PlayToSource Класс

Определение

Пространство имен:

Windows.Media.PlayTo

Представляет элемент мультимедиа для подключения к целевому объекту воспроизведения.

public ref class PlayToSource sealed

/// [Windows.Foundation.Metadata.ContractVersion(Windows.Foundation.UniversalApiContract, 65536)]
/// [Windows.Foundation.Metadata.MarshalingBehavior(Windows.Foundation.Metadata.MarshalingType.Agile)]
/// [Windows.Foundation.Metadata.Threading(Windows.Foundation.Metadata.ThreadingModel.Both)]
/// [Windows.Foundation.Metadata.Deprecated("PlayToSource may be altered or unavailable for releases after Windows 10. Instead, use CastingSource.", Windows.Foundation.Metadata.DeprecationType.Deprecate, 65536, "Windows.Foundation.UniversalApiContract")]
class PlayToSource final

[Windows.Foundation.Metadata.ContractVersion(typeof(Windows.Foundation.UniversalApiContract), 65536)]
[Windows.Foundation.Metadata.MarshalingBehavior(Windows.Foundation.Metadata.MarshalingType.Agile)]
[Windows.Foundation.Metadata.Threading(Windows.Foundation.Metadata.ThreadingModel.Both)]
[Windows.Foundation.Metadata.Deprecated("PlayToSource may be altered or unavailable for releases after Windows 10. Instead, use CastingSource.", Windows.Foundation.Metadata.DeprecationType.Deprecate, 65536, "Windows.Foundation.UniversalApiContract")]
public sealed class PlayToSource

Public NotInheritable Class PlayToSource

Наследование

Object Platform::Object IInspectable PlayToSource

Атрибуты

ContractVersionAttribute DeprecatedAttribute MarshalingBehaviorAttribute ThreadingAttribute

Требования к Windows

Семейство устройств	Windows 10 (появилось в 10.0.10240.0)
API contract	Windows.Foundation.UniversalApiContract (появилось в v1.0)

Примеры

IReadOnlyList<Windows.Storage.StorageFile> imageList;   // contains the list of images to show
bool streaming = false;      // true when streaming using Play To; otherwise false
int timeLapse = 5;           // time between images (5 seconds)
int imageSize = 600;         // size of current displayed image
int thumbnailSize = 200;     // size of "thumbnail" of next image
int currentImage = 0;        // index of the current image from imageList

// Get the list of images from the Pictures folder and start the slide show.
async private void StartSlideShow()
{
    var resultsLibrary = await
        Windows.Storage.KnownFolders.PicturesLibrary.GetFilesAsync();
    imageList = resultsLibrary;
    if (imageList.Count > 0)
    {
        var image = QueueImage(0, true);
    }
    else
    {
        MessageBlock.Text = "There are no images in the Pictures library.";
    }
}

// PlayNextImage
// Called when a new image is displayed due to a timeout.
// Removes the current image object and queues a new next image.
// Sets the next image index as the new current image, and increases the size 
// of the new current image. Then sets the timeout to display the next image.

private async void PlayNextImage(int num)
{
    // Stop the timer to avoid repeating.
    if (timer != null) { timer.Stop(); }

    await dispatcher.RunAsync(Windows.UI.Core.CoreDispatcherPriority.Normal,
        async () =>
        {
            SlideShowPanel.Children.Remove((UIElement)(SlideShowPanel.FindName("image" + num)));
            var i = await QueueImage(num + 2, false);

            currentImage = num + 1;
            ((Image)SlideShowPanel.FindName("image" + currentImage)).Width = imageSize;
        });

    timer = new Windows.UI.Xaml.DispatcherTimer();
    timer.Interval = new TimeSpan(0, 0, timeLapse);
    timer.Tick += delegate(object sender, object e)
    {
        PlayNextImage(num + 1);
    };
    timer.Start();
}

// QueueImage
// Called to create an image object for the displayed images.

private async System.Threading.Tasks.Task<Image> QueueImage(int num, bool isFirstImage)
{
    // Create the image element for the specified image index and add to the
    // slide show div.

