IMContext
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
andn_chars
are in characters not in bytes which differs from the usage other places inGtkIMContext
.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 callingset_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.
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 callingset_surrounding_with_selection
.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 iftext
is nul-terminatedcursor_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 iftext
is nul-terminatedcursor_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
isFalse
(default isTrue
), 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.
- 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_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
andn_chars
are in characters not in bytes which differs from the usage other places inGtkIMContext
.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.
- 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.
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 callingset_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.
- 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.
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 callingset_surrounding_with_selection
.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 iftext
is nul-terminatedcursor_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
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 iftext
is nul-terminatedcursor_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
isFalse
(default isTrue
), 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