xref: /xsrc/external/mit/libXi/dist/man/XGetDeviceProperty.txt

XGETDEVICEPROPERTY(libmansuffix)
================================

NAME
----

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

SYNOPSIS
--------

   #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)


   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 whether 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(libmansuffix)