Struct IOHIDQueue

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pub struct IOHIDQueue { /* private fields */ }

Available on crate feature hid only.

Expand description

This is the type of a reference to the IOHIDQueue.

Implementations§

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impl IOHIDQueue

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pub fn new( allocator: Option<&CFAllocator>, device: &IOHIDDevice, depth: CFIndex, options: IOOptionBits, ) -> Option<CFRetained<IOHIDQueue>>

Creates an IOHIDQueue object for the specified device.

Take care in specifying an appropriate depth to prevent dropping events.

Parameter allocator: Allocator to be used during creation.

Parameter device: IOHIDDevice object

Parameter depth: The number of values that can be handled by the queue.

Parameter options: Reserved for future use.

Returns: Returns a new IOHIDQueueRef.

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pub fn device(&self) -> CFRetained<IOHIDDevice>

Obtain the device associated with the queue.

Parameter queue: IOHIDQueue to be queried.

Returns: Returns the a reference to the device.

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pub fn depth(&self) -> CFIndex

Obtain the depth of the queue.

Parameter queue: IOHIDQueue to be queried.

Returns: Returns the queue depth.

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pub fn set_depth(&self, depth: CFIndex)

Sets the depth of the queue.

Set the appropriate depth value based on the number of elements contained in a queue.

Parameter queue: IOHIDQueue object to be modified.

Parameter depth: The new queue depth.

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pub fn add_element(&self, element: &IOHIDElement)

Adds an element to the queue

Parameter queue: IOHIDQueue object to be modified.

Parameter element: Element to be added to the queue.

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pub fn remove_element(&self, element: &IOHIDElement)

Removes an element from the queue

Parameter queue: IOHIDQueue object to be modified.

Parameter element: Element to be removed from the queue.

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pub fn contains_element(&self, element: &IOHIDElement) -> bool

Queries the queue to determine if elemement has been added.

Parameter queue: IOHIDQueue object to be queried.

Parameter element: Element to be queried.

Returns: Returns true or false depending if element is present.

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pub fn start(&self)

Starts element value delivery to the queue.

When a dispatch queue is assocaited with the IOHIDQueue via IOHIDQueueSetDispatchQueue, the queue does not need to be explicity started, this will be done during activation when IOHIDQueueActivate is called.

Parameter queue: IOHIDQueue object to be started.

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pub fn stop(&self)

Stops element value delivery to the queue.

When a dispatch queue is assocaited with the IOHIDQueue via IOHIDQueueSetDispatchQueue, the queue does not need to be explicity stopped, this will be done during cancellation when IOHIDQueueCancel is called.

Parameter queue: IOHIDQueue object to be stopped.

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pub unsafe fn schedule_with_run_loop( &self, run_loop: &CFRunLoop, run_loop_mode: &CFString, )

Schedules queue with run loop.

Formally associates queue with client’s run loop. Scheduling this queue with the run loop is necessary before making use of any asynchronous APIs.

Parameter queue: IOHIDQueue object to be modified.

Parameter runLoop: RunLoop to be used when scheduling any asynchronous activity.

Parameter runLoopMode: Run loop mode to be used when scheduling any asynchronous activity.

§Safety

run_loop possibly has additional threading requirements.

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pub unsafe fn unschedule_from_run_loop( &self, run_loop: &CFRunLoop, run_loop_mode: &CFString, )

Unschedules queue with run loop.

Formally disassociates queue with client’s run loop.

Parameter queue: IOHIDQueue object to be modified.

Parameter runLoop: RunLoop to be used when scheduling any asynchronous activity.

Parameter runLoopMode: Run loop mode to be used when scheduling any asynchronous activity.

§Safety

run_loop possibly has additional threading requirements.

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pub unsafe fn set_dispatch_queue(&self, dispatch_queue: &DispatchQueue)

Available on crate feature dispatch2 only.

Sets the dispatch queue to be associated with the IOHIDQueue. This is necessary in order to receive asynchronous events from the kernel.

An IOHIDQueue should not be associated with both a runloop and dispatch queue. A call to IOHIDQueueSetDispatchQueue should only be made once.

After a dispatch queue is set, the IOHIDQueue must make a call to activate via IOHIDQueueActivate and cancel via IOHIDQueueCancel. All calls to “Register” functions should be done before activation and not after cancellation.

Parameter queue: Reference to an IOHIDQueue

Parameter dispatchQueue: The dispatch queue to which the event handler block will be submitted.

§Safety

dispatch_queue possibly has additional threading requirements.

