XkbFreeServerMap(3)

💖 XkbFreeServerMap(3) 💖

okay bestie, you’re in the XKB FUNCTIONS chapter, and today’s main character is XkbFreeServerMap(3). she frees memory, she sets pointers to NULL, she does not miss a single component. slay 💅

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🌸 NAME 🌸

XkbFreeServerMap — frees the memory used by the server member of an XkbDescRec structure. periodt.

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✨ SYNOPSIS ✨

       void XkbFreeServerMap (XkbDescPtr xkb, unsigned int which, Bool
              free_all);

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🎀 ARGUMENTS 🎀

• xkb — the keyboard description that contains the server map you’re freeing, bestie.
• which — a mask identifying which components of the map to free.
• free_all — True => free all server map components and server itself.

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🦋 DESCRIPTION 🦋

okay so XkbFreeServerMap frees the specified components of the server map inside the XkbDescRec structure specified by the xkb parameter, and it sets the corresponding structure component values to NULL. literally doing the cleanup so you don’t have to 🧹✨

the which parameter specifies a combination of the server map masks, and it is a bitwise inclusive OR of the masks listed in Table 1. iykyk.

if free_all is True, then which is ignored and XkbFreeServerMap frees every non-NULL structure component in the server map, frees the XkbServerMapRec structure referenced by the server member of the xkb parameter, and sets the server member to NULL. no cap, that’s the whole glow-up.

🧚 Table 1 XkbAllocServerMap Masks 🧚

• XkbExplicitComponentsMask — the min_key_code and max_key_code fields of the xkb parameter are used to allocate the explicit field of the server map.
• XkbKeyActionsMask — the min_key_code and max_key_code fields of the xkb parameter are used to allocate the key_acts field of the server map. the count_acts parameter is used to allocate the acts field of the server map.
• XkbKeyBehaviorsMask — the min_key_code and max_key_code fields of the xkb parameter are used to allocate the behaviors field of the server map.
• XkbVirtualModMapMask — the min_key_code and max_key_code fields of the xkb parameter are used to allocate the vmodmap field of the server map.

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🌸 STRUCTURES 🌸

the complete description of an Xkb keyboard is given by an XkbDescRec. the component structures in the XkbDescRec represent the major Xkb components. here’s the whole struct, exact fields and comments, looking iconic:

       typedef struct {
          struct _XDisplay * display;      /* connection to X server */
          unsigned short     flags;        /* private to Xkb, do not modify */
          unsigned short     device_spec;  /* device of interest */
          KeyCode            min_key_code; /* minimum keycode for device */
          KeyCode            max_key_code; /* maximum keycode for device */
          XkbControlsPtr     ctrls;        /* controls */
          XkbServerMapPtr    server;       /* server keymap */
          XkbClientMapPtr    map;          /* client keymap */
          XkbIndicatorPtr    indicators;   /* indicator map */
          XkbNamesPtr        names;        /* names for all components */
          XkbCompatMapPtr    compat;       /* compatibility map */
          XkbGeometryPtr     geom;         /* physical geometry of keyboard */
       } XkbDescRec, *XkbDescPtr;

the display field points to an X display structure. the flags field is private to the library: modifying flags may yield unpredictable results. ⚠️ like bestie please do not touch.

the device_spec field specifies the device identifier of the keyboard input device, or XkbUseCoreKeyboard, which specifies the core keyboard device. the min_key_code and max_key_code fields specify the least and greatest keycode that can be returned by the keyboard.

each structure component has a corresponding mask bit that is used in function calls to indicate that the structure should be manipulated in some manner, such as allocating it or freeing it. these masks and their relationships to the fields in the XkbDescRec are shown in Table 2. 🫶

💅 Table 2 Mask Bits for XkbDescRec 💅

• XkbControlsMask — field ctrls, value (1L<<0)
• XkbServerMapMask — field server, value (1L<<1)
• XkbIClientMapMask — field map, value (1L<<2)
• XkbIndicatorMapMask — field indicators, value (1L<<3)
• XkbNamesMask — field names, value (1L<<4)
• XkbCompatMapMask — field compat, value (1L<<5)
• XkbGeometryMask — field geom, value (1L<<6)
• XkbAllComponentsMask — field All Fields, value (0x7f)

the Xkb server map contains the information the server needs to interpret key events and is of type XkbServerMapRec. here’s that exact struct energy:

       #define XkbNumVirtualMods          16

       typedef struct {                    /* Server Map */
           unsigned short    num_acts;     /* # of occupied entries in acts */
           unsigned short    size_acts;    /* # of entries in acts */
           XkbAction *       acts;         /* linear 2d tables of key actions, 1 per keycode */
           XkbBehavior *     behaviors;    /* key behaviors,1 per keycode */
           unsigned short *  key_acts;     /* index into acts, 1 per keycode */
           unsigned char *   explicit;     /* explicit overrides of core remapping, 1 per key */
           unsigned char     vmods[XkbNumVirtualMods]; /* real mods bound to virtual mods */
           unsigned short *  vmodmap;      /* virtual mods bound to key, 1 per keycode*/
       } XkbServerMapRec, *XkbServerMapPtr;

and that’s the whole page, mwah 💋 — X Version 11 / libX11 1.8.14 / XkbFreeServerMap(3) signing off 🫶✨