XLookupString这个函数是干什么用的？

windwhinny

在看fcitx源代码的时候经常遇见这个函数，这是干什么用的？

xiaoshao_0_0

DESCRIPTION
       The XLookupKeysym function uses a given keyboard event and the index
       you specified to return the KeySym from the list that corresponds to
       the KeyCode member in the XKeyPressedEvent or XKeyReleasedEvent struc-
       ture.  If no KeySym is defined for the KeyCode of the event, XLookup-
       Keysym returns NoSymbol.

       The XRefreshKeyboardMapping function refreshes the stored modifier and
       keymap information.  You usually call this function when a MappingNo-
       tify event with a request member of MappingKeyboard or MappingModifier
       occurs.  The result is to update Xlib’s knowledge of the keyboard.

       The XLookupString function translates a key event to a KeySym and a
       string.  The KeySym is obtained by using the standard interpretation of
       the Shift, Lock, group, and numlock modifiers as defined in the X Pro-
       tocol specification.  If the KeySym has been rebound (see XRebind-
       Keysym), the bound string will be stored in the buffer.  Otherwise, the
       KeySym is mapped, if possible, to an ISO Latin-1 character or (if the
       Control modifier is on) to an ASCII control character, and that charac-
       ter is stored in the buffer.  XLookupString returns the number of char-
       acters that are stored in the buffer.

       If present (non-NULL), the XComposeStatus structure records the state,
       which is private to Xlib, that needs preservation across calls to
       XLookupString to implement compose processing.  The creation of XCom-
       poseStatus structures is implementation-dependent; a portable program
       must pass NULL for this argument.

       The XRebindKeysym function can be used to rebind the meaning of a
       KeySym for the client.  It does not redefine any key in the X server
       but merely provides an easy way for long strings to be attached to
       keys.  XLookupString returns this string when the appropriate set of
       modifier keys are pressed and when the KeySym would have been used for
       the translation.  No text conversions are performed; the client is
       responsible for supplying appropriately encoded strings.  Note that you
       can rebind a KeySym that may not exist.