Code:
/ DotNET / DotNET / 8.0 / untmp / WIN_WINDOWS / lh_tools_devdiv_wpf / Windows / wcp / Framework / System / Windows / Controls / SoundPlayerAction.cs / 2 / SoundPlayerAction.cs
/****************************************************************************\ * * File: SoundPlayerAction.cs * * A SoundPlayerAction causes a sound to be played in response to a trigger. * * Copyright (C) by Microsoft Corporation. All rights reserved. * \***************************************************************************/ using MS.Internal; using MS.Internal.PresentationFramework; using MS.Utility; using System; using System.Collections; using System.ComponentModel; // DefaultValueAttribute using System.IO; using System.IO.Packaging; using System.Media; using System.Net; using System.Windows; using System.Windows.Documents; using System.Windows.Markup; using System.Windows.Media; using System.Windows.Navigation; using System.Windows.Threading; using System.Diagnostics; using System.Runtime.InteropServices; using System.Runtime.Remoting; using System.Security; using System.Security.Permissions; namespace System.Windows.Controls { ////// A class that describes a sound playback action to perform for a trigger /// [RuntimeNameProperty("Name")] // Enables INameScope.FindName to find SoundPlayerAction objects. public class SoundPlayerAction : TriggerAction, IDisposable { ////// Creates an instance of the SoundPlayerAction object. /// public SoundPlayerAction() : base() { } ////// Dispose. /// public void Dispose() { if (m_player != null) { m_player.Dispose(); } } ////// DependencyProperty for Source /// public static readonly DependencyProperty SourceProperty = DependencyProperty.Register( "Source", typeof(Uri), typeof(SoundPlayerAction), new FrameworkPropertyMetadata( new PropertyChangedCallback(OnSourceChanged))); ////// A class that describes a sound playback action to perform for a trigger /// public Uri Source { get { return (Uri)GetValue(SourceProperty); } set { SetValue(SourceProperty, value); } } private static void OnSourceChanged(DependencyObject d, DependencyPropertyChangedEventArgs e) { SoundPlayerAction soundPlayerAction = (SoundPlayerAction)d; soundPlayerAction.OnSourceChangedHelper((Uri)e.NewValue); } // To avoid blocking the UI thread, SoundPlayerAction performs an asynchronous // download of the WebResponse and later, the response Stream. However, // PackWebRequest does not support the asynchonous Begin/EndGetResponse pattern. // To work around this, we use our own asynchronous worker pool thread, // and then use the regular synchronous WebRequest.GetResponse() method. // Once we obtain the WebResponse, we will use SoundPlayer's async API // to download the content of the stream. private void OnSourceChangedHelper(Uri newValue) { if (newValue == null || newValue.IsAbsoluteUri) { m_lastRequestedAbsoluteUri = newValue; } else { // When we are given a relative Uri path, expand to an absolute Uri by resolving // it against the Application's base Uri. This would typically return a Pack Uri. m_lastRequestedAbsoluteUri = BaseUriHelper.GetResolvedUri(BaseUriHelper.BaseUri, newValue); } // Invalidate items that depend on the Source uri m_player = null; m_playRequested = false; // Suppress earlier requests to Play the sound if (m_streamLoadInProgress) { // There is already a worker thread downloading the previous URI stream, // or the SoundPlayer is copying the stream into its buffer. Make a note // that the URI has been changed and we will have to reload everything. m_uriChangedWhileLoadingStream = true; } else { BeginLoadStream(); } } ////// Invoke the SoundPlayer action. /// internal sealed override void Invoke(FrameworkElement el, FrameworkContentElement ctntEl, Style targetStyle, FrameworkTemplate targetTemplate, Int64 layer) { PlayWhenLoaded(); } ////// invoke the SoundPlayer action. /// internal sealed override void Invoke(FrameworkElement el) { PlayWhenLoaded(); } ////// Plays the /// private void PlayWhenLoaded() { if (m_streamLoadInProgress) { m_playRequested = true; } else if (m_player != null) { // If the Player has not yet loaded, m_streamLoadInProgress must be true Debug.Assert(m_player.IsLoadCompleted); m_player.Play(); } } private void BeginLoadStream() { if (m_lastRequestedAbsoluteUri != null) // Only reload if the new source is non-null { m_streamLoadInProgress = true; // Step 1: Perform an asynchronous load of the WebResponse and its associated Stream LoadStreamCaller downloadStreamCaller = new LoadStreamCaller(LoadStreamAsync); IAsyncResult asyncResult = downloadStreamCaller.BeginInvoke(m_lastRequestedAbsoluteUri, new AsyncCallback(LoadStreamCallback), downloadStreamCaller); } } private delegate Stream LoadStreamCaller(Uri uri); ////// This is the actual code that runs in our worker thread. /// private Stream LoadStreamAsync(Uri uri) { return WpfWebRequestHelper.CreateRequestAndGetResponseStream(uri); } ////// This code runs in the worker thread when LoadStreamAsync() finishes. /// /// private void LoadStreamCallback(IAsyncResult asyncResult) { // Now have the UI thread regain control and initialize the SoundPlayer DispatcherOperationCallback loadStreamCompletedCaller = new DispatcherOperationCallback(OnLoadStreamCompleted); Dispatcher.BeginInvoke(DispatcherPriority.Normal, loadStreamCompletedCaller, asyncResult); } ////// Called on the UI thread when the Stream object is initialized. /// Begins asynchronous download of the Stream content into SoundPlayer's local buffer. /// private Object OnLoadStreamCompleted(Object asyncResultArg) { // Necessary for proper cleanup of async resources IAsyncResult asyncResult = (IAsyncResult)asyncResultArg; LoadStreamCaller caller = (LoadStreamCaller)asyncResult.AsyncState; Stream newStream = caller.EndInvoke(asyncResult); if (m_uriChangedWhileLoadingStream) // The source URI was changed, redo Stream loading { m_uriChangedWhileLoadingStream = false; if (newStream != null) // Don't hold on to the new stream - it's not needed anymore { newStream.Dispose(); } BeginLoadStream(); } else if (newStream != null) // We loaded the Stream, begin buffering it { if (m_player == null) { m_player = new SoundPlayer((Stream)newStream); } else { m_player.Stream = (Stream)newStream; } m_player.LoadCompleted += new AsyncCompletedEventHandler(OnSoundPlayerLoadCompleted); m_player.LoadAsync(); // Begin preloading the stream into SoundPlayer's local buffer } return null; } private void OnSoundPlayerLoadCompleted(Object sender, AsyncCompletedEventArgs e) { Debug.Assert(Object.ReferenceEquals(m_player, sender)); Debug.Assert(m_player.IsLoadCompleted); if (m_uriChangedWhileLoadingStream) // The source URI was changed, redo Stream loading again { m_player = null; m_uriChangedWhileLoadingStream = false; BeginLoadStream(); } else { m_streamLoadInProgress = false; if (m_playRequested) // URI is correct, m_player is ready, play it if requested { m_playRequested = false; m_player.Play(); } } } private SoundPlayer m_player; private Uri m_lastRequestedAbsoluteUri; private bool m_streamLoadInProgress; private bool m_playRequested; private bool m_uriChangedWhileLoadingStream; } } // File provided for Reference Use Only by Microsoft Corporation (c) 2007. // Copyright (c) Microsoft Corporation. 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