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FrameworkPropertyMetadata.AffectsMeasure Property

Gets or sets a value that indicates whether a dependency property potentially affects the measure pass during layout engine operations.

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

public bool AffectsMeasure { get; set; }
/** @property */
public boolean get_AffectsMeasure ()

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

public function get AffectsMeasure () : boolean

public function set AffectsMeasure (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 potentially affects the measure pass; 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.

FrameworkElement and FrameworkContentElement include an implementation of OnPropertyChanged that monitors effective value changes to all dependency properties that exist on an element. As part of that logic, dependency properties that change effective value and have metadata with AffectsMeasure set to true will initiate a deferred request to invalidate the visuals for that element. Because this WPF framework-level implementation is already in place, you typically do not need to look for dependency properties with AffectsMeasure unless you are substantially replacing or modifying the WPF framework-level layout behavior.

Custom OnPropertyChanged implementations might choose to have similar behavior for dependency property changes where AffectsMeasure is true.

Properties on 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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