Code:
/ 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / wpf / src / Base / System / Windows / Threading / DispatcherTimer.cs / 1305600 / DispatcherTimer.cs
using System; using System.Threading; using System.Windows; using System.Diagnostics; using System.Collections.Generic; using MS.Internal.WindowsBase; namespace System.Windows.Threading { ////// A timer that is integrated into the Dispatcher queues, and will /// be processed after a given amount of time at a specified priority. /// public class DispatcherTimer { ////// Creates a timer that uses the current thread's Dispatcher to /// process the timer event at background priority. /// public DispatcherTimer() : this(DispatcherPriority.Background) // NOTE: should be Priority Dispatcher.BackgroundPriority { } ////// Creates a timer that uses the current thread's Dispatcher to /// process the timer event at the specified priority. /// /// /// The priority to process the timer at. /// public DispatcherTimer(DispatcherPriority priority) // NOTE: should be Priority { Initialize(Dispatcher.CurrentDispatcher, priority, TimeSpan.FromMilliseconds(0)); } ////// Creates a timer that uses the specified Dispatcher to /// process the timer event at the specified priority. /// /// /// The priority to process the timer at. /// /// /// The dispatcher to use to process the timer. /// public DispatcherTimer(DispatcherPriority priority, Dispatcher dispatcher) // NOTE: should be Priority { if(dispatcher == null) { throw new ArgumentNullException("dispatcher"); } Initialize(dispatcher, priority, TimeSpan.FromMilliseconds(0)); } ////// Creates a timer that is bound to the specified dispatcher and /// will be processed at the specified priority, after the /// specified timeout. /// /// /// The interval to tick the timer after. /// /// /// The priority to process the timer at. /// /// /// The callback to call when the timer ticks. /// /// /// The dispatcher to use to process the timer. /// public DispatcherTimer(TimeSpan interval, DispatcherPriority priority, EventHandler callback, Dispatcher dispatcher) // NOTE: should be Priority { // if(callback == null) { throw new ArgumentNullException("callback"); } if(dispatcher == null) { throw new ArgumentNullException("dispatcher"); } if (interval.TotalMilliseconds < 0) throw new ArgumentOutOfRangeException("interval", SR.Get(SRID.TimeSpanPeriodOutOfRange_TooSmall)); if (interval.TotalMilliseconds > Int32.MaxValue) throw new ArgumentOutOfRangeException("interval", SR.Get(SRID.TimeSpanPeriodOutOfRange_TooLarge)); Initialize(dispatcher, priority, interval); Tick += callback; Start(); } ////// Gets the dispatcher this timer is associated with. /// public Dispatcher Dispatcher { get { return _dispatcher; } } ////// Gets or sets whether the timer is running. /// public bool IsEnabled { get { return _isEnabled; } set { lock(_instanceLock) { if(!value && _isEnabled) { Stop(); } else if(value && !_isEnabled) { Start(); } } } } ////// Gets or sets the time between timer ticks. /// public TimeSpan Interval { get { return _interval; } set { bool updateWin32Timer = false; if (value.TotalMilliseconds < 0) throw new ArgumentOutOfRangeException("value", SR.Get(SRID.TimeSpanPeriodOutOfRange_TooSmall)); if (value.TotalMilliseconds > Int32.MaxValue) throw new ArgumentOutOfRangeException("value", SR.Get(SRID.TimeSpanPeriodOutOfRange_TooLarge)); lock(_instanceLock) { _interval = value; if(_isEnabled) { _dueTimeInTicks = Environment.TickCount + (int)_interval.TotalMilliseconds; updateWin32Timer = true; } } if(updateWin32Timer) { _dispatcher.UpdateWin32Timer(); } } } ////// Starts the timer. /// public void Start() { lock(_instanceLock) { if(!_isEnabled) { _isEnabled = true; Restart(); } } } ////// Stops the timer. /// public void Stop() { bool updateWin32Timer = false; lock(_instanceLock) { if(_isEnabled) { _isEnabled = false; updateWin32Timer = true; // If the operation is in the queue, abort it. if(_operation != null) { _operation.Abort(); _operation = null; } } } if(updateWin32Timer) { _dispatcher.RemoveTimer(this); } } ////// Occurs when the specified timer interval has elapsed and the /// timer is enabled. /// public event EventHandler Tick; ////// Any data that the caller wants to pass along with the timer. /// public object Tag { get { return _tag; } set { _tag = value; } } private void Initialize(Dispatcher dispatcher, DispatcherPriority priority, TimeSpan interval) { // Note: all callers of this have a "priority" parameter. Dispatcher.ValidatePriority(priority, "priority"); if(priority == DispatcherPriority.Inactive) { throw new ArgumentException(SR.Get(SRID.InvalidPriority), "priority"); } _dispatcher = dispatcher; _priority = priority; _interval = interval; } private void Restart() { lock(_instanceLock) { if (_operation != null) { // Timer has already been restarted, e.g. Start was called form the Tick handler. return; } // BeginInvoke a new operation. _operation = _dispatcher.BeginInvoke( DispatcherPriority.Inactive, new DispatcherOperationCallback(FireTick), null); _dueTimeInTicks = Environment.TickCount + (int) _interval.TotalMilliseconds; if (_interval.TotalMilliseconds == 0 && _dispatcher.CheckAccess()) { // shortcut - just promote the item now Promote(); } else { _dispatcher.AddTimer(this); } } } internal void Promote() // called from Dispatcher { lock(_instanceLock) { // Simply promote the operation to it's desired priority. if(_operation != null) { _operation.Priority = _priority; } } } private object FireTick(object unused) { // The operation has been invoked, so forget about it. _operation = null; // The dispatcher thread is calling us because item's priority // was changed from inactive to something else. if(Tick != null) { Tick(this, EventArgs.Empty); } // If we are still enabled, start the timer again. if(_isEnabled) { Restart(); } return null; } // This is the object we use to synchronize access. private object _instanceLock = new object(); // Note: We cannot BE a dispatcher-affinity object because we can be // created by a worker thread. We are still associated with a // dispatcher (where we post the item) but we can be accessed // by any thread. private Dispatcher _dispatcher; private DispatcherPriority _priority; // NOTE: should be Priority private TimeSpan _interval; private object _tag; private DispatcherOperation _operation; private bool _isEnabled; internal int _dueTimeInTicks; // used by Dispatcher } } // File provided for Reference Use Only by Microsoft Corporation (c) 2007. // Copyright (c) Microsoft Corporation. All rights reserved.
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