Linux Certif

Toute la documentation sur la certification Linux LPI

XQueryDeviceState

NAME

XQueryDeviceState - query the state of an extension input device.

SYNOPSIS

 #include <X11/extensions/XInput.h>
 

 XDeviceState* XQueryDeviceState( Display *display,
                                  XDevice *device);
 

 display
        Specifies the connection to the X server.
 

 device
        Specifies the device whose state is to be queried.
 

DESCRIPTION

 The XQueryDeviceState request queries the state of an input
 device. The current state of keys and buttons (up or down), and
 valuators (current value) on the device is reported by this
 request. Each key or button is represented by a bit in the
 XDeviceState structure that is returned. Valuators on the
 device report 0 if they are reporting relative information, and
 the current value if they are reporting absolute information.
 

 XQueryDeviceState can generate a BadDevice error.
 

 Structures:
 

 The XDeviceState structure contains:
 

 typedef struct {
     XID device_id;
     int num_classes;
     XInputClass *data;
 } XDeviceState;
 

 The XValuatorState structure contains:
 

 typedef struct {
     unsigned char class;
     unsigned char length;
     unsigned char num_valuators;
     unsigned char mode;
     int *valuators;
 } XValuatorState;
 

 The XKeyState structure contains:
 

 typedef struct {
     unsigned char class;
     unsigned char length;
     short     num_keys;
     char keys[32];
 } XKeyState;
 

 The XButtonState structure contains:
 

 typedef struct {
     unsigned char class;
     unsigned char length;
     short     num_buttons;
     char buttons[32];
 } XButtonState;
 

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 some
        other client has caused the specified device to become
        the X keyboard or X pointer device via the
        XChangeKeyboardDevice or XChangePointerDevice requests.