NAME

       XISelectEvents, XIGetSelectedEvents - select for or get selected XI2 events on the window.

SYNOPSIS

       #include <X11/extensions/XInput2.h>

       Status XISelectEvents( Display *display,
                              Window win,
                              XIEventMask *masks,
                              int num_masks);

       display
              Specifies the connection to the X server.

       masks
              Device event mask.

       num_masks
              Number of masks in masks.

       win
              Specifies the window.

       XIEventMask *XIGetSelectedEvents( Display *display,
                                         Window win,
                                         int *num_masks_return);

       display
              Specifies the connection to the X server.

       num_masks_return
              Number of masks in the return value.

       win
              Specifies the window.

DESCRIPTION

           XI2 events must be selected using XISelectEvents.

           XISelectEvents sets the event mask for this client on win.
           Further events are only reported to this client if the event
           type matches the selected event mask. The masks overrides the
           previously selected event mask for the given device.

           If deviceid is a valid device, the event mask is selected only
           for this device. If deviceid is XIAllDevices or
           XIAllMasterDevices, the event mask is selected for all devices
           or all master devices, respectively. The effective event mask
           is the bit-wise OR of the XIAllDevices, XIAllMasterDevices and
           the respective device's event mask.

           typedef struct {
               int deviceid;
               int mask_len;
               unsigned char* mask;
           } XIEventMask;

           The mask_len specifies the length of mask in bytes. mask is a
           binary mask in the form of (1 << event type). deviceid must be
           either a device or XIAllDevices or XIAllMasterDevices. A client
           may submit several masks with the same deviceid in one request
           but only the last mask will be effective.

           XISelectEvents can generate a BadValue, a BadDevice, and a
           BadWindow error.

           XIGetSelectedEvents returns the events selected by this client on the given
           window. If no events were selected on this window, XIGetSelectedEvents
           returns NULL and num_masks_return is set to 0. If an internal error occurs,
           XIGetSelectedEvents returns NULL and num_masks_return is set to -1.
           Otherwise, XIGetSelectedEvent returns the selected event masks for all
           devices including the masks for XIAllDevices and XIAllMasterDevices

           The caller must free the returned data using XFree().

DIAGNOSTICS

           BadValue
                  A value is outside of the permitted range.

           BadWindow
                  A value for a Window argument does not name a defined
                  window.

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

                                            05/04/2023                          XISELECTEVENTS(3)