Defines an object that has a modifiable state and a read-only (frozen) state. Classes that derive from provide detailed change notification, can be made immutable, and can clone themselves.
Assembly: WindowsBase (in WindowsBase.dll)
Thetype exposes the following members.
|CanFreeze||Gets a value that indicates whether the object can be made unmodifiable.|
|DependencyObjectType||Gets the DependencyObjectType that wraps the CLR type of this instance. (Inherited from DependencyObject.)|
|Dispatcher||Gets the Dispatcher this DispatcherObject is associated with. (Inherited from DispatcherObject.)|
|IsFrozen||Gets a value that indicates whether the object is currently modifiable.|
|IsSealed||Gets a value that indicates whether this instance is currently sealed (read-only). (Inherited from DependencyObject.)|
|CheckAccess||Determines whether the calling thread has access to this DispatcherObject. (Inherited from DispatcherObject.)|
|ClearValue(DependencyProperty)||Clears the local value of a property. The property to be cleared is specified by a DependencyProperty identifier. (Inherited from DependencyObject.)|
|ClearValue(DependencyPropertyKey)||Clears the local value of a read-only property. The property to be cleared is specified by a DependencyPropertyKey. (Inherited from DependencyObject.)|
|Clone||Creates a modifiable clone of the , making deep copies of the object's values. When copying the object's dependency properties, this method copies expressions (which might no longer resolve) but not animations or their current values.|
|CloneCore||Makes the instance a clone (deep copy) of the specified using base (non-animated) property values.|
|CloneCurrentValue||Creates a modifiable clone (deep copy) of the using its current values.|
|CloneCurrentValueCore||Makes the instance a modifiable clone (deep copy) of the specified using current property values.|
|CoerceValue||Coerces the value of the specified dependency property. This is accomplished by invoking any CoerceValueCallback function specified in property metadata for the dependency property as it exists on the calling DependencyObject. (Inherited from DependencyObject.)|
|CreateInstance||Initializes a new instance of the class.|
|CreateInstanceCore||When implemented in a derived class, creates a new instance of the derived class.|
|Equals||Determines whether a provided DependencyObject is equivalent to the current DependencyObject. (Inherited from DependencyObject.)|
|Finalize||Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.)|
|Freeze()||Makes the current object unmodifiable and sets its IsFrozen property to true.|
|Freeze(Freezable, Boolean)||If the isChecking parameter is true, this method indicates whether the specified can be made unmodifiable. If the isChecking parameter is false, this method attempts to make the specified unmodifiable and indicates whether the operation succeeded.|
|FreezeCore||Makes the object unmodifiable or tests whether it can be made unmodifiable.|
|GetAsFrozen||Creates a frozen copy of the , using base (non-animated) property values. Because the copy is frozen, any frozen sub-objects are copied by reference.|
|GetAsFrozenCore||Makes the instance a frozen clone of the specified using base (non-animated) property values.|
|GetCurrentValueAsFrozen||Creates a frozen copy of the using current property values. Because the copy is frozen, any frozen sub-objects are copied by reference.|
|GetCurrentValueAsFrozenCore||Makes the current instance a frozen clone of the specified . If the object has animated dependency properties, their current animated values are copied.|
|GetHashCode||Gets a hash code for this DependencyObject. (Inherited from DependencyObject.)|
|GetLocalValueEnumerator||Creates a specialized enumerator for determining which dependency properties have locally set values on this DependencyObject. (Inherited from DependencyObject.)|
|GetType||Gets the Type of the current instance. (Inherited from Object.)|
|GetValue||Returns the current effective value of a dependency property on this instance of a DependencyObject. (Inherited from DependencyObject.)|
|InvalidateProperty||Re-evaluates the effective value for the specified dependency property (Inherited from DependencyObject.)|
|MemberwiseClone||Creates a shallow copy of the current Object. (Inherited from Object.)|
|OnChanged||Called when the current object is modified.|
|OnFreezablePropertyChanged(DependencyObject, DependencyObject)||Ensures that appropriate context pointers are established for a DependencyObjectType data member that has just been set.|
|OnFreezablePropertyChanged(DependencyObject, DependencyObject, DependencyProperty)||This member supports the Windows Presentation Foundation (WPF) infrastructure and is not intended to be used directly from your code.|
|OnPropertyChanged||Overrides the DependencyObject implementation of OnPropertyChanged to also invoke any Changed handlers in response to a changing dependency property of type . (Overrides DependencyObject.OnPropertyChanged(DependencyPropertyChangedEventArgs).)|
|ReadLocalValue||Returns the local value of a dependency property, if it exists. (Inherited from DependencyObject.)|
|ReadPreamble||Ensures that the is being accessed from a valid thread. Inheritors of must call this method at the beginning of any API that reads data members that are not dependency properties.|
|SetCurrentValue||Sets the value of a dependency property without changing its value source. (Inherited from DependencyObject.)|
|SetValue(DependencyProperty, Object)||Sets the local value of a dependency property, specified by its dependency property identifier. (Inherited from DependencyObject.)|
|SetValue(DependencyPropertyKey, Object)||Sets the local value of a read-only dependency property, specified by the DependencyPropertyKey identifier of the dependency property. (Inherited from DependencyObject.)|
|ShouldSerializeProperty||Returns a value that indicates whether serialization processes should serialize the value for the provided dependency property. (Inherited from DependencyObject.)|
|ToString||Returns a string that represents the current object. (Inherited from Object.)|
|VerifyAccess||Enforces that the calling thread has access to this DispatcherObject. (Inherited from DispatcherObject.)|
|WritePostscript||Raises the Changed event for the and invokes its OnChanged method. Classes that derive from should call this method at the end of any API that modifies class members that are not stored as dependency properties.|
|WritePreamble||Verifies that the is not frozen and that it is being accessed from a valid threading context. inheritors should call this method at the beginning of any API that writes to data members that are not dependency properties.|
The class provides special features that can help improve application performance when using objects that are expensive to modify or copy. Examples of objects include the following:
Deriving From Freezable
A class that derives from gains the following features:
Special states: a read-only (frozen) state and a writable state.
Thread safety: a frozen object can be shared across threads.
Detailed change notification: Unlike other DependencyObject objects, a object provides change notifications when sub-property values change.
Easy cloning: the Freezable class has already implemented several methods that produce deep clones.
For information on using and creating your own objects, see Freezable Objects Overview.
This example shows how to make a read-only by calling its Freeze method.
You cannot freeze a object if any one of the following conditions is true about the object:
It has animated or data bound properties.
It has properties that are set by a dynamic resource. For more information about dynamic resources, see the XAML Resources.
It contains sub-objects that cannot be frozen.
If these conditions are false for your object and you do not intend to modify it, consider freezing it to gain performance benefits.
The following example freezes a SolidColorBrush, which is a type of object.
For more information about objects, see the Freezable Objects Overview.
|How to: Obtain a Writable Copy of a Read-Only Freezable||This example shows how to use the Clone method to create a writable copy of a read-only .|
|How to: Determine Whether a Freezable Is Frozen||This example shows how to determine whether a object is frozen. If you try to modify a frozen object, it throws an InvalidOperationException. To avoid throwing this exception, use the IsFrozen property of the object to determine whether it is frozen.|
Any public static members of this type are thread safe. Any instance members are not guaranteed to be thread safe.
When the IsFrozen property is false, a object can be accessed only from the thread on which it was created. Attempting to access it from another thread throws an InvalidOperationException. The Dispatcher.Invoke and Dispatcher.BeginInvoke methods provide support for marshalling to the correct thread.