IMContext

class IMContext(**properties: Any)

Superclasses: Object

Subclasses: IMContextSimple, IMMulticontext

GtkIMContext defines 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 preedit_start, preedit_changed and preedit_end signals.

For instance, the built-in GTK input method IMContextSimple 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 IMMulticontext.

Methods

class IMContext

activate_osk(event: Event | None = None) → bool

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

This method will return True if this request was actually performed to the platform, other environmental factors may result in an on-screen keyboard effectively not showing up.

Added in version 4.14.

Parameters:: event – a Event

delete_surrounding(offset: int, n_chars: int) → bool

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

Note that offset and n_chars are in characters not in bytes which differs from the usage other places in GtkIMContext.

In order to use this function, you should first call get_surrounding 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 substitutions in the existing text in response to new input. It is not useful for applications.

Parameters:

offset – offset from cursor position in chars; a negative value means start before the cursor.
n_chars – number of characters to delete.

filter_key(press: bool, surface: Surface, device: Device, time: int, keycode: int, state: ModifierType, group: int) → bool

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

Parameters:

press – whether to forward a key press or release event
surface – the surface the event is for
device – the device that the event is for
time – the timestamp for the event
keycode – the keycode for the event
state – modifier state for the event
group – the active keyboard group for the event

filter_keypress(event: Event) → bool

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.

Parameters:: event – the key event

focus_in() → None

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.

focus_out() → None

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.

get_preedit_string() → tuple[str, AttrList, int]

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.

get_surrounding() → tuple[bool, str, int]

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 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 set_surrounding.

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.

Deprecated since version 4.2: Use get_surrounding_with_selection instead.

get_surrounding_with_selection() → tuple[bool, str, int, int]

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.

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.

Added in version 4.2.

reset() → None

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_client_widget(widget: Widget | None = None) → None

Set the client widget for the input context.

This is the GtkWidget holding the input focus. This widget is used in order to correctly position status windows, and may also be used for purposes internal to the input method.

Parameters:: widget – the client widget. This may be None to indicate that the previous client widget no longer exists.

set_cursor_location(area: Rectangle) → None

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

The location is relative to the client widget.

Parameters:: area – new location

set_surrounding(text: str, len: int, cursor_index: int) → None

Sets surrounding context around the insertion point and preedit string.

This function is expected to be called in response to the retrieve_surrounding signal, and will likely have no effect if called at other times.

Deprecated since version 4.2: Use set_surrounding_with_selection instead

Parameters:

text – text surrounding the insertion point, as UTF-8. the preedit string should not be included within text
len – the length of text, or -1 if text is nul-terminated
cursor_index – the byte index of the insertion cursor within text.

set_surrounding_with_selection(text: str, len: int, cursor_index: int, anchor_index: int) → None

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

Added in version 4.2.

Parameters:

text – text surrounding the insertion point, as UTF-8. the preedit string should not be included within text
len – the length of text, or -1 if text is nul-terminated
cursor_index – the byte index of the insertion cursor within text
anchor_index – the byte index of the selection bound within text

set_use_preedit(use_preedit: bool) → None

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.

Parameters:: use_preedit – whether the IM context should use the preedit string.

Properties

class IMContext

props.input_hints: InputHints: Additional hints that allow input methods to fine-tune their behaviour.

props.input_purpose: InputPurpose

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

This property can be used by on-screen keyboards and other input methods to adjust their behaviour.

Signals

class IMContext.signals

commit(str: str) → None

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

If the commit comes after a preediting sequence, the ::commit signal is emitted after ::preedit-end.

This can be a single character immediately after a key press or the final result of preediting.

Parameters:: str – the completed character(s) entered by the user

delete_surrounding(offset: int, n_chars: int) → bool

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

Parameters:

offset – the character offset from the cursor position of the text to be deleted. A negative value indicates a position before the cursor.
n_chars – the number of characters to be deleted

preedit_changed() → None

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

It is also emitted at the end of a preedit sequence, in which case get_preedit_string returns the empty string.

preedit_end() → None: The ::preedit-end signal is emitted when a preediting sequence has been completed or canceled.

preedit_start() → None: The ::preedit-start signal is emitted when a new preediting sequence starts.

retrieve_surrounding() → bool

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

The callback should set the input method surrounding context by calling the set_surrounding method.

Virtual Methods

class IMContext

do_activate_osk() → None

do_activate_osk_with_event(event: Event) → bool

Parameters:: event

do_commit(str: str) → None

Default handler of the commit signal.

Parameters:: str

do_delete_surrounding(offset: int, n_chars: int) → bool

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

Note that offset and n_chars are in characters not in bytes which differs from the usage other places in GtkIMContext.

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

Parameters:

offset – offset from cursor position in chars; a negative value means start before the cursor.
n_chars – number of characters to delete.

do_filter_keypress(event: Event) → bool

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.

Parameters:: event – the key event

do_focus_in() → None

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.

do_focus_out() → None

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.

do_get_preedit_string() → tuple[str, AttrList, int]

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.

do_get_surrounding() → tuple[bool, str, int]

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.

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.

Deprecated since version 4.2: Use get_surrounding_with_selection instead.

do_get_surrounding_with_selection() → tuple[bool, str, int, int]

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.

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.

Added in version 4.2.

do_preedit_changed() → None: Default handler of the preedit_changed signal.

do_preedit_end() → None: Default handler of the preedit_end signal.

do_preedit_start() → None: Default handler of the preedit_start signal.

do_reset() → None

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.

do_retrieve_surrounding() → bool: Default handler of the retrieve_surrounding signal.

do_set_client_widget(widget: Widget | None = None) → None

Set the client widget for the input context.

This is the GtkWidget holding the input focus. This widget is used in order to correctly position status windows, and may also be used for purposes internal to the input method.

Parameters:: widget – the client widget. This may be None to indicate that the previous client widget no longer exists.

do_set_cursor_location(area: Rectangle) → None

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

The location is relative to the client widget.

Parameters:: area – new location

do_set_surrounding(text: str, len: int, cursor_index: int) → None

Sets surrounding context around the insertion point and preedit string.

This function is expected to be called in response to the retrieve_surrounding signal, and will likely have no effect if called at other times.

Deprecated since version 4.2: Use set_surrounding_with_selection instead

Parameters:

text – text surrounding the insertion point, as UTF-8. the preedit string should not be included within text
len – the length of text, or -1 if text is nul-terminated
cursor_index – the byte index of the insertion cursor within text.

do_set_surrounding_with_selection(text: str, len: int, cursor_index: int, anchor_index: int) → None

Added in version 4.2.

Parameters:

text – text surrounding the insertion point, as UTF-8. the preedit string should not be included within text
len – the length of text, or -1 if text is nul-terminated
cursor_index – the byte index of the insertion cursor within text
anchor_index – the byte index of the selection bound within text

do_set_use_preedit(use_preedit: bool) → None

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.

Parameters:: use_preedit – whether the IM context should use the preedit string.

Fields

class IMContext

parent_instance