The core protocol does not provide any means to prevent a modifier from being reported in events sent to clients; Xkb, however makes this possible via the InternalMods control. It specifies modifiers that should be consumed by the server and not reported to clients. When a key is pressed and a modifier that has its bit set in the InternalMods control is reported to the server, the server uses the modifier when determining the actions to apply for the key. The server then clears the bit, so it is not actually reported to the client. In addition, modifiers specified in the InternalMods control are not used to determine grabs and are not used to calculate core protocol compatibility state.
Manipulate the InternalMods control via the internal field in the XkbControlsRec structure, using XkbSetControls and XkbGetControls. Alternatively, use XkbSetServerInternalMods.
XkbSetServerInternalMods sends a request to the server to change the internal modifiers consumed by the server. affect_real and real_values are masks of real modifier bits indicating which real modifiers are to be added and removed from the server's internal modifiers control. Modifiers selected by both affect_real and real_values are added to the server's internal modifiers control; those selected by affect_real but not by real_values are removed from the server's internal modifiers mask. Valid values for affect_real and real_values consist of any combination of the eight core modifier bits: ShiftMask, LockMask, ControlMask, Mod1Mask - Mod5Mask. affect_virtual and virtual_values are masks of virtual modifier bits indicating which virtual modifiers are to be added and removed from the server's internal modifiers control. Modifiers selected by both affect_virtual and virtual_values are added to the server's internal modifiers control; those selected by affect_virtual but not by virtual_values are removed from the server's internal modifiers control. See below for a discussion of virtual modifier masks to use in affect_virtual and virtual_values. XkbSetServerInternalMods does not wait for a reply from the server. It returns True if the request was sent and False otherwise.
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.
The complete description of an Xkb keyboard is given by an XkbDescRec. The component structures in the XkbDescRec represent the major Xkb components outlined in Figure 1.1.
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.
| 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) |