# The X Input Extension 2.x

Authors:

- Peter Hutterer (Red Hat) <peter.hutterer@redhat.com>

- Daniel Stone (Collabora Ltd.) <daniel@fooishbar.org>

- Chase Douglas (Canonical, Ltd.) <chase.douglas@canonical.com>

## 1. History

- v2.3, December 2012: Pointer barrier events added

- v2.2, March 2012: Multitouch support added

- v2.1, December 2011: new raw event behaviour, smooth scrolling support added

- v2.0, October 2009: Initial release of XI2 protocol

## 2. Introduction

The X Input Extension version 2.0 (XI2) is the second major release of the X Input Extension.

XI2 provides a number of enhancements over version 1.5, including:

- use of XGE and GenericEvents. GenericEvents are of flexible length with a minimum length of 32 bytes.

- explicit device hierarchy of master and slave devices. See Section The Master/Slave device hierarchy.

- use of multiple independent master devices (Multi-Pointer X or MPX).

- the ability for devices to change capabilities at runtime.

- raw device events

XI2’s intent is to replace both core input processing and prior versions of the X Input Extension. Historically, the majority of applications employed the core protocol requests and events to handle user input. The core protocol does not provide information about which device generated the event. The X Input Extension version up to 1.5 requires the differentiation between core and extended devices. Extended devices may not be core devices and thus cannot be used on applications employing the core protocol. XI2 addresses both of these issues by enabling devices to be both extended and core devices and providing device information in each event (with the exception of core events).

## 3. Changes in version 2.1

- RawEvents are sent regardless of the grab state.

- Addition of the ScrollClass for smooth scrolling

## 4. Changes in version 2.2

- Multitouch support added

## 5. Changes in version 2.3

- Pointer barrier events added

## 6. Notations used in this document

Notation for requests:

    ┌───
        Name of request
            name of request field:       type of request field
            name of request field:       type of request field
            ▶
            name of reply field:         type of reply field
    └───

Notation for events:

    ┌───
        Name of event
            name of field:               type of field
            name of field:               type of field
    └───

Complex fields are specified in the following notation:

    name of field:                  COMPLEXFIELDTYPE

or, if multiple of these fields exist:

    name of field:                  LISTofCOMPLEXFIELDTYPE

    COMPLEXFIELDTYPE:  { name of subfield:   type of subfield,
                         name of subfield:   type of subfield }

## 7. Interoperability between version 1.x and 2.0

There is little interaction between 1.x and 2.x versions of the X Input Extension. Clients are requested to avoid mixing XI1.x and XI2 code as much as possible. Several direct incompatibilities are observable:

### 7.1. Limitations resulting from different variable ranges

XI2 provides a larger range for some fields than XI1. As a result, XI1 clients may not receive data an XI2 client receives. These fields include:

- devices with a deviceid of greater than 127 are invisible to XI1 clients.

- key events and key grabs featuring larger than 255 can only be sent to XI2 clients.

- no subpixel information is available to XI1 clients. If motion events are in a subpixel range only, the server may omit these events and an XI 1.x client will not receive events until the pixel boundary is crossed.

### 7.2. Blocking of grabs

XI1 grabs are different to XI2 grab and a device may not be grabbed through an XI2 grab if an XI1 grab is currently active on this device or vice versa. Likewise, a keycode or button already grabbed by an XI 1.x or XI2 client may not be grabbed with the same modifier combination by an XI2 or XI 1.x client, respectively.

### 7.3. Invisibility of Master Devices

XI 1.x was not designed with support for multiple master devices. As a result, only the first master pointer and master keyboard are visible to XI 1.x clients; all other master devices are invisible and cannot be accessed from XI 1.x calls.

### 7.4. Smooth scrolling

Historically, X implemented scrolling events by using button press events: button 4 was one “click” of the scroll wheel upwards, button 5 was downwards, button 6 was one unit of scrolling left, and button 7 was one unit of scrolling right. This is insufficient for e.g. touchpads which are able to provide scrolling events through multi-finger drag gestures, or simply dragging your finger along a designated strip along the side of the touchpad.

Newer X servers may provide scrolling information through valuators to provide clients with more precision than the legacy button events. This scrolling information is part of the valuator data in device events. Scrolling events do not have a specific event type.

Valuators for axes sending scrolling information must have one ScrollClass for each scrolling axis. If scrolling valuators are present on a device, the server must provide two-way emulation between these valuators and the legacy button events for each delta unit of scrolling.

One unit of scrolling in either direction is considered to be equivalent to one button event, e.g. for a unit size of 1.0, -2.0 on an valuator type Vertical sends two button press/release events for button 4. Likewise, a button press event for button 7 generates an event on the Horizontal valuator with a value of +1.0. The server may accumulate deltas of less than one unit of scrolling.

Any server providing this behaviour marks emulated button or valuator events with the XIPointerEmulated flag for DeviceEvents, and the XIRawEmulated flag for raw events, to hint at applications which event is a hardware event.

If more than one scroll valuator of the same type is present on a device, the valuator marked with Preferred for the same scroll direction is used to convert legacy button events into scroll valuator events. If no valuator is marked Preferred or more than one valuator is marked with Preferred for this scroll direction, this should be considered a driver bug and the behaviour is implementation-dependent.

## 8. The Master/Slave device hierarchy

XI2 introduces a device hierarchy split up into so-called Master Devices (MD) and Slave Devices (SD).

### 8.1. Master devices

An MD is a virtual device created and managed by the server. MDs may send core events and XI events. However, an MD does not represent a physical device and relies on SDs for event generation. MDs come in two forms: as master pointers or as master keyboards. A master pointer is represented by a visible cursor on the screen. A master keyboard is represented by a keyboard focus.

Each master pointer is paired with the respective master keyboard and vice versa, and this pairing is constant for the lifetime of both input devices. Clients can use this pairing behaviour to implement input paradigms that require pointer and keyboard interation (e.g. SHIFT + Click).

### 8.2. Slave devices

An SD is usually a physical device configured in the server. SDs are not represented by a cursor or keyboard focus and may be attached to a master pointer or master keyboard. SDs can only be attached to any master of the same type (e.g. a physical pointer device can be attached to any master pointer).

If an event is generated by an SD

- if the SD is attached to a master pointer, it changes the position and/or button state of the master pointer.

- if the SD has a keyboard focus other than None, the key event is sent to the focus window.

- if the SD is attached to a master keyboard, it sends events to this keyboard’s focus window (if applicable) and/or changes the modifier state of this keyboard.

- if the SD is not attached to an MD ("floating"), it does not change any master device. The SD has its own (invisible) sprite and its own focus. Both the sprite and the focus must be managed explicitly by the client program.

Note: the keyboard focus of an attached slave device is independent to that of the master device. Two keyboard events are generated, once with deviceid and sourceid set to the slave device. This keyboard event is sent to the slave device’s focus window. The second event has a deviceid of the master and a sourceid of the slave device. This second event is delivered to the master keyboard’s focus window.

### 8.3. Event processing for attached slave devices

Whenever an SD changes its logical state,

- the event is delivered as an XI event to any interested clients. If the device is floating, event processing stops. Otherwise, if the device is attached,

- the master device changes its classes to reflect the SD’s capabilities. All interested clients are notified of this device change.

- then, the event is delivered as an XI event from the MD to any interested clients. If the event has been delivered, event processing stops. Otherwise,

- the event is delivered as a core event to any interested clients.

Given that W is the event window, and P the parent window of W, event delivery to P is only attempted if neither the XI event, nor the core event has been delivered on W. Once an event has been delivered as either XI or core event, event processing stops.

### 8.4. The ClientPointer principle

Many core protocol and some extension requests are ambiguous when multiple master devices are available (e.g. QueryPointer does not specify which pointer). The X server does not have the knowledge to chose the contextually correct master device. For each client, one master pointer is designated as this clients’s "ClientPointer". Whenever a client sends an ambiguous request (e.g. QueryPointer), the ClientPointer or the keyboard paired with the ClientPointer is chosen to provide the data for this request.

This ClientPointer may be explicitly assigned to a client with the SetClientPointer call. If no ClientPointer is set when a client issues an ambiguous request, the server choses one device as the ClientPointer. The method of chosing a ClientPointer from the available master pointers is implementation-specific.

If the master pointer currently set as ClientPointer for one or more clients is removed, the server may either unset the ClientPointer setting or change the ClientPointer to a different master pointer.

## 9. Touch device support

XI 2.2 introduces support for multi-touch devices. The traditional pointer/keyboard approach enforced by XI 2.0 with the master/slave device hierarchy is not always suitable for multi-touch devices that can provide a dynamic number of touchpoints per physical device; it is not known without client-specific interpretation whether the touchpoints must be considered separately or grouped together.

The additions in XI 2.2 aim to:

- support a dynamic number of simultaneous touch points,

- support devices that are both multi-touch and traditional pointer devices,

- allow touchpoints to be either grouped together or handled separately,

- be backwards-compatible to pre-XI 2.2 clients through emulation of XI 2.x/XI 1.x and core pointer events.

Touch events are only available to clients supporting version 2.2 or later of the X Input Extension. Clients must use the XIQueryVersion request to announce support for this version. Touch devices may generate emulated pointer events alongside XI 2.2 touch events to support older clients; see Section Touch event delivery.

Touch event processing differs from normal event processing in a few ways. The most notable differences are that touch events are processed partially out-of-band from pointer and keyboard events, and that touch events may be sent to multiple clients simultaneously. For more details see Section Touch event delivery.

### 9.1. Touch event sequences

Touch input follows a three-stage cycle:

    begin - update - update - ... - end

i.e. “begin” the sequence by touching the device, “update” the current touch location or properties any number of times, and finally “end” the sequence by ceasing to touch the device. Within this document, the term "touch sequence" is used to describe the above sequence of events. In the protocol, the three stages are represented with the event types TouchBegin, TouchUpdate, and TouchEnd, respectively. A touch sequence always generates TouchBegin and TouchEnd events, and may also generate TouchUpdate events. Clients must select for all three of these events simultaneously.

When a touch starts, clients are sent a TouchBegin event detailing the position of the touchpoint, as well as the initial properties of the touchpoint. Note that the logical state of the device (as seen through the input protocol) may lag the physical state if event processing is affected by grabs. Multiple touchpoints may be active on the same device at any time, potentially owned by and/or delivered to a different set of clients.

Whenever the touch position or any other property of the touchpoint changes, a TouchUpdate event is sent to all clients listening to events for that touchpoint with the updated information.

