `GtkIMContext::preedit-changed` and `GtkIMContext::preedit-end` signals.

For instance, the built-in GTK input method `GtkIMContextSimple` 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. For example,

    Ctrl+Shift+u 2 0 A C

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 provides a `GIOExtension` for the extension point named “gtk-im-module”.

To connect a widget to the users preferred input method, you should use `GtkIMMulticontext`.

#### Ancestors

- GObject

#### Descendants

- GtkIMContextSimple
- GtkIMMulticontext

#### Instance methods

###### gtk_im_context_activate_osk

Requests the platform to show an on-screen keyboard for user input.

since: 4.14

###### gtk_im_context_delete_surrounding

Asks the widget that the input context is attached to delete characters around the cursor position by emitting the `::delete_surrounding` signal.

###### gtk_im_context_filter_key

Allow an input method to forward key press and release events to another input method without necessarily having a `GdkEvent` available.

###### gtk_im_context_filter_keypress

Allow an input method to internally handle key press and release events.

###### gtk_im_context_focus_in

Notify the input method that the widget to which this input context corresponds has gained focus.

###### gtk_im_context_focus_out

Notify the input method that the widget to which this input context corresponds has lost focus.

###### gtk_im_context_get_client_widget

Retrieves the client widget for the input context.

unstable since: 4.24

###### gtk_im_context_get_preedit_string

Retrieve the current preedit string for the input context, and a list of attributes to apply to the string.

###### gtk_im_context_get_surrounding

Retrieves context around the insertion point.

deprecated: 4.2

###### gtk_im_context_get_surrounding_with_selection

Retrieves context around the insertion point.

since: 4.2

###### gtk_im_context_reset

Notify the input method that a change such as a change in cursor position has been made.

###### gtk_im_context_set_client_widget

Set the client widget for the input context.

###### gtk_im_context_set_cursor_location

Notify the input method that a change in cursor position has been made.

###### gtk_im_context_set_surrounding

Sets surrounding context around the insertion point and preedit string.

deprecated: 4.2

###### gtk_im_context_set_surrounding_with_selection

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.

since: 4.2

###### gtk_im_context_set_use_preedit

Sets whether the IM context should use the preedit string to display feedback.

##### Methods inherited from GObject (43)

Please see GObject for a full list of methods.

#### Properties

###### Gtk.IMContext:input-hints

Additional hints that allow input methods to fine-tune their behaviour.

###### Gtk.IMContext:input-purpose

The purpose of the text field that the `GtkIMContext is connected to.

#### Signals

###### Gtk.IMContext::commit

The ::commit signal is emitted when a complete input sequence has been entered by the user.

###### Gtk.IMContext::delete-surrounding

The ::delete-surrounding signal is emitted when the input method needs to delete all or part of the context surrounding the cursor.

###### Gtk.IMContext::invalid-composition

Emitted when the filtered keys do not compose to a single valid character.

since: 4.22

###### Gtk.IMContext::preedit-changed

The ::preedit-changed signal is emitted whenever the preedit sequence currently being entered has changed.

###### Gtk.IMContext::preedit-end

The ::preedit-end signal is emitted when a preediting sequence has been completed or canceled.

###### Gtk.IMContext::preedit-start

The ::preedit-start signal is emitted when a new preediting sequence starts.

###### Gtk.IMContext::retrieve-surrounding

The ::retrieve-surrounding signal is emitted when the input method requires the context surrounding the cursor.

##### Signals inherited from GObject (1)

###### GObject::notify

The notify signal is emitted on an object when one of its properties has its value set through g_object_set_property(), g_object_set(), et al.

