User Guide

484 Chapter 2: ActionScript Language Reference
Mouse.onMouseWheel
Availability
Flash Player 6 (Windows only).
Usage
someListener.onMouseWheel = function ( [ delta [, scrollTarget ] ] ) {
// your statements here
}
Parameters
delta
An optional number indicating how many lines should be scrolled for each notch the
user rolls the mouse wheel. A positive
delta value indicates an upward scroll; a negative value
indicates a downward scroll. Typical values are from 1 to 3; faster scrolling can produce larger
values.
scrollTarget An optional parameter that indicates the topmost movie clip instance under the
mouse pointer when the mouse wheel is rolled. If you want to specify a value for
scrollTarget
but don’t want to specify a value for
delta, pass null for delta.
Returns
Nothing.
Description
Listener; notified when the user rolls the mouse wheel. To use the onMouseWheel listener, you
must create a listener object. You can then define a function for
onMouseWheel and use
addListener() to register the listener with the Mouse object.
Note: Mouse wheel event listeners are available only in Windows versions of Flash Player.
Example
The following example shows how to create a listener object that responds to mouse wheel events.
In this example, the x coordinate of a movie clip object named
clip_mc changes each time the
user rotates the mouse wheel:
var mouseListener:Object = new Object();
mouseListener.onMouseWheel = function(delta) {
clip_mc._x += delta;
}
Mouse.addListener(mouseListener);
The following example draws a line that rotates when you rotate the mouse wheel. Click the SWF
file at runtime and then rotate your mouse wheel to see the movie clip in action.
this.createEmptyMovieClip("line_mc", this.getNextHighestDepth());
line_mc.lineStyle(2, 0xFF0000, 100);
line_mc.moveTo(0, 100);
line_mc.lineTo(0, 0);
line_mc._x = 200;
line_mc._y = 200;
var mouseListener:Object = new Object();