Code:
/ 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / wpf / src / Core / CSharp / System / Windows / Media / MediaSystem.cs / 1477649 / MediaSystem.cs
//+---------------------------------------------------------------------------- // // Copyright (c) Microsoft Corporation. All rights reserved. // // Abstract: // Media system holds the relation between an application // domain and the underlying transport system. // //----------------------------------------------------------------------------- using System; using System.Windows.Threading; using System.Collections; using System.Diagnostics; using System.Windows.Media.Animation; using System.Windows.Media.Composition; using Microsoft.Win32; using Microsoft.Internal; using MS.Internal; using MS.Internal.FontCache; using MS.Win32; using System.Security; using System.Security.Permissions; using SR=MS.Internal.PresentationCore.SR; using SRID=MS.Internal.PresentationCore.SRID; using UnsafeNativeMethods=MS.Win32.PresentationCore.UnsafeNativeMethods.MilCoreApi; using SafeNativeMethods=MS.Win32.PresentationCore.SafeNativeMethods; namespace System.Windows.Media { ////// The MediaSystem class controls the media layer. /// ////// Use internal static class MediaSystem { ///to start up the media system and to /// shut down the mediasystem. /// /// This function initializes the MediaSystem. It must be called before any functions in the Media namespace /// can be used. /// ////// /// Critical -- gets and stores an unmanaged pointer to the current transport from milcore. /// TreatAsSafe -- starting up the transport is considered a safe operation. Worst case is that /// we will create a transport object nobody is going to use. Access to the transport /// object pointer is security critical. /// [SecurityCritical, SecurityTreatAsSafe ] public static bool Startup(MediaContext mc) { // // Note to stress triagers: // // This call will fail if PresentationCore.dll and milcore.dll have mismatched // versions -- please make sure that both binaries have been properly built // and deployed. // // *** Failure here does NOT indicate a bug in MediaContext.Startup! *** // HRESULT.Check(UnsafeNativeMethods.MilVersionCheck(MS.Internal.Composition.Version.MilSdkVersion)); using (CompositionEngineLock.Acquire()) { _mediaContexts.Add(mc); //Is this the first startup? if (0 == s_refCount) { HRESULT.Check(SafeNativeMethods.MilCompositionEngine_InitializePartitionManager( 0 // THREAD_PRIORITY_NORMAL )); s_forceSoftareForGraphicsStreamMagnifier = UnsafeNativeMethods.WgxConnection_ShouldForceSoftwareForGraphicsStreamClient(); ConnectTransport(); // Read a flag from the registry to determine whether we should run // animation smoothing code. ReadAnimationSmoothingSetting(); } s_refCount++; } // return true; } internal static bool ConnectChannels(MediaContext mc) { bool fCreated = false; using (CompositionEngineLock.Acquire()) { if (IsTransportConnected) { mc.CreateChannels(); fCreated = true; } } return fCreated; } ////// Reads a value from the registry to decide whether to disable the animation /// smoothing algorithm. /// ////// Critical - asserts registry permissions to read from HKEY_LOCAL_MACHINE. /// Treat as safe - we only read a binary value used exclusively for Avalon. /// ////// The code is only present in internal builds /// [SecurityCritical, SecurityTreatAsSafe ] private static void ReadAnimationSmoothingSetting() { #if PRERELEASE // Acquire permissions to read the one key we care about from the registry RegistryPermission permission = new RegistryPermission( RegistryPermissionAccess.Read, System.Security.AccessControl.AccessControlActions.View, @"HKEY_LOCAL_MACHINE\Software\Microsoft\Avalon.Graphics"); permission.Assert(); try { RegistryKey key = Registry.LocalMachine.OpenSubKey(@"Software\Microsoft\Avalon.Graphics"); if (key != null) { object keyValue = key.GetValue("AnimationSmoothing"); // The Regkey now turns off AnimationSmoothing s_animationSmoothing = !(keyValue is int && ((int)keyValue) == 0); } } finally { RegistryPermission.RevertAssert(); } #endif } ////// This deinitializes the MediaSystem and frees any resources that it maintains. /// ////// Critical -- results in the release of an unmanaged pointer to the current transport. /// TreatAsSafe -- shutting down the transport is considered a safe operation. Worst case /// is that the client stops rendering Avalon content. /// [SecurityCritical, SecurityTreatAsSafe ] internal static void Shutdown(MediaContext mc) { using (CompositionEngineLock.Acquire()) { Debug.Assert(s_refCount > 0); _mediaContexts.Remove(mc); s_refCount--; if (0 == s_refCount) { // We can shut-down. // Debug.WriteLine("MediSystem::NotifyDisconnect Stop Transport\n"); if (IsTransportConnected) { DisconnectTransport(); } HRESULT.Check(SafeNativeMethods.MilCompositionEngine_DeinitializePartitionManager()); } } } ////// Handle DWM messages that indicate that the state of the connection needs to change. /// ////// Critical because NotifyRedirectionEnvironmentChanged calls methods that /// control the composition engine in native code. TreatAsSafe since caller /// cannot cause any damages with it besides starting and stopping his application's /// own composition engine whicih would worst cases prevent his app from rendering. /// No critical data is being passed in or out since there are no arguments or return values. /// [SecurityCritical, SecurityTreatAsSafe] internal static void NotifyRedirectionEnvironmentChanged() { using (CompositionEngineLock.Acquire()) { // Check to see if we need to force software for the Vista Magnifier s_forceSoftareForGraphicsStreamMagnifier = UnsafeNativeMethods.WgxConnection_ShouldForceSoftwareForGraphicsStreamClient(); foreach (MediaContext mc in _mediaContexts) { mc.PostInvalidateRenderMode(); } } } ////// Connect the transport. /// ////// Critical - Creates a channel, calls