    Image image = new Image();
    image.Width = isFirstImage ? imageSize : thumbnailSize;
    image.Name = "image" + num;
    image.VerticalAlignment = VerticalAlignment.Bottom;
    var fileContents = await imageList[num % imageList.Count].OpenReadAsync();
    var imageBitmap = new Windows.UI.Xaml.Media.Imaging.BitmapImage();
    imageBitmap.SetSource(fileContents);
    image.Source = imageBitmap;

    await dispatcher.RunAsync(Windows.UI.Core.CoreDispatcherPriority.Normal,
        () =>
        {
            SlideShowPanel.Children.Add(image);
        });

    // If this is the first image of the slide show, queue the next image. Do
    // not queue if streaming as images are already queued before
    // streaming using Play To.

    if (isFirstImage && !streaming)
    {
        var i = await QueueImage(num + 1, false);

        timer = new Windows.UI.Xaml.DispatcherTimer();
        timer.Interval = new TimeSpan(0, 0, timeLapse);
        timer.Tick += delegate(object sender, object e)
        {
            PlayNextImage(num);
        };
        timer.Start();
    }

    // Use the transferred event of the Play To connection for the current image object
    // to "move" to the next image in the slide show. The transferred event occurs
    // when the PlayToSource.playNext() method is called, or when the Play To
    // Receiver selects the next image.

    image.PlayToSource.Connection.Transferred += 
        async delegate(Windows.Media.PlayTo.PlayToConnection sender, 
                 Windows.Media.PlayTo.PlayToConnectionTransferredEventArgs e)
           { 
               currentImage = num + 1;

               await dispatcher.RunAsync(Windows.UI.Core.CoreDispatcherPriority.Normal,
                   () =>
                   {
                       ((Image)SlideShowPanel.FindName("image" + currentImage)).Width = imageSize;
                   });
           };


// Use the statechanged event to determine which action to take or to respond
// if the Play To Receiver is disconnected.
image.PlayToSource.Connection.StateChanged += 
    async delegate(Windows.Media.PlayTo.PlayToConnection sender,
             Windows.Media.PlayTo.PlayToConnectionStateChangedEventArgs e)
    {
        switch (e.CurrentState) {
            case Windows.Media.PlayTo.PlayToConnectionState.Disconnected:

                // If the state is disconnected and the current image index equals the 
                // num value passed to queueImage, then the image element is not connected 
                // to the Play To Receiver any more. Restart the slide show.
                // Otherwise, the current image has been discarded and the slide show
                // has moved to the next image. Clear the current image object and
                // remove it from the slide show div.

                if (currentImage == num)
                {
                    await dispatcher.RunAsync(Windows.UI.Core.CoreDispatcherPriority.Normal, 
                        async () =>
                        {
                            MessageBlock.Text = "Slideshow disconnected";

                            // Cancel any existing timeout
                            if (timer != null) { timer.Stop(); }

                            // Clear all image objects from the slide show div
                            SlideShowPanel.Children.Clear();

                            // Reset the slide show objects and values to their beginning state
                            streaming = false;
                            DisconnectButton.Visibility = Visibility.Collapsed;
                            InstructionsBlock.Visibility = Visibility.Visible;
                            DisconnectButton.Click -= DisconnectButtonClick;

                            // Restart the slide show from the current image index
                            var i = await QueueImage(currentImage, true);
                        });
                } 
                else 
                { 
                    await dispatcher.RunAsync(Windows.UI.Core.CoreDispatcherPriority.Normal,
                            () =>
                            {
                                image.PlayToSource.Next = null;

                                if (streaming)
                                {
                                    SlideShowPanel.Children.Remove(image);
                                }   
                            });
                }

                break;
            
            case Windows.Media.PlayTo.PlayToConnectionState.Connected:

                // If the state is connected and the previous state is disconnected, 
                // then the image element is newly connected. Queue up the next image so 
                // that it is loaded while the current image is being displayed.
                // If the previous state is rendering, then the user has paused the slideshow 
                // on the Play To Receiver. Clear the current timeout until the user restarts
                // the slide show.
                await dispatcher.RunAsync(Windows.UI.Core.CoreDispatcherPriority.Normal,
                    async () =>
                    {
                        if (e.PreviousState ==  Windows.Media.PlayTo.PlayToConnectionState.Disconnected)
                        {
                            var imageNext = await QueueImage(num + 1, false);
                            image.PlayToSource.Next = imageNext.PlayToSource;
                        } 
                        else if (e.PreviousState == Windows.Media.PlayTo.PlayToConnectionState.Rendering) 
                        {
                            if (timer != null) { timer.Stop(); }
                        }