When the touch has physically ended, or a client will otherwise not receive any more events for a given touchpoint, a TouchEnd event will be sent to that client.

Passive touch grabs are similar to standard input event grabs in that they take precedence over event selections and are searched from the root window to the child window (as opposed to selections, which start their search at the child window and continue up to the root window). When a touch grab activates, the client whose grab activates becomes the “owner” of this touch sequence, and must decide what to do with it, as per Section Ownership of touch sequences. See the XIPassiveGrabDevice request documentation for more information on passive grab activation.

Only one client may select for touch events from a given device on a window.

#### 9.1.1. Ownership of touch sequences

Once a grabbing client becomes the owner of a touch, it must either “accept” or "reject" the touch sequence using the XIAllowEvents request. If a touch sequence is rejected, a TouchEnd event is sent to the rejecting client, and it will not receive any more events for this touch. The server then looks to the next window in the stack for another passive grab, and attempts to pass ownership on to the next candidate for a passive grab (i.e. the next window towards the final child window with a matching grab), or to the first applicable event selection if there are no more grabs.

If a touch sequence is accepted by its owner, all other clients receive TouchEnd events, and the touch sequence is exclusively delivered to the owner from that point on.

If the touch sequence physically ends while the owner of the touch sequence has not yet accepted or rejected ownership, the owner receives a TouchEnd event and all other clients receive a TouchUpdate event with the TouchPendingEnd flag set. The owner must still accept or reject the sequence nonetheless. If the owner rejects the touch sequence, the server will still attempt to exhaust all other passive grabs and/or event selections looking for a final owner.

If the touch sequence has not physically ended yet and the owner of the touch sequence rejects, the owner receives a TouchEnd event and ownership is passed to the next client.

Clients may opt for touch events to be delivered before they become the owner of the touch sequence. In this case, the logical state of the device (as seen by means of the protocol) always matches the physical state of the device. Clients must use caution if they opt for this feature; any action taken must be undone if the touch sequence ends without the client becoming the owner.

To select for touch events regardless of ownership, a client must set the TouchOwnership event mask in addition to the TouchBegin, TouchUpdate and TouchEnd mask. When selected, a client will receive touch events as they occur on the device. If and when the client becomes the owner of a touch sequence, a TouchOwnership event is sent to the client. If the client is the initial owner of the sequence, the TouchBegin is immediately followed by the TouchOwnership event. Otherwise, TouchUpdate events may preceed a TouchOwnership event. A client is not guaranteed to become the owner of any given touch sequence.

The server delivers touch events to all clients that have selected for TouchOwnership and to the current owner of the sequence in parallel.

If a client has selected for TouchOwnership and is not the current owner of the sequence and the current owner accepts the sequence, the client receives a TouchEnd event and no further events from this sequence are sent to this client.

If a client has selected for TouchOwnership and the physical touch ends before the current owner has accepted or rejected the sequence, the client receives a TouchUpdate event with the TouchPendingEnd flag set. No further TouchUpdate events will be sent for this sequence. If the current owner accepts the sequence, the client receives a TouchEnd event. Otherwise, if the current owner rejects the sequence, the client may become the owner of the touch sequence and receive a TouchOwnership event and a TouchEnd event.

### 9.2. Touch device modes

Touch devices come in many different forms with varying capabilities. The following device modes are defined for this protocol:

DirectTouch: These devices map their input region to a subset of the screen region. Touch events are delivered to window at the location of the touch. "direct" here refers to the user manipulating objects at their screen location. An example of a DirectTouch device is a touchscreen.

DependentTouch: These devices do not have a direct correlation between a touch location and a position on the screen. Touch events are delivered according to the location of the device’s cursor and often need to be interpreted relative to the current position of that cursor. Such interactions are usually the result of a gesture performed on the device, rather than direct manipulation. An example of a DependentTouch device is a trackpad.

A device is identified as only one of the device modes above at any time, and the touch mode may change at any time. If a device’s touch mode changes, an XIDeviceChangedEvent is generated.

### 9.3. Touch event delivery

For direct touch devices, the window set for event propagation is the set of windows from the root window to the topmost window lying at the co-ordinates of the touch.

For dependent devices, the window set for event propagation is the set of windows from the root window to the window that contains the device’s pointer. A dependent device may only have one window set at a time, for all touches. Any future touch sequence will use the same window set. The window set is cleared when all touch sequences on the device end.

A window set is calculated on TouchBegin and remains constant until the end of the sequence. Modifications to the window hierarchy, new grabs or changed event selection do not affect the window set.

#### 9.3.1. Pointer control of dependent devices

On a dependent device, the device may differ between a pointer-controlling touch and a non-pointer-controlling touch. For example, on a touchpad the first touch is pointer-controlling (i.e. serves only to move the visible pointer). Multi-finger gestures on a touchpad cause all touches to be non-pointer-controlling.

For pointer-controlling touches, no touch events are sent; the touch generates regular pointer events instead. Non-pointer-controlling touches send touch events. A touch may change from pointer-controlling to non-pointer-controlling, or vice versa.

- If a touch changes from pointer-controlling to non-pointer-controlling, a new touch ID is assigned and a TouchBegin is sent for the last known position of the touch. Further events are sent as TouchUpdate events, or as TouchEnd event if the touch terminates.

- If a touch changes from non-pointer-controlling to pointer-controlling, a TouchEnd is sent for that touch at the last known position of the touch. Further events are sent as pointer events.

The conditions to switch from pointer-controlling to non-pointer-controlling touch is implementation-dependent. A device may support touches that are both pointer-controlling and a touch event.

In the dependent touch example event sequence below, touches are marked when switching to pointer-controlling (pc) or to non-pointer-controlling (np).

Table 1. Dependent touch example event sequence on a touchpad
Finger 1 | Finger 2 | Event generated(touchid)
--- | --- | ---
down |  | Motion
move |  | Motion
move |  | Motion
(np) | down | TouchBegin(0), TouchBegin(1)
move | — | TouchUpdate(0)
— | move | TouchUpdate(1)
up | (pc) | TouchEnd(0), TouchEnd(1)
| move | Motion
down | (np) | TouchBegin(2), TouchBegin(3)
move | — | TouchUpdate(2)
up | (pc) | TouchEnd(2), TouchEnd(3)
| up | Motion
down |  | Motion
(np) | down | TouchBegin(4), TouchBegin(5)
(pc) | up | TouchEnd(4), TouchEnd(5)
move |  | Motion
up |  | Motion

#### 9.3.2. Pointer emulation from multitouch events

Touch sequences from direct touch devices may emulate pointer events. Only one touch sequence from a device may emulate pointer events at a time; which touch sequence emulates pointer events is implementation-dependent.

Pointer events are emulated as follows:

- A TouchBegin event generates a pointer motion event to the location of the touch with the same axis values of the touch event, followed by a button press event for button 1.

- A TouchUpdate event generates a pointer motion event to the location of the touch and/or to update axis values of the pointer device. The button state as seen from the protocol includes button 1 set.

- A TouchEnd event generates a pointer motion event to the location of the touch and/or to update the axis values if either have changed, followed by a button release event for button 1. The button state as seen from the protocol includes button 1 set.

If a touch sequence emulates pointer events and an emulated pointer event triggers the activation of a passive grab, the grabbing client becomes the owner of the touch sequence.

The touch sequence is considered to have been accepted if

- the grab mode is asynchronous, or

- the grab mode is synchronous and the device is thawed as a result of AllowEvents with AsyncPointer or AsyncDevice

Otherwise, if the button press is replayed by the client, the touch sequence is considered to be rejected.

Touch event delivery precedes pointer event delivery. A touch event emulating pointer events is delivered:

- as a touch event to the top-most window of the current window set if a client has a touch grab on this window,

- otherwise, as a pointer event to the top-most window of the current window set if a client has a pointer grab on this window,

- otherwise, to the next child window in the window set until a grab has been found.

If no touch or pointer grab on any window is active and the last window in the window set has been reached, the event is delivered:

- as a touch event to the window if a client has selected for touch events on this window

- otherwise, as a pointer event to the window if a client has selected for pointer events.

- otherwise, to the next parent window in the window set until a selection has been found.

Emulated pointer events will have the PointerEmulated flag set. A touch event that emulates pointer events has the TouchEmulatingPointer flag set.

#### 9.3.3. Pointer barrier events

If a master pointer moves against a pointer barrier blocking movement in that pointer’s direction, the movement of the pointer is clamped to the x or y coordinate of the barrier, whichever applies. For a description of pointer barriers and barrier creation and destruction see the XFixes protocol specification v 5.0 or later. http://cgit.freedesktop.org/xorg/proto/fixesproto/plain/fixesproto.txt

A pointer hitting a blocking barrier creates a new barrier event sequence, identified by a unique event ID. A new event ID is assigned when the pointer first hits a barrier. Subsequent movements against or along the pointer barrier are assigned the same event ID. The event generated by the pointer leaving the barrier, or being released by a client request, is the last event with this event ID. Any future movements of this device blocked by this barrier will be assigned a new event ID.

Pointer barrier events are delivered exclusively to the client that created the barrier, and to the window specified in the CreatePointerBarrier request (the "barrier window"). A pointer barrier blocks pointer movement regardless of whether its window is mapped and/or viewable. If the pointer barrier window is destroyed, the pointer barrier remains blocking but a client will not receive further events.

If a device is actively grabbed by a client or a passive grab activated for this client, and the pointer moves against a pointer barrier created by this client and the grab-window is the barrier window, that client will receive pointer barrier events if: - owner-events is true or false and the grab’s event mask includes pointer barrier events, or - owner-events is true and the client has selected for barrier events on the barrier window.

If the grab-window is not the barrier window, the client will receive events if: - the client has selected for barrier events on the barrier window.

If the barrier is not owned by this client, no barrier events are sent to this client. The client owning the barrier will receive events if: - the client has pointer barrier events selected on the window associated with the pointer barrier

The BarrierDeviceIsGrabbed flag is set whenever a pointer barrier event is generated while the device is actively grabbed by any client or a passive grab has activated for this device prior to the event.

## 10. Notations used in this document

Notation for requests:

    ┌───
        Name of request
            name of request field:       type of request field
            name of request field:       type of request field
            ▶
            name of reply field:         type of reply field
    └───

Notation for events:

    ┌───
        Name of event
            name of field:               type of field
            name of field:               type of field
    └───

Complex fields are specified in the following notation:

    name of field:                  COMPLEXFIELDTYPE

or, if multiple of these fields exist:

    name of field:                  LISTofCOMPLEXFIELDTYPE

    COMPLEXFIELDTYPE:  { name of subfield:   type of subfield,
                         name of subfield:   type of subfield }

## 11. Data types

    BUTTONMASK
            A binary mask defined as (1 << button number).
            A SETofBUTTONMASK is a binary OR of zero or more BUTTONMASK.

