User Guide

ScrollPane.scroll 1117
Event object
In addition to the standard event object properties, there are two additional properties defined
for the
scroll event: a type property whose value is "scroll", and a direction property
whose value can be
"vertical" or "horizontal".
In addition to the standard event object properties, there are two additional properties defined
for the
ProgressBar.progress event: current (the loaded value equals total), and total
(the total value).
Description
Event; broadcast to all registered listeners when a user clicks the scroll bar buttons, scroll box
(thumb), or scroll track. Unlike other events, the
scroll event is broadcast when a user
presses the mouse button on the scroll bar and continues broadcasting until the button
is released.
The first usage example uses a dispatcher/listener event model. A component instance
(
scrollPaneInstance) 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. Finally, you call the
EventDispatcher.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.
For more information, see “EventDispatcher class” on page 499.
The second usage example uses an
on() handler and must be attached directly to a ScrollPane
instance. The keyword
this, used inside an on() handler attached to a component, refers to
the component instance. For example, the following code, attached to the instance
my_sp,
sends “_level0.my_sp” to the Output panel:
on (scroll) {
trace(this);
}
Example
This example creates a ScrollPane instance called my_sp, loads it with an image, and creates a
listener for the scroll event. When a scroll event occurs, the example displays the horizontal
(
hPosition) and vertical (vPosition) scroll positions in the Output panel.