/*************************************************************************************
cImagePreloader class
written by Ondra Zizka 2005-08-01, ondra@dynawest.cz, ondra.zizka.cz
Preloads images. Upon completion, it may call a callback function.
*************************************************************************************/
/* Usage:
*/
/** Constructor
@param asImageUrls: Array of filenames or space-separated list of files to preload.
@param fCallback: Callback function to call upon completion.
*/
function cImagePreloader(asImageUrls, fCallback){
if(typeof(asImageUrls) == "string")
asImageUrls = asImageUrls.split(" ");
// record the number of images.
this.nImages = asImageUrls.length;
// Store the fCallback
this.fCallback = fCallback;
// Initialize internal state.
this.nLoaded = 0;
this.nProcessed = 0;
this.aImages = new Array;
// for each image, call preload()
for ( var i = 0; i < asImageUrls.length; i++ )
this.preload(asImageUrls[i]);
}
/** cImagePreloader::preload() */
cImagePreloader.prototype.preload = function(sImageUrl){
// create new Image object and add to array
var oImage = new Image;
this.aImages.push(oImage);
// set up event handlers for the Image object
oImage.onload = cImagePreloader.onload;
oImage.onerror = cImagePreloader.onerror;
oImage.onabort = cImagePreloader.onabort;
// assign pointer back to this.
oImage.oImagePreloader = this;
oImage.bLoaded = false;
// assign the .src property of the Image object
oImage.src = sImageUrl;
}
/** cImagePreloader::onComplete() */
cImagePreloader.prototype.onComplete = function(){
this.nProcessed++;
if( this.fCallback && this.nProcessed == this.nImages ){
this.fCallback(this.aImages, this.nLoaded);
}
}
/** Callback functions - applied on the Image object (this) */
cImagePreloader.onload = function(){
this.bLoaded = true;
this.oImagePreloader.nLoaded++;
this.oImagePreloader.onComplete();
}
cImagePreloader.onerror = function(){
this.bError = true;
this.oImagePreloader.onComplete();
}
cImagePreloader.onabort = function(){
this.bAbort = true;
this.oImagePreloader.onComplete();
}