PlayToSource.PlayNext 方法
定义
重要
一些信息与预发行产品相关，相应产品在发行之前可能会进行重大修改。 对于此处提供的信息，Microsoft 不作任何明示或暗示的担保。
将下一个“播放到”源元素连接到“播放到”目标。
public:
virtual void PlayNext() = PlayNext;/// [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)]
void PlayNext();/// [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")]
void PlayNext();[Windows.Foundation.Metadata.Deprecated("PlayToSource may be altered or unavailable for releases after Windows 10. Instead, use CastingSource.", Windows.Foundation.Metadata.DeprecationType.Deprecate, 65536, typeof(Windows.Foundation.UniversalApiContract))]
public void PlayNext();[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 void PlayNext();function playNext()Public Sub PlayNext ()- 属性
示例
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
注解
可以使用 PlayNext 方法停止将当前播放到源媒体流式传输到目标，然后开始将 由 Next 属性标识的“播放到”源流式传输到“播放到”目标。