www.LinuxHowtos.org

XkbGetVirtualMods

Section: XKB FUNCTIONS (3)
Updated: libX11 1.6.4
Index Return to Main Contents

NAME

XkbGetVirtualMods - Obtain a subset of the virtual modifier bindings (the vmods array) in a keyboard description

SYNOPSIS

Status XkbGetVirtualMods (Display *dpy, unsigned int which, XkbDescPtr xkb);

ARGUMENTS

- dpy: connection to server
- which: mask indicating virtual modifier bindings to get
- xkb: Xkb description where results will be placed

DESCRIPTION

XkbGetVirtualMods sends a request to the server to obtain the vmods entries for the virtual modifiers specified in the mask, which, and waits for a reply.

Virtual modifiers are named by converting their string name to an X Atom and storing the Atom in the names.vmods array in an XkbDescRec structure. The position of a name Atom in the names.vmods array defines the bit position used to represent the virtual modifier and also the index used when accessing virtual modifier information in arrays: the name in the i-th (0 relative) entry of names.vmods is the i-th virtual modifier, represented by the mask (1<<i). Throughout Xkb, various functions have a parameter that is a mask representing virtual modifier choices. In each case, the i-th bit (0 relative) of the mask represents the i-th virtual modifier.

To set the name of a virtual modifier, use XkbSetNames, using XkbVirtualModNamesMask in which and the name in the xkb argument; to retrieve indicator names, use XkbGetNames.

For each bit set in which, XkbGetVirtualMods updates the corresponding virtual modifier definition in the server->vmods array of xkb. The xkb parameter must be a pointer to a valid Xkb keyboard description. If successful, XkbGetVirtualMods returns Success.

Virtual Modifier Names and Masks

To set the name of a virtual modifier, use XkbSetNames, using XkbVirtualModNamesMask in which and the name in the xkb argument; to retrieve indicator names, use XkbGetNames.

If the server map has not been allocated in the xkb parameter, XkbGetVirtualMods allocates and initializes it before obtaining the virtual modifier bindings.

If the server does not have a compatible version of Xkb, or the Xkb extension has not been properly initialized, XkbGetVirtualMods returns BadMatch. Any errors in allocation cause XkbGetVirtualMods to return BadAlloc.

RETURN VALUES

Success: The XkbGetVirtualMods function returns Success when it successfully updates the corresponding virtual modifier definition in the server->vmods array of xkb.

STRUCTURES

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 1.

Table 1 Mask Bits for XkbDescRec

Mask Bit	XkbDescRec Field	Value

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

DIAGNOSTICS

BadAlloc: Unable to allocate storage
BadMatch: A compatible version of Xkb was not available in the server or an argument has correct type and range, but is otherwise invalid