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Functions
Description
Key values are the codes which are sent whenever a key is pressed or released.
They appear in the GdkEventKey.keyval field of the
GdkEventKey structure, which is passed to signal handlers for the
“key-press-event” and “key-release-event” signals.
The complete list of key values can be found in the
gdk/gdkkeysyms.h
header file.
Key values are regularly updated from the upstream X.org X11 implementation, so new values are added regularly. They will be prefixed with GDK_KEY_ rather than XF86XK_ or XK_ (for older symbols).
Key values can be converted into a string representation using
gdk_keyval_name()
. The reverse function, converting a string to a key value,
is provided by gdk_keyval_from_name()
.
The case of key values can be determined using gdk_keyval_is_upper()
and
gdk_keyval_is_lower()
. Key values can be converted to upper or lower case
using gdk_keyval_to_upper()
and gdk_keyval_to_lower()
.
When it makes sense, key values can be converted to and from
Unicode characters with gdk_keyval_to_unicode()
and gdk_unicode_to_keyval()
.
Groups
One GdkKeymap object exists for each user display. gdk_keymap_get_default()
returns the GdkKeymap for the default display; to obtain keymaps for other
displays, use gdk_keymap_get_for_display()
. A keymap
is a mapping from GdkKeymapKey to key values. You can think of a GdkKeymapKey
as a representation of a symbol printed on a physical keyboard key. That is, it
contains three pieces of information. First, it contains the hardware keycode;
this is an identifying number for a physical key. Second, it contains the
“level” of the key. The level indicates which symbol on the
key will be used, in a vertical direction. So on a standard US keyboard, the key
with the number “1“ on it also has the exclamation point (”!”) character on
it. The level indicates whether to use the “1” or the “!” symbol. The letter
keys are considered to have a lowercase letter at level 0, and an uppercase
letter at level 1, though only the uppercase letter is printed. Third, the
GdkKeymapKey contains a group; groups are not used on standard US keyboards,
but are used in many other countries. On a keyboard with groups, there can be 3
or 4 symbols printed on a single key. The group indicates movement in a
horizontal direction. Usually groups are used for two different languages. In
group 0, a key might have two English characters, and in group 1 it might have
two Hebrew characters. The Hebrew characters will be printed on the key next to
the English characters.
In order to use a keymap to interpret a key event, it’s necessary to first
convert the keyboard state into an effective group and level. This is done via a
set of rules that varies widely according to type of keyboard and user
configuration. The function gdk_keymap_translate_keyboard_state()
accepts a
keyboard state -- consisting of hardware keycode pressed, active modifiers, and
active group -- applies the appropriate rules, and returns the group/level to be
used to index the keymap, along with the modifiers which did not affect the
group and level. i.e. it returns “unconsumed modifiers.” The keyboard group may
differ from the effective group used for keymap lookups because some keys don't
have multiple groups - e.g. the Enter key is always in group 0 regardless of
keyboard state.
Note that gdk_keymap_translate_keyboard_state()
also returns the keyval, i.e. it
goes ahead and performs the keymap lookup in addition to telling you which
effective group/level values were used for the lookup. GdkEventKey already
contains this keyval, however, so you don’t normally need to call
gdk_keymap_translate_keyboard_state()
just to get the keyval.
Functions
gdk_keymap_get_default ()
GdkKeymap *
gdk_keymap_get_default (void
);
Returns the GdkKeymap attached to the default display.
gdk_keymap_get_for_display ()
GdkKeymap *
gdk_keymap_get_for_display (GdkDisplay *display
);
Returns the GdkKeymap attached to display
.
Since 2.2
gdk_keymap_lookup_key ()
guint gdk_keymap_lookup_key (GdkKeymap *keymap
,const GdkKeymapKey *key
);
Looks up the keyval mapped to a keycode/group/level triplet.