                        if (currentImage == num) 
                        {
                            MessageBlock.Text = "Slideshow connected";
                        }
                    });
                break;

            case  Windows.Media.PlayTo.PlayToConnectionState.Rendering:

                // If the state is rendering and the previous state is
                // connected, then the Play To Receiver has restarted
                // the slide show.
                    await dispatcher.RunAsync(Windows.UI.Core.CoreDispatcherPriority.Normal,
                        () =>
                        {
                            if (e.PreviousState == Windows.Media.PlayTo.PlayToConnectionState.Connected)
                            {
                                // Clear any existing timeout.
                                if (timer != null) { timer.Stop(); }

                                // Restart the slide show.
                                timer = new Windows.UI.Xaml.DispatcherTimer();
                                timer.Interval = new TimeSpan(0, 0, timeLapse);
                                timer.Tick += delegate(object s, object args)
                                {
                                    image.PlayToSource.PlayNext();
                                };
                                timer.Start();
                            }

                            if (currentImage == num)
                            {
                                MessageBlock.Text = "Slideshow rendering";
                            }
                       }); 
                break;
            }
        };

    return image;
}

Private imageList As IReadOnlyList(Of Windows.Storage.StorageFile)    ' contains the list of images to show
Private streaming As Boolean = False       ' true when streaming using Play To otherwise false
Private timeLapse As Integer = 5           ' time between images (5 seconds)
Private imageSize As Integer = 600         ' size of current displayed image
Private thumbnailSize As Integer = 200     ' size of "thumbnail" of next image
Private currentImage As Integer = 0        ' index of the current image from imageList

' Get the list of images from the Pictures folder and start the slide show.
Private Async Sub StartSlideShow()
    Dim resultsLibrary =
        Await Windows.Storage.KnownFolders.PicturesLibrary.GetFilesAsync()
    imageList = resultsLibrary
    If (imageList.Count > 0) Then
        Dim image = QueueImage(0, True)
    Else
        MessageBlock.Text = "There are no images in the Pictures library."
    End If
End Sub

' PlayNextImage
' Called when a new image is displayed due to a timeout.
' Removes the current image object and queues a new next image.
' Sets the next image index as the new current image, and increases the size 
' of the new current image. Then sets the timeout to display the next image.

Private Async Sub PlayNextImage(num As Integer)
    ' Stop the timer to avoid repeating.
    If timer IsNot Nothing Then timer.Stop()

    Await Dispatcher.RunAsync(Windows.UI.Core.CoreDispatcherPriority.Normal,
        Async Sub()
            SlideShowPanel.Children.Remove(CType(SlideShowPanel.FindName("image" & num), UIElement))
            Dim i = Await QueueImage(num + 2, False)

            currentImage = num + 1
            CType(SlideShowPanel.FindName("image" & currentImage), Image).Width = imageSize
        End Sub)

    timer = New Windows.UI.Xaml.DispatcherTimer()
    timer.Interval = New TimeSpan(0, 0, timeLapse)
    AddHandler timer.Tick, Sub(sender As Object, e As Object)
                               PlayNextImage(num + 1)
                           End Sub
    timer.Start()
End Sub

' QueueImage
' Called to create an image object for the displayed images.

Private Async Function QueueImage(num As Integer, isFirstImage As Boolean) As Task(Of Image)
    ' Create the image element for the specified image index and add to the
    ' slide show div.

    Dim image = New Image()
    image.Width = If(isFirstImage, imageSize, thumbnailSize)
    image.Name = "image" & num
    image.VerticalAlignment = VerticalAlignment.Bottom
    Dim fileContents = Await imageList(num Mod imageList.Count).OpenReadAsync()
    Dim imageBitmap = New BitmapImage()
    imageBitmap.SetSource(fileContents)
    image.Source = imageBitmap

    Await Dispatcher.RunAsync(Windows.UI.Core.CoreDispatcherPriority.Normal,
        Sub()
            SlideShowPanel.Children.Add(image)
        End Sub)

    ' If this is the first image of the slide show, queue the next image. Do
    ' not queue if streaming as images are already queued before
    ' streaming using Play To.