methods performing elevations. /// TreatAsSafe - Transport initialization is considered safe. Service channel /// creation is safe. /// [SecurityCritical, SecurityTreatAsSafe] private static void ConnectTransport() { if (IsTransportConnected) { throw new System.InvalidOperationException(SR.Get(SRID.MediaSystem_OutOfOrderConnectOrDisconnect)); } // // Create a default transport to be used by this media system. // If creation fails, fall back to a local transport. // HRESULT.Check(UnsafeNativeMethods.WgxConnection_Create( false, // false means asynchronous transport out s_pConnection)); // Create service channel used by global glyph cache. This channel is // the first channel created for the app, and by creating it with // a null channel reference it creates a new partition. // All subsequent channel creates will pass in a reference to this // channel thus using its partition. s_serviceChannel = new DUCE.Channel( null, false, // not out of band s_pConnection, false); IsTransportConnected = true; } ////// Disconnect the transport. If we are calling this function from a disconnect /// request we want to keep the service channel around. So that media contexts that /// have not yet received disconnect event do not crash. /// ////// Critical - Closes a channel. Shuts down the transport. /// TreatAsSafe - Shutting down the transport is considered safe. /// Closing the service channel is safe. /// [SecurityCritical, SecurityTreatAsSafe] private static void DisconnectTransport() { if (!IsTransportConnected) { return; } // Close global glyph cache channel. s_serviceChannel.Close(); HRESULT.Check(UnsafeNativeMethods.WgxConnection_Disconnect(s_pConnection)); // Release references to global glyph cache and service channel. s_serviceChannel = null; s_pConnection = IntPtr.Zero; IsTransportConnected = false; } ////// Checks if to CAO have the same context affinity. This is for example important for /// ContainerVisual.Children.Add to ensure that the scene graph is homogenously build out /// of object that have the same context affinity. /// /// Reference to which to compare to. This argument is usually the this /// pointer and can not be null. /// Object for which the check is performed. ////// Example: /// /// class Visual /// { /// ... /// void Add(Visual child) /// { /// VerifyContext(this); /// AssertSameContext(this, child); /// ... /// } /// } /// /// Note that VerifyContext(A) AND AssertSameContext(A, B) implies that VerifyContext(B) holds. Hence you /// don't need to check the context for each argument if you assert the same context. /// internal static void AssertSameContext( DispatcherObject reference, DispatcherObject other) { Debug.Assert(reference != null, "The reference object can not be null."); // DispatcherObjects may be created with the option of becoming unbound. // An unbound DO may be created without a Dispatcher or may detach from // its Dispatcher (e.g., a Freezable). Unbound DOs return null for their // Dispatcher and should be accepted anywhere. if (other != null && reference.Dispatcher != null && other.Dispatcher != null && reference.Dispatcher != other.Dispatcher) { throw new ArgumentException(SR.Get(SRID.MediaSystem_ApiInvalidContext)); } } ////// This flag indicates if the transport has been disabled by a session disconnect. /// If the transport has been disabled we need to defer all media system startup requests /// until we get the next connect message /// internal static bool IsTransportConnected { get { return s_isConnected; } set { s_isConnected = value; } } ////// This flag indicates if all rendering should be in software. /// ////// Critical because s_forceSoftareForGraphicsStreamMagnifier is security critical, but /// only if it can be set (since that controls if rendering is sw/hw). Because /// this method does not allow setting s_forceSoftareForGraphicsStreamMagnifier, it cannot /// be used to control rendering mode. Reading it is safe since this is information /// we volunteer anyhow in the tiering API. /// internal static bool ForceSoftwareRendering { [SecurityCritical, SecurityTreatAsSafe] get { using (CompositionEngineLock.Acquire()) { return s_forceSoftareForGraphicsStreamMagnifier; } } } ////// Returns the service channel for the current media system. This channel /// is used by the glyph cache infrastructure. /// ////// Critical - Controlled unmanaged resource. /// internal static DUCE.Channel ServiceChannel { [SecurityCritical] get { return s_serviceChannel; } } ////// Returns the pointer to the unmanaged transport object. /// ////// Critical - Controlled unmanaged resource. /// internal static IntPtr Connection { [SecurityCritical] get { return s_pConnection; } } internal static bool AnimationSmoothing { get { return s_animationSmoothing; } } ////// Keeps track of how often MediaSystem.Startup is called. So that the MediaSystem can be shut down at the right /// point in time. /// private static int s_refCount = 0; private static ArrayList _mediaContexts = new ArrayList(); private static bool s_isConnected = false; ////// Service channel to serve global glyph cache. /// ////// Critical - Controlled unmanaged resource. /// [SecurityCritical] private static DUCE.Channel s_serviceChannel; private static bool s_animationSmoothing = true; ////// Pointer to the unmanaged transport object. /// ////// Critical - Controlled unmanaged resource. /// [SecurityCritical] private static IntPtr s_pConnection; ////// Indicates if a graphics stream client is present. If a graphics stream client is present, /// we drop back to sw rendering to enable the Vista magnifier. /// ////// Critical - controls rendering mode (hw/sw). /// [SecurityCritical] private static bool s_forceSoftareForGraphicsStreamMagnifier; } } // File provided for Reference Use Only by Microsoft Corporation (c) 2007.
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