gtk-0.12.2: Binding to the Gtk+ graphical user interface library.

Portability | portable (depends on GHC)
Stability | provisional
Maintainer | gtk2hs-users@lists.sourceforge.net

Graphics.UI.Gtk.Gdk.Keymap

Contents

- Details
- Class Hierarchy
- Types
- Methods
- Signals

Description

Functions for manipulating keyboard codes

Synopsis

- data Keymap
- class GObjectClass o => KeymapClass o
- castToKeymap :: GObjectClass obj => obj -> Keymap
- toKeymap :: KeymapClass o => o -> Keymap
- data KeymapKey
- keymapGetDefault :: IO Keymap
- keymapGetForDisplay :: Display -> IO Keymap
- keymapLookupKey :: KeymapClass self => Maybe self -> KeymapKey -> IO Int
- keymapTranslateKeyboardState :: KeymapClass self => self -> Int -> Modifier -> Int -> IO (Maybe (Int, Int, Int, Modifier))
- keymapGetEntriesForKeyval :: KeymapClass self => self -> KeyVal -> IO (Maybe [KeymapKey])
- keymapGetEntriesForKeycode :: KeymapClass self => self -> Int -> IO (Maybe ([KeymapKey], [KeyVal]))
- keymapGetDirection :: KeymapClass self => self -> IO PangoDirection
- keymapHaveBidiLayouts :: KeymapClass self => self -> IO Bool
- keymapGetCapsLockState :: KeymapClass self => self -> IO Bool
- keymapDirectionChanged :: KeymapClass self => Signal self (IO ())
- keymapKeysChanged :: KeymapClass self => Signal self (IO ())
- keymapStateChanged :: KeymapClass self => Signal self (IO ())

# Details

Key values are the codes which are sent whenever a key is pressed or released. They appear in the keyval field of the `EventKey` structure, which is passed to signal handlers for the `keyPressEvent` and `keyReleaseEvent` signals.

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 ' (for older symbols)'.

Key values can be converted into a string representation using `keyvalName`. The reverse function, converting a string to a key value, is provided by `keyvalFromName`.

The case of key values can be determined using `keyvalIsUpper`. Key values can be converted to upper or lower case using `keyvalToUpper` and `keyvalToLower`.

When it makes sense, key values can be converted to and from Unicode characters with `keyvalToUnicode`.

One `Keymap` object exists for each user display. `keymapGetDefault` returns the `Keymap` for the default display; to obtain keymaps for other displays, use `keymapGetForDisplay`. A keymap is a mapping from `KeymapKey` to key values. You can think of a `KeymapKey` 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 `KeymapKey` 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 `keymapTranslateKeyboardState` 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 `keymapTranslateKeyboardState` 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. `EventKey` already contains this keyval, however, so you don't normally need to call `keymapTranslateKeyboardState` just to get the keyval.

# Class Hierarchy

     | GObject
     | +----Keymap

# Types

data Keymap

Instances

Eq Keymap |
Ord Keymap |
GObjectClass Keymap |
KeymapClass Keymap |

class GObjectClass o => KeymapClass o

Instances

KeymapClass Keymap |

castToKeymap :: GObjectClass obj => obj -> Keymap

toKeymap :: KeymapClass o => o -> Keymap

data KeymapKey

A `KeymapKey` is a hardware key that can be mapped to a keyval.

Instances

Eq KeymapKey |
Show KeymapKey |
Storable KeymapKey |

# Methods

keymapGetDefault

Arguments

:: IO Keymap | returns the `Keymap` attached to the default display.

Returns the `Keymap` attached to the default display.

keymapGetForDisplay

Arguments

:: Display | `display` - the `Display`.
-> IO Keymap | returns the `Keymap` attached to `display`.

Returns the `Keymap` attached to `display`.

- Available since Gdk version 2.2

keymapLookupKey

Arguments

:: KeymapClass self |
=> Maybe self | `keymap` a `Keymap` or `Nothing` to use the default keymap
-> KeymapKey | `key` - a `KeymapKey` with keycode, group, and level initialized
-> IO Int | returns a keyval, or 0 if none was mapped to the given `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 `keymapTranslateKeyboardState` instead of this function, since the effective group/level may not be the same as the current keyboard state.

keymapTranslateKeyboardState

Arguments

:: KeymapClass self |
=> self |
-> Int | `hardwareKeycode` - a keycode
-> Modifier | `state` - a modifier state
-> Int | `group` - active keyboard group
-> IO (Maybe (Int, Int, Int, Modifier)) |

Translates the contents of a `EventKey` into a keyval, effective group, and level. Modifiers that affected the translation and are thus unavailable for application use are returned in `consumedModifiers`. See `keyvalGetKeys` for an explanation of groups and levels. The `effectiveGroup` 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, `EventKey` already contains the translated keyval, so this function isn't as useful as you might think.

keymapGetEntriesForKeyval

Arguments

:: KeymapClass self |
=> self |
-> KeyVal | `keyval` - a keyval, such as `GDK_a`, `GDK_Up`, `GDK_Return`, etc.
-> IO (Maybe [KeymapKey]) |

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. `EventKey` contains a `group` field that indicates the active keyboard group. The level is computed from the modifier mask.

keymapGetEntriesForKeycode

Arguments

:: KeymapClass self |
=> self |
-> Int | `hardwareKeycode` - a keycode
-> IO (Maybe ([KeymapKey], [KeyVal])) |

Returns the keyvals bound to `hardwareKeycode`. The Nth `KeymapKey` in `keys` is bound to the Nth keyval in `keyvals`. 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 `keymapTranslateKeyboardState`.

keymapGetDirection

Arguments

:: KeymapClass self |
=> self |
-> IO PangoDirection | returns `DirectionLtr` or `DirectionRtl` if it can determine the direction. `DirectionNeutral` otherwise.

Returns the direction of effective layout of the keymap.

Returns the direction of the keymap.

keymapHaveBidiLayouts

Arguments

:: KeymapClass self |
=> self |
-> IO Bool | returns `True` if there are layouts in both directions, `False` otherwise

Determines if keyboard layouts for both right-to-left and left-to-right languages are in use.

- Available since Gdk version 2.12

keymapGetCapsLockState

Arguments

:: KeymapClass self |
=> self |
-> IO Bool | returns `True` if Caps Lock is on

Returns whether the Caps Lock modifer is locked.

- Available since Gdk version 2.16

# Signals

keymapDirectionChanged :: KeymapClass self => Signal self (IO ())

The `keymapDirectionChanged` signal gets emitted when the direction of the keymap changes.

- Available since Gdk version 2.0

keymapKeysChanged :: KeymapClass self => Signal self (IO ())

The `keymapKeysChanged` signal is emitted when the mapping represented by `keymap` changes.

- Available since Gdk version 2.2

keymapStateChanged :: KeymapClass self => Signal self (IO ())

The `keymapStateChanged` signal is emitted when the state of the keyboard changes, e.g when Caps Lock is turned on or off. See `keymapGetCapsLockState`.

- Available since Gdk version 2.16