    DEVICE { DEVICEID, AllDevices, AllMasterDevices }
            A DEVICE specifies either a DEVICEID or AllDevices or
            AllMasterDevices.

    DEVICEID { CARD16 }
            A DEVICEID is a numerical ID for a device currently available in the
            server. The server may re-use a device ID after a device's removal.
            The device IDs 0 and 1 are reserved.
            AllDevices ........ 0
            AllMasterDevices .. 1

    DEVICEUSE { MasterPointer, MasterKeyboard, SlavePointer,
                SlaveKeyboard, FloatingSlave }
            A DEVICEUSE field specifies the current use of a device in the MD/SD
            device hierarchy. See Section "The Master/Slave device hierarchy"
            for more information.

    EVTYPEMASK
            An EVTYPEMASK is a binary mask defined as (1 << event type).
            A SETofEVTYPEMASK is a binary OR of zero or more EVTYPEMASK.

    FP1616
            Fixed point decimal in 16.16 format as one INT16 and one CARD16.
            The INT16 contains the integral part, the CARD16 the decimal fraction
            shifted by 16.

    FP3232
            Fixed point decimal in 32.32 format as one INT32 and one CARD32.
            The INT32 contains the integral part, the CARD32 the decimal fraction
            shifted by 32.

    MODIFIERMASK
            A MODIFIERMASK is a binary mask defined as (1 << modifier map index).
            A SETofMODIFIERMASK is a binary OR of zero or more MODIFIERMASK or
            GrabAnyModifier.

    VALUATORMASK
            A binary mask defined as (1 << valuator number).
            A SETofVALUATORMASK is a binary OR of zero or more VALUATORMASK.

## 12. Errors

Errors are sent using core X error reports.

    Device
            A value for a DEVICE argument does not specify a valid DEVICE.

## 13. Requests

The server does not guarantee that the length of a reply remains constant in future revisions of XI2. A client must always retrieve the exact length of the protocol reply from the connection, even if the reply is longer than defined for the XI2 version supported by the client. Additional bytes in a request may include data supported in later versions of XI2. Clients should ignore this data. Padding bytes in XI2 protocol requests are required to be 0.

### 13.1. Requests introduced in version 2.0

#### 13.1.1. XIQueryVersion

    ┌───
        XIQueryVersion
        major_version:          CARD16
        minor_version:          CARD16
        ▶
        major_version:          CARD16
        minor_version:          CARD16
    └───

The client sends the highest supported version to the server and the server sends the highest version it supports, but no higher than the requested version. Major versions changes can introduce incompatibilities in existing functionality, minor version changes introduce only backward compatible changes. It is the client’s responsibility to ensure that the server supports a version which is compatible with its expectations.

    major_version
        Major XI2 version.
    minor_version
        Minor XI2 version.

If major_version is less than 2, a BadValue error occurs.

#### 13.1.2. XIQueryDevice

    ┌───
        XIQueryDevice
        DEVICE                  deviceid
        ▶
        num_devices:            CARD16
        deviceinfo:             LISTofDEVICEINFO
    └───

    DEVICEINFO { deviceid:              DEVICEID
                 use:                   DEVICEUSE
                 attachment:            DEVICEID
                 enabled:               BOOL
                 num_classes:           CARD16
                 name_len:              CARD16
                 name:                  LISTofCHAR8
                 classes:               LISTofCLASS }

    CLASS { BUTTONCLASS, KEYCLASS, VALUATORCLASS, SCROLLCLASS, TOUCHCLASS }

    BUTTONCLASS   { type:                 ButtonClass
                    length:               CARD16
                    sourceid:             CARD16
                    num_buttons:          CARD16
                    state:                SETofBUTTONMASK
                    labels:               LISTofATOM }

    KEYCLASS      { type:                 KeyClass
                    length:               CARD16
                    sourceid:             CARD16
                    num_keys:             CARD16
                    keys:                 LISTofCARD32 }

    VALUATORCLASS { type:                 ValuatorClass
                    length:               CARD16
                    sourceid:             CARD16
                    number:               CARD16
                    label:                ATOM
                    min:                  FP3232
                    max:                  FP3232
                    value:                FP3232
                    resolution:           CARD32
                    mode:                 CARD8 }

    SCROLLCLASS¹  { type:                 ScrollClass
                    length:               CARD16
                    sourceid:             CARD16
                    number:               CARD16
                    scroll_type:          SCROLLTYPE
                    flags:                SETofSCROLLFLAGS
                    increment:            FP3232 }

    SCROLLTYPE { Vertical, Horizontal }

    SCROLLFLAGS { NoEmulation, Preferred }

    TOUCHCLASS² { type:                 TouchClass
                  length:               CARD16
                  sourceid:             CARD16
                  mode:                 TOUCHMODE
                  num_touches:          CARD16 }

    TOUCHMODE { DirectTouch, DependentTouch }

    ¹ since XI 2.1
    ² since XI 2.2

XIQueryDevice details information about the requested input devices.

    devices
        The device to list. If devices is AllDevices, all enabled and
        disabled devices are listed. If devices is AllMasterDevices, all
        enabled and disabled master devices are listed. If devices is a
        valid DEVICE, only this DEVICE is listed and num_devices is 1.
    num_devices
        The number of deviceinfos returned.

Each deviceinfo is detailed as follows:

    deviceid
        The unique ID of the device. Device IDs may get re-used when a device
        is removed.
    use
        If the device is a master pointer, use is MasterPointer.
        If the device is a master keyboard, use is MasterKeyboard.
        If the device is a slave pointer, use is SlavePointer.
        If the device is a slave keyboard, use is SlaveKeyboard.
        If the device is a floating slave, use is FloatingSlave.
    attachment
        If the device is a master pointer or a master keyboard, attachment
        specifies the paired master keyboard, or the paired master pointer,
        respectively.  If the device is a non-floating slave device
        attachment specifies the master device this device is attached to.
        If the device is a floating slave, attachment is undefined.
    enabled
        Zero if the device is disabled, non-zero otherwise.
    num_classes
        Number of classes provided.
    name_len
        Length of the name in bytes not including padding.
    classes
        Details the available classes provided by the device in an undefined
        order.
    name
        The device's name. padded to a multiple of 4 bytes.

For all classes, type specifies the device class. Clients are required to ignore unknown device classes. The length field specifies the length of the class in 4 byte units. The following classes may occur only once: ButtonClass, KeyClass

    ButtonClass:
    type
        Always ButtonClass.
    length
        Length in 4 byte units.
    sourceid
        The device this class originates from.
    num_buttons
        Number of buttons provided by the device.
    labels
        List of Atoms specifying the label for each button. An Atom of None
        specifies an unlabeled button. Buttons are listed in the device-native
        order regardless of the current button mapping.
    state
        The current button mask for this device after button mapping is
        applied. Each bit representing a button is 1 if this button is
        logically down, or 0 otherwise. State is a multiple of 4-byte units
        and always contains at least num_buttons bits.

    KeyClass:
    type
        Always KeyClass.
    length
        Length in 4 byte units.
    sourceid
        The device this class originates from.
    num_keys
        Number of keycodes provided by the device.
    keys
        List of keycodes provided.

    ValuatorClass:
    type
        Always ValuatorClass.
    length
        Length in 4 byte units.
    sourceid
        The device this class originates from.
    number
        Valuator number of this axis. The valuator number is in device-native
        order and potential axis mappings are ignored.
    label
        Atom specifying the axis name. An Atom of None specifies an unlabeled
        axis.
    min
        Minimum value.
    max
        Minimum value.
    resolution
        Resolution in counts/meter.
    mode
        Relative or Absolute.
    value
        Last published axis value (if mode is absolute).

An axis in Relative mode may specify min and max as a hint to the client. If no min and max information is available, both must be 0.

    ScrollClass:
    type
        Always ScrollClass.
    number
        Valuator number that is referred to. This valuator number must be listed in
        the ValuatorClassInfo.
    scroll_type:
        Vertical for a vertical scrolling axis, Horizontal for a horizontal
        scrolling axis.
    flags:
        A set of flags that apply to this scroll axis.
        NoEmulation: no legacy scroll button events are generated for events
                     on this scrolling axis.
        Preferred: This axis is the preferred axis for emulating valuator
                   events from legacy scroll button events.
    increment:
        The valuator delta equivalent to one positive unit of scrolling.

A ScrollClass may only exist if the device has at least one ValuatorClass and each valuator number listed in any ScrollClass. Only one ScrollClass may exist per ValuatorClass.

    TouchClass:
    type
        Always TouchClass.
    length
        Length in 4 byte units.
    sourceid
        The device this class originates from.
    mode
        The device type of the touch device.  This mode may change at runtime.
    num_touches
        The maximum number of simultaneous touchpoints the device may send.
        If num_touches is 0, the number of supported touches is unknown or
        unlimited.

Devices with a TouchClass emit touch events with the same axes as pointer events.

#### 13.1.3. XISelectEvents

    ┌───
        XISelectEvents
            window:         Window
            num_masks:      CARD16
            masks:          LISTofEVENTMASK

    └───

    EVENTMASK { deviceid:          DEVICE,
                mask_len:          CARD16,
                mask:              SETofEVTYPEMASK }

    window
        The window to select the events on.
    num_masks
        Number of items in masks.
    deviceid
        Numerical deviceid, or AllDevices, or AllMasterDevices.
    mask_len
        Length of mask in 4 byte units.
    mask
        Event mask. An event mask for an event type T is defined as (1 << T).

XISelectEvents selects for XI2 events on window.

If num_masks is 0, a BadValue error occurs.

Each mask sets the (and overwrites a previous) event mask for the DEVICE specified through deviceid. The device AllDevices or AllMasterDevices is treated as a separate device by server. A client’s event mask is the union of AllDevices, AllMasterDevices and the per-device event mask. The removal of device from the server unsets the event masks for the device. If an event mask is set for AllDevices or AllMasterDevices, the event mask is not cleared on device removal and affects all future devices.

If mask_len is 0, the event mask for the given device is cleared.

The mask for XIHierarchyEvents may only be selected for XIAllDevices. Setting it for any other device results in a BadValue error.

