Wpf звук ошибки

Для воспроизведения стандартных системных звуков есть функция PlaySound. В .NET функция частично обёрнута классом System.Media.SystemSounds. Там не все звуки, но для ваших целей хватит.

Стандартные картинки добываются с помощью функции LoadIcon. В .NET функция обёрнута классом SystemIcons.

Всё это классы Windows.Forms. Если вы используете WPF, то вам надо будет конвертировать классы в WPF’ные. Используйте для этого класс Imaging.

Если вам нужны продвинутые сообщения, в новых версиях системы они встроены, находятся где-то в районе функций оболочки. Обёртки для этих функций есть в библиотеке Windows API Code Pack. Microsoft про эту библиотеку подзабыла, но в разных формах она всё ещё жива и доступна. См. Windows API Code Pack: Where is it?

I’ve recently begun work on an audio application using C#.NET. I’ve begun some basic implementation of the NAudio library which I intend to use throughout the project. While looking at NAudio’s documentation on CodePlex I found a link to the WPF Sound Visualization Library, I was attracted by one of its features in particular which I knew I would require in my app.
So I downloaded and added it to my project References.
I’ve copied how it is referenced within a window’s XAML document, like so:

xmlns:svl="clr-namespace:WPFSoundVisualizationLib;assembly=WPFSoundVisualizationLib"

and then tried to add a control within the library using:

<svl:WaveformTimeline x:Name="testWaveformTimeline"/> 

The problem is that the designer/XMAL editor claims: «svl:WaveformTimeline» does not exist in namespace «clr-namespace:WPFSoundVisualizationLib;assembly=WPFSoundVisualizationLib».

Now I know that it does exist. I can make reference to the WaveformTimeline object in the class file, and the object shows up in Visual Studio’s Object Browser.

I’m not at all sure why this is the case. If anyone knows any possible solutions to this, or things I should check any help would be appreciated.

WPF has several options for playing sound.  One of these is the SoundPlayer, which can be useful for simple, relatively small, .wav files.   You pass in the details of the source file to the  SoundPlayer’s Play method:

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Imports System.Media

Class MainWindow

    Private Sub MainWindow_Loaded(sender As Object, e As RoutedEventArgs) Handles Me.Loaded
        Dim player As New SoundPlayer("C:TempRing01.wav")
        player.Play()
    End Sub

By default the sound will play asynchronously, so the application will continue about its business while the sound is playing.  This is mostly what you’ll want, but this class also offers a PlaySync method if you want to freeze the application while the sound plays.  

If you want the sound to loop, you can use the PlayLooping method.  If you do this, you’ll probably want to also include some way of letting the user stop the loop. 

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Imports System.Media

Class MainWindow

    Dim player As New SoundPlayer("C:TempRing01.wav")

    Private Sub MainWindow_Loaded(sender As Object, e As RoutedEventArgs) Handles Me.Loaded
        player.PlayLooping()
    End Sub

    Private Sub MainWindow_MouseDoubleClick(sender As Object, e As MouseButtonEventArgs) Handles Me.MouseDoubleClick
        player.Stop()
    End Sub
End Class

One thing to note is that the audio file isn’t loaded until the first time the sound is played.  So if the audio file is big and/or the system’s computing power is small, you can get unacceptable delays.  To get round this, the best thing to do is run the Load method at any suitable time before the Play method is called.  This will set the SoundPlayer up in advance and avoid those potential ugly pauses.  Alternatively, and especially if you’re loading a large file or a sound file from an external source, you might want to use the LoadAsync method instead. 

My example above points to a sound file in the C:Temp folder.  If you can’t be sure that the file will be there, you can add it to the project in the usual way in Solution Explorer. If you do this, check that the Build Action is set to Content and the Copy to Output Directory to Copy Always.  You can then access it simply by using the file name and extension.

Very occasionally, you might have a situation where you want to access the SoundPlayer in XAML.   WPF offers you the SoundPlayerAction in this case.   Most times you’ll find procedural code a better alternative, although SoundPlayerAction can be useful when you want to combine and synchronize sound with animation. 

The example below combines a SoundPlayerAction  with an EventTrigger to make it play.  Clearly, you could achieve the same effect using code behind, but this snippet does at least show how you can use the Xaml approach if you you need it.

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        <Image Name="Image1" Stretch="Fill" Source="/Exclamation.png" Width="90" Height="90" >

            <Image.Triggers>
                <EventTrigger RoutedEvent="Image.MouseEnter">
                    <EventTrigger.Actions>
                        <SoundPlayerAction Source="Ring02.wav"/>
                    </EventTrigger.Actions>
                </EventTrigger>
            </Image.Triggers>
        </Image>

You can also play some of the built in Windows sounds without having to directly reference a wav file.  These are Asterisk, Beep, Exclamation, Hand and Question.   Keep in mind though that the sound that each of these produces is user configurable from the Control Panel, so you should avoid these if you need to guarantee that you will get a particular sound.

The syntax of SystemSounds is simple:

        System.Media.SystemSounds.Exclamation.Play()

The above features are useful, but limited.  You can start and stop the player, but not much else and you’re limited to .wav files.  And the five system sounds can be handy for flagging up problems, but you’ll often need a wider range.  For this, you’ll need the media player, which I’ll deal with next.

Posted
May 27 2013, 08:37 PM
by
Ged Mead