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pub unsafe fn set_cancel_handler(&self, handler: dispatch_block_t)

Available on crate feature dispatch2 only.

Sets a cancellation handler for the dispatch queue associated with IOHIDQueueSetDispatchQueue.

The cancellation handler (if specified) will be will be submitted to the queue’s dispatch queue in response to a call to IOHIDQueueCancel after all the events have been handled.

IOHIDQueueSetCancelHandler should not be used when scheduling with a run loop.

The IOHIDQueueRef should only be released after the queue has been cancelled, and the cancel handler has been called. This is to ensure all asynchronous objects are released. For example:

dispatch_block_t cancelHandler = dispatch_block_create(0, ^{ CFRelease(queue); }); IOHIDQueueSetCancelHandler(queue, cancelHandler); IOHIDQueueActivate(queue); IOHIDQueueCancel(queue);

Parameter queue: Reference to an IOHIDQueue.

Parameter handler: The cancellation handler block to be associated with the dispatch queue.

§Safety

handler must be a valid pointer.

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pub fn activate(&self)

Activates the IOHIDQueue object.

An IOHIDQueue object associated with a dispatch queue is created in an inactive state. The object must be activated in order to receive asynchronous events from the kernel.

A dispatch queue must be set via IOHIDQueueSetDispatchQueue before activation.

An activated queue must be cancelled via IOHIDQueueCancel. All calls to “Register” functions should be done before activation and not after cancellation.

Calling IOHIDQueueActivate on an active IOHIDQueue has no effect.

Parameter queue: Reference to an IOHIDQueue

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pub fn cancel(&self)

Cancels the IOHIDQueue preventing any further invocation of its event handler block.

Cancelling prevents any further invocation of the event handler block for the specified dispatch queue, but does not interrupt an event handler block that is already in progress.

Explicit cancellation of the IOHIDQueue is required, no implicit cancellation takes place.

Calling IOHIDQueueCancel on an already cancelled queue has no effect.

The IOHIDQueueRef should only be released after the queue has been cancelled, and the cancel handler has been called. This is to ensure all asynchronous objects are released. For example:

dispatch_block_t cancelHandler = dispatch_block_create(0, ^{ CFRelease(queue); }); IOHIDQueueSetCancelHandler(queue, cancelHandler); IOHIDQueueActivate(queue); IOHIDQueueCancel(queue);

Parameter queue: Reference to an IOHIDQueue

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pub unsafe fn register_value_available_callback( &self, callback: IOHIDCallback, context: *mut c_void, )

Sets callback to be used when the queue transitions to non-empty.

In order to make use of asynchronous behavior, the queue needs to be scheduled with the run loop or dispatch queue. If a dispatch queue is set, this call must occur before activation.

Parameter queue: IOHIDQueue object to be modified.

Parameter callback: Callback of type IOHIDCallback to be used when data is placed on the queue.

Parameter context: Pointer to data to be passed to the callback.

§Safety

callback must be implemented correctly.
context must be a valid pointer or null.

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pub fn next_value(&self) -> Option<CFRetained<IOHIDValue>>

Dequeues a retained copy of an element value from the head of an IOHIDQueue.

Because the value is a retained copy, it is up to the caller to release the value using CFRelease. Use with setValueCallback to avoid polling the queue for data.

Parameter queue: IOHIDQueue object to be queried.

Returns: Returns valid IOHIDValueRef if data is available.

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pub fn next_value_with_timeout( &self, timeout: CFTimeInterval, ) -> Option<CFRetained<IOHIDValue>>

Dequeues a retained copy of an element value from the head of an IOHIDQueue. This method will block until either a value is available or it times out.

Because the value is a retained copy, it is up to the caller to release the value using CFRelease. Use with setValueCallback to avoid polling the queue for data.

Parameter queue: IOHIDQueue object to be queried.

Parameter timeout: Timeout before aborting an attempt to dequeue a value from the head of a queue.

Returns: Returns valid IOHIDValueRef if data is available.

Methods from Deref<Target = CFType>§

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pub fn downcast_ref<T>(&self) -> Option<&T>
where T: ConcreteType,

Attempt to downcast the type to that of type T.

This is the reference-variant. Use CFRetained::downcast if you want to convert a retained type. See also ConcreteType for more details on which types support being converted to.

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pub fn retain_count(&self) -> usize

Get the reference count of the object.

This function may be useful for debugging. You normally do not use this function otherwise.

Beware that some things (like CFNumbers, small CFStrings etc.) may not have a normal retain count for optimization purposes, and can return usize::MAX in that case.