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IOHIDQueueInterface

Declared In:

Overview

CFPlugin object subclass which provides an interface for input queues from HID devices. Created by an IOHIDDeviceInterface object.

Functions

addElement: Adds an element to the queue.
create(void *): Disposes of the current queue.
create(void *, uint32_t, uint32_t): Creates the current queue.
createAsyncEventSource: Creates an async event source.
createAsyncPort: Creates an async port.
dispose: Disposes of the current queue.
getAsyncEventSource: Obtains the current event source.
getAsyncPort: Obtains the current async port.
getEventCallout: Gets the event callout.
getNextEvent: Reads next event from the queue.
hasElement: Checks whether an element has been added to the queue.
removeElement: Removes an element from the queue.
setEventCallout: Sets the event callout to be called when the queue transitions to non-empty.
start: Starts event delivery to the queue.
stop: Stops event delivery to the queue.

addElement

Adds an element to the queue.

IOReturn ( *addElement)(
    void *self, 
    IOHIDElementCookie elementCookie, 
    uint32_t flags);

Parameters

elementCookie: The element of interest.
flags

Return Value

Returns an IOReturn code.

Discussion

If the element has already been added to queue, an error will be returned.

create(void *)

Disposes of the current queue.

IOReturn ( *dispose)(
    void *self);

Return Value

Returns an IOReturn code.

create(void *, uint32_t, uint32_t)

Creates the current queue.

IOReturn ( *create)(
    void *self, 
    uint32_t flags, 
    uint32_t depth);

Parameters

flags: Pass kIOHIDQueueOptionsTypeEnqueueAll option to force the IOHIDQueue to enqueue all events, relative or absolute, regardless of change.
depth: The maximum number of elements in the queue before the oldest elements in the queue begin to be lost.

Return Value

Returns an IOReturn code.

createAsyncEventSource

Creates an async event source.

IOReturn ( *createAsyncEventSource)(
    void *self, 
    CFRunLoopSourceRef *source);

Parameters

source: The newly created event source.

Return Value

Returns an IOReturn code.

Discussion

This will be used with setEventCallout.

createAsyncPort

Creates an async port.

IOReturn ( *createAsyncPort)(
    void *self,
    mach_port_t *port);

Parameters

port: The newly created async port.

Return Value

Returns an IOReturn code.

Discussion

This will be used with createAsyncEventSource.

dispose

Disposes of the current queue.

IOReturn ( *dispose)(
    void *self);

Return Value

Returns an IOReturn code.

getAsyncEventSource

Obtains the current event source.

CFRunLoopSourceRef ( *getAsyncEventSource)(
    void *self);

Return Value

Returns a CFRunLoopSourceRef.

getAsyncPort

Obtains the current async port.

mach_port_t ( *getAsyncPort)(
    void *self);

Return Value

Returns a mach_port_t.

getEventCallout

Gets the event callout.

IOReturn ( *getEventCallout)(
    void *self, 
    IOHIDCallbackFunction *outCallback, 
    void **outCallbackTarget, 
    void **outCallbackRefcon);

Parameters

callback: if non-NULL is a callback to be called when data is inserted to the queue
callbackTarget: The callback target passed to the callback
callbackRefcon: The callback refcon passed to the callback

Return Value

Returns an IOReturn code.

Discussion

This callback will be called the queue transitions to non-empty.

getNextEvent

Reads next event from the queue.

IOReturn ( *getNextEvent)(
    void *self, 
    IOHIDEventStruct *event, 
    AbsoluteTime maxTime, 
    uint32_t timeoutMS);

Parameters

event: The event that will be filled. If a long value is present, it is up to the caller to deallocate it.
maxtime: UNSUPPORTED. If non-zero, limits read events to those that occured on or before maxTime.
timoutMS: UNSUPPORTED. The timeout in milliseconds, a zero timeout will cause this call to be non-blocking (returning queue empty) if there is a NULL callback, and blocking forever until the queue is non-empty if there is a valid callback.

Return Value

Returns an IOReturn code.

hasElement

Checks whether an element has been added to the queue.

Boolean ( *hasElement)(
    void *self,
    IOHIDElementCookie elementCookie);

Parameters

elementCookie: The element of interest.

Return Value

Returns a Boolean value.

Discussion

Will return true if present, otherwise will return false.

removeElement

Removes an element from the queue.

IOReturn ( *removeElement)(
    void *self,
    IOHIDElementCookie elementCookie);

Parameters

elementCookie: The element of interest.

Return Value

Returns an IOReturn code.

Discussion

If the element has not been added to queue, an error will be returned.

setEventCallout

Sets the event callout to be called when the queue transitions to non-empty.

IOReturn ( *setEventCallout)(
    void *self, 
    IOHIDCallbackFunction callback, 
    void *callbackTarget, 
    void *callbackRefcon);

Parameters

callback: if non-NULL is a callback to be called when data is inserted to the queue
callbackTarget: The callback target passed to the callback
callbackRefcon: The callback refcon passed to the callback.

Return Value

Returns an IOReturn code.

Discussion

In order for this to work correctly, you must call createAsyncPort and createAsyncEventSource.

start

Starts event delivery to the queue.

IOReturn ( *start)(
    void *self);

Return Value

Returns an IOReturn code.

stop

Stops event delivery to the queue.

IOReturn ( *stop)(
    void *self);

Return Value

Returns an IOReturn code.

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Last Updated: 2009-02-23