DispatcherQueue.TryEnqueue Method

Definition

Namespace:

Microsoft.UI.Dispatching

Overloads

TryEnqueue(DispatcherQueueHandler)	Adds a task to the DispatcherQueue that will be executed on the thread associated with the DispatcherQueue.
TryEnqueue(DispatcherQueuePriority, DispatcherQueueHandler)	Adds a task to the DispatcherQueue that will be executed on the thread associated with the DispatcherQueue with the specified priority.

TryEnqueue(DispatcherQueueHandler)

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

public:
 virtual bool TryEnqueue(DispatcherQueueHandler ^ callback) = TryEnqueue;

[Windows.Foundation.Metadata.Overload("TryEnqueue")]
public bool TryEnqueue(DispatcherQueueHandler callback);

function tryEnqueue(callback)

Public Function TryEnqueue (callback As DispatcherQueueHandler) As Boolean

Parameters

callback

DispatcherQueueHandler

A delegate to the task to execute.

Returns

Boolean

bool

True if the task was added to the queue. Otherwise, false.

Attributes

OverloadAttribute

Examples

The following example shows how to create a new thread and initialize a DispatcherQueueController and run a DispatcherQueue event loop on it.

// 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.
bool isQueued = _queue.TryEnqueue(
        () =>
        {
            // task to perform on another thread.
        });

Remarks

The queue will invoke callback serially.

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

TryEnqueue(DispatcherQueuePriority, DispatcherQueueHandler)

Adds a task to the DispatcherQueue that will be executed on the thread associated with the DispatcherQueue with the specified priority.

public:
 virtual bool TryEnqueue(DispatcherQueuePriority priority, DispatcherQueueHandler ^ callback) = TryEnqueue;

[Windows.Foundation.Metadata.Overload("TryEnqueueWithPriority")]
public bool TryEnqueue(DispatcherQueuePriority priority, DispatcherQueueHandler callback);

function tryEnqueue(priority, callback)

Public Function TryEnqueue (priority As DispatcherQueuePriority, callback As DispatcherQueueHandler) As Boolean

Parameters

priority

DispatcherQueuePriority

The priority of the task (such as Low, Normal, or High).

callback

DispatcherQueueHandler

A delegate to the task to execute.

Returns

Boolean

bool

True if the task was added to the queue. Otherwise, false.

Attributes

OverloadAttribute

Examples

The following example shows how to create a new thread and initialize a DispatcherQueueController and run a DispatcherQueue event loop on it.

// 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.