A client selecting for any of XI_TouchBegin, XI_TouchUpdate, or XI_TouchEnd must select for all three events at the same time, else a BadValue error will be generated. A client selecting for XI_TouchOwnership must select for all three of the other touch events. If the selection for these touch events overlaps a current selection by another client (e.g. selecting for a specific device when another client has a selection for XIAllDevices), a BadAccess error occurs.

#### 13.1.4. XIGetSelectedEvents

    ┌───
        XIGetSelectedEvents
            window:         Window
            ▶
            num_masks:      CARD16
            masks:          LISTofEVENTMASK
    └───

    window
        The window to select the events on.
    num_masks
        Number of items in masks.
    masks
        Selected event masks by this client.

Masks are returned on a per-device basis, with masks for AllDevices and AllMasterDevices returned separately. A client can calculate the effective mask for a device with a bitwise OR of the AllDevices, the AllMasterDevices and the device-specific mask.

If num_masks is 0, no events have been selected by this client on the given window.

#### 13.1.5. XIQueryPointer

    ┌───
        XIQueryPointer
            window:         Window
            deviceid:       DEVICEID
            ▶
            root:           Window
            child:          Window
            root_x:         FP1616
            root_y:         FP1616
            win_x:          FP1616
            win_y:          FP1616
            same_screen:    BOOL
            mods:           MODIFIERINFO
            group:          GROUPINFO
            buttons_len:    CARD16
            buttons:        SETofBUTTONMASK
    └───

Query a master pointer device for its current position.

    root
        The root window the pointer is logically on.
    child
        The child window of window that contains the pointer or None.
    root_x
    root_y
        Pointer position relative to the root window's origin.
    win_x
    win_y
        Pointer position relative to window or 0 if same_screen is false.
    same_screen
        True if window is on the same screen as the pointer.
    mods
        XKB modifier state on the paired device.
    group
        XKB group state on the paired device.
    buttons_len
        The length of buttons in 4 byte units.
    buttons
        Button state.

If the device is not a master pointer device or not a floating slave pointer, a BadDevice error results.

#### 13.1.6. XIWarpPointer

    ┌───
        XIWarpPointer
            src_win:         Window
            dst_win:         Window
            src_x:           FP1616
            src_y:           FP1616
            src_width:       INT16
            src_height:      INT16
            dst_x:           FP1616
            dst_y:           FP1616
            deviceid:        DEVICEID
    └───

WarpPointer moves the pointer of deviceid as if the user had moved the pointer. WarpPointer can only be called for MasterPointer and FloatingSlave devices.

    src_win
       If src_window is not None, the move only takes place if src_window
       contains the pointer and the pointer is contained in the specified
       rectangle of src_window.
    dst_win
       If dst_win is None, this request moves the pointer by offsets
       dst_x/dst_y relative to the current position of the pointer. If
        dst_window is a window, this request moves the pointer to
       dst_x/dst_y relative to dst_win's origin.
    src_x
    src_y
    src_width
    src_height
       Specifies the source window rectangle.
    dst_x
    dst_y
        The relative coordinates to move the pointer if dst_win is None, or
        the absolute coordinates if dst_win is a window.
    deviceid
        The device to warp.

This request cannot be used to move the pointer outside the confine-to window of an active pointer grab. An attempt will only move the pointer as far as the closest edge of the confine-to window.

This request will generate events just as if the user had instantaneously moved the pointer.

#### 13.1.7. XIChangeCursor

    ┌───
        XIChangeCursor
            win:             Window
            cursor:          Cursor
            deviceid:        DEVICEID
    └───

Change a master pointer’s cursor on the specified window.

    window
        The window.
    cursor
        The new cursor or None.
    deviceid
        The master pointer device.

Whenever device enters a window W, the cursor shape is selected in the following order:

- if the current window has a device cursor C(d) defined for device, display this cursor C(d).

- otherwise, if the current window has a cursor C(w) defined in the core protocol’s window attributes, display cursor C(w).

- repeat on parent window until a cursor has been found.

The device cursor for a given window is reset once the window is destroyed or the device is removed, whichever comes earlier.

If deviceid does not specify a master pointer, a BadDevice error is returned.

#### 13.1.8. XIChangeHierarchy

    ┌───
        XIChangeHierarchy
            num_changes:     CARD8
            changes:         LISTofHIERARCHYCHANGES
    └───

    HIERARCHYCHANGE { ADDMASTER, REMOVEMASTER, ATTACHSLAVE, DETACHSLAVE }

    HIERARCHYCHANGETYPE { AddMaster, RemoveMaster, AttachSlave, DetachSlave }

    CHANGEMODE { Float, Attach }

    ADDMASTER { type:        HIERARCHYCHANGETYPE
                length:      CARD16
                name_len:    CARD16
                send_core:   BOOL
                enable:      BOOL
                name:        LISTofCHAR8 }

    REMOVEMASTER { type:            HIERARCHYCHANGETYPE
                   length:          CARD16
                   deviceid:        DEVICEID
                   return_mode:     CHANGEMODE
                   return_pointer:  DEVICEID
                   return_keyboard: DEVICEID }

    ATTACHSLAVE   { type:        HIERARCHYCHANGETYPE
                    length:      CARD16
                    deviceid:    DEVICEID
                    master:      DEVICEID }

    DETACHSLAVE { type:       HIERARCHYCHANGETYPE
                  length:     CARD16
                  deviceid:   DEVICEID }

XIChangeHierarchy allows a client to modify the Master/Slave device hierarchy.

    num_changes
        The number of changes to apply to the current hierarchy.
    changes
        The list of changes.

The server processes the changes in the order received from the client and applies each requested change immediately. If an error occurs, processing stops at the current change and returns the number of successfully applied changes in the error.

    ADDMASTER creates a pair of master devices.
    type
        Always AddMaster.
    length
        Length in 4 byte units.
    name_len
        Length of name in bytes.
    send_core
        True if the device should send core events.
    enable
        True if the device is to be enabled immediately.
    name
        The name for the new master devices. The master pointer's name is
        automatically appended with " pointer", the master keyboard's name is
        automatically appended with " keyboard".

    REMOVEMASTER removes an existing master device.
    type
        Always RemoveMaster.
    length
        Length in 4 byte units.
    deviceid
        The device to remove.
    return_mode
        Return mode for attached slave devices.
        If return_mode is Float, all slave devices are set to floating.
        If return_mode is Attach, slave pointers are attached to
        return_pointer and slave keyboards are attached to
        return_keyboard.
    return_pointer
    return_keyboard
        The master pointer and master keyboard to attach slave devices to, if
        return_mode is Attach. If return_mode is Float, return_pointer
        and return_keyboard are undefined.

Removing a master pointer removes the paired master keyboard and vice versa.

    ATTACHSLAVE attaches a slave device to a given master device.
    type
        Always ChangeAttachment.
    length
        Length in 4 byte units.
    deviceid
        Deviceid of the slave device.
    master
        The new master device to attach this slave device to.

If any clients are selecting for touch events from the slave device, their selection will be canceled.

    DETACHSLAVE detaches a slave device from its current master device.
    type
        Always ChangeAttachment.
    length
        Length in 4 byte units.
    deviceid
        Deviceid of the slave device.

#### 13.1.9. XISetClientPointer

    ┌───
        XISetClientPointer
            win:             Window
            deviceid:        DEVICEID
    └───

Set the ClientPointer for the client owning win to the given device.

    win
         Window or client ID.
    deviceid
         The master pointer or master keyboard that acts as ClientPointer.

Some protocol requests are ambiguous and the server has to choose a device to provide data for a request or a reply. By default, the server will choose a client’s ClientPointer device to provide the data, unless the client currently has a grab on another device. See section The ClientPointer principle for more details.

If win is None, the ClientPointer for this client is set to the given device. Otherwise, if win is a valid window, the ClientPointer for the client owning this window is set to the given device. Otherwise, if win is not a valid window but a client with the client mask equal to win exists, this client’s ClientPointer is set to the given device.

If deviceid does not specify a master pointer or master keyboard, a BadDevice error is returned.

If window does not specify a valid window or client ID and is not None, a BadWindow error is returned.

#### 13.1.10. XIGetClientPointer

    ┌───
        XIGetClientPointer
            win:             Window
            ▶
            set:             BOOL
            deviceid:        DEVICEID
    └───

Query the ClientPointer for the client owning win.

    win
        The window or client ID.
    set
        True if the client has a ClientPointer set.
    deviceid
        The master pointer that acts as a ClientPointer if set is True.

No difference is made between a ClientPointer set explicitly through XISetClientPointer and a ClientPointer implicitly assigned by the server in response to an ambiguous request.

#### 13.1.11. XISetFocus

    ┌───
        XISetFocus
            focus:           Window
            deviceid:        DEVICEID
            time:            Time
    └───

Set the focus for the given device to the given window. Future key events from this device are sent to this window. This request generates FocusIn and FocusOut events.

    focus
        A viewable window or None.
    deviceid
        The device to modify the focus window for.
    time
        Specifies the time to change the focus or CurrentTime.

If focus is None, key events from this device are discarded until a new focus window is set. If focus is a viewable window, key events from this device are sent to this window. If the window becomes unviewable, the window’s first viewable ancestor automatically becomes the focus window and FocusIn and FocusOut events are sent as if a client had changed the focus window. This is equivalent to RevertToParent in the core XSetInputFocus window.

This request has no effect if the specified time is earlier than the current last-focus-change time or is later than the current X server time. Otherwise, the last-focus-change time is set to the specified time.

#### 13.1.12. XIGetFocus

    ┌───
        XIGetFocus
            deviceid:        DEVICEID
            ▶
            focus:           Window
    └───

Return the current focus window for the given device.

#### 13.1.13. XIGrabDevice

    ┌───
        XIGrabDevice
            deviceid:        DEVICEID
            grab_window:     Window
            owner_events:    BOOL
            grab_mode:       { Synchronous, Asynchronous }
            paired_device_mode: { Synchronous, Asynchronous }
            time:            TIMESTAMP or CurrentTime
            cursor:          Cursor
            mask_len:        CARD16
            masks:           SETofEVTYPEMASK
            ▶
            status:          Success, AlreadyGrabbed, Frozen, InvalidTime, NotViewable
    └───

This request actively grabs control of the specified input device. Further input events from this device are reported only to the grabbing client. This request overides any previous active grab by this client for this device. This request does not affect the processing of XI 2.2 touch events.

    deviceid
        The device to grab.
    grab_window
        Events are reported relative to the grab window.
    owner_events
        Specifies whether event will be reported normally or relative to the
        grab window.
    grab_mode
        Specifies if this device will be frozen as a result of the grab.
    paired_device_mode
        Specifies if the master device paired with this device will be frozen
        as a result of the grab.
    time
        A valid server time or CurrentTime.
    cursor
        The cursor to display for the duration of the grab or None.
    mask_len
        Length of mask in 4 byte units.
    mask
        Event mask. An event mask for an event type T is defined as (1 << T).
    status
        Success or the reason why the grab could not be established.

