DispatcherQueue DispatcherQueue DispatcherQueue DispatcherQueue Class

Prerelease. Creates a DispatcherQueueTimer on the DispatcherQueue to execute a task periodically after a time interval has elapsed.

public : DispatcherQueueTimer CreateTimer()public DispatcherQueueTimer CreateTimer()Public Function CreateTimer() As DispatcherQueueTimer// This API is not available in Javascript.

Remarks

By default, a repeating timer is created. Set IsRepeating to false to make it non-repeating.

Prerelease. Gets the DispatcherQueue associated with the current thread.

public : static DispatcherQueue GetForCurrentThread()public static DispatcherQueue GetForCurrentThread()Public Static Function GetForCurrentThread() As DispatcherQueue// This API is not available in Javascript.

Prerelease. Adds a task to the DispatcherQueue which will be executed on the thread associated with the DispatcherQueue.

public : PlatForm::Boolean TryEnqueue(DispatcherQueueHandler callback)public bool TryEnqueue(DispatcherQueueHandler callback)Public Function TryEnqueue(callback As DispatcherQueueHandler) As bool// This API is not available in Javascript.

Examples

// Create a new thread and initialize a DispatcherQueueController
// and run a DispatcherQueue event loop on it.


_queueController =

    DispatcherQueueController.CreateOnDedicatedThread();

_queue = _queueController.DispatcherQueue;


// This is the first TryEnqueue() after creating the DispatcherQueue
// The callback is guaranteed to be invoked first despite Priority on the
// newly created thread.


bool isQueued = _queue.TryEnqueue(

        () =>

        {

            // task to perform on another thread.

        });

Remarks

The task will be queued at Normal priority. The queue will invoke callback serially and in priority order.

Once ShutdownQueueAsync() has been called, the queue will not queue new tasks and this method will return false.

Prerelease. Adds a task to the DispatcherQueue which will be executed on the thread associated with the DispatcherQueue.

public : PlatForm::Boolean TryEnqueue(DispatcherQueuePriority priority, DispatcherQueueHandler callback)public bool TryEnqueue(DispatcherQueuePriority priority, DispatcherQueueHandler callback)Public Function TryEnqueue(priority As DispatcherQueuePriority, callback As DispatcherQueueHandler) As bool// This API is not available in Javascript.

Examples

// Create a new thread and initialize a DispatcherQueueController
// and run a DispatcherQueue event loop on it.


_queueController =

    DispatcherQueueController.CreateOnDedicatedThread();

_queue = _queueController.DispatcherQueue;


// This is the first TryEnqueue() after creating the DispatcherQueue. The
// first TryEnqueue task is guaranteed //to be invoked first on the new
// thread, regardless of what priority it was enqueued at.




bool isQueued = _queue.TryEnqueue(Windows.System.DispatcherQueuePriority.High,

        () =>

        {

            // task to perform on another thread.

        });

Remarks

The queue will invoke callback serially and in priority order.

Once ShutdownQueueAsync() has been called, the queue will not queue new tasks and this method will return false.

Prerelease. Fires after the DispatcherQueue event loop stops which is the last step in the DispatcherQueue shutdown process.

public : event TypedEventHandler ShutdownCompleted<DispatcherQueue,  object>public event TypedEventHandler ShutdownCompleted<DispatcherQueue,  object>Public Event ShutdownCompleted<DispatcherQueue,  object>// This API is not available in Javascript.

Examples

// Invoked after the DispatcherQueue event loop exits.
_dispatcherQueue.ShutdownCompleted += (s, e) =>
{

    // clean up state

};

Remarks

The event is fired on the thread running the DispatcherQueue event loop. After this event is fired, any work posted to the DispatcherQueue will not be scheduled.

Prerelease. Fires before the dispatcher queue initiates an exit from its event loop.

public : event TypedEventHandler ShutdownStarting<DispatcherQueue,  DispatcherQueueShutdownStartingEventArgs>public event TypedEventHandler ShutdownStarting<DispatcherQueue,  DispatcherQueueShutdownStartingEventArgs>Public Event ShutdownStarting<DispatcherQueue,  DispatcherQueueShutdownStartingEventArgs>// This API is not available in Javascript.

Examples

_dispatcherQueue.ShutdownStarting += (s, e) =>
{
    // Queue is shutting down, do this last operation to  
    // update state before the dispatcher loop exits
    _queue.TryEnqueue(
        () =>
        {
            // clean up state
        });
};

Remarks

The event is fired on the thread running the DispatcherQueue event loop.

This event fires before the DispatcherQueue initiates the exit from the event loop. Event handlers for this event can queue work from within the handler. The event handler can take a deferral and continue to post work to the DispatcherQueue until the deferral completes. Once the deferral completes, no new work will be accepted by the DispatcherQueue.