If no keyval is bound to key
, returns 0. For normal user input,
you want to use gdk_keymap_translate_keyboard_state()
instead of
this function, since the effective group/level may not be
the same as the current keyboard state.
gdk_keymap_translate_keyboard_state ()
gboolean gdk_keymap_translate_keyboard_state (GdkKeymap *keymap
,guint hardware_keycode
,GdkModifierType state
,gint group
,guint *keyval
,gint *effective_group
,gint *level
,GdkModifierType *consumed_modifiers
);
Translates the contents of a GdkEventKey into a keyval, effective
group, and level. Modifiers that affected the translation and
are thus unavailable for application use are returned in
consumed_modifiers
.
See Groups for an explanation of
groups and levels. The effective_group
is the group that was
actually used for the translation; some keys such as Enter are not
affected by the active keyboard group. The level
is derived from
state
. For convenience, GdkEventKey already contains the translated
keyval, so this function isn’t as useful as you might think.
consumed_modifiers
gives modifiers that should be masked outfrom state
when comparing this key press to a hot key. For instance, on a US keyboard,
the plus
symbol is shifted, so when comparing a key press to a
<Control>plus
accelerator <Shift>
should be masked out.
1 2 3 4 5 6 7 8 |
// We want to ignore irrelevant modifiers like ScrollLock #define ALL_ACCELS_MASK (GDK_CONTROL_MASK | GDK_SHIFT_MASK | GDK_MOD1_MASK) gdk_keymap_translate_keyboard_state (keymap, event->hardware_keycode, event->state, event->group, &keyval, NULL, NULL, &consumed); if (keyval == GDK_PLUS && (event->state & ~consumed & ALL_ACCELS_MASK) == GDK_CONTROL_MASK) // Control was pressed |
An older interpretation consumed_modifiers
was that it contained
all modifiers that might affect the translation of the key;
this allowed accelerators to be stored with irrelevant consumed
modifiers, by doing:
1 2 3 4 |
// XXX Don’t do this XXX if (keyval == accel_keyval && (event->state & ~consumed & ALL_ACCELS_MASK) == (accel_mods & ~consumed)) // Accelerator was pressed |
However, this did not work if multi-modifier combinations were
used in the keymap, since, for instance, <Control>
would be
masked out even if only <Control><Alt>
was used in the keymap.
To support this usage as well as well as possible, all single
modifier combinations that could affect the key for any combination
of modifiers will be returned in consumed_modifiers
; multi-modifier
combinations are returned only when actually found in state
. When
you store accelerators, you should always store them with consumed
modifiers removed. Store <Control>plus
, not <Control><Shift>plus
,
Parameters
keymap |
||
hardware_keycode |
a keycode |
|
state |
a modifier state |
|
group |
active keyboard group |
|
keyval |
return location for keyval, or |
[out][allow-none] |
effective_group |
return location for effective
group, or |
[out][allow-none] |
level |
return location for level, or |
[out][allow-none] |
consumed_modifiers |
return location for modifiers
that were used to determine the group or level, or |
[out][allow-none] |
gdk_keymap_get_entries_for_keyval ()
gboolean gdk_keymap_get_entries_for_keyval (GdkKeymap *keymap
,guint keyval
,GdkKeymapKey **keys
,gint *n_keys
);
Obtains a list of keycode/group/level combinations that will
generate keyval
. Groups and levels are two kinds of keyboard mode;
in general, the level determines whether the top or bottom symbol
on a key is used, and the group determines whether the left or
right symbol is used. On US keyboards, the shift key changes the
keyboard level, and there are no groups. A group switch key might
convert a keyboard between Hebrew to English modes, for example.
GdkEventKey contains a group
field that indicates the active
keyboard group. The level is computed from the modifier mask.
The returned array should be freed
with g_free()
.