The masks parameter specifies which events the client wishes to receive while the device is grabbed.

If owner-events is False, input events generated from this device are reported with respect to grab-window, and are only reported if selected by being included in the event-list. If owner-events is True, then if a generated event would normally be reported to this client, it is reported normally, otherwise the event is reported with respect to the grab-window, and is only reported if selected by being included in the event-list. For either value of owner-events, unreported events are discarded.

If grab-mode is Asynchronous, device event processing continues normally. If the device is currently frozen by this client, then processing of device events is resumed. If grab-mode is Synchronous, the state of the grabbed device (as seen by means of the protocol) appears to freeze, and no further device events are generated by the server until the grabbing client issues a releasing XIAllowEvents request or until the device grab is released. Actual device input events are not lost while the device is frozen; they are simply queued for later processing.

If the device is a slave device, the paired-device-mode is ignored. Otherwise, if this device is a master device and paired-device-mode is Asynchronous, event processing is unaffected by activation of the grab. If this device is a master device and paired-device-mode is Synchronous, the state of the master device paired with this device (as seen by means of the protocol) appears to freeze, and no further events are generated by the server until the grabbing client issues a releasing XIAllowEvents request or until the device grab is released. Actual events are not lost while the devices are frozen; they are simply queued for later processing.

If the cursor is not None and the device is a master pointer device, the cursor will be displayed until the device is ungrabbed.

This request fails and returns:

    AlreadyGrabbed: If the device is actively grabbed by some other client.
    NotViewable: If grab-window is not viewable.
    InvalidTime: If the specified time is earlier than the last-grab-time for
                 the specified device or later than the current X server time.
                 Otherwise, the last-grab-time for the specified device is set
                 to the specified time and CurrentTime is replaced by the
                 current X server time.
    Frozen: If the device is frozen by an active grab of another client.

To release a grab of a device, use XIUngrabDevice.

#### 13.1.14. XIUngrabDevice

    ┌───
        XIUngrabDevice
            deviceid:        DEVICEID
            time:            TIMESTAMP or CurrentTime
    └───

This request releases the device if this client has it actively grabbed (from either XIGrabDevice or XIPassiveGrabDevice) and releases any queued events. If any devices were frozen by the grab, XIUngrabDevice thaws them.

    deviceid
        The device to grab.
    time
        A valid server time or CurrentTime.

The request has no effect if the specified time is earlier than the last-device-grab time or is later than the current server time. This request generates FocusIn and FocusOut events. An XIUngrabDevice is performed automatically if the event window for an active device grab becomes not viewable.

#### 13.1.15. XIAllowEvents

    ┌───
        XIAllowEvents
            deviceid:        DEVICEID
            time:            TIMESTAMP or CurrentTime
            event_mode:      { AsyncDevice, SyncDevice,
                               AsyncPairedDevice, SyncPairedDevice,
                               ReplayDevice, AsyncPair, SyncPair,
                               AcceptTouch¹, RejectTouch¹ }
            touchid¹:        CARD32
            grab_window¹:    Window
    └───

    ¹ since XI 2.2

The XIAllowEvents request releases some queued events if the client has caused a device to freeze. It also is used to handle touch grab and ownership processing.

    deviceid
        The device to grab.
    time
        A valid server time or CurrentTime.
    event_mode
        Specifies whether a device is to be thawed and events are to be
        replayed, or how to handle a grabbed touch sequence.
    touchid
        The ID of the touch sequence to accept or reject. The value is undefined
        for event modes other than AcceptTouch and RejectTouch.
    grab_window
        The window on which to accept or reject a touch sequence grab. The value
        is undefined for event modes other than AcceptTouch and RejectTouch.

The request has no effect if the specified time is earlier than the last-grab time of the most recent active grab for the client, or if the specified time is later than the current X server time. The time parameter must be CurrentTime for requests with event modes of AcceptTouch and RejectTouch.

When event-mode is AcceptTouch, a BadValue error occurs if the touch ID is invalid. A BadAccess error occurs if this client is not the current or potential owner of the specified touch ID.

The following describes the processing that occurs depending on what constant you pass to the event-mode argument:

    AsyncDevice:
        If the specified device is frozen by the client, event processing for that
        device continues as usual. If the device is frozen multiple times  by the
        client on behalf of multiple separate grabs, AsyncDevice thaws for
        all.
        AsyncDevice has no effect if the specified device is not frozen by the
        client, but the device need not be grabbed by the client.
    SyncDevice:
        If the specified device is frozen and actively grabbed by the client,
        event processing for that device continues normally until the next
        event is reported to the client. At this time, the specified device
        again appears to freeze. However, if the reported event causes the
        grab to be released, the specified device does not freeze.
        SyncDevice has no effect if the specified device is not frozen by the
        client or is not grabbed by the client.
     ReplayDevice:
        If the specified device is actively grabbed by the client and is frozen
        as the result of an event having been sent to the client (either from
        the activation of a XIGrabButton or from a previous XIAllowEvents with
        mode SyncDevice, but not from a Grab), the grab is released and
        that event is completely reprocessed.  This time, however, the request
        ignores any passive grabs at or above (towards the root) the
        grab-window of the grab just released.
        The request has no effect if the specified device is not grabbed by
        the client or if it is not frozen as the result of an event.
     AsyncPairedDevice
        If the paired master device is frozen by the client, event processing
        for it continues as usual. If the paired device is frozen multiple
        times by the client on behalf of multiple separate grabs,
        AsyncPairedDevice thaws for all.
        AsyncPairedDevice has no effect if the device is not frozen by the
        client, but those devices need not be grabbed by the client.
        AsyncPairedDevice has no effect if deviceid specifies a slave device.
     SyncPairedDevice
        If the paired master device is frozen by the client, event processing (for
        the paired master device) continues normally until the next button or key
        event is reported to the client for the grabbed device (button event for
        the grabbed device, key or motion event for the device), at which time
        the device again appears to freeze. However, if the reported event causes
        the grab to be released, then the device does not freeze.
        SyncPairedDevice has no effect if the specified device is not grabbed
        by the client or if it is no frozen as the result of an event.
        SyncPairedDevice has no effect if deviceid specifies a slave device.
     SyncPair
        If both the device and the paired master device are frozen by the
        client, event processing (for both devices) continues normally until
        the next XIButtonPress, XIButtonRelease, XIKeyPress, or XIKeyRelease
        event is reported to the client for a grabbed device (button event for
        a pointer, key event for a keyboard), at which time the devices again
        appear to freeze. However, if the reported event causes the grab to be
        released, then the devices do not freeze (but if the other device is
        still grabbed, then a subsequent event for it will still cause both
        devices to freeze).
        SyncPair has no effect unless both the device and the paired master
        device are frozen by the client. If the device or paired master device
        is frozen twice by the client on behalf of two separate grabs,
        SyncPair thaws for both (but a subsequent freeze for SyncPair will
        only freeze each device once).
        SyncPair has no effect if deviceid specifies a slave device.
     AsyncPair
        If the device and the paired master device are frozen by the client,
        event processing for both devices continues normally. If a device is
        frozen twice by the client on behalf of two separate grabs, AsyncBoth
        thaws for both. AsyncPair has no effect unless both the device and the
        paired master device frozen by the client.
        AsyncPair has no effect if deviceid specifies a slave device.
     AcceptTouch
        The client is deemed to have taken control of the touch sequence once it
        owns the sequence. TouchEnd events will be sent to all clients listening
        to the touch sequence that have either grabbed the touch sequence on a
        child window of the grab_window or have received events for the touch
        sequence through event selection. These clients will no longer receive
        any TouchUpdate events.
     RejectTouch
        The client is no longer interested in the touch sequence, and will
        receive a TouchEnd event. If the client is the current owner of the
        sequence, ownership will be passed on to the next listener.

#### 13.1.16. XIPassiveGrabDevice

    ┌───
        XIPassiveGrabDevice
            deviceid:        DEVICE
            detail:          CARD32
            grab_type:       GRABTYPE
            time:            TIMESTAMP
            grab_window:     Window
            cursor:          Cursor
            owner_events:    Bool
            grab_mode:       { Synchronous, Asynchronous, Touch¹ }
            paired_device_mode: { Synchronous, Asynchronous }
            num_modifiers:   INT16
            mask_len:        CARD16
            masks:           SETofEVTYPEMASK
            modifiers:       LISTofSETofMODIFIERMASK
            ▶
            num_modifiers_return:    INT16
            modifiers_return:        LISTofGRABMODIFIERINFO
    └───

    GRABTYPE         { GrabtypeButton, GrabtypeKeycode, GrabtypeEnter,
                       GrabtypeFocusIn, GrabtypeTouchBegin¹ }

    GRABMODIFIERINFO {   status:    Access
                         modifiers: SETofMODIFIERMASK }

    ¹ since XI 2.2

Establish an explicit passive grab for a button or keycode on the specified input device.

    cursor
        The cursor to display for the duration of the grab. If grab_type
        is not GrabtypeButton, this argument is ignored.
    deviceid
        The device to establish the passive grab on or AllDevices or
        AllMasterDevices.
    detail
        The button number, or key symbol to grab for.
        Must be 0 for GrabtypeEnter, GrabtypeFocusIn, and
        GrabtypeTouchBegin.
    grab_type
        The type of grab to establish.
    grab_window
        Events are reported relative to the grab window.
    grab_mode
        If grab-mode is Asynchronous, device event processing continues
        normally.  If the device is currently frozen by this client, then
        processing of device events is resumed. If grab-mode is
        Synchronous, the state of the grabbed device (as seen by means of
        the protocol) appears to freeze, and no further device events are
        generated by the server until the grabbing client issues a
        releasing XIAllowEvents request or until the device grab is
        released. Actual device input events are not lost while the device
        is frozen; they are simply queued for later processing. If grab_type
        is GrabtypeTouchBegin, grab_mode must be set to Touch.
    mask_len
        Length of mask in 4 byte units.
    mask
        Event mask. An event mask for an event type T is defined as (1 << T).
    modifiers
        XKB modifier state to activate this passive grab.
    num_modifiers
        Number of elements in modifiers.
    owner_events
        Specifies whether event will be reported normally or relative to the
        grab window.
    num_modifiers_return
        Number of elements in modifiers_return
    modifiers_return
        XKB modifier state that could not be grabbed.
    time
        This field is unused.

