ComboBox.scroll

Availability

Flash Player 6 (6.0.79.0).

Edition

Flash MX 2004.

Usage

var listenerObject:Object = new Object();
listenerObject.scroll = function(eventObject:Object) {
    // Your code here.
};
comboBoxInstance.addEventListener("scroll", listenerObject);

Event object

Along with the standard event object properties, the scroll event has one additional property, direction. It is a string with two possible values, "horizontal" or "vertical". For a ComboBox scroll event, the value is always "vertical".

Description

Event; broadcast to all registered listeners when the drop-down list is scrolled. This is a List component event that is available to the ComboBox component.

Using a dispatcher/listener event model, a component instance (comboBoxInstance) dispatches an event (in this case, scroll) and the event is handled by a function, also called a handler, on a listener object (listenerObject) that you create. You define a method with the same name as the event on the listener object; the method is called when the event is triggered. When the event is triggered, it automatically passes an event object (eventObject) to the listener object method. Each event object has properties that contain information about the event. You can use these properties to write code that handles the event. For more information, see EventDispatcher class.

Finally, you call the addEventListener() method on the component instance that broadcasts the event to register the listener with the instance. When the instance dispatches the event, the listener is called.

Example

With a ComboBox component instance my_cb, the following example sends a message to the Output panel that indicates the index of the item that the list scrolled to:

// Add Items to List.
my_cb.addItem({data:1, label:"First Item"});
my_cb.addItem({data:2, label:"Second Item"});
my_cb.addItem({data:3, label:"Third Item"});
my_cb.addItem({data:4, label:"Fourth Item"});

// Display scroll bar if ComboBox has more than 2 items.
my_cb.rowCount = 3;

// Create Listener Object.
var cbListener:Object = new Object();
cbListener.scroll = function(evt_obj:Object) {
 trace("The list had been scrolled to item # "+evt_obj.position);
};

// Add Listener.
my_cb.addEventListener("scroll", cbListener);