Parameters
keymap |
||
keyval |
a keyval, such as |
|
keys |
return location for an array of GdkKeymapKey. |
[out][array length=n_keys][transfer full] |
n_keys |
return location for number of elements in returned array |
gdk_keymap_get_entries_for_keycode ()
gboolean gdk_keymap_get_entries_for_keycode (GdkKeymap *keymap
,guint hardware_keycode
,GdkKeymapKey **keys
,guint **keyvals
,gint *n_entries
);
Returns the keyvals bound to hardware_keycode
.
The Nth GdkKeymapKey in keys
is bound to the Nth
keyval in keyvals
. Free the returned arrays with g_free()
.
When a keycode is pressed by the user, the keyval from
this list of entries is selected by considering the effective
keyboard group and level. See gdk_keymap_translate_keyboard_state()
.
Parameters
keymap |
||
hardware_keycode |
a keycode |
|
keys |
return
location for array of GdkKeymapKey, or |
[out][array length=n_entries][transfer full] |
keyvals |
return
location for array of keyvals, or |
[out][array length=n_entries][transfer full] |
n_entries |
length of |
gdk_keymap_get_direction ()
PangoDirection
gdk_keymap_get_direction (GdkKeymap *keymap
);
Returns the direction of effective layout of the keymap.
gdk_keymap_have_bidi_layouts ()
gboolean
gdk_keymap_have_bidi_layouts (GdkKeymap *keymap
);
Determines if keyboard layouts for both right-to-left and left-to-right languages are in use.
Since 2.12
gdk_keymap_get_caps_lock_state ()
gboolean
gdk_keymap_get_caps_lock_state (GdkKeymap *keymap
);
Returns whether the Caps Lock modifer is locked.
Since 2.16
gdk_keymap_get_num_lock_state ()
gboolean
gdk_keymap_get_num_lock_state (GdkKeymap *keymap
);
Returns whether the Num Lock modifer is locked.
Since 3.0
gdk_keymap_get_modifier_state ()
guint
gdk_keymap_get_modifier_state (GdkKeymap *keymap
);
Returns the current modifier state.
Since 3.4
gdk_keymap_add_virtual_modifiers ()
void gdk_keymap_add_virtual_modifiers (GdkKeymap *keymap
,GdkModifierType *state
);
Maps the non-virtual modifiers (i.e Mod2, Mod3, ...) which are set
in state
to the virtual modifiers (i.e. Super, Hyper and Meta) and
set the corresponding bits in state
.
GDK already does this before delivering key events, but for compatibility reasons, it only sets the first virtual modifier it finds, whereas this function sets all matching virtual modifiers.
This function is useful when matching key events against accelerators.
Since 2.20
gdk_keymap_map_virtual_modifiers ()
gboolean gdk_keymap_map_virtual_modifiers (GdkKeymap *keymap
,GdkModifierType *state
);
Maps the virtual modifiers (i.e. Super, Hyper and Meta) which
are set in state
to their non-virtual counterparts (i.e. Mod2,
Mod3,...) and set the corresponding bits in state
.
This function is useful when matching key events against accelerators.
Returns
TRUE
if no virtual modifiers were mapped to the
same non-virtual modifier. Note that FALSE
is also returned
if a virtual modifier is mapped to a non-virtual modifier that
was already set in state
.
Since 2.20
gdk_keymap_get_modifier_mask ()
GdkModifierType gdk_keymap_get_modifier_mask (GdkKeymap *keymap
,GdkModifierIntent intent
);
Returns the modifier mask the keymap
’s windowing system backend
uses for a particular purpose.
Note that this function always returns real hardware modifiers, not
virtual ones (e.g. it will return GDK_MOD1_MASK rather than
GDK_META_MASK if the backend maps MOD1 to META), so there are use
cases where the return value of this function has to be transformed
by gdk_keymap_add_virtual_modifiers()
in order to contain the
expected result.
Since 3.4
gdk_keyval_name ()
gchar *
gdk_keyval_name (guint keyval
);
Converts a key value into a symbolic name.