    If isFirstImage AndAlso Not streaming Then

        Dim i = Await QueueImage(num + 1, False)

        timer = New Windows.UI.Xaml.DispatcherTimer()
        timer.Interval = New TimeSpan(0, 0, timeLapse)
        AddHandler timer.Tick, Sub(sender As Object, e As Object)
                                   PlayNextImage(num)
                               End Sub
        timer.Start()
    End If

' Use the transferred event of the Play To connection for the current image object
' to "move" to the next image in the slide show. The transferred event occurs
' when the PlayToSource.playNext() method is called, or when the Play To
' Receiver selects the next image.

    AddHandler image.PlayToSource.Connection.Transferred,
        Async Sub(sender As Windows.Media.PlayTo.PlayToConnection,
                  e As Windows.Media.PlayTo.PlayToConnectionTransferredEventArgs)

            currentImage = num + 1

            Await Dispatcher.RunAsync(Windows.UI.Core.CoreDispatcherPriority.Normal,
                Sub()
                    CType(SlideShowPanel.FindName("image" & currentImage), Image).Width = imageSize
                End Sub)
        End Sub


    ' Use the statechanged event to determine which action to take or to respond
    ' if the Play To Receiver is disconnected.
    AddHandler image.PlayToSource.Connection.StateChanged,
        Async Sub(sender As Windows.Media.PlayTo.PlayToConnection,
                  e As Windows.Media.PlayTo.PlayToConnectionStateChangedEventArgs)

            Select Case e.CurrentState
                Case Windows.Media.PlayTo.PlayToConnectionState.Disconnected

                    ' If the state is disconnected and the current image index equals the 
                    ' num value passed to queueImage, then the image element is not connected 
                    ' to the Play To Receiver any more. Restart the slide show.
                    ' Otherwise, the current image has been discarded and the slide show
                    ' has moved to the next image. Clear the current image object and
                    ' remove it from the slide show div.

                    If currentImage = num Then
                        Await Dispatcher.RunAsync(Windows.UI.Core.CoreDispatcherPriority.Normal,
                            Async Sub()
                                MessageBlock.Text = "Slideshow disconnected"

                                ' Cancel any existing timeout
                                If timer IsNot Nothing Then timer.Stop()

                                ' Clear all image objects from the slide show div
                                SlideShowPanel.Children.Clear()

                                ' Reset the slide show objects and values to their beginning state
                                streaming = False
                                DisconnectButton.Visibility = Visibility.Collapsed
                                InstructionsBlock.Visibility = Visibility.Visible
                                AddHandler DisconnectButton.Click, AddressOf DisconnectButtonClick

                                ' Restart the slide show from the current image index
                                Dim i = Await QueueImage(currentImage, True)
                            End Sub)
                    Else 
                           Await Dispatcher.RunAsync(Windows.UI.Core.CoreDispatcherPriority.Normal,
                                Sub()
                                    image.PlayToSource.Next = Nothing

                                    If streaming Then
                                        SlideShowPanel.Children.Remove(image)
                                    End If
                                End Sub)
                    End If

                Case Windows.Media.PlayTo.PlayToConnectionState.Connected

                ' If the state is connected and the previous state is disconnected, 
                ' then the image element is newly connected. Queue up the next image so 
                ' that it is loaded while the current image is being displayed.
                ' If the previous state is rendering, then the user has paused the slideshow 
                ' on the Play To Receiver. Clear the current timeout until the user restarts
                ' the slide show.
                Await Dispatcher.RunAsync(Windows.UI.Core.CoreDispatcherPriority.Normal,
                    Async Sub()
                            If e.PreviousState = Windows.Media.PlayTo.PlayToConnectionState.Disconnected Then
                                Dim imageNext = Await QueueImage(num + 1, False)
                                image.PlayToSource.Next = imageNext.PlayToSource
                            ElseIf e.PreviousState = Windows.Media.PlayTo.PlayToConnectionState.Rendering Then
                                If timer IsNot Nothing Then timer.Stop()
                            End If

