Code:
/ 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / wpf / src / Framework / MS / Internal / Ink / HighContrastHelper.cs / 1305600 / HighContrastHelper.cs
//---------------------------------------------------------------------------- // // File: HighContrastHelper.cs // // Description: // A helper class for tracking the change of the system high contrast setting. // // Features: // // History: // 06/15/2005 waynezen: Created // // Copyright (C) 2001 by Microsoft Corporation. All rights reserved. // //--------------------------------------------------------------------------- using System; using System.Collections.Generic; using System.Diagnostics; using System.Security; using System.Security.Permissions; using System.Windows; using System.Windows.Media; using System.Windows.Threading; namespace MS.Internal.Ink { ////// HighContrastCallback Classs - An abstract helper class /// internal abstract class HighContrastCallback { ////// TurnHighContrastOn /// /// internal abstract void TurnHighContrastOn(Color highContrastColor); ////// TurnHighContrastOff /// internal abstract void TurnHighContrastOff(); ////// Returns the dispatcher if the object is associated to a UIContext. /// internal abstract Dispatcher Dispatcher { get; } } ////// StylusEditingBehavior - a base class for all stylus related editing behaviors /// internal static class HighContrastHelper { //------------------------------------------------------------------------------- // // Constructors // //------------------------------------------------------------------------------- #region Constructors ////// Constructor /// static HighContrastHelper() { __highContrastCallbackList = new List(); __increaseCount = 0; } #endregion Constructors //-------------------------------------------------------------------------------- // // Internal Methods // //------------------------------------------------------------------------------- #region Internal Methods /// /// Register the weak references for HighContrastCallback /// /// internal static void RegisterHighContrastCallback(HighContrastCallback highContrastCallback) { lock ( __lock ) { int count = __highContrastCallbackList.Count; int i = 0; int j = 0; // Every 100 items, We go through the list to remove the references // which have been collected by GC. if ( __increaseCount > CleanTolerance ) { while ( i < count ) { WeakReference weakRef = __highContrastCallbackList[j]; if ( weakRef.IsAlive ) { j++; } else { // Remove the unavaliable reference from the list __highContrastCallbackList.RemoveAt(j); } i++; } // Reset the count __increaseCount = 0; } __highContrastCallbackList.Add(new WeakReference(highContrastCallback)); __increaseCount++; } } ////// The method is called from SystemResources.SystemThemeFilterMessage /// internal static void OnSettingChanged() { UpdateHighContrast(); } #endregion Internal Methods //-------------------------------------------------------------------------------- // // Private Methods // //-------------------------------------------------------------------------------- #region Private Methods ////// UpdateHighContrast which calls out all the registered callbacks. /// private static void UpdateHighContrast() { lock ( __lock ) { int count = __highContrastCallbackList.Count; int i = 0; int j = 0; // Now go through the list, // And we will notify the alive callbacks // or remove the references which have been collected by GC. while ( i < count ) { WeakReference weakRef = __highContrastCallbackList[j]; if ( weakRef.IsAlive ) { HighContrastCallback highContrastCallback = weakRef.Target as HighContrastCallback; if ( highContrastCallback.Dispatcher != null ) { highContrastCallback.Dispatcher.BeginInvoke(DispatcherPriority.Background, new UpdateHighContrastCallback(OnUpdateHighContrast), highContrastCallback); } else { OnUpdateHighContrast(highContrastCallback); } j++; } else { // Remove the dead ones __highContrastCallbackList.RemoveAt(j); } i++; } // Reset the count __increaseCount = 0; } } private delegate void UpdateHighContrastCallback(HighContrastCallback highContrastCallback); ////// Invoke the callback /// /// private static void OnUpdateHighContrast(HighContrastCallback highContrastCallback) { // Get the current setting. bool isHighContrast = SystemParameters.HighContrast; Color windowTextColor = SystemColors.WindowTextColor; if ( isHighContrast ) { highContrastCallback.TurnHighContrastOn(windowTextColor); } else { highContrastCallback.TurnHighContrastOff(); } } #endregion Private Methods //------------------------------------------------------------------------------- // // Private Fields // //-------------------------------------------------------------------------------- #region Private Fields private static object __lock = new object(); private static List__highContrastCallbackList; private static int __increaseCount; private const int CleanTolerance = 100; #endregion Private Fields } } // File provided for Reference Use Only by Microsoft Corporation (c) 2007. // Copyright (c) Microsoft Corporation. All rights reserved.
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