If owner-events is False, input events generated from this device are reported with respect to grab-window, and are only reported if selected by being included in the event-list. If owner-events is True, then if a generated event would normally be reported to this client, it is reported normally, otherwise the event is reported with respect to the grab-window, and is only reported if selected by being included in the event-list. For either value of owner-events, unreported events are discarded.

If deviceid specifies a master pointer, the modifiers of the paired master keyboard are used. If deviceid specifies a slave pointer the modifiers of the master keyboard paired with the attached master pointers are used. If deviceid specifies a slave keyboard, the modifiers of the attached master keyboard are used. Note that activating a grab on a slave device detaches the device from its master. In this case, the modifiers after activation of the grab are from the slave device only and may be different to the modifier state when the grab was triggered.

In the future, if grab_type is GrabtypeButton or GrabtypeKeyboard, the device is actively grabbed if:

- the device is not grabbed, and

- the specified modifier keys are down, and

- the grab_type is GrabtypeButton and the button specified in detail is logically pressed or the grab_type is GrabtypeKeycode and the keycode specified in detail is logically pressed, and

- the grab_window contains the pointer, and

- a passive grab on the same button/keycode + modifier combination does not exist on an ancestor of grab_window.

Otherwise, if grab_type is GrabtypeEnter or GrabtypeFocusIn, the device is actively grabbed if:

- the device is not actively grabbed, and

- the specified modifier keys are down, and

- the grab_type is GrabtypeEnter and the device’s pointer has moved into grab_window or a descendant of grab_window, or the grab_type is GrabtypeFocusIn and the device’s focus has been set to the grab_window or a descendant of grab_window, and

- a passive grab of the same grab_type + modifier combination does not does not exist on an ancestor of grab_window.

Otherwise, if grab_type is GrabtypeTouchBegin, a touch grab begins if:

- the device is not actively grabbed, and

- the specified modifier keys are down

- a touch begins in grab_window or a descendant of grab_window, and

- a passive grab of the same grab_type + modifier combination does not does not exist on an ancestor of grab_window.

Ownership of the touch sequence is granted to the grabbing client if:

- a TouchBegin or pointer grab for an emulated touch sequence of a direct touch device with the same modifier set does not exist on an ancestor of grab_window, or all applicable grabs have released ownership.

A modifier of GrabAnyModifier is equivalent to issuing the request for all possible modifier combinations (including no modifiers). A client may request a grab for GrabAnyModifier and explicit modifier combinations in the same request.

A GrabtypeButton or GrabtypeKeyboard grab is released when all buttons or keycode are released, independent of the state of modifier keys. A GrabtypeEnter or GrabtypeFocusIn grab is released when the pointer or focus leaves the window and all of its descendants, independent of the state of modifier keys. A GrabtypeTouchBegin grab is released when the touch sequence ends or the client uses XIAllowEvents with mode RejectTouch. Note that the logical state of a device (as seen by means of the protocol) may lag the physical state if device event processing is frozen.

This request overrides all previous passive grabs by the same client on the same button/key/enter/focus in + modifier combinations on the same window.

If some other client already has issued a XIPassiveGrabDevice request with the same button or keycode and modifier combination, the failed modifier combinations is returned in modifiers_return. If some other client already has issued an XIPassiveGrabDevice request of grab_type XIGrabtypeEnter, XIGrabtypeFocusIn, or XIGrabtypeTouchBegin with the same grab_window and the same modifier combination, the failed modifier combinations are returned in modifiers_return. If num_modifiers_return is zero, all passive grabs have been successful.

If a button grab or enter grab activates, EnterNotify and LeaveNotify events with mode Grab are generated as if the pointer were to suddenly warp from its current position some position in the grab_window. However, the pointer does not warp, and the pointer position is used as both the initial and final positions for the events.

If a keycode grab or focus grab activates, FocusIn and FocusOut events with mode Grab are generated as if the focus were to change from the current window to the grab_window.

If an enter or focus in grab activates, additional EnterNotify events with mode XIPassiveGrabNotify are generated as if the pointer or focus were to suddenly warp from its current position to some position in the grab window. These events are sent to the grabbing client only and only if the grab event mask has selected for it. If such a passive grab deactivates, addional LeaveNotify events with mode XIPassiveUngrabNotify are generated and sent to the grabbing client before the grab deactivates.

For GrabtypeTouchBegin, grab_mode must be Touch or a BadValue error is generated.

See section Ownership of touch sequences for additional notes on touch grabs, as they do not behave like traditional grabs: in particular, they do not freeze the device, and delivery of touch events continues even if the device is frozen due to a grab by another client.

#### 13.1.17. XIPassiveUngrabDevice

    ┌───
        XIPassiveUngrabDevice
            deviceid:        DEVICEID
            detail:          CARD32
            grab_type:       GRABTYPE
            grab_window:     Window
            num_modifiers:   INT16
            modifiers:       LISTofSETofMODIFIERMASK
    └───

Release an explicit passive grab on the specified input device.

    deviceid
        The device to establish the passive grab on.
    detail
        The button number or key symbol to ungrab.
        Must be 0 for GrabtypeEnter, GrabtypeFocusIn, and
        GrabtypeTouchBegin.
    grab_type
        The type of grab to establish.
    grab_window
        Events are reported relative to the grab window.
    modifiers
        XKB modifier state to activate this passive grab.
    num_modifiers
        Number of elements in modifiers.

This request has no effect if the client does not have a passive grab of the same type, same button or keycode (if applicable) and modifier combination on the grab_window.

#### 13.1.18. XIListProperties

    ┌───
        XIListProperties
            deviceid:        DEVICEID
            ▶
            num_properties:  INT16
            properties:      LISTofATOM
    └───

List the properties associated with the given device.

    deviceid
        The device to list the properties for.
    num_properties
        Number of properties in the reply
    properties
        All properties on the device.

#### 13.1.19. XIChangeProperty

    ┌───
        XIChangeProperty
            deviceid:        DEVICEID
            property:        ATOM
            type:            ATOM
            format:          { 8, 16, 32 }
            mode:            { Append, Prepend, Replace }
            num_items:       CARD32
            data:            LISTofINT8, or LISTofINT16, or LISTofINT32
    └───

Change the given property on the given device.

    deviceid
        The device to change the property on.
    property
        The property to modify.
    type
        The property's type.
    mode
        One of Append, Prepend, or Replace
    num_items
        Number of items following this request.
    data
        Property data (nitems * format/8 bytes)

The type is uninterpreted by the server. The format specifies whether the data should be viewed as a list of 8-bit, 16-bit, or 32-bit quantities so that the server can correctly byte-swap as necessary.

If the mode is Replace, the previous propert y value is discarded. If the mode is Prepend or Append, then the type and format must match the existing property value (or a Match error results). If the property is undefined, it is treated as defined with the correct type and format with zero-length data. For Prepend, the data is tacked on to the beginning of the existing data, and for Append, it is tacked on to the end of the existing data.

The lifetime of a property is not tied to the storing client. Properties remain until explicitly deleted, until the device is removed, or until server reset.

A property cannot be deleted by setting nitems to zero. To delete a property, use XIDeleteProperty.

This request generates an XIPropertyEvent.

#### 13.1.20. XIDeleteProperty

    ┌───
        XIDeleteProperty
            deviceid:        DEVICEID
            property:        ATOM
    └───

Deletes the given property on the given device.

    deviceid
        The device to delete the property on.
    property
        The property to delete.

If the property is deleted, an XIPropertyEvent is generated on the device. If the property does not exist, this request does nothing.

#### 13.1.21. XIGetProperty

    ┌───
        XIGetProperty
            deviceid:        DEVICEID
            property:        ATOM
            type:            Atom or AnyPropertyType
            offset:          CARD32
            len:             CARD32
            delete:          BOOL
            ▶
            type:            Atom
            bytes_after:     CARD32
            num_items:       CARD32
            format:          { 8, 16, 32 }
            data:            LISTofINT8, or LISTofINT16, or LISTofINT32
    └───

Get the data for the given property on the given device.

    deviceid
        The device to retrieve the property data from.
    property
        The property to retrieve the data from..
    type
        The property type to retrieve or AnyPropertyType
    offset
        The offset in 4-byte units.
    len
        Number of bytes to receive in 4-byte units.
    delete
        Delete the property after retrieving the data.
    bytes_after
        Number of unread bytes in the stored property
    num_items
        Number of items in data
    format
        8, 16, or 32
    data
        Property data (nitems * format/8 bytes)

If the specified property does not exist for the specified device, then the return type is None, the format and bytes-after are zero, and the value is empty. The delete argument is ignored in this case. If the specified property exists but its type does not match the specified type, then the return type is the actual type of the property, the format is the actual format of the property (never zero), the bytes-after is the length of the property in bytes (even if the format is 16 or 32), and the value is empty. The delete argument is ignored in this case. If the specified property exists and either AnyPropertyType is specified or the specified type matches the actual type of the property, then the return type is the actual type of the property, the format is the actual format of the property (never zero), and the bytes-after and value are as follows, given: N = actual length of the stored property in bytes (even if the format is 16 or 32) I = 4 * long-offset T = N−I L = MINIMUM(T, 4 * long-length) A = N − (I + L) The returned value starts at byte index I in the property (indexing from 0), and its length in bytes is L. However, it is a Value error if offset is given such that L is negative. The value of bytes_after is A, giving the number of trailing unread bytes in the stored property. If delete is True and the bytes_after is zero, the property is also deleted from the device, and a XIPropertyNotify event is generated on the device.

### 13.2. Requests introduced in version 2.3

#### 13.2.1. XIBarrierReleasePointer

    ┌───
        XIBarrierReleasePointer
            num_items:       CARD32
            ▶
            data:            LISTofBARRIERRELEASEINFO
    └───

    BARRIERRELEASEINFO { deviceid: DEVICEID,
                         barrier:  Barrier,
                         eventid: CARD32 }

Release a pointer currently blocked by a barrier. In the future, movement of this pointer against the barrier will not be blocked.

    deviceid
        The device currently being blocked by a barrier
    barrier
        The barrier currently blocking the device
    eventid
        The unique event ID assigned to this barrier event sequence

If the barrier given does not currently block this device, or the eventid is invalid, this request does nothing.

Releasing a pointer barrier is only valid during one barrier event sequence, and only applies to the next movement of this device against this barrier. If the pointer moves away from the barrier following a XIBarrierReleasePointer request, the release request is discarded. In the future, if the pointer moves against the barrier again, a new eventid is assigned and the client must re-issue the XIBarrierReleasePointer request.