The names are the same as those in the
gdk/gdkkeysyms.h
header file
but without the leading “GDK_KEY_”.
Returns
a string containing the name of the key,
or NULL
if keyval
is not a valid key. The string should not be
modified.
[transfer none]
gdk_keyval_from_name ()
guint
gdk_keyval_from_name (const gchar *keyval_name
);
Converts a key name to a key value.
The names are the same as those in the
gdk/gdkkeysyms.h
header file
but without the leading “GDK_KEY_”.
gdk_keyval_convert_case ()
void gdk_keyval_convert_case (guint symbol
,guint *lower
,guint *upper
);
Obtains the upper- and lower-case versions of the keyval symbol
.
Examples of keyvals are GDK_KEY_a, GDK_KEY_Enter, GDK_KEY_F1, etc.
gdk_keyval_to_upper ()
guint
gdk_keyval_to_upper (guint keyval
);
Converts a key value to upper case, if applicable.
gdk_keyval_to_lower ()
guint
gdk_keyval_to_lower (guint keyval
);
Converts a key value to lower case, if applicable.
gdk_keyval_is_upper ()
gboolean
gdk_keyval_is_upper (guint keyval
);
Returns TRUE
if the given key value is in upper case.
gdk_keyval_is_lower ()
gboolean
gdk_keyval_is_lower (guint keyval
);
Returns TRUE
if the given key value is in lower case.
gdk_keyval_to_unicode ()
guint32
gdk_keyval_to_unicode (guint keyval
);
Convert from a GDK key symbol to the corresponding ISO10646 (Unicode) character.
Types and Values
GdkKeymap
typedef struct _GdkKeymap GdkKeymap;
A GdkKeymap defines the translation from keyboard state (including a hardware key, a modifier mask, and active keyboard group) to a keyval. This translation has two phases. The first phase is to determine the effective keyboard group and level for the keyboard state; the second phase is to look up the keycode/group/level triplet in the keymap and see what keyval it corresponds to.
struct GdkKeymapKey
struct GdkKeymapKey { guint keycode; gint group; gint level; };
A GdkKeymapKey is a hardware key that can be mapped to a keyval.
Members
guint |
the hardware keycode. This is an identifying number for a physical key. |
|
gint |
indicates movement in a horizontal direction. Usually groups are used for two different languages. In group 0, a key might have two English characters, and in group 1 it might have two Hebrew characters. The Hebrew characters will be printed on the key next to the English characters. |
|
gint |
indicates which symbol on the key will be used, in a vertical direction. So on a standard US keyboard, the key with the number “1” on it also has the exclamation point ("!") character on it. The level indicates whether to use the “1” or the “!” symbol. The letter keys are considered to have a lowercase letter at level 0, and an uppercase letter at level 1, though only the uppercase letter is printed. |
Signal Details
The “direction-changed”
signal
void user_function (GdkKeymap *keymap, gpointer user_data)
The ::direction-changed signal gets emitted when the direction of the keymap changes.
Parameters
keymap |
the object on which the signal is emitted |
|
user_data |
user data set when the signal handler was connected. |
Flags: Run Last
Since 2.0
The “keys-changed”
signal
void user_function (GdkKeymap *keymap, gpointer user_data)
The ::keys-changed signal is emitted when the mapping represented by
keymap
changes.
Parameters
keymap |
the object on which the signal is emitted |
|
user_data |
user data set when the signal handler was connected. |
Flags: Run Last
Since 2.2
The “state-changed”
signal
void user_function (GdkKeymap *keymap, gpointer user_data)
The ::state-changed signal is emitted when the state of the
keyboard changes, e.g when Caps Lock is turned on or off.
See gdk_keymap_get_caps_lock_state()
.
Parameters
keymap |
the object on which the signal is emitted |
|
user_data |
user data set when the signal handler was connected. |
Flags: Run Last
Since 2.16