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Table of Contents
XGetFeedbackControl, XChangeFeedbackControl - query and
change input device feedbacks
- XFeedbackState *XGetFeedbackControl(Display
*display, XDevice
- *device, int *num_feedbacks);
- int XChangeFeedbackControl(Display
*display, XDevice
- *device, Mask mask, XFeedbackControl *control);
- display
- Specifies the connection to the X server.
- device
- Specifies the device whose
feedbacks are to be queried or modified.
- num_feedbacks
- Specifies an address
into which the number of feedbacks supported by the device is to be returned.
- mask
- Specifies a mask specific to each type of feedback that describes
how the feedback is to be modified.
- control
- Specifies the address of
an XFeedbackControl structure that contains the new values for the feedback.
These requests are provided to manipulate those input devices
that support feedbacks. A BadMatch error will be generated if the requested
device does not support feedbacks. Whether or not a given device supports
feedbacks can be determined by examining the information returned by the
XOpenDevice request. For those devices that support feedbacks, XOpenDevice
will return an XInputClassInfo structure with the input_class field equal
to the constant FeedbackClass (defined in the file XI.h).
The XGetFeedbackControl
request returns a pointer to a list of XFeedbackState structures. Each
item in this list describes one of the feedbacks supported by the device.
The items are variable length, so each contains its length to allow traversal
to the next item in the list.
The feedback classes that are currently defined
are: KbdFeedbackClass, PtrFeedbackClass, StringFeedbackClass, IntegerFeedbackClass,
LedFeedbackClass, and BellFeedbackClass. These constants are defined in
the file XI.h. An input device may support zero or more classes of feedback,
and may support multiple feedbacks of the same class. Each feedback contains
a class identifier and an id that is unique within that class for that
input device. The id is used to identify the feedback when making an XChangeFeedbackControl
request.
XGetFeedbackControl can generate a BadDevice or BadMatch error.
The XChangeFeedbackControl request modifies the values of one feedback
on the specified device. The feedback is identified by the id field of
the XFeedbackControl structure that is passed with the request. The fields
of the feedback that are to be modified are identified by the bits of the
mask that is passed with the request.
XChangeFeedbackControl can generate
a BadDevice, BadMatch, or BadValue error.
Each class of feedback
is described by a structure specific to that class. These structures are
defined in the file XInput.h. XFeedbackState and XFeedbackControl are generic
structures that contain three fields that are at the beginning of each
class of feedback:
typedef struct {
XID class;
int length;
XID id;
} XFeedbackState, XFeedbackControl;
The XKbdFeedbackState structure defines
the attributes that are returned for feedbacks equivalent to those on the
X keyboard.
typedef struct {
XID class;
int length;
XID id;
int click;
int percent;
int pitch;
int duration;
int led_mask;
int global_auto_repeat;
char auto_repeats[32];
} XKbdFeedbackState;
The XPtrFeedbackState structure defines the attributes that are returned
for feedbacks equivalent to those on the the X pointer.
typedef struct {
XID class;
int length;
XID id;
int accelNum;
int accelDenom;
int threshold;
} XPtrFeedbackState;
The XIntegerFeedbackState structure defines attributes that are returned
for integer feedbacks.
typedef struct {
XID class;
int length;
XID id;
int resolution;
int minVal;
int maxVal;
} XIntegerFeedbackState;
The XStringFeedbackState structure defines the attributes that are returned
for string feedbacks.
typedef struct {
XID class;
int length;
XID id;
int max_symbols;
int num_syms_supported;
KeySym *syms_supported;
} XStringFeedbackState;
The XBellFeedbackState structure defines the attributes that are returned
for bell feedbacks.
typedef struct {
XID class;
int length;
XID id;
int percent;
int pitch;
int duration;
} XBellFeedbackState;
The XLedFeedbackState structure defines the attributes that are returned
for LED feedbacks.
typedef struct {
XID class;
int length;
XID id;
int led_values;
} XLedFeedbackState;
The XPrtFeedbackControl structure defines the attributes that can be controlled
for pointer feedbacks.
typedef struct {
XID class;
int length;
XID id;
int accelNum;
int accelDenom;
int threshold;
} XPtrFeedbackControl;
The XKbdFeedbackControl structure defines the attributes that can be controlled
for keyboard feedbacks.
typedef struct {
XID class;
int length;
XID id;
int click;
int percent;
int pitch;
int duration;
int led_mask;
int led_value;
int key;
int auto_repeat_mode;
} XKbdFeedbackControl;
The XStringFeedbackControl structure defines the attributes that can be
controlled for string feedbacks.
typedef struct {
XID class;
int length;
XID id;
int num_keysyms;
KeySym *syms_to_display;
} XStringFeedbackControl;
The XIntegerFeedbackControl structure defines the attributes that can
be controlled for integer feedbacks.
typedef struct {
XID class;
int length;
XID id;
int int_to_display;
} XIntegerFeedbackControl;
The XBellFeedbackControl structure defines the attributes that can be
controlled for bell feedbacks.
typedef struct {
XID class;
int length;
XID id;
int percent;
int pitch;
int duration;
} XBellFeedbackControl;
The XLedFeedbackControl structure defines the attributes that can be controlled
for LED feedbacks.
typedef struct {
XID class;
int length;
XID id;
int led_mask;
int led_values;
} XLedFeedbackControl;
- 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.
- BadMatch
- This error may occur if an XGetFeedbackControl
request was made specifying a device that has no feedbacks, or an XChangeFeedbackControl
request was made with an XFeedbackControl structure that contains an invalid
feedback type. It may also occur if an invalid combination of mask bits
is specified (DvKey but no DvAutoRepeatMode for keyboard feedbacks), or
if an invalid KeySym is specified for a string feedback.
- BadValue
- Some
numeric value falls outside the range of values accepted by the XChangeFeedbackControl
request. Unless a specific range is specified for an argument, the full
range defined by the argument's type is accepted. Any argument defined as
a set of alternatives can generate this error.
Programming With Xlib
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