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FrameworkPropertyMetadata.BindsTwoWayByDefault Property

Gets or sets a value that indicates whether the property binds two-way by default.

Namespace: System.Windows
Assembly: PresentationFramework (in presentationframework.dll)
XML Namespace:  http://schemas.microsoft.com/winfx/2006/xaml/presentation

public bool BindsTwoWayByDefault { get; set; }
/** @property */
public boolean get_BindsTwoWayByDefault ()

/** @property */
public void set_BindsTwoWayByDefault (boolean value)

public function get BindsTwoWayByDefault () : boolean

public function set BindsTwoWayByDefault (value : boolean)

 Members of this class are either not typically used in XAML, or cannot be used in XAML. 

Property Value

true if the dependency property on which this metadata exists binds two-way by default; otherwise, false. The default is false.

Exception typeCondition

InvalidOperationException

The metadata has already been applied to a dependency property operation, so that metadata is sealed and properties of the metadata cannot be set.

In absence of this property being true, binding updates are one-way by default, based on the default behavior of the Binding constructors or equivalent XAML syntax.

In existing elements, you will usually find this property set to true in metadata for dependency properties that both report state and are modifiable by user action, for example Selector.IsSelected.

This property only reports the default binding update characteristics of the dependency property in general. Any binding set to this property on an instance can locally set the Mode property of the binding and change this default.

Properties on any derived classes of PropertyMetadata are typically defined in the object model as read-write. This is so they can be adjusted after initialization of the instance. However, after the metadata is consumed as part of a call to Register, AddOwner, or OverrideMetadata, the property system will seal that metadata instance and properties that convey the specifics of the metadata are now considered immutable. Attempting to set this property after IsSealed is true on this metadata instance will raise an exception.

The following example obtains the default metadata from various dependency property fields, queries the value of various FrameworkPropertyMetadata properties on it, and uses the information to populate a table to implement a "metadata browser".

    pm = dp.GetMetadata(dp.OwnerType);

...

    FrameworkPropertyMetadata fpm = pm as FrameworkPropertyMetadata;
    if (fpm!=null) {
        AffectsArrange.Text = (fpm.AffectsArrange) ? "Yes" : "No";
        AffectsMeasure.Text = (fpm.AffectsMeasure) ? "Yes" : "No";
        AffectsRender.Text = (fpm.AffectsRender) ? "Yes" : "No";
        Inherits.Text = (fpm.Inherits) ? "Yes" : "No";
        IsDataBindingAllowed.Text = (fpm.IsDataBindingAllowed) ? "Yes" : "No";
        BindsTwoWayByDefault.Text = (fpm.BindsTwoWayByDefault) ? "Yes" : "No";
    }         

Windows 98, Windows Server 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0
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