If the device is not a master pointer device, a BadDevice error results. If the barrier does not name a valid barrier, a BadValue error results.

## 14. Events

An event specifies its length in 4-byte units after the initial 32 bytes. Future versions of the protocol may provide additional information in the same event, thus increasing the event size. Clients are required to always read the number of bytes specified by the event, not the size of the event they may have been compiled against.

The following event types are available in XI2.

Version 2.0:

- HierarchyChanged

- DeviceChanged

- KeyPress

- KeyRelease

- ButtonPress

- ButtonRelease

- Motion

- RawKeyPress

- RawKeyRelease

- RawButtonPress

- RawButtonRelease

- RawMotion

- Enter

- Leave

- FocusIn

- FocusOut

- PropertyEvent

Version 2.2:

- TouchBegin

- TouchUpdate

- TouchOwnership

- TouchEnd

- RawTouchBegin

- RawTouchUpdate

- RawTouchEnd

Version 2.3:

- BarrierHit

- BarrierLeave

All events have a set of common fields specified as EVENTHEADER.

    EVENTHEADER { type:                       BYTE
                  extension:                  BYTE
                  sequenceNumber:             CARD16
                  length:                     CARD32
                  evtype:                     CARD16
                  deviceid:                   DEVICEID
                  time:                       Time }

    type
        Always GenericEvent.
    extension
        Always the X Input extension offset.
    sequenceNumber
        Sequence number of last request processed by the server.
    length
        Length in 4-byte units after the initial 32 bytes.
    evtype
        XI-specific event type.
    deviceid
        Numerical device id for a device.
    time
        Time in ms when the event occurred.

### 14.1. Events introduced in version 2.0

#### 14.1.1. HierarchyEvent

    ┌───
        HierarchyEvent
            EVENTHEADER
            flags:                      SETofHIERARCHYMASK
            num_info:                   CARD16
            info:                       LISTofHIERARCHYINFO
    └───

    HIERARCHYMASK { MasterAdded, MasterRemoved, SlaveAttached, SlaveDetached,
                    SlaveAdded, SlaveRemoved, DeviceEnabled, DeviceDisabled }

    HIERARCHYINFO { deviceid:           DEVICEID,
                    attachment:         DEVICEID,
                    type:               DEVICEUSE
                    enabled:            BOOL
                    flags:              SETofHIERARCHYMASK}

    flags
        Set of the changes that have occured, causing this event.
    num_info
        The number of device info structs following the request.
    info:
        The current hierarchy information.

An XIHierarchyEvent is sent whenever the device hierarchy been changed. The flags specify all types of hierarchy modifiations that have occured. For all devices, info details the hierarchy information after the modification of the hierarchy has occured. For each device specified with deviceid:

- if type is MasterPointer or MasterKeyboard, attachment decribes the pairing of this device.

- if type is SlavePointer or SlaveKeyboard, attachment describes the master device this device is attached to.

- if type is FloatingSlave device, attachment is undefined.

      enabled
           True if the device is enabled and can send events. A disabled master
           device will not forward events from an attached, enabled slave
           device.

Note: Multiple devices may be affected in one hierarchy change, deviceid in an XIHierarchyEvent is always the first affected device. Clients should ignore deviceid and instead use the devices list.

#### 14.1.2. DeviceChangedEvent

    ┌───
        DeviceChangedEvent
            EVENTHEADER
            reason:                CHANGEREASON
            source:                DEVICEID
            num_classes:           CARD16
            classes:               LISTofCLASS
    └───

    CHANGEREASON { SlaveSwitch, DeviceChange }

A DeviceChangeEvent is sent whenever a device changes it’s capabilities. This can happen either by a new slave device sending events through a master device, or by a physical device changing capabilities at runtime.

    reason
        The reason for generating this event.
        If reason is SlaveSwitch, the slave device sending events through
        this device has changed and source specifies the new slave device.
        A SlaveSwitch reason can only occur on a master device.
        If reason is DeviceChange, the device itself has changed through
        other means (e.g. a physical device change) and source is
        the device itself.
    source
        The source of the new classes.
    num_classes
        Number of classes provided.
    classes
        Details the available classes provided by the device.  The order the
        classes are provided in is undefined.

For a detailed description of classes, see the XIQueryDevice request.

#### 14.1.3. DeviceEvent

    ┌───
        DeviceEvent
            EVENTHEADER
            detail:                     CARD32
            root:                       Window
            event:                      Window
            child:                      Window
            root_x:                     FP1616
            root_y:                     FP1616
            event_x:                    FP1616
            event_y:                    FP1616
            buttons_len:                CARD16
            valuators_len:              CARD16
            sourceid:                   DEVICEID
            mods:                       MODIFIERINFO
            group:                      GROUPINFO
            flags:                      DEVICEEEVENTFLAGS
            buttons:                    SETofBUTTONMASK
            valuators:                  SETofVALUATORMASK
            axisvalues:                 LISTofFP3232
    └───

    BUTTONBIT { (1 << Button1), (1 << Button2), ... , (1 << ButtonN) }
    VALUATORBIT { (1 << 1), ( 1 << 2), ... ( 1 << n) }

    MODIFIERINFO  { base_mods:           CARD32,
                    latched_mods:        CARD32,
                    locked_mods:         CARD32,
                    effective_mods:      CARD32}
    GROUPINFO     { base_group:          CARD8,
                    latched_group:       CARD8,
                    locked_group:        CARD8,
                    effective_group:     CARD8}

    DEVICEEVENTFLAGS (all events): none
    DEVICEEVENTFLAGS (key events only): { KeyRepeat }
    DEVICEEVENTFLAGS (pointer events only): { PointerEmulated }
    DEVICEEVENTFLAGS (touch events only): { TouchPendingEnd,
                                            TouchEmulatingPointer }

An XIDeviceEvent is generated whenever the logical state of a device changes in response to a button press, a button release, a motion, a key press or a key release. The event type may be one of KeyPress, KeyRelease, ButtonPress, ButtonRelease, Motion.

XI 2.2: The event type may also be TouchBegin, TouchUpdate, or TouchEnd.

    detail
        The button number, key code, touch ID, or 0.
    root
    event
    child
        The root window, event window or subwindow, respectively. See core
        protocol specification for more detail.
    root_x
    root_y
        The position of the pointer in screen coordinates (16.16 fixed point).
    event_x
    event_y
        The position of the pointer in screen coordinates relative to the
        event window (16.16 fixed point).

    buttons_len
        The length of buttons in 4 byte units.
    valuators_len
        The length of valuators in 4 byte units.
    sourceid
        The source device that originally generated the event.
    mods
        XKB modifier state before the event occured.
    group
        XKB group state before the event.
    buttons
        Button state before the event.
    valuators
        Bitmask of valuators provided in axisvalues.
    axisvalues
        Valuator data in device-native resolution. This is a non-sparse
        array, value N represents the axis corresponding to the Nth bit set
        in valuators.
    flags
        Miscellaneous information about this event; the union of the
        common flag set and either the key or pointer flag set,
        depending on the event type.
        KeyRepeat means that this event is for repeating purposes, and
        the physical state of the key has not changed.  This is only
        valid for KeyPress events.
        PointerEmulated signals that the event has been emulated from another
        XI 2.x event for legacy client support, and that this event should
        be ignored if the client listens for these events.  This flag is
        set on scroll ButtonPress and RawButtonPress events (buttons 4, 5, 6
        and 7) if a smooth-scrolling event on the Rel Vert Scroll or
        Rel Horiz Scroll axes was also generated. It is also set on Motion,
        ButtonPress, and ButtonRelease events generated by direct touch devices.
        TouchPendingEnd (for touch events only) means that the touch
        has physically ended, however another client still holds a grab, so the
        touch should be considered alive until all grabbing clients have
        accepted or passed on ownership.  The touch will not generate any
        further TouchUpdate events once an event with TouchPendingEnd has been
        received.
        TouchEmulatingPointer is set on touch events that emulate pointer
        events.

Modifier state in mods is detailed as follows:

    base_mods
        XKB base modifier state.
    latched_mods
        XKB latched modifier state.
    locked_mods
        XKB locked modifier state.

Group state in group is detailed as follows:

    base_group
        XKB base group state.
    latched_group
        XKB latched group state.
    locked_group
        XKB locked group state.

In servers supporting XI 2.2, a TouchBegin event is generated whenever a new touch sequence initializes. A TouchEnd event is generated whenever a touch sequence ceases. A TouchUpdate event is generated whenever a valuator value changes, or a flag flag (e.g. pending end) has changed for that touch sequence; this may result in a TouchUpdate event being sent with zero valuators.

The average finger size is significantly larger than one pixel. The selection of the hotspot of a touchpoint is implementation dependent and may not be the logical center of the touch.

Touch tracking IDs are provided in the detail field of touch events. Its value is always provided in every touch event. Tracking IDs are represented as unsigned 32-bit values and increase strictly monotonically in value for each new touch, wrapping back to 0 upon reaching the numerical limit of IDs. The increment between two touch IDs is indeterminate. Clients may not assume that any future touches will have specific touch IDs. IDs are globally unique.

The button state in touch events represents the state of the device’s physical buttons only, even if that sequence is emulating pointer events.

Touch events do not generate enter/leave events.

#### 14.1.4. RawEvent

    ┌───
        RawEvent
            EVENTHEADER
            detail:                    CARD32
            sourceid¹:                 DEVICEID
            flags:                     DEVICEEVENTFLAGS
            valuators_len:             CARD16
            valuators:                 SETofVALUATORMASK
            axisvalues:                LISTofFP3232
            axisvalues_raw:            LISTofFP3232
    └───

    ¹ since XI 2.1

A RawEvent provides the information provided by the driver to the client. RawEvent provides both the raw data as supplied by the driver and transformed data as used in the server. Transformations include, but are not limited to, axis clipping and acceleration. Transformed valuator data may be equivalent to raw data. In this case, both raw and transformed valuator data is provided. RawEvents are sent exclusively to all root windows. Clients supporting XI 2.0 receive raw events when the device is not grabbed, or when the device is grabbed by the client but not when the device is grabbed by another client. Clients supporting XI 2.1 or later receive raw events at all times, even when the device is grabbed by another client.

    eventtype
        The type of event that occured on the device.
    detail
        The button number, keycode or touch ID¹.
    sourceid
        The source device that originally generated the event. The sourceid
        is undefined for clients not supporting XI 2.1.
    flags
        Flags as described in DeviceEvent.
    valuators_len
        The length of valuators in 4 byte units.
    valuators
        Bitmask of valuators provided in axisvalues and axisvalues_raw.
    axisvalues
        Valuator data in device-native resolution. This is a non-sparse
        array, value N represents the axis corresponding to the Nth bit set
        in valuators.
    axisvalues_raw
        Untransformed valuator data in device-native resolution. This is a
        non-sparse array, value N represents the axis corresponding to the
        Nth bit set in valuators.

