MACROMEDIA FLASH MX 2004 - ACTIONSCRIPT, Reference Manual

Page: 199 / 816

Preloading external media 199
Preloading SWF and JPEG files
To preload SWF and JPEG files into movie clip instances, you can use the MovieClipLoader class .
This class provides an event listener mechanism to give notification about the status of file
downloads into movie clips. Using a MovieClipLoader object to preload SWF and JPEG files
involves the following steps:
Create a new MovieClipLoader object
You can use a single MovieClipLoader object to track
the download progress of multiple files, or create a separate object for each file’s progress.
var loader:MovieClipLoader = new MovieClipLoader();
Create a listener object and create event handlers The listener object can be any
ActionScript object, such as a generic Object object, a movie clip, or a custom component.
For example, the following code creates a generic listener object named
loadListener
, and
defines for itself
onLoadStart
,
onLoadProgress
, and
onLoadComplete
functions.
// Create listener object:
var loadListener:Object = new Object();
loadListener.onLoadStart = function (loadTarget) {
trace("Loading into " + load " has started.");
}
loadListener.onLoadProgress = function(loadTarget, bytesLoaded, bytesTotal) {
var percentLoaded = bytesLoaded/bytesTotal * 100;
trace("%" + percent " into target " + loadTarget);
}
loadListener.onLoadComplete = function(loadTarget) {
trace("Load completed into: " + loadTarget);
}
Register the listener object with the MovieClipLoader object In order for the listener object
to receive the loading events, you must register it with the MovieClipLoader object.
loader.addListener(loadListener);
Begin loading the file (JPEG or SWF) into a target clip
To start the download of the JPEG or
SWF file, you use the
MovieClipLoader.loadClip()
method.
loader.loadClip("scene_2.swf");
Note: You can use only MovieClipLoader methods to track the download progress of files loaded
with the
MovieClipLoader.loadClip()
method. You cannot use the
loadMovie()
function or
MovieClip.loadMovie()
method.
The following example uses the
setProgress()
method of the ProgressBar component to
display the download progress of a SWF file. (See “ProgressBar component” in Using
Components Help.)