Key Values

## Key Values Key Values — Functions for manipulating keyboard codes |

## Synopsis

    #include <gdk/gdk.h>

                        GdkKeymap;
    struct              GdkKeymapKey;
    GdkKeymap *         gdk_keymap_get_default              (void);
    GdkKeymap *         gdk_keymap_get_for_display          (GdkDisplay *display);
    guint               gdk_keymap_lookup_key               (GdkKeymap *keymap,
                                                             const GdkKeymapKey *key);
    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);
    gboolean            gdk_keymap_get_entries_for_keyval   (GdkKeymap *keymap,
                                                             guint keyval,
                                                             GdkKeymapKey **keys,
                                                             gint *n_keys);
    gboolean            gdk_keymap_get_entries_for_keycode  (GdkKeymap *keymap,
                                                             guint hardware_keycode,
                                                             GdkKeymapKey **keys,
                                                             guint **keyvals,
                                                             gint *n_entries);
    PangoDirection      gdk_keymap_get_direction            (GdkKeymap *keymap);
    gboolean            gdk_keymap_have_bidi_layouts        (GdkKeymap *keymap);
    gboolean            gdk_keymap_get_caps_lock_state      (GdkKeymap *keymap);
    gboolean            gdk_keymap_get_num_lock_state       (GdkKeymap *keymap);
    guint               gdk_keymap_get_modifier_state       (GdkKeymap *keymap);
    void                gdk_keymap_add_virtual_modifiers    (GdkKeymap *keymap,
                                                             GdkModifierType *state);
    gboolean            gdk_keymap_map_virtual_modifiers    (GdkKeymap *keymap,
                                                             GdkModifierType *state);
    GdkModifierType     gdk_keymap_get_modifier_mask        (GdkKeymap *keymap,
                                                             GdkModifierIntent intent);

    gchar *             gdk_keyval_name                     (guint keyval);
    guint               gdk_keyval_from_name                (const gchar *keyval_name);

    void                gdk_keyval_convert_case             (guint symbol,
                                                             guint *lower,
                                                             guint *upper);
    guint               gdk_keyval_to_upper                 (guint keyval);
    guint               gdk_keyval_to_lower                 (guint keyval);
    gboolean            gdk_keyval_is_upper                 (guint keyval);
    gboolean            gdk_keyval_is_lower                 (guint keyval);

    guint32             gdk_keyval_to_unicode               (guint keyval);
    guint               gdk_unicode_to_keyval               (guint32 wc);

## Object Hierarchy

      GObject
       +----GdkKeymap

## Signals

      "direction-changed"                              : Run Last
      "keys-changed"                                   : Run Last
      "state-changed"                                  : Run Last

## 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()`.

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.

## Details

### 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.

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.

### 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`.

`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.

`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 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.

### Note

`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.

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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`,

`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()`.

`keymap` : | a GdkKeymap
`keyval` : | a keyval, such as `GDK_a`, `GDK_Up`, `GDK_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()`.

`keymap` : | a GdkKeymap
`hardware_keycode` : | a keycode
`keys` : | return location for array of GdkKeymapKey, or `NULL`. [out][array length=n_entries][transfer full]
`keyvals` : | return location for array of keyvals, or `NULL`. [out][array length=n_entries][transfer full]
`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.

`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.

`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.

`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.

`keymap` : | a GdkKeymap
Returns : | `TRUE` if Num Lock is on

Since 3.0

### gdk_keymap_get_modifier_state ()

    guint               gdk_keymap_get_modifier_state       (GdkKeymap *keymap);

Returns the current modifier state.

`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.

`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.

`keymap` : | a GdkKeymap
`state` : | pointer to the modifier state to map. [inout]
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.

`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_".

`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. [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_".

`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.

`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.

`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.

`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.

`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.

`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.

`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.

`wc` : | a ISO10646 encoded character
Returns : | the corresponding GDK key symbol, if one exists. or, if there is no corresponding symbol, wc | 0x01000000

## Signal Details

### The `"direction-changed"` signal

    void                user_function                      (GdkKeymap *keymap,
                                                            gpointer   user_data)      : Run Last

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.

Since 2.0

### The `"keys-changed"` signal

    void                user_function                      (GdkKeymap *keymap,
                                                            gpointer   user_data)      : Run Last

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.

Since 2.2

### The `"state-changed"` signal

    void                user_function                      (GdkKeymap *keymap,
                                                            gpointer   user_data)      : Run Last

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.

Since 2.16