#### Class structure

    struct GtkIMContextClass {
      void (* preedit_start) (
        GtkIMContext* context
      );
      void (* preedit_end) (
        GtkIMContext* context
      );
      void (* preedit_changed) (
        GtkIMContext* context
      );
      void (* commit) (
        GtkIMContext* context,
        const char* str
      );
      gboolean (* retrieve_surrounding) (
        GtkIMContext* context
      );
      gboolean (* delete_surrounding) (
        GtkIMContext* context,
        int offset,
        int n_chars
      );
      void (* set_client_widget) (
        GtkIMContext* context,
        GtkWidget* widget
      );
      void (* get_preedit_string) (
        GtkIMContext* context,
        char** str,
        PangoAttrList** attrs,
        int* cursor_pos
      );
      gboolean (* filter_keypress) (
        GtkIMContext* context,
        GdkEvent* event
      );
      void (* focus_in) (
        GtkIMContext* context
      );
      void (* focus_out) (
        GtkIMContext* context
      );
      void (* reset) (
        GtkIMContext* context
      );
      void (* set_cursor_location) (
        GtkIMContext* context,
        GdkRectangle* area
      );
      void (* set_use_preedit) (
        GtkIMContext* context,
        gboolean use_preedit
      );
      void (* set_surrounding) (
        GtkIMContext* context,
        const char* text,
        int len,
        int cursor_index
      );
      gboolean (* get_surrounding) (
        GtkIMContext* context,
        char** text,
        int* cursor_index
      );
      void (* set_surrounding_with_selection) (
        GtkIMContext* context,
        const char* text,
        int len,
        int cursor_index,
        int anchor_index
      );
      gboolean (* get_surrounding_with_selection) (
        GtkIMContext* context,
        char** text,
        int* cursor_index,
        int* anchor_index
      );
      void (* activate_osk) (
        GtkIMContext* context
      );
      gboolean (* activate_osk_with_event) (
        GtkIMContext* context,
        GdkEvent* event
      );
      gboolean (* invalid_composition) (
        GtkIMContext* context,
        const char* str
      );
      void (* _gtk_reserved3) (
    void
      );
      void (* _gtk_reserved4) (
    void
      );

    }

No description available.

###### Class members

`preedit_start: void (* preedit_start) ( GtkIMContext* context )`

  Default handler of the `GtkIMContext::preedit-start` signal.

`preedit_end: void (* preedit_end) ( GtkIMContext* context )`

  Default handler of the `GtkIMContext::preedit-end` signal.

`preedit_changed: void (* preedit_changed) ( GtkIMContext* context )`

  Default handler of the `GtkIMContext::preedit-changed` signal.

`commit: void (* commit) ( GtkIMContext* context, const char* str )`

  Default handler of the `GtkIMContext::commit` signal.

`retrieve_surrounding: gboolean (* retrieve_surrounding) ( GtkIMContext* context )`

  Default handler of the `GtkIMContext::retrieve-surrounding` signal.

`delete_surrounding: gboolean (* delete_surrounding) ( GtkIMContext* context, int offset, int n_chars )`

  Default handler of the `GtkIMContext::delete-surrounding` signal.

`set_client_widget: void (* set_client_widget) ( GtkIMContext* context, GtkWidget* widget )`

  Called via `gtk_im_context_set_client_widget()` when the text input widget attached to the IM context changes. Override this to keep track of the current text input widget, for instance for the purpose of positioning a status display of your input method.

`get_preedit_string: void (* get_preedit_string) ( GtkIMContext* context, char** str, PangoAttrList** attrs, int* cursor_pos )`

  Called via `gtk_im_context_get_preedit_string()` to retrieve the text currently being preedited for display at the cursor position. Any input method which composes complex characters or any other compositions from multiple sequential key presses should override this method to provide feedback.

`filter_keypress: gboolean (* filter_keypress) ( GtkIMContext* context, GdkEvent* event )`

  Called via `gtk_im_context_filter_keypress()` on every key press or release event. Every non-trivial input method needs to override this in order to implement the mapping from key events to text. A return value of `TRUE` indicates to the caller that the event was consumed by the input method. In that case, the `GtkIMContext::commit` signal should be emitted upon completion of a key sequence to pass the resulting text back to the input widget. Alternatively, `FALSE` may be returned to indicate that the event wasn’t handled by the input method. If a builtin mapping exists for the key, it is used to produce a character.

`focus_in: void (* focus_in) ( GtkIMContext* context )`

  Called via `gtk_im_context_focus_in()` when the input widget has gained focus. May be overridden to keep track of the current focus.

`focus_out: void (* focus_out) ( GtkIMContext* context )`

  Called via `gtk_im_context_focus_out()` when the input widget has lost focus. May be overridden to keep track of the current focus.

`reset: void (* reset) ( GtkIMContext* context )`

  Called via `gtk_im_context_reset()` to signal a change such as a change in cursor position. An input method that implements preediting should override this method to clear the preedit state on reset.

`set_cursor_location: void (* set_cursor_location) ( GtkIMContext* context, GdkRectangle* area )`

  Called via `gtk_im_context_set_cursor_location()` to inform the input method of the current cursor location relative to the client window. May be overridden to implement the display of popup windows at the cursor position.

`set_use_preedit: void (* set_use_preedit) ( GtkIMContext* context, gboolean use_preedit )`

  Called via `gtk_im_context_set_use_preedit()` to control the use of the preedit string. Override this to display feedback by some other means if turned off.