                            If currentImage = num Then
                                MessageBlock.Text = "Slideshow connected"

                            End If
                        End Sub)

                Case Windows.Media.PlayTo.PlayToConnectionState.Rendering

                ' If the state is rendering and the previous state is
                ' connected, then the Play To Receiver has restarted
                ' the slide show.
                Await Dispatcher.RunAsync(Windows.UI.Core.CoreDispatcherPriority.Normal,
                   Sub()
                           If e.PreviousState = Windows.Media.PlayTo.PlayToConnectionState.Connected Then

                               ' Clear any existing timeout.
                               If timer IsNot Nothing Then timer.Stop()

                               ' Restart the slide show.
                               timer = New Windows.UI.Xaml.DispatcherTimer()
                               timer.Interval = New TimeSpan(0, 0, timeLapse)
                               AddHandler timer.Tick, Sub(s As Object, args As Object)
                                                          image.PlayToSource.PlayNext()
                                                      End Sub
                               timer.Start()
                           End If

                           If currentImage = num Then
                               MessageBlock.Text = "Slideshow rendering"
                           End If
                       End Sub)
            End Select
            End Function

    Return image
End Function

// Set up the Play To contract.

// Used to pass an image to Play To that will not be removed/destroyed
// by the slide show logic. For example, if the user opens the Devices
// charm and the sourcerequested event fires, but the image display timeout
// completes before the user selects a target device, then the image that
// was being displayed is removed and destroyed. initialImage is never 
// destroyed so Play To will always have a valid source to stream.
Image initialImage = null;

private async void SourceRequested(Windows.Media.PlayTo.PlayToManager sender, 
                             Windows.Media.PlayTo.PlayToSourceRequestedEventArgs e)
{
    var deferral = e.SourceRequest.GetDeferral();

    await dispatcher.RunAsync(Windows.UI.Core.CoreDispatcherPriority.Normal,
    () =>
    {
        initialImage = new Image();

        // Use the statechanged event of the image passed to Play To to determine when
        // the image is finally connected to the Play To Receiver.
        initialImage.PlayToSource.Connection.StateChanged += InitialImageConnectionStateChanged;

        // Provide Play To with the first image to stream.
        e.SourceRequest.SetSource(initialImage.PlayToSource);

        deferral.Complete();
    });
}

private async void InitialImageConnectionStateChanged(Windows.Media.PlayTo.PlayToConnection sender,
                                                      Windows.Media.PlayTo.PlayToConnectionStateChangedEventArgs e)
{
        if (e.CurrentState == Windows.Media.PlayTo.PlayToConnectionState.Connected) {

            await dispatcher.RunAsync(Windows.UI.Core.CoreDispatcherPriority.Normal, 
                async () =>
                {
                    // Clear any existing timeout.
                    if (timer != null) { timer.Stop(); }

                    // Clear the slide show panel.
                    SlideShowPanel.Children.Clear();

                    // Set the slide show objects and values to show that we are streaming.
                    streaming = true;
                    DisconnectButton.Visibility = Visibility.Visible;
                    InstructionsBlock.Visibility = Visibility.Collapsed;

                    // Queue and display the next image.
                    var image = await QueueImage(currentImage, true);
                    initialImage.PlayToSource.Next = image.PlayToSource;
                    initialImage.PlayToSource.PlayNext();
                });
        };
}

// Update the once the user has selected a device to stream to.

private async void SourceSelected(Windows.Media.PlayTo.PlayToManager sender, 
                            Windows.Media.PlayTo.PlayToSourceSelectedEventArgs e)
{
    await dispatcher.RunAsync(Windows.UI.Core.CoreDispatcherPriority.Normal,
        () =>
        {
            DisconnectButton.Click += DisconnectButtonClick;
            MessageBlock.Text = "Streaming to " + e.FriendlyName + "...";
            DeviceBlock.Text = e.FriendlyName + ".\nClick here to disconnect.";
            var imageBitmap = new Windows.UI.Xaml.Media.Imaging.BitmapImage();
            imageBitmap.SetSource(e.Icon);
            IconImage.Source = imageBitmap;
        });
}

private void DisconnectButtonClick(object sender, RoutedEventArgs e)
{
    Windows.Media.PlayTo.PlayToManager.ShowPlayToUI();
}

' Set up the Play To contract.

