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XGetDeviceProperty

NAME

XGetDeviceProperty, XChangeDeviceProperty, XDeleteDeviceProperty - Get, change or delete a device's property.

SYNTAX

 #include <X11/extensions/XInput.h>
 

int XGetDeviceProperty(Display *display, XDevice *device, Atom property, long offset, long length, Bool delete, Bool pending, Atom req_type, Atom *actual_type_return, int *actual_format_return, unsigned long *nitems_return, unsigned long *bytes_after_return, unsigned char **prop_return);

void XChangeDeviceProperty(Display *display, XDevice *device, Atom property, Atom type, int format, int mode, const char *data, int nelements);

void XDeleteDeviceProperty(Display *display, XDevice *device, Atom property);

ARGUMENTS

actual_type_return

Returns an atom identifier that defines the actual type of the property.

actual_format_return

Returns the actual format of the property.

bytes_after_return

Returns the number of bytes remaining to be read in the property if a partial read was performed.

data

Specifies the property data.

delete

Specifies a Boolean value that determines wether the property is deleted.

display

Specifies the connection to the X server.

device

The device to grab.

format

Specifies whether the data should be viewed as a list of 8-bit, 16-bit, or 32-bit quantities. Possible values are 8, 16, and 32. This information allows the X server to correctly perform byte-swap operations as necessary. If the format is 16-bit or 32-bit, you must explicitly cast the data pointer to an (unsigned char*) in the call to XChangeDeviceProperty.

length

Specifies the length in 32-bit multiplies of the data to be retrieved.

mode

Specifies the mode of operation. You can pass PropModeReplace, PropModePrepend, or PropModeAppend.

nelements

Specifies the number of elements in data.

nitems_return

Returns the actual number of 8-bit, 16-bit, or 32-bit items stored in the prop_return array.

num_values

Specifies the number of elements in the values list.

offset

Specifies the offset in the specified property (in 32-bit quantities) where the data is to be retrieved.

pending

Specifies whether to retrieve the pending state of the property or the current state.

property

Specifies the property to modify or query.

prop_return

Returns the data in the specified format. If the returned format is 8, the returned data is represented as a char array. If the returned format is 16, the returned data is represented as an array of short int type and should be cast to that type to obtain the elements. If the returned format is 32, the property data will be stored as an array of longs (which in a 64-bit application will be 64-bit values that are padded in the upper 4 bytes).

req_type

Specifies the atom identifier associated with the property type or AnyPropertyType.

DESCRIPTION

The XGetDeviceProperty function returns the actual type of the property; the actual format of the property; the number of 8-bit, 16-bit, or 32-bit items transferred; the number of bytes remaining to be read in the property; and a pointer to the data actually returned. For a detailed description of this function, see the man page to XGetWindowProperty.

The XChangeDeviceProperty function alters the property for the specified device and causes the server to generate a XPropertyNotifyEvent event on that device. For a detailed description of this function, see the man page to XChangeProperty.

The XDeleteDeviceProperty function deletes the specified device property. Note that a client cannot delete a property created by a driver or the server. Attempting to do so will result in a BadAtom error.

XGetDeviceProperty can generate a BadAtom, BadDevice error.

XChangeDeviceProperty can generate a BadDevice, a BadMatch, a BadAtom, and a BadValue error.

XDeleteDeviceProperty can generate a BadDevice, and a BadAtom error.

DIAGNOSIS

BadAtom

A value does not describe a valid named identifier or the client attempted to remove a driver-allocated property.

BadDevice

An invalid device was specified. The device does not exist.

SEE ALSO

XListDeviceProperties, XQueryDeviceProperty, XConfigureDeviceProperty.

AUTHOR

Peter Hutterer

Specification and implementation.