AmbientValueAttribute Class
 

Specifies the value to pass to a property to cause the property to get its value from another source. This is known as ambience. This class cannot be inherited.

Namespace:   System.ComponentModel
Assembly:  System (in System.dll)

SystemObject
   SystemAttribute
    System.ComponentModelAmbientValueAttribute

[AttributeUsageAttribute(AttributeTargets.All)]
public sealed class AmbientValueAttribute : Attribute
[AttributeUsageAttribute(AttributeTargets::All)]
public ref class AmbientValueAttribute sealed : Attribute
[<Sealed>]
[<AttributeUsageAttribute(AttributeTargets.All)>]
type AmbientValueAttribute = 
    class
        inherit Attribute
    end
<AttributeUsageAttribute(AttributeTargets.All)>
Public NotInheritable Class AmbientValueAttribute
	Inherits Attribute
NameDescription
System_CAPS_pubmethod AmbientValueAttribute

Initializes a new instance of the AmbientValueAttribute class, given a Boolean value for its value.

System_CAPS_pubmethod AmbientValueAttribute

Initializes a new instance of the AmbientValueAttribute class, given an 8-bit unsigned integer for its value.

System_CAPS_pubmethod AmbientValueAttribute

Initializes a new instance of the AmbientValueAttribute class, given a Unicode character for its value.

System_CAPS_pubmethod AmbientValueAttribute

Initializes a new instance of the AmbientValueAttribute class, given a double-precision floating-point number for its value.

System_CAPS_pubmethod AmbientValueAttribute

Initializes a new instance of the AmbientValueAttribute class, given a 16-bit signed integer for its value.

System_CAPS_pubmethod AmbientValueAttribute

Initializes a new instance of the AmbientValueAttribute class, given a 32-bit signed integer for its value.

System_CAPS_pubmethod AmbientValueAttribute

Initializes a new instance of the AmbientValueAttribute class, given a 64-bit signed integer for its value.

System_CAPS_pubmethod AmbientValueAttribute

Initializes a new instance of the AmbientValueAttribute class, given an object for its value.

System_CAPS_pubmethod AmbientValueAttribute

Initializes a new instance of the AmbientValueAttribute class, given a single-precision floating point number for its value.

System_CAPS_pubmethod AmbientValueAttribute

Initializes a new instance of the AmbientValueAttribute class, given a string for its value.

System_CAPS_pubmethod AmbientValueAttribute

Initializes a new instance of the AmbientValueAttribute class, given the value and its type.

NameDescription
System_CAPS_pubproperty

When implemented in a derived class, gets a unique identifier for this Attribute.(Inherited from Attribute.)

System_CAPS_pubproperty

Gets the object that is the value of this AmbientValueAttribute.

NameDescription
System_CAPS_pubmethod Equals

Determines whether the specified AmbientValueAttribute is equal to the current AmbientValueAttribute.(Overrides AttributeEquals.)

System_CAPS_pubmethod GetHashCode

Returns the hash code for this instance.(Overrides AttributeGetHashCode.)

System_CAPS_pubmethod GetType

Gets the Type of the current instance.(Inherited from Object.)

System_CAPS_pubmethod IsDefaultAttribute

When overridden in a derived class, indicates whether the value of this instance is the default value for the derived class.(Inherited from Attribute.)

System_CAPS_pubmethod Match

When overridden in a derived class, returns a value that indicates whether this instance equals a specified object.(Inherited from Attribute.)

System_CAPS_pubmethod ToString

Returns a string that represents the current object.(Inherited from Object.)

NameDescription
System_CAPS_pubinterface System_CAPS_privmethod _AttributeGetIDsOfNames

Maps a set of names to a corresponding set of dispatch identifiers.(Inherited from Attribute.)

System_CAPS_pubinterface System_CAPS_privmethod _AttributeGetTypeInfo

Retrieves the type information for an object, which can be used to get the type information for an interface.(Inherited from Attribute.)

System_CAPS_pubinterface System_CAPS_privmethod _AttributeGetTypeInfoCount

Retrieves the number of type information interfaces that an object provides (either 0 or 1).(Inherited from Attribute.)

System_CAPS_pubinterface System_CAPS_privmethod _AttributeInvoke

Provides access to properties and methods exposed by an object.(Inherited from Attribute.)

If a property on a control has ambient behavior, this attribute must be present. Ambient properties query their parent for their value, for example, a property or a property.

Typically, a visual designer uses the AmbientValueAttribute attribute to decide which value to persist for a property. This is usually a value that causes the property to get its value from another source. An example of an ambient value is ColorEmpty as the ambient value for the property. If you have a control on a form and the property of the control is set to a different color than the property of the form, you can reset the property of the control to that of the form by setting the of the control to ColorEmpty.

The following code example demonstrates using AmbientValueAttribute to enforce ambient behavior for a property called AlertForeColor. For a full code listing, see How to: Apply Attributes in Windows Forms Controls.

[AmbientValue(typeof(Color), "Empty")]
[Category("Appearance")]
[DefaultValue(typeof(Color), "White")]
[Description("The color used for painting alert text.")]
public Color AlertForeColor
{
    get
    {
        if (this.alertForeColorValue == Color.Empty &&
            this.Parent != null)
        {
            return Parent.ForeColor;
        }

        return this.alertForeColorValue;
    }

    set
    {
        this.alertForeColorValue = value;
    }
}

// This method is used by designers to enable resetting the
// property to its default value.
public void ResetAlertForeColor()
{
    this.AlertForeColor = AttributesDemoControl.defaultAlertForeColorValue;
}

// This method indicates to designers whether the property
// value is different from the ambient value, in which case
// the designer should persist the value.
private bool ShouldSerializeAlertForeColor()
{
    return (this.alertForeColorValue != AttributesDemoControl.ambientColorValue);
}
<AmbientValue(GetType(Color), "Empty"), _
Category("Appearance"), _
DefaultValue(GetType(Color), "White"), _
Description("The color used for painting alert text.")> _
Public Property AlertForeColor() As Color
    Get
        If Me.alertForeColorValue = Color.Empty AndAlso (Me.Parent IsNot Nothing) Then
            Return Parent.ForeColor
        End If

        Return Me.alertForeColorValue
    End Get

    Set(ByVal value As Color)
        Me.alertForeColorValue = value
    End Set
End Property

' This method is used by designers to enable resetting the
' property to its default value.
Public Sub ResetAlertForeColor()
    Me.AlertForeColor = AttributesDemoControl.defaultAlertForeColorValue
End Sub

' This method indicates to designers whether the property
' value is different from the ambient value, in which case
' the designer should persist the value.
Private Function ShouldSerializeAlertForeColor() As Boolean
    Return Me.alertForeColorValue <> AttributesDemoControl.ambientColorValue
End Function
.NET Framework
Available since 1.1

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

Return to top