' Used to pass an image to Play To that will not be removed/destroyed
' by the slide show logic. For example, if the user opens the Devices
' charm and the sourcerequested event fires, but the image display timeout
' completes before the user selects a target device, then the image that
' was being displayed is removed and destroyed. initialImage is never 
' destroyed so Play To will always have a valid source to stream.
Private initialImage As Image = Nothing

Private Async Sub SourceRequested(sender As Windows.Media.PlayTo.PlayToManager,
                             e As Windows.Media.PlayTo.PlayToSourceRequestedEventArgs)

    Dim deferral = e.SourceRequest.GetDeferral()

    Await Dispatcher.RunAsync(Windows.UI.Core.CoreDispatcherPriority.Normal,
    Sub()
        initialImage = New Image()

        ' Use the statechanged event of the image passed to Play To to determine when
        ' the image is finally connected to the Play To Receiver.
        AddHandler initialImage.PlayToSource.Connection.StateChanged, AddressOf InitialImageConnectionStateChanged

        ' Provide Play To with the first image to stream.
        e.SourceRequest.SetSource(initialImage.PlayToSource)

        deferral.Complete()
    End Sub)
End Sub

Private Async Sub InitialImageConnectionStateChanged(sender As Windows.Media.PlayTo.PlayToConnection,
                                                         e As Windows.Media.PlayTo.PlayToConnectionStateChangedEventArgs)

    If e.CurrentState = Windows.Media.PlayTo.PlayToConnectionState.Connected Then

        Await Dispatcher.RunAsync(Windows.UI.Core.CoreDispatcherPriority.Normal,
            Async Sub()
                ' Clear any existing timeout.
                If timer IsNot Nothing Then timer.Stop()

                ' Clear the slide show panel.
                SlideShowPanel.Children.Clear()

                ' Set the slide show objects and values to show that we are streaming.
                streaming = True
                DisconnectButton.Visibility = Visibility.Visible
                InstructionsBlock.Visibility = Visibility.Collapsed

                ' Queue and display the next image.
                Dim image = Await QueueImage(currentImage, True)
                initialImage.PlayToSource.Next = image.PlayToSource
                initialImage.PlayToSource.PlayNext()
            End Sub)
    End If
End Sub

' Update the once the user has selected a device to stream to.

Private Async Sub SourceSelected(sender As Windows.Media.PlayTo.PlayToManager,
                                 e As Windows.Media.PlayTo.PlayToSourceSelectedEventArgs)

    Await Dispatcher.RunAsync(Windows.UI.Core.CoreDispatcherPriority.Normal,
        Sub()
            AddHandler DisconnectButton.Click, AddressOf DisconnectButtonClick
            MessageBlock.Text = "Streaming to " & e.FriendlyName & "..."
            DeviceBlock.Text = e.FriendlyName & "." & vbCr & "Click here to disconnect."
            Dim imageBitmap = New Windows.UI.Xaml.Media.Imaging.BitmapImage()
            imageBitmap.SetSource(e.Icon)
            IconImage.Source = imageBitmap
        End Sub)
End Sub

Private Sub DisconnectButtonClick()
    Windows.Media.PlayTo.PlayToManager.ShowPlayToUI()
End Sub

Комментарии

Пример использования класса PlayToSource см. в разделе Приведение мультимедиа.

Свойства

Connection	Получает подключение к целевому объекту "Воспроизвести".
Next	Возвращает или задает следующий исходный элемент Play To.
PreferredSourceUri	Указывает предпочтительный универсальный код ресурса (URI) для потока мультимедиа, например облачный сервер мультимедиа, используемый для воспроизведения по ссылке.

Методы

PlayNext()

Подключает следующий исходный элемент Play To к целевому объекту Play To.

См. также раздел

• Пример "Воспроизвести на"
• Пример PlayToReceiver
• Пример сервера мультимедиа