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Key values are the codes which are sent whenever a key is pressed or released.
They appear in the 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. <gdk/gdkkeysyms.h> is not included in <gdk/gdk.h>,
it must be included independently, because the file is quite large.
Key values are regularly updated from the upstream X.org X11 implementation, so new values are added regularly. They will be prefixed with GDK_ 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().
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.
GdkKeymap *
gdk_keymap_get_default (void);
Returns the GdkKeymap attached to the default display.
GdkKeymap *
gdk_keymap_get_for_display (GdkDisplay *display);
Returns the GdkKeymap attached to display
.
Since: 2.2
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.
Note that passing NULL for keymap
is deprecated and will stop
to work in GTK+ 3.0. Use gdk_keymap_get_for_display() instead.
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 the section called “Description” 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 out
from 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,
Note that passing NULL for keymap
is deprecated and will stop
to work in GTK+ 3.0. Use gdk_keymap_get_for_display() instead.
keymap |
[allow-none] | |
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] |
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().
Note that passing NULL for keymap
is deprecated and will stop
to work in GTK+ 3.0. Use gdk_keymap_get_for_display() instead.
keymap |
[allow-none] | |
keyval |
a keyval, such as |
|
keys |
return location for an array of GdkKeymapKey. |
[out] |
n_keys |
return location for number of elements in returned array. |
[out] |
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().
Note that passing NULL for keymap
is deprecated and will stop
to work in GTK+ 3.0. Use gdk_keymap_get_for_display() instead.
keymap |
[allow-none] | |
hardware_keycode |
a keycode |
|
keys |
return location for array of GdkKeymapKey, or |
[out] |
keyvals |
return location for array of keyvals, or |
[out] |
n_entries |
length of |
PangoDirection
gdk_keymap_get_direction (GdkKeymap *keymap);
Returns the direction of effective layout of the keymap.
Note that passing NULL for keymap
is deprecated and will stop
to work in GTK+ 3.0. Use gdk_keymap_get_for_display() instead.
Returns the direction of the keymap.
PANGO_DIRECTION_LTR or PANGO_DIRECTION_RTL
if it can determine the direction. PANGO_DIRECTION_NEUTRAL
otherwise.
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.
Note that passing NULL for keymap
is deprecated and will stop
to work in GTK+ 3.0. Use gdk_keymap_get_for_display() instead.
Since: 2.12
gboolean
gdk_keymap_get_caps_lock_state (GdkKeymap *keymap);
Returns whether the Caps Lock modifer is locked.
Since: 2.16
void gdk_keymap_add_virtual_modifiers (GdkKeymap *keymap,GdkModifierType *state);
Adds virtual modifiers (i.e. Super, Hyper and Meta) which correspond
to the real modifiers (i.e Mod2, Mod3, ...) in modifiers
.
are set in state
to their non-virtual counterparts (i.e. Mod2,
Mod3,...) 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
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.
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
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_".
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_".
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]
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_".
Converts a key name to a key value.
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_a, GDK_Enter, GDK_F1, etc.
guint
gdk_keyval_to_upper (guint keyval);
Converts a key value to upper case, if applicable.
guint
gdk_keyval_to_lower (guint keyval);
Converts a key value to lower case, if applicable.
gboolean
gdk_keyval_is_upper (guint keyval);
Returns TRUE if the given key value is in upper case.
gboolean
gdk_keyval_is_lower (guint keyval);
Returns TRUE if the given key value is in lower case.
guint32
gdk_keyval_to_unicode (guint keyval);
Convert from a GDK key symbol to the corresponding ISO10646 (Unicode) character.
struct 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 {
guint keycode;
gint group;
gint level;
};
A GdkKeymapKey is a hardware key that can be mapped to a keyval.
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. |
“direction-changed” signalvoid user_function (GdkKeymap *keymap, gpointer user_data)
The ::direction-changed signal gets emitted when the direction of the keymap changes.
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
“keys-changed” signalvoid user_function (GdkKeymap *keymap, gpointer user_data)
The ::keys-changed signal is emitted when the mapping represented by
keymap
changes.
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
“state-changed” signalvoid 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().
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