jquery图片滚动jquery.scrlooAnimation.js

;
(function ($, window, document, undefined) {

var pluginName = "scrollAnimations",
/**
* This SearchHintOptions object can be overridden during initialization
* @type {{offset: number}}
*/
defaults = {
offset: 0.8
};

var timer;

/**
* ScrollAnimations - applies an animate class to elements when scrolled into the viewport
*
* @author Westley Mon <wmarchment@mindgruve.com>
* @version 1.0.1
*
* @param {jQuery} element jQuery instance of selected elements
* @param {ScrollAnimationsOptions} options Custom options will be merged with the defaults
* @constructor
*/
function ScrollAnimations(element, options) {
if (element) {
this.element = element;
this.animationElements = [];
this.triggerPoint = null;
this.lastScrollPos = -1;

// jQuery has an extend method which merges the contents of two or
// more objects, storing the result in the first object. The first object
// is generally empty as we don't want to alter the default options for
// future instances of the plugin
this.options = $.extend( {}, defaults, options );
this._defaults = defaults;
this._name = pluginName;
window.onload = this.init();
}
}

ScrollAnimations.prototype = {

init: function() {
var _this = this;

var $els = $(this.element);

//setup all items
_this.setup($els);

// start an interval to update the page rather than onscroll
var scrollIntervalID = setInterval(function () {
_this.updatePage(_this);
}, 10);

$(window).on('resize', function () {
_this.resize();
});
},

resize: function () {
var _this = this;

clearTimeout(timer);

timer = setTimeout(function () {
_this.setTriggerpoint();
}, 50);
},

setTriggerpoint: function() {
this.triggerPoint = window.innerHeight * this.options.offset;
},

setup: function(items) {
this.setTriggerpoint();

var $this = $(items),
$children = $this.find('[data-animation-child]');

if ($children.length) {

// setup children
$children.each(function() {
var $child = $(this);
var $delay = $child.attr('data-animation-delay');

$child.css({
'-webkit-animation-delay': $delay,
'-moz-animation-delay': $delay,
'-ms-animation-delay': $delay,
'-o-animation-delay': $delay,
'animation-delay': $delay
});
});

} else {

var $delay = $this.attr('data-animation-delay');

// setup single item
$this.css({
'-webkit-animation-delay': $delay,
'-moz-animation-delay': $delay,
'-ms-animation-delay': $delay,
'-o-animation-delay': $delay,
'animation-delay': $delay
});

}

this.animationElements.push($this);

},

updatePage: function (plugin) {
var _this = plugin;

window.requestAnimationFrame(function () {
_this.animateElements();
});
},

animateElements: function() {
var _this = this;
var scrollPos = window.pageYOffset;

// have we scrolled since the last rAF? if not, return.
if (scrollPos === this.lastScrollPos) return;

this.lastScrollPos = scrollPos;

$(_this.animationElements).each(function() {
var $this = $(this),
$children = $this.find('[data-animation-child]');

if ($this.hasClass('animated') || (scrollPos < $this.offset().top - _this.triggerPoint))
return; // don't continue if its already been animated or scroll position hasn't hit the trigger point yet

if ($children.length) {

$this.addClass('animated');

// animate the children
$children.each(function() {
$(this).addClass('animated').addClass( $(this).attr('data-animation') )
});

} else {

// animate the single item
$this.addClass('animated').addClass( $this.attr('data-animation') );

}
});
}

};

$.fn[ pluginName ] = function (options) {
return this.each(function() {
if (!$.data(this, "plugin_" + pluginName)) {
$.data(this, "plugin_" + pluginName,
new ScrollAnimations(this, options));
}
});
};

//add support for amd
if (typeof define === "function" && define.amd) {
define(function () {
return ScrollAnimations;
});
}

})(jQuery, window, document);