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ADC Home > Reference Library > Reference > Hardware & Drivers > I/O Kit Framework Reference
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IOHIDQueue |
| Includes: | <CoreFoundation/CoreFoundation.h> <IOKit/hid/IOHIDBase.h> |
IOHIDQueue defines an object used to queue values from input parsed items (IOHIDElement) contained within a Human Interface Device (HID) object. This object is useful when you need to keep track of all values of an input element, rather than just the most recent one. IOHIDQueue is a CFType object and as such conforms to all the conventions expected such object.
IOHIDQueue should be considered optional and is only useful for working with complex input elements. These elements include those whose length are greater than sizeof(CFIndex) or elements that are duplicate items. Whenever possible please defer to using IOHIDManagerRegisterInputValueCallback or IOHIDDeviceRegisterInputValueCallback.
Note:Absolute element values (based on a fixed origin) will only be placed on a queue if there is a change in value.
This documentation assumes that you have a basic understanding of the material contained in Accessing Hardware From Applications
For definitions of I/O Kit terms used in this documentation, such as matching dictionary, family, and driver, see the overview of I/O Kit terms and concepts
in the "Device Access and the I/O Kit" chapter of Accessing Hardware From Applications.
This documentation also assumes you have read Human Interface Device & Force Feedback.
Please review documentation before using this reference.
All of the information described in this document is contained in the header file IOHIDQueue.h found at /System/Library/Frameworks/IOKit.framework/Headers/hid/IOHIDQueue.h.
IOHIDQueueAddElement |
Adds an element to the queue
CF_EXPORT void IOHIDQueueAddElement( IOHIDQueueRef queue, IOHIDElementRef element) ;
queueelementIOHIDQueueContainsElement |
Queries the queue to determine if elemement has been added.
CF_EXPORT Boolean IOHIDQueueContainsElement( IOHIDQueueRef queue, IOHIDElementRef element) ;
queueelementReturns true or false depending if element is present.
IOHIDQueueCopyNextValue |
Dequeues a retained copy of an element value from the head of an IOHIDQueue.
CF_EXPORT IOHIDValueRef IOHIDQueueCopyNextValue( IOHIDQueueRef queue) ;
queueReturns valid IOHIDValueRef if data is available.
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.
IOHIDQueueCopyNextValueWithTimeout |
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.
CF_EXPORT IOHIDValueRef IOHIDQueueCopyNextValueWithTimeout( IOHIDQueueRef queue, CFTimeInterval timeout) ;
queuetimeoutReturns valid IOHIDValueRef if data is available.
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.
IOHIDQueueCreate |
Creates an IOHIDQueue object for the specified device.
CF_EXPORT IOHIDQueueRef IOHIDQueueCreate( CFAllocatorRef allocator, IOHIDDeviceRef device, CFIndex depth, IOOptionBits options) ;
allocatordevicedepthoptionsReturns a new IOHIDQueueRef.
Take care in specifying an appropriate depth to prevent dropping events.
IOHIDQueueGetDepth |
Obtain the depth of the queue.
CF_EXPORT CFIndex IOHIDQueueGetDepth( IOHIDQueueRef queue) ;
queueReturns the queue depth.
IOHIDQueueGetDevice |
Obtain the device associated with the queue.
CF_EXPORT IOHIDDeviceRef IOHIDQueueGetDevice( IOHIDQueueRef queue) ;
queueReturns the a reference to the device.
IOHIDQueueGetTypeID |
Returns the type identifier of all IOHIDQueue instances.
CF_EXPORT CFTypeID IOHIDQueueGetTypeID( void) ;
IOHIDQueueRegisterValueAvailableCallback |
Sets callback to be used when the queue transitions to non-empty.
CF_EXPORT void IOHIDQueueRegisterValueAvailableCallback( IOHIDQueueRef queue, IOHIDCallback callback, void *context) ;
queuecallbackcontextIn order to make use of asynchronous behavior, the queue needs to be scheduled with the run loop.
IOHIDQueueRemoveElement |
Removes an element from the queue
CF_EXPORT void IOHIDQueueRemoveElement( IOHIDQueueRef queue, IOHIDElementRef element) ;
queueelementIOHIDQueueScheduleWithRunLoop |
Schedules queue with run loop.
CF_EXPORT void IOHIDQueueScheduleWithRunLoop( IOHIDQueueRef queue, CFRunLoopRef runLoop, CFStringRef runLoopMode) ;
queuerunLooprunLoopModeFormally associates queue with client's run loop. Scheduling this queue with the run loop is necessary before making use of any asynchronous APIs.
IOHIDQueueSetDepth |
Sets the depth of the queue. @disussion Set the appropriate depth value based on the number of elements contained in a queue.
CF_EXPORT void IOHIDQueueSetDepth( IOHIDQueueRef queue, CFIndex depth) ;
queuedepthIOHIDQueueStart |
Starts element value delivery to the queue.
CF_EXPORT void IOHIDQueueStart( IOHIDQueueRef queue) ;
queueIOHIDQueueStop |
Stops element value delivery to the queue.
CF_EXPORT void IOHIDQueueStop( IOHIDQueueRef queue) ;
queueIOHIDQueueUnscheduleFromRunLoop |
Unschedules queue with run loop.
CF_EXPORT void IOHIDQueueUnscheduleFromRunLoop( IOHIDQueueRef queue, CFRunLoopRef runLoop, CFStringRef runLoopMode) ;
queuerunLooprunLoopModeFormally disassociates queue with client's run loop.
IOHIDQueueRef |
typedef struct __IOHIDQueue * IOHIDQueueRef;
This is the type of a reference to the IOHIDQueue.
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