XkbGetMap (3) - Linux Manuals

XkbGetMap: Allocate an XkbDescRec structure and populate it with the server's


XkbGetMap - Allocate an XkbDescRec structure and populate it with the server's keyboard client map and server map


XkbDescPtr XkbGetMap (Display *display, unsigned int which, unsigned int device_spec);


- display
connection to X server
- which
mask selecting subcomponents to populate
- device_spec
device_id, or XkbUseCoreKbd


Xkb provides two functions to obtain the keyboard mapping components from the server. The first function, XkbGetMap, allocates an XkbDescRec structure, retrieves mapping components from the server, and stores them in the XkbDescRec structure it just allocated. The second function, XkbGetUpdatedMap, retrieves mapping components from the server and stores them in an XkbDescRec structure that has previously been allocated.

To allocate an XkbDescRec structure and populate it with the server's keyboard client map and server map, use XkbGetMap. XkbGetMap is similar to XkbGetKeyboard, but is used only for obtaining the address of an XkbDescRec structure that is populated with keyboard mapping components. It allows finer control over which substructures of the keyboard mapping components are to be populated. XkbGetKeyboard always returns fully populated components, while XkbGetMap can be instructed to return a partially populated component.

The which mask is a bitwise inclusive OR of the masks defined in Table 14.1. Only those portions of the keyboard server map and the keyboard client maps that are specified in which are allocated and populated.

In addition to allocating and obtaining the server map and the client map, XkbGetMap also sets the device_spec, the min_key_code, and max_key_code fields of the keyboard description.

XkbGetMap is synchronous; it queries the server for the desired information, waits for a reply, and then returns. If successful, XkbGetMap returns a pointer to the XkbDescRec structure it allocated. If unsuccessful, XkbGetMap returns NULL. When unsuccessful, one of the following protocol errors is also generated: BadAlloc (unable to allocate the XkbDescRec structure), BadValue (some mask bits in which are undefined), or BadImplementation (a compatible version of the Xkb extension is not available in the server). To free the returned data, use XkbFreeKeyboard.

Xkb also provides convenience functions to get partial component definitions from the server. These functions are specified in the "convenience functions" column in Table 1. Refer to the sections listed in the table for more information on these functions.

Table 1 Xkb Mapping Component Masks
and Convenience Functions


XkbKeyTypesMask (1<<0)client types
XkbKeySymsMask (1<<1)client syms
XkbModifierMapMask (1<<2)clientmodmap XkbGetKeyModifierMap
XkbExplicitComponentsMask (1<<3)server explicit XkbGetKeyExplicitComponents
XkbKeyActionsMask (1<<4)server key_acts
XkbKeyBehaviorsMask (1<<5)server behaviors XkbGetKeyBehaviors
XkbVirtualModsMask (1<<6)server vmods XkbGetVirtualMods
XkbVirtualModMapMask (1<<7)server vmodmap XkbGetVirtualModMap

Xkb defines combinations of these masks for convenience:
   #define XkbResizableInfoMask   (XkbKeyTypesMask)
   #define XkbAllClientInfoMask   (XkbKeyTypesMask | XkbKeySymsMask |
   #define XkbAllServerInfoMask   (XkbExplicitComponentsMask |
                                   XkbKeyActionsMask | 
                                   XkbKeyBehaviorsMask |
                                   XkbVirtualModsMask | 
   #define XkbAllMapComponentsMask XkbAllClientInfoMask | 
Key types, symbol maps, and actions are all interrelated: changes in one require changes in the others. The convenience functions make it easier to edit these components and handle the interdependencies.


The complete description of an Xkb keyboard is given by an XkbDescRec. The component structures in the XkbDescRec represent the major Xkb components.

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. 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

Mask BitXkbDescRec FieldValue

XkbAllComponentsMaskAll Fields(0x7f)