Macromedia flex 2 Manual
Adding properties and methods to a component
133
For example, in the section
created a class with the public property
maxFontSize
. You can use the
maxFontSize
property
as the destination of a binding expression, as the following example shows:
<?xml version="1.0"?>
<!-- as/MainTextAreaFontControlBindingDest.mxml -->
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"
xmlns:MyComp="myComponents.*" >
<!-- as/MainTextAreaFontControlBindingDest.mxml -->
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"
xmlns:MyComp="myComponents.*" >
<MyComp:TextAreaFontControl id="myTA"
maxFontSize="{Number(myTI.text)}"/>
maxFontSize="{Number(myTI.text)}"/>
<mx:Label text="Enter max font size."/>
<mx:TextInput id="myTI" text="25"/>
<mx:TextInput id="myTI" text="25"/>
</mx:Application>
In this example, any value that the user enters into the
TextInput
control is automatically
copied to the
maxFontSize
property.
Using properties as the source of a data binding expression
When a property is the source of a data binding expression, Flex automatically copies the
value of the source property to any destination property when the source property changes.
However, in order to signal to Flex to perform the copy, you must register the property with
Flex and the source property must dispatch an event.
value of the source property to any destination property when the source property changes.
However, in order to signal to Flex to perform the copy, you must register the property with
Flex and the source property must dispatch an event.
To register a property as a source for data bindings, you use the
[Bindable]
metadata tag.
You can use this tag in three places:
■
Before a class definition to make all public properties defined as variables or by using setter
and getter methods usable as the source of a binding expression
and getter methods usable as the source of a binding expression
■
Before a property that a variable defines to make that specific property support binding
■
Before a getter method for a property implemented by using setter and getter methods
For more information on the
[Bindable]
metadata tag, see
.
NO
TE
When you use the
[Bindable]
metadata tag before a public class definition, it only
applies to public properties; it does not apply to private or protected properties, or to
properties defined in any other namespace. You must insert the
properties defined in any other namespace. You must insert the
[Bindable]
metadata
tag before a nonpublic property to make it usable as the source for a data binding
expression.
expression.