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javascript/yui/build/imageloader/imageloader-experimental.js  view on Meta::CPAN

	var wrappedFetch = function() {
		this.fetch();
	};
	this._triggers.push([trigEl, trigAct, wrappedFetch]);
	YAHOO.util.Event.addListener(trigEl, trigAct, wrappedFetch, this, true);
};

/**
 * Setup to do in the window's onload
 * Initiates time limit for group; executes the fold check for the images
 * @method _onloadTasks
 * @private
 */
YAHOO.util.ImageLoader.group.prototype._onloadTasks = function() {
	if (this.timeoutLen && typeof(this.timeoutLen) == 'number' && this.timeoutLen > 0) {
		this._timeout = setTimeout(this._getFetchTimeout(), this.timeoutLen * 1000);
	}

	if (this.foldConditional) {
		this._foldCheck();
	}
};

/**
 * Returns the group's fetch method, with the proper closure, for use with setTimeout
 * @method _getFetchTimeout
 * @return {Function}  group's fetch method
 * @private
 */
YAHOO.util.ImageLoader.group.prototype._getFetchTimeout = function() {
	var self = this;
	return function() { self.fetch(); };
};

/**
 * Registers a background image with the group
 * @method registerBgImage
 * @param {String}	domId	HTML DOM id of the image element
 * @param {String}	url	URL for the image
 * @return {Object}	bgImgObj that was registered, for modifying any attributes in the object
 */
YAHOO.util.ImageLoader.group.prototype.registerBgImage = function(domId, url) {
	this._imgObjs[domId] = new YAHOO.util.ImageLoader.bgImgObj(domId, url);
	return this._imgObjs[domId];
};
/**
 * Registers a src image with the group
 * @method registerSrcImage
 * @param {String}	domId	HTML DOM id of the image element
 * @param {String}	url	URL for the image
 * @param {Int}	width	pixel width of the image - defaults to image's natural size
 * @param {Int}	height	pixel height of the image - defaults to image's natural size
 * @return {Object}	srcImgObj that was registered, for modifying any attributes in the object
 */
YAHOO.util.ImageLoader.group.prototype.registerSrcImage = function(domId, url, width, height) {
	this._imgObjs[domId] = new YAHOO.util.ImageLoader.srcImgObj(domId, url, width, height);
	return this._imgObjs[domId];
};
/**
 * Registers an alpha-channel-type png background image with the group
 * @method registerPngBgImage
 * @param {String}	domId	HTML DOM id of the image element
 * @param {String}	url	URL for the image
 * @return {Object}	pngBgImgObj that was registered, for modifying any attributes in the object
 */
YAHOO.util.ImageLoader.group.prototype.registerPngBgImage = function(domId, url) {
	this._imgObjs[domId] = new YAHOO.util.ImageLoader.pngBgImgObj(domId, url);
	return this._imgObjs[domId];
};

/**
 * Displays the images in the group
 * @method fetch
 */
YAHOO.util.ImageLoader.group.prototype.fetch = function() {
	YAHOO.log('Fetching images in group: "' + this.name + '".', 'info', 'imageloader');

	clearTimeout(this._timeout);
	// remove all listeners
	for (var i=0; i < this._triggers.length; i++) {
		YAHOO.util.Event.removeListener(this._triggers[i][0], this._triggers[i][1], this._triggers[i][2]);
	}

	// fetch whatever we need to by className
	this._fetchByClass();

	// fetch registered images
	for (var id in this._imgObjs) {
		if (YAHOO.lang.hasOwnProperty(this._imgObjs, id)) {
			this._imgObjs[id].fetch();
		}
	}
};

/**
 * Checks the position of each image in the group. If any part of the image is within the client viewport, shows the image immediately.
 * @method _foldCheck
 * @private
 */
YAHOO.util.ImageLoader.group.prototype._foldCheck = function() {
	YAHOO.log('Checking for images above the fold in group: "' + this.name + '"', 'info', 'imageloader');
	var scrollTop = (document.compatMode != 'CSS1Compat') ? document.body.scrollTop : document.documentElement.scrollTop;
	var viewHeight = YAHOO.util.Dom.getViewportHeight();
	var hLimit = scrollTop + viewHeight;
	var scrollLeft = (document.compatMode != 'CSS1Compat') ? document.body.scrollLeft : document.documentElement.scrollLeft;
	var viewWidth = YAHOO.util.Dom.getViewportWidth();
	var wLimit = scrollLeft + viewWidth;
	for (var id in this._imgObjs) {
		if (YAHOO.lang.hasOwnProperty(this._imgObjs, id)) {
			var elPos = YAHOO.util.Dom.getXY(this._imgObjs[id].domId);
			if (elPos[1] < hLimit && elPos[0] < wLimit) {
				YAHOO.log('Image with id "' + this._imgObjs[id].domId + '" is above the fold. Fetching image.', 'info', 'imageloader');
				this._imgObjs[id].fetch();
			}
		}
	}
	// and by class
	if (this.className) {
		this._classImageEls = YAHOO.util.Dom.getElementsByClassName(this.className);
		for (var i=0; i < this._classImageEls.length; i++) {
			var elPos = YAHOO.util.Dom.getXY(this._classImageEls[i]);
			if (elPos[1] < hLimit && elPos[0] < wLimit) {
				YAHOO.log('Image with id "' + this._classImageEls[i].id + '" is above the fold. Fetching image. (Image registered by class name with the group - may not have an id.)', 'info', 'imageloader');
				YAHOO.util.Dom.removeClass(this._classImageEls[i], this.className);
			}
		}