    ¹ since XI 2.2

#### 14.1.5. Enter or Leave or FocusIn or FocusOut

    ┌───
        Enter or Leave or FocusIn or FocusOut
            EVENTHEADER
            root:               Window
            event:              Window
            child:              Window
            sourceid:           DEVICEID
            root_x:             FP1616
            root_y:             FP1616
            event_x             FP1616
            event_y:            FP1616
            mode:               NOTIFYMODE
            detail:             NOTIFYDETAIL
            same_screen:        BOOL
            focus:              BOOL
            mods:               MODIFIERINFO
            group:              GROUPINFO
            buttons_len:        CARD16
            buttons:            SETofBUTTONMASK
    └───

    NOTIFYMODE { Normal, Grab, Ungrab }
    NOTIFYDETAIL { Ancestor, Virtual, Inferior, Nonlinear, NonlinearVirtual,
                   Pointer, PointerRoot, None }

Enter or Leave events are sent whenever a device’s pointer enters or leaves a window. FocusIn or FocusOut events are sent whenever a device’s focus is set to or away from a window. The enter/leave and focus in/out model is described in the core protocol specification, Section 11. (EnterNotify, LeaveNotify events).

For enter and leave events, the modifier and group state is the state of the paired master device if the device is a master device, or the state of the attached master keyboard if the device is an attached slave device, or zero if the device is a floating slave device.

For focus in and out events, the button state is the state of the paired master device if the device is a master device, or the state of the attached master keyboard if the device is an attached slave device, or zero if the device is a floating slave device.

    root
    event
    child
        The root window, event window, and child window, respectively. See the
        core protocol specification for more detail.
    sourceid
        The device that caused the pointer to move.
    root_x
    root_y
        The pointer coordinates relative to the root window.
    event_x
    event_y
        The pointer coordinates relative to the event window.
    mode
        Normal pointer motion events have mode Normal. Pseudo-motion events
        when a grab activates have mode Grab, and pseudo-motion events when a
        grab deactivates have mode Ungrab. Pseudo-motion events caused by the
        activation or deactivation of a passive enter or focus in grab have mode
        XIPassiveGrabNotify or XIPassiveUngrabNotify.
    detail
        Specifies the relation of the event window to the window the pointer
        entered or left. See the core protocol spec for details.
    same_screen
        True if the event window is on the same screen as the pointer's root
        window.
    focus
        If the event window is the focus window or an inferior of the focus
        window, then focus is True. Otherwise, focus is False. This field is
        unspecified for focus in/out events.
    mods
        XKB modifier state before the event occured.
    group
        XKB group state before the event.
    buttons_len
        The length of buttons in 4 byte units.
    buttons
        Button state before the event.

#### 14.1.6. XIPropertyEvent

    ┌───
        XIPropertyEvent
            EVENTHEADER
            property:           ATOM
            what:               { PropertyCreated, PropertyDeleted, PropertyModified }
    └───

XIPropertyEvents are sent whenever a device property is created, deleted or modified by a client.

    property
        The property that has been created, deleted, or modified
    what
        Specifies what has been changed.

### 14.2. Events introduced in version 2.2

#### 14.2.1. TouchOwnershipEvent

    ┌───
        TouchOwnershipEvent
            EVENTHEADER
            touchid:                    CARD32
            root:                       Window
            event:                      Window
            child:                      Window
            sourceid:                   DEVICEID
            flags:                      SETofTOUCHOWNERSHIPFLAGS
    └───

    TOUCHOWNERSHIPFLAGS:    (none currently defined)

A TouchOwnershipEvent indicates that ownership has changed, and the client is now the owner of the touch sequence specified by touchid.

    touchid
        The identifier of the touch sequence.
    root
    event
    child
        The root window, event window, and child window, respectively. See the
        core protocol specification for more detail.
    sourceid
        The source device that originally generated the event.
    flags
        A bitmask of flags for this event.

### 14.3. Events introduced in version 2.3

#### 14.3.1. BarrierEvent

    ┌───
        BarrierEvent
            EVENTHEADER
            eventid:                    CARD32
            root:                       Window
            event:                      Window
            barrier:                    Barrier
            dtime:                      CARD32
            flags:                      SETofBARRIERFLAGS
            sourceid:                   DEVICEID
            root_x:                     FP1616
            root_y:                     FP1616
            dx:                         FP3232
            dy:                         FP3232
    └───

    BARRIERFLAGS { PointerReleased, DeviceIsGrabbed }

A BarrierEvent indicates interaction between a barrier and a pointer device. If the event type is BarrierHit, pointer movement has been blocked by a barrier. If the event type is BarrierLeave, a pointer previously blocked by a barrier has moved away from that barrier, or has moved through the blocking barrier following an earlier XIBarrierReleasePointer request.

    eventid
       The unique event ID for this barrier event sequence.
    root
    event
        The root window or barrier window, respectively. The barrier window
        is always the drawable specified in in the CreatePointerBarrier request.
    barrier
        The barrier blocking pointer movement.
    dtime
        The relative time in milliseconds between the last event and this
        event.
    flags
        A set of flags that apply to this barrier event
        PointerReleased:
           The pointer has moved through the barrier following a
           XIBarrierReleasePointer request (BarrierLeave only).
        DeviceIsGrabbed:
           The pointer device that generated this event is currently
           grabbed.
    sourceid
        The source device that originally generated the event.
    root_x
    root_y
        The position of the pointer in screen coordinates (16.16 fixed
        point), after being constrained by barrier and/or screen extents.
    dx
    dy
        The relative movement of the pointer from its previous position to
        the new position if pointer movement were not constrained by this
        barrier.

Root coordinates in barrier events represent the position of the cursor after confinement by barriers, screens and RandR output extents.

Barrier event IDs are provided in the eventid field of barrier events. Its value is always provided in every barrier event. Event IDs are represented as unsigned 32-bit values and increase strictly monotonically in value for each new barrier event sequence, wrapping back to 0 upon reaching the numerical limit of IDs. The increment between two event IDs is indeterminate. Clients may not assume that any future barrier constraints will have specific event IDs. IDs are unique per device per barrier.

If a pointer is actively grabbed after a barrier event sequence has initiated, future barrier events of this sequence continue to use the same eventid, but all barrier events have the DeviceIsGrabbed flag set. If the pointer is ungrabbed, future events of this sequence have the same eventid and the DeviceIsGrabbed flag is unset.

The PointerReleased flag may only be set on a BarrierLeave event. A BarrierLeave(PointerReleased) event is generated when the pointer moves through the barrier following a XIBarrierReleasePointer request. The time between the XIBarrierReleasePointer and the BarrierLeave event thus depends on user input. A BarrierLeave(PointerReleased) event is also generated if the barrier is destroyed while pointer movement is constrained by the barrier, or the master pointer blocked by the barrier is removed. This event has a dx/dy of 0/0.

## Appendix A: XI 2.2 Use-cases

All use-cases that include the receiving and processing of touch events require the client to announce XI 2.2 support in the XIQueryVersion request.

### Client C wants to process touch events from a device D on window W.

- C calls XISelectEvent for XI_Touch{Begin|Update|End} from D on W.

- C receives TouchBegin whenever a touch sequence starts within W’s borders.

- C receives TouchUpdate events whenever an axis valuator value changes for a touch sequence it received a TouchBegin event for.

- C receives TouchEnd whenever a touch it received a TouchBegin event for ceases.

#### While client I wants to pre-process touch events from device D on the parent window of W.

- C calls XISelectEvent for XI_Touch{Begin|Update|Ownership|End} from D on W.

- I calls XIPassiveGrab for XI_Touch{Begin|Update|Ownership|End} from D on a parent window of W.

- I receives TouchBegin whenever a touch begins within window W, as well as a TouchOwnership event indicating that it currently owns the touch sequence. C receives a TouchBegin event as well, but without TouchOwnership.

- When an axis valuator changes in this touch sequence, both I and C receive a TouchUpdate event. I may process the event to determine if it is going to accept or reject the touch, whereas C may perform reversible processing.

- If I decides it is going to claim the touch sequence for its exclusive processing, it calls XIAllowEvents with an event mode of XIAcceptTouch; at this point, C receives a TouchEnd event, and undoes any processing it has already performed due to the touch sequence. Further TouchUpdate events are delivered only to I.

- Alternatively, if I decides it does not want to receive further events from this touch sequence, it calls XIAllowEvents with an event mode of XIRejectTouch; at this point, I receives a TouchEnd event confirming that it has rejected the touch. C receives a TouchOwnership event confirming that it is now the new owner of the touch, and further TouchUpdate events are delivered only to C. As C now owns the touch, it is free to perform irreversible processing of the sequence.

- When the touch physically ceases, a TouchEnd event is sent to C.

#### While client I wants to process pointer events on window W’s parent, window Y.

- I calls XIPassiveGrab for XI_{ButtonPress,MotionNotify,ButtonRelease} to create a synchronous pointer grab from D on Y.

- C calls XISelectEvent for XI_Touch{Begin|Update|Ownership|End} from D on W.

- I receives a ButtonPress event whenever a touch begins within W, and is considered the owner of the event. C receives a TouchBegin event, but does not receive a TouchOwnership event.

- When the touchpoint moves, C will receive a TouchUpdate event. Event delivery to I is subject to the synchronous delivery mechanism. The emulated motion notify event is queued in the server while the device is frozen.

- I may assert ownership by calling XIAllowEvents on Y with any mode other than ReplayDevice, which will cause all further events to be sent only to I, with a TouchEnd event being sent to C.

- Alternatively, I may reject the touch sequence by calling XIAllowEvents on Y with mode ReplayDevice, which will cause no further events from that touch to be sent to I, and a TouchOwnership event to be sent to C, with subsequent motion events being sent as TouchUpdate events.

### Driver DRV provides touch support from tracked device D:

- DRV initializes a TouchClass for the device.

- DRV parses D’s device protocol and selects one touch sequence to be emulated as pointer event.

- DRV calls the respective input driver API with the touch sequence data. The touch sequence emulating a pointer has the respective flag set. DRV does not submit pointer data for any touchpoint.