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Freezable Class

  • Reference

Definition

Namespace:
System.Windows
Assembly:
WindowsBase.dll

Defines an object that has a modifiable state and a read-only (frozen) state. Classes that derive from Freezable provide detailed change notification, can be made immutable, and can clone themselves.

public ref class Freezable abstract : System::Windows::DependencyObject
public abstract class Freezable : System.Windows.DependencyObject
type Freezable = class
    inherit DependencyObject
Public MustInherit Class Freezable
Inherits DependencyObject
Inheritance
Object
DispatcherObject
DependencyObject
Freezable
Derived

Remarks

The Freezable class provides special features that can help improve application performance when using objects that are expensive to modify or copy. Examples of Freezable objects include the following:

Deriving From Freezable

A class that derives from Freezable gains the following features:

  • Special states: a read-only (frozen) state and a writable state.

  • Thread safety: a frozen Freezable object can be shared across threads.

  • Detailed change notification: Unlike other DependencyObject objects, a Freezable 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 Freezable objects, see Freezable Objects Overview.

Constructors

Freezable()

Initializes a new instance of a Freezable derived class.

Properties

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)

Methods

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 Freezable, 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(Freezable)

Makes the instance a clone (deep copy) of the specified Freezable using base (non-animated) property values.
CloneCurrentValue()

Creates a modifiable clone (deep copy) of the Freezable using its current values.
CloneCurrentValueCore(Freezable)

Makes the instance a modifiable clone (deep copy) of the specified Freezable using current property values.
CoerceValue(DependencyProperty)

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 Freezable class.
CreateInstanceCore()

When implemented in a derived class, creates a new instance of the Freezable derived class.
Equals(Object)

Determines whether a provided DependencyObject is equivalent to the current DependencyObject.

(Inherited from DependencyObject)
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 Freezable can be made unmodifiable. If the isChecking parameter is false, this method attempts to make the specified Freezable unmodifiable and indicates whether the operation succeeded.
FreezeCore(Boolean)

Makes the Freezable object unmodifiable or tests whether it can be made unmodifiable.
GetAsFrozen()

Creates a frozen copy of the Freezable, using base (non-animated) property values. Because the copy is frozen, any frozen sub-objects are copied by reference.
GetAsFrozenCore(Freezable)

Makes the instance a frozen clone of the specified Freezable using base (non-animated) property values.
GetCurrentValueAsFrozen()

Creates a frozen copy of the Freezable using current property values. Because the copy is frozen, any frozen sub-objects are copied by reference.
GetCurrentValueAsFrozenCore(Freezable)

Makes the current instance a frozen clone of the specified Freezable. 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(DependencyProperty)

Returns the current effective value of a dependency property on this instance of a DependencyObject.

(Inherited from DependencyObject)
InvalidateProperty(DependencyProperty)

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 Freezable object is modified.
OnFreezablePropertyChanged(DependencyObject, DependencyObject, DependencyProperty)

This member supports the Windows Presentation Foundation (WPF) infrastructure and is not intended to be used directly from your code.
OnFreezablePropertyChanged(DependencyObject, DependencyObject)

Ensures that appropriate context pointers are established for a DependencyObjectType data member that has just been set.
OnPropertyChanged(DependencyPropertyChangedEventArgs)

Overrides the DependencyObject implementation of OnPropertyChanged(DependencyPropertyChangedEventArgs) to also invoke any Changed handlers in response to a changing dependency property of type Freezable.
ReadLocalValue(DependencyProperty)

Returns the local value of a dependency property, if it exists.

(Inherited from DependencyObject)
ReadPreamble()

Ensures that the Freezable is being accessed from a valid thread. Inheritors of Freezable must call this method at the beginning of any API that reads data members that are not dependency properties.
SetCurrentValue(DependencyProperty, Object)

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(DependencyProperty)

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 Freezable and invokes its OnChanged() method. Classes that derive from Freezable 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 Freezable is not frozen and that it is being accessed from a valid threading context. Freezable inheritors should call this method at the beginning of any API that writes to data members that are not dependency properties.

Events

Changed

Occurs when the Freezable or an object it contains is modified.

Applies to

Thread Safety

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 Freezable object can be accessed only from the thread on which it was created. Attempting to access it from another thread throws an InvalidOperationException. The Invoke and BeginInvoke methods provide support for marshaling to the correct thread.

When their IsFrozen property is true, Freezable objects are free-threaded. For more information, see Freezable Objects Overview.