text property. This
* is easy to write using data-binding, but has the negative
* consequence that the renderer cannot be re-used in another column
* of a DataGrid or another List with different fields.
* IDropInListItemRenderer allows a renderer to be re-used. The list
* classes will pass more information to the renderer so that it
* can determine which field to use at run-time.
*
* Components that you want to use as drop-in item renderers or drop-in * item editors must implement the IDropInListItemRenderer interface. * Many Flex component implement this interface, and therefore are usable * as drop-in item renderers and drop-in item editors in any column or * list.
* *Drop-in item renderers or drop-in item editors also must implement
* the IDataRenderer interface to define the data property.
When a component is used as a drop-in item renderer or drop-in
* item editor, Flex initializes the listData property
* of the component with the appropriate data from the list control.
* The component can then use the listData property
* to initialize the data property of the drop-in
* item renderer or drop-in item editor.
The listData property is of type BaseListData,
* where the BaseListData class has four subclasses:
* DataGridListData, ListData, TreeListData, and MenuListData.
* The actual data type of the value of the listData property
* depends on the control using the drop-in item renderer or item editor.
* For a DataGrid control, the value is of type DataGridListData,
* for a List control the value is of type ListData,
* for a Tree control, the value is of type TreeListData,
* and for a Menu control, the value is of type MenuListData..
The following example shows the setter method for the
* data property for the NumericStepper control
* that initializes NumericStepper's value property
* based on the value of the listData property:
* public function set data(value:Object):void
* {
* _data = value;
*
* this.value = _listData ? parseFloat(_listData.label) : Number(_data);
*
* dispatchEvent(new FlexEvent(FlexEvent.DATA_CHANGE));
* }
*
*
* In the example above, the NumericStepper control ignores the
* data property when setting NumericStepper's
* value property, and uses the listData
* property instead.
To implement the IDropInListItemRenderer interface,
* you define a setter and getter method to implement
* the listData property.
* Typically, the setter method writes the value of the
* listData property to an internal variable.
* The list class always assigns this property then sets
* the data provider item in the data property.
Notice that the setter method for the listData property
* does not dispatch an event.
* This is because the list classes always set listData,
* then set the data property.
* Setting the data property also dispatches the dataChange event.
* You never set listData on its own,
* so it does not need to dispatch its own event.
The data setter method could call the invalidateProperties() method
* if it did something that required the control to update itself.
* It would then be up to the component developer to write a commitProperties() method
* to determine that listData was modified, and handle it accordingly.
The getter method returns the current value * of the internal variable, as the following example shows:
* *
* // Internal variable for the property value.
* private var _listData:BaseListData;
*
* // Make the listData property bindable.
* [Bindable("dataChange")]
*
* // Define the getter method.
* public function get listData():BaseListData
* {
* return _listData;
* }
*
* // Define the setter method,
* public function set listData(value:BaseListData):void
* {
* _listData = value;
* }
*
*
* @see mx.controls.listClasses.BaseListData
* @see mx.core.IDataRenderer
*
* @langversion 3.0
* @playerversion Flash 9
* @playerversion AIR 1.1
* @productversion Flex 3
*/
public interface IDropInListItemRenderer
{
//--------------------------------------------------------------------------
//
// Properties
//
//--------------------------------------------------------------------------
//----------------------------------
// listData
//----------------------------------
/**
* Implements the listData property
* using setter and getter methods.
*
* @langversion 3.0
* @playerversion Flash 9
* @playerversion AIR 1.1
* @productversion Flex 3
*/
function get listData():BaseListData;
/**
* @private
*/
function set listData(value:BaseListData):void;
}
}