Key Values

Key Values — Functions for manipulating keyboard codes

Types and Values

Object Hierarchy

    GObject
    ╰── GdkKeymap

Includes

#include <gdk/gdk.h>

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.

Returns

the GdkKeymap attached to the default display.

[transfer none]


gdk_keymap_get_for_display ()

GdkKeymap *
gdk_keymap_get_for_display (GdkDisplay *display);

Returns the GdkKeymap attached to display .

Parameters

display

the GdkDisplay.

 

Returns

the GdkKeymap attached to display .

[transfer none]

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.

Parameters

keymap

a GdkKeymap

 

key

a GdkKeymapKey with keycode, group, and level initialized

 

Returns

a keyval, or 0 if none was mapped to the given key


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.

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// 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:

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// 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

a GdkKeymap

 

hardware_keycode

a keycode

 

state

a modifier state

 

group

active keyboard group

 

keyval

return location for keyval, or NULL.

[out][allow-none]

effective_group

return location for effective group, or NULL.

[out][allow-none]

level

return location for level, or NULL.

[out][allow-none]

consumed_modifiers

return location for modifiers that were used to determine the group or level, or NULL.

[out][allow-none]

Returns

TRUE if there was a keyval bound to the keycode/state/group


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

a GdkKeymap

 

keyval

a keyval, such as GDK_KEY_a, GDK_KEY_Up, GDK_KEY_Return, etc.

 

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

 

Returns

TRUE if keys were found and returned


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

a GdkKeymap

 

hardware_keycode

a keycode

 

keys

return location for array of GdkKeymapKey, or NULL.

[out][array length=n_entries][transfer full][optional]

keyvals

return location for array of keyvals, or NULL.

[out][array length=n_entries][transfer full][optional]

n_entries

length of keys and keyvals

 

Returns

TRUE if there were any entries


gdk_keymap_get_direction ()

PangoDirection
gdk_keymap_get_direction (GdkKeymap *keymap);

Returns the direction of effective layout of the keymap.

Parameters

keymap

a GdkKeymap

 

Returns

PANGO_DIRECTION_LTR or PANGO_DIRECTION_RTL if it can determine the direction. PANGO_DIRECTION_NEUTRAL otherwise.


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.

Parameters

keymap

a GdkKeymap

 

Returns

TRUE if there are layouts in both directions, FALSE otherwise

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.

Parameters

keymap

a GdkKeymap

 

Returns

TRUE if Caps Lock is on

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.

Parameters

keymap

a GdkKeymap

 

Returns

TRUE if Num Lock is on

Since: 3.0


gdk_keymap_get_scroll_lock_state ()

gboolean
gdk_keymap_get_scroll_lock_state (GdkKeymap *keymap);

Returns whether the Scroll Lock modifer is locked.

Parameters

keymap

a GdkKeymap

 

Returns

TRUE if Scroll Lock is on

Since: 3.18


gdk_keymap_get_modifier_state ()

guint
gdk_keymap_get_modifier_state (GdkKeymap *keymap);

Returns the current modifier state.

Parameters

keymap

a GdkKeymap

 

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.

Parameters

keymap

a GdkKeymap

 

state

pointer to the modifier mask to change.

[inout]

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.

Parameters

keymap

a GdkKeymap

 

state

pointer to the modifier state to map.

[inout]

Returns

FALSE if two 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.

Parameters

keymap

a GdkKeymap

 

intent

the use case for the modifier mask

 

Returns

the modifier mask used for intent .

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_”.

Parameters

keyval

a key value

 

Returns

a string containing the name of the key, or NULL if keyval is not a valid key. The string should not be modified.

[nullable][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_”.

Parameters

keyval_name

a key name

 

Returns

the corresponding key value, or GDK_KEY_VoidSymbol if the key name is not a valid 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.

Parameters

symbol

a keyval

 

lower

return location for lowercase version of symbol .

[out]

upper

return location for uppercase version of symbol .

[out]

gdk_keyval_to_upper ()

guint
gdk_keyval_to_upper (guint keyval);

Converts a key value to upper case, if applicable.

Parameters

keyval

a key value.

 

Returns

the upper case form of keyval , or keyval itself if it is already in upper case or it is not subject to case conversion.


gdk_keyval_to_lower ()

guint
gdk_keyval_to_lower (guint keyval);

Converts a key value to lower case, if applicable.

Parameters

keyval

a key value.

 

Returns

the lower case form of keyval , or keyval itself if it is already in lower case or it is not subject to case conversion.


gdk_keyval_is_upper ()

gboolean
gdk_keyval_is_upper (guint keyval);

Returns TRUE if the given key value is in upper case.

Parameters

keyval

a key value.

 

Returns

TRUE if keyval is in upper case, or if keyval is not subject to case conversion.


gdk_keyval_is_lower ()

gboolean
gdk_keyval_is_lower (guint keyval);

Returns TRUE if the given key value is in lower case.

Parameters

keyval

a key value.

 

Returns

TRUE if keyval is in lower case, or if keyval is not subject to case conversion.


gdk_keyval_to_unicode ()

guint32
gdk_keyval_to_unicode (guint keyval);

Convert from a GDK key symbol to the corresponding ISO10646 (Unicode) character.

Parameters

keyval

a GDK key symbol

 

Returns

the corresponding unicode character, or 0 if there is no corresponding character.


gdk_unicode_to_keyval ()

guint
gdk_unicode_to_keyval (guint32 wc);

Convert from a ISO10646 character to a key symbol.

Parameters

wc

a ISO10646 encoded character

 

Returns

the corresponding GDK key symbol, if one exists. or, if there is no corresponding symbol, wc | 0x01000000

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 keycode;

the hardware keycode. This is an identifying number for a physical key.

 

gint 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.

 

gint 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.

 

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