Programming Visual Basic .NET

Component Attributes

As explained in Chapter 2, attributes can be added to code elements to provide additional information about those elements. The System.ComponentModel namespace defines several attributes for use in component, control, and form declarations. These attributes don’t affect component behavior. Rather, they provide information that is used or displayed by the Visual Studio .NET IDE. The following is a description of each attribute:

AmbientValueAttribute

For ambient properties, specifies the property value that will mean “get this property’s actual value from wherever ambient values come from for this property.” Ambient properties are properties able to get their values from another source. For example, the BackColor property of a Label control can be set either to a specific Color value or to the special value Color.Empty, which causes the Label’s background color to be the same as the background color of the form on which it is placed.

Putting this attribute on a property definition isn’t what causes the property to behave as an ambient property: the control itself must be written such that when the special value is written to the property, the control gets the actual value from the appropriate location. This attribute simply provides the Windows Forms Designer with a way to discover what the special value is.

When specifying this attribute, pass the special value to the attribute’s constructor. For example, <AmbientValue(0)>.

BindableAttribute

Indicates whether ...