C# Windows.Freezable类代码示例

        /// <summary>
        ///     Copies data into a cloned instance.
        /// </summary>
        /// <param name="source">
        ///     The original instance to copy data from.
        /// </param>
        /// <remarks>
        ///     When a Freezable's "current value" is cloned, WPF will make
        ///     deep clones of the "current values" of all writable,
        ///     locally-set properties. This has the effect of resolving
        ///     expressions to their values. WPF skips read only DPs.
        ///     
        ///     If you derive from this class and have additional non-DP state
        ///     that should be transfered to copies, you should override the
        ///     CopyCommon method.
        /// </remarks>
        protected sealed override void CloneCurrentValueCore(Freezable source)
        {
            base.CloneCurrentValueCore(source);

            CustomBitmap customBitmapSource = (CustomBitmap)source;
            CopyCore(customBitmapSource, /*useCurrentValue*/ true, /*willBeFrozen*/ false);
        }

        public void FreezableBasicTest()
        {
            int resourcesChangedCount = 0;
            object resourceValue;

            Freezable freezable = new Freezable();
            freezable.ResourcesChanged += (sender, e) => resourcesChangedCount++;

            FrameworkElement element = new FrameworkElement();
            element.DataContext = "data-context";
            element.Resources = new ResourceDictionary();
            element.Resources.Add("key1", "value1");

            Assert.AreNotEqual("data-context", freezable.GetValue(FrameworkElement.DataContextProperty));
            Assert.IsFalse(freezable.TryGetResource("key1", out resourceValue));

            element.SetValue(ValueProperty, freezable);
            Assert.AreEqual("data-context", freezable.GetValue(FrameworkElement.DataContextProperty));
            Assert.AreEqual(1, resourcesChangedCount);
            Assert.IsTrue(freezable.TryGetResource("key1", out resourceValue));
            Assert.AreEqual("value1", resourceValue);

            element.Resources.Add("key2", "value2");
            Assert.AreEqual(2, resourcesChangedCount);
            Assert.IsTrue(freezable.TryGetResource("key2", out resourceValue));
            Assert.AreEqual("value2", resourceValue);
        }

 /// <summary>
 ///     Stores a frozen copy of defaultValue
 /// </summary>
 internal FreezableDefaultValueFactory(Freezable defaultValue)
 {
     Debug.Assert(defaultValue != null,
         "Null can not be made mutable.  Do not use FreezableDefaultValueFactory.");
     Debug.Assert(defaultValue.CanFreeze,
         "The defaultValue prototype must be freezable.");
     
     _defaultValuePrototype = defaultValue.GetAsFrozen();
 }

        /// <summary>
        ///     Semantically equivilent to Freezable.Clone().Freeze() except that
        ///     GetAsFrozen avoids copying any portions of the Freezable graph
        ///     which are already frozen.
        /// </summary>
        public static Freezable GetAsFrozen(Freezable freezable)
        {
            if (freezable == null)
            {
                return null;
            }

            return freezable.GetAsFrozen();
        }

        //------------------------------------------------------
        //
        //  Constructors
        //
        //------------------------------------------------------
        
        //------------------------------------------------------
        //
        //  Internal Methods
        //
        //------------------------------------------------------

        #region Internal Methods
        
        /// <summary>
        ///     A null-safe wrapper around Freezable.Clone().  (If a null
        ///     is encountered it returns null.)
        /// </summary>
        internal static Freezable Clone(Freezable freezable)
        {
            if (freezable == null)
            {
                return null;
            }

            return freezable.Clone();
        }

      /// <summary/>
      protected override void CloneCore(Freezable sourceFreezable) {
         base.CloneCore(sourceFreezable);

         //TODO: Investigate why the following loop is needed. From the API docs, the Children collection should have cloned itself.
         var sourceCollection = ((CompositeEffect)sourceFreezable).Children;
         foreach (var child in sourceCollection) {
            Children.Add((Effect)child.Clone());
         }
      }

            public FreezableProxyCommand(Freezable freezable, string name)
                : base(null, name)
            {
                _freezable = freezable;

                var evt = _freezable.GetType().GetEvent("InheritanceContextChanged",
                    BindingFlags.Instance | BindingFlags.NonPublic);
                var addMethod = evt.GetAddMethod(true);
                addMethod.Invoke(freezable, new[] {new EventHandler(OnInheritanceContextChanged)});

