AmbientValueAttribute Class

Definition

Namespace:

System.ComponentModel

Assembly:

System.ComponentModel.TypeConverter.dll

Source:

AmbientValueAttribute.cs

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.

public ref class AmbientValueAttribute sealed : Attribute

[System.AttributeUsage(System.AttributeTargets.All)]
public sealed class AmbientValueAttribute : Attribute

[<System.AttributeUsage(System.AttributeTargets.All)>]
type AmbientValueAttribute = class
    inherit Attribute

Public NotInheritable Class AmbientValueAttribute
Inherits Attribute

Inheritance

Object

Attribute

AmbientValueAttribute

Attributes

AttributeUsageAttribute

Examples

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

Remarks

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 Control.Font property or a Control.BackColor 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 Color.Empty as the ambient value for the BackColor property. If you have a control on a form and the BackColor property of the control is set to a different color than the BackColor property of the form, you can reset the BackColor property of the control to that of the form by setting the BackColor of the control to Color.Empty.

Constructors

AmbientValueAttribute(Boolean)	Initializes a new instance of the AmbientValueAttribute class, given a Boolean value for its value.
AmbientValueAttribute(Byte)	Initializes a new instance of the AmbientValueAttribute class, given an 8-bit unsigned integer for its value.
AmbientValueAttribute(Char)	Initializes a new instance of the AmbientValueAttribute class, given a Unicode character for its value.
AmbientValueAttribute(Double)	Initializes a new instance of the AmbientValueAttribute class, given a double-precision floating-point number for its value.
AmbientValueAttribute(Int16)	Initializes a new instance of the AmbientValueAttribute class, given a 16-bit signed integer for its value.
AmbientValueAttribute(Int32)	Initializes a new instance of the AmbientValueAttribute class, given a 32-bit signed integer for its value.
AmbientValueAttribute(Int64)	Initializes a new instance of the AmbientValueAttribute class, given a 64-bit signed integer for its value.
AmbientValueAttribute(Object)	Initializes a new instance of the AmbientValueAttribute class, given an object for its value.
AmbientValueAttribute(Single)	Initializes a new instance of the AmbientValueAttribute class, given a single-precision floating point number for its value.
AmbientValueAttribute(String)	Initializes a new instance of the AmbientValueAttribute class, given a string for its value.
AmbientValueAttribute(Type, String)	Initializes a new instance of the AmbientValueAttribute class, given the value and its type.

Properties

TypeId	When implemented in a derived class, gets a unique identifier for this Attribute. (Inherited from Attribute)
Value	Gets the object that is the value of this AmbientValueAttribute.

Methods

Equals(Object)	Determines whether the specified AmbientValueAttribute is equal to the current AmbientValueAttribute.
GetHashCode()	Returns the hash code for this instance.
GetType()	Gets the Type of the current instance. (Inherited from Object)
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)
Match(Object)	When overridden in a derived class, returns a value that indicates whether this instance equals a specified object. (Inherited from Attribute)
MemberwiseClone()	Creates a shallow copy of the current Object. (Inherited from Object)
ToString()	Returns a string that represents the current object. (Inherited from Object)