NAME
SYNOPSIS
DESCRIPTION
DIAGNOSTICS
XGetDeviceMotionEvents, XDeviceTimeCoord − get device motion history
#include <X11/extensions/XInput.h>
XDeviceTimeCoord
*XGetDeviceMotionEvents( Display *display,
XDevice *device,
Time start,
Time stop,
int *nevents_return,
int *mode_return,
int *axis_count_return);
display
Specifies the connection to the X server.
device
Specifies the device whose motion history is to be
queried.
start, stop
Specify the time interval in which the events are
returned from the motionhistory buffer.You can pass a
timestamp or CurrentTime.
nevents_return
Returns the number of events from the motion history
buffer.
mode_return
Returns the mode of the device (Absolute or Relative).
axis_count_return
Returns the count of axes being reported.
The server may
retain the recent history of the device motion
and do so to a finer granularity than is reported by
DeviceMotionNotify events. The XGetDeviceMotionEvents
request
makes this history available.
The
XGetDeviceMotionEvents request returns all events in the
motion history buffer that fall between the specified start
and
stop times, inclusive. If the start time is later than the
stop
time or if the start time is in the future, no events are
returned. If the stop time is in the future, it is
equivalent
to specifying CurrentTime.
The mode
indicates whether the device is reporting absolute
positional data (mode = Absolute ) or relative motion data
(mode = Relative ). Some devices allow their mode to be
changed
via the XSetDeviceMode request. These constants are defined
in
the file XI.h. The axis_count returns the number of axes or
valuators being reported by the device.
XGetDeviceMotionEvents
can generate a BadDevice, or BadMatch
error.
Structures
The XDeviceTimeCoord structure contains:
typedef struct
{
Time time;
int *data;
} XDeviceTimeCoord;
The time member
is set to the time, in milliseconds. The data
member is a pointer to an array of integers. These integers
are
set to the values of each valuator or axis reported by the
device. There is one element in the array per axis of motion
reported by the device. The value of the array elements
depends
on the mode of the device. If the mode is Absolute, the
values
are the raw values generated by the device. These may be
scaled
by client programs using the maximum values that the device
can
generate. The maximum value for each axis of the device is
reported in the max_val field of the XAxisInfo returned by
the
XListInputDevices request. If the mode is Relative, the data
values are the relative values generated by the device.
You should use
XFreeDeviceMotionEvents to free the data
returned by this request.
Errors returned by this request: BadDevice, BadMatch.
BadDevice
An invalid device was specified. The specified device
does not exist or has not been opened by this client via
XOpenInputDevice. This error may also occur if the
specified device is the X keyboard or X pointer device.
BadMatch
This error may occur if an XGetDeviceMotionEvents
request is made specifying a device that has no
valuators and reports no axes of motion.