                SetFrameworkElementFromInheritanceContext();
            }

        /// <summary>
        /// If freezable is already frozen, it returns freezable
        /// If freezable is not frozen, it returns a copy that is frozen if possible
        /// </summary>
        internal static Freezable GetAsFrozenIfPossible(Freezable freezable)
        {
            if (freezable == null)
            {
                return null;
            }

            if (freezable.CanFreeze)
            {
                freezable = freezable.GetAsFrozen();
            }

            return freezable;
        }

        public void FreezableCollectionBasicTest()
        {
            int resources1ChangedCount = 0;
            object resourceValue;

            Freezable freezable1 = new Freezable();
            freezable1.ResourcesChanged += (sender, e) => resources1ChangedCount++;

            FreezableCollection<Freezable> freezableCollection = new FreezableCollection<Freezable> { freezable1 };

            FrameworkElement element = new FrameworkElement();
            element.DataContext = "data-context";
            element.Resources = new ResourceDictionary();
            element.Resources.Add("key1", "value1");

            Assert.IsNull(freezable1.GetValue(FrameworkElement.DataContextProperty));
            Assert.IsFalse(freezable1.TryGetResource("key1", out resourceValue));

            element.SetValue(ValueProperty, freezableCollection);
            Assert.AreEqual("data-context", freezable1.GetValue(FrameworkElement.DataContextProperty));
            Assert.AreEqual(2, resources1ChangedCount);
            Assert.IsTrue(freezable1.TryGetResource("key1", out resourceValue));
            Assert.AreEqual("value1", resourceValue);

            Freezable freezable2 = new Freezable();
            freezableCollection.Add(freezable2);
            Assert.AreEqual("data-context", freezable2.GetValue(FrameworkElement.DataContextProperty));
            Assert.IsTrue(freezable2.TryGetResource("key1", out resourceValue));
            Assert.AreEqual("value1", resourceValue);

            freezableCollection.Clear();
            Assert.AreNotEqual("data-context", freezable1.GetValue(FrameworkElement.DataContextProperty));
            Assert.AreNotEqual("data-context", freezable2.GetValue(FrameworkElement.DataContextProperty));
            Assert.AreEqual(3, resources1ChangedCount);
            Assert.IsFalse(freezable1.TryGetResource("key1", out resourceValue));
            Assert.IsFalse(freezable2.TryGetResource("key1", out resourceValue));
        }

	protected override void GetCurrentValueAsFrozenCore (Freezable sourceFreezable)
	{
		throw new NotImplementedException ();
	}

        protected override void GetCurrentValueAsFrozenCore(Freezable sourceFreezable)
        {
            base.GetCurrentValueAsFrozenCore(sourceFreezable);

            CloneCommon(sourceFreezable);
        } 

        /// <summary>
        /// Implementation of <see cref="System.Windows.Freezable.GetCurrentValueAsFrozenCore(Freezable)">Freezable.GetCurrentValueAsFrozenCore</see>.
        /// </summary>
        protected override void GetCurrentValueAsFrozenCore(Freezable source)
        {
            CharAnimationUsingKeyFrames sourceAnimation = (CharAnimationUsingKeyFrames) source;
            base.GetCurrentValueAsFrozenCore(source);

            CopyCommon(sourceAnimation, /* isCurrentValueClone = */ true);
        }

        /// <summary>
        /// Implementation of <see cref="System.Windows.Freezable.GetAsFrozenCore(Freezable)">Freezable.GetAsFrozenCore</see>.
        /// </summary>
        protected override void GetAsFrozenCore(Freezable source)
        {
            DecimalAnimationUsingKeyFrames sourceAnimation = (DecimalAnimationUsingKeyFrames) source;
            base.GetAsFrozenCore(source);

            CopyCommon(sourceAnimation, /* isCurrentValueClone = */ false);
        }

            public void AddChangedHandler(Freezable resource)
            {
                // If _resource already exists, unhook the event handler.
                if (_resource != null)
                {
                    RemoveChangedHandler();
                }

                _resource = resource;
            
                Debug.Assert(!_resource.IsFrozen);
                _resource.Changed += new EventHandler(this.InvalidateTargetSubProperty);
            }

        /// <summary>
        /// Implementation of Freezable.CloneCore()
        /// </summary>
        protected override void CloneCore(Freezable source)
        {
            base.CloneCore(source);

            StreamGeometry sourceStream = (StreamGeometry) source;

            if ((sourceStream._data != null) && (sourceStream._data.Length > 0))
            {
                _data = new byte[sourceStream._data.Length];
                sourceStream._data.CopyTo(_data, 0);
            }
        }