XDeviceTimeCoord

Langue: en

Autres versions - même langue

Version: 10/02/2009 (ubuntu - 24/10/10)

Section: 3 (Bibliothèques de fonctions)

Sommaire

NAME

XGetDeviceMotionEvents, XDeviceTimeCoord - get device motion history

SYNOPSIS

 #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.

DESCRIPTION

 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.

DIAGNOSTICS

 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.