`set_surrounding: void (* set_surrounding) ( GtkIMContext* context, const char* text, int len, int cursor_index )`

  Called via `gtk_im_context_set_surrounding()` in response to `GtkIMContext::retrieve-surrounding` signal to update the input method’s idea of the context around the cursor. It is not necessary to override this method even with input methods which implement context-dependent behavior. The base implementation is sufficient for `gtk_im_context_get_surrounding()` to work.

`get_surrounding: gboolean (* get_surrounding) ( GtkIMContext* context, char** text, int* cursor_index )`

  Called via `gtk_im_context_get_surrounding()` to update the context around the cursor location. It is not necessary to override this method even with input methods which implement context-dependent behavior. The base implementation emits `GtkIMContext::retrieve-surrounding` and records the context received by the subsequent invocation of `Gtk.IMContextClass.get_surrounding`.

`set_surrounding_with_selection: void (* set_surrounding_with_selection) ( GtkIMContext* context, const char* text, int len, int cursor_index, int anchor_index )`

  Called via `gtk_im_context_set_surrounding_with_selection()` in response to the `GtkIMContext::retrieve-surrounding` signal to update the input method’s idea of the context around the cursor. It is not necessary to override this method even with input methods which implement context-dependent behavior. The base implementation is sufficient for `gtk_im_context_get_surrounding()` to work.

`get_surrounding_with_selection: gboolean (* get_surrounding_with_selection) ( GtkIMContext* context, char** text, int* cursor_index, int* anchor_index )`

  Called via `gtk_im_context_get_surrounding_with_selection()` to update the context around the cursor location. It is not necessary to override this method even with input methods which implement context-dependent behavior. The base implementation emits `GtkIMContext::retrieve-surrounding` and records the context received by the subsequent invocation of `Gtk.IMContextClass.get_surrounding`.

`activate_osk: void (* activate_osk) ( GtkIMContext* context )`

  No description available.

`activate_osk_with_event: gboolean (* activate_osk_with_event) ( GtkIMContext* context, GdkEvent* event )`

  No description available.

`invalid_composition: gboolean (* invalid_composition) ( GtkIMContext* context, const char* str )`

  Default handler of the `GtkIMContext::invalid-composition` signal. Since: 4.22.

`_gtk_reserved3: void (* _gtk_reserved3) ( void )`

  No description available.

`_gtk_reserved4: void (* _gtk_reserved4) ( void )`

  No description available.

#### Virtual methods

###### Gtk.IMContextClass.activate_osk

No description available.

###### Gtk.IMContextClass.activate_osk_with_event

No description available.

###### Gtk.IMContextClass.commit

Default handler of the `GtkIMContext::commit` signal.

###### Gtk.IMContextClass.delete_surrounding

Asks the widget that the input context is attached to delete characters around the cursor position by emitting the `::delete_surrounding` signal.

###### Gtk.IMContextClass.filter_keypress

Allow an input method to internally handle key press and release events.

###### Gtk.IMContextClass.focus_in

Notify the input method that the widget to which this input context corresponds has gained focus.

###### Gtk.IMContextClass.focus_out

Notify the input method that the widget to which this input context corresponds has lost focus.

###### Gtk.IMContextClass.get_preedit_string

Retrieve the current preedit string for the input context, and a list of attributes to apply to the string.

###### Gtk.IMContextClass.get_surrounding

Retrieves context around the insertion point.

deprecated: 4.2

###### Gtk.IMContextClass.get_surrounding_with_selection

Retrieves context around the insertion point.

since: 4.2

###### Gtk.IMContextClass.invalid_composition

Default handler of the `GtkIMContext::invalid-composition` signal. Since: 4.22.

###### Gtk.IMContextClass.preedit_changed

Default handler of the `GtkIMContext::preedit-changed` signal.

###### Gtk.IMContextClass.preedit_end

Default handler of the `GtkIMContext::preedit-end` signal.

###### Gtk.IMContextClass.preedit_start

Default handler of the `GtkIMContext::preedit-start` signal.

###### Gtk.IMContextClass.reset

Notify the input method that a change such as a change in cursor position has been made.

###### Gtk.IMContextClass.retrieve_surrounding

Default handler of the `GtkIMContext::retrieve-surrounding` signal.

###### Gtk.IMContextClass.set_client_widget

Set the client widget for the input context.

###### Gtk.IMContextClass.set_cursor_location

Notify the input method that a change in cursor position has been made.

###### Gtk.IMContextClass.set_surrounding

Sets surrounding context around the insertion point and preedit string.

deprecated: 4.2

###### Gtk.IMContextClass.set_surrounding_with_selection

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.

since: 4.2

###### Gtk.IMContextClass.set_use_preedit

Sets whether the IM context should use the preedit string to display feedback.