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craigtmckay
09-24-2014, 08:07 AM
Hello,
I am using Mike Tuupola's great lazy load for a grid portfolio layout.
But I also want each image to crossfade to a second image on hover.
The original image is grayscale, on hover a color version crossfades in.
I would prefer to use a second image rather than a .css grayscale convert,
so I can accurately create my gray image in photoshop.
Currently I can do either separately (lazyload or hover effect) but I do not know how to combine.
My current html looks like this (lazyload working):


<head>
<script type="text/javascript" src="js/transition.js"></script>
<script src="js/jquery.lazyload.js" type="text/javascript"></script>
</head>

<script>

$(function() {
$("img").lazyload({
placeholder : "images/place.gif",
effect : "fadeIn",
effectspeed: 1000
});
});

</script>

<div id="container">
<div class="block">
<a href="1_1.html"><img class="lazy" data-original="images/14_grey.jpg" width="170" height="170"></a>
</div>
</div>


Crossfading works using the below:



<li> <a href="1_1.html"><img src="images/14_grey.jpg" class="grey" /></a>
<img src="images/14_colour.jpg" class="colour" />
</li>

Using styles:


img.grey {
position: absolute;
left: 0;
top: 0;
z-index: 10;
height: 170px;
width: 170px;
}

img.colour {
position: absolute;
left: 0; top: 0;
height: 170px;
width: 170px;
}



transition.js:


$(document).ready(function(){
$("img.grey").hover(
function() {
$(this).stop().animate({"opacity": "0"}, 500);
},
function() {
$(this).stop().animate({"opacity": "1"}, 500);
});
});



jquery.lazyload.js:



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

$.fn.lazyload = function(options) {
var elements = this;
var $container;
var settings = {
threshold : 0,
failure_limit : 0,
event : "scroll",
effect : "show",
container : window,
data_attribute : "original",
skip_invisible : true,
appear : null,
load : null,
placeholder : "data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAAAXNSR0IArs4c6QAAAARnQU1BAACxjwv8YQUAAAAJcEhZcwAADsQAAA7EAZUrDhsAAAANSURBVBhXYzh8+PB/AAffA0nNPuCLAAAAAElFTkSuQmCC"
};

function update() {
var counter = 0;

elements.each(function() {
var $this = $(this);
if (settings.skip_invisible && !$this.is(":visible")) {
return;
}
if ($.abovethetop(this, settings) ||
$.leftofbegin(this, settings)) {
/* Nothing. */
} else if (!$.belowthefold(this, settings) &&
!$.rightoffold(this, settings)) {
$this.trigger("appear");
/* if we found an image we'll load, reset the counter */
counter = 0;
} else {
if (++counter > settings.failure_limit) {
return false;
}
}
});

}

if(options) {

if (undefined !== options.failurelimit) {
options.failure_limit = options.failurelimit;
delete options.failurelimit;
}
if (undefined !== options.effectspeed) {
options.effect_speed = options.effectspeed;
delete options.effectspeed;
}

$.extend(settings, options);
}


$container = (settings.container === undefined ||
settings.container === window) ? $window : $(settings.container);


if (0 === settings.event.indexOf("scroll")) {
$container.bind(settings.event, function() {
return update();
});
}

this.each(function() {
var self = this;
var $self = $(self);

self.loaded = false;


if ($self.attr("src") === undefined || $self.attr("src") === false) {
if ($self.is("img")) {
$self.attr("src", settings.placeholder);
}
}


$self.one("appear", function() {
if (!this.loaded) {
if (settings.appear) {
var elements_left = elements.length;
settings.appear.call(self, elements_left, settings);
}
$("<img />")
.bind("load", function() {

var original = $self.attr("data-" + settings.data_attribute);
$self.hide();
if ($self.is("img")) {
$self.attr("src", original);
} else {
$self.css("background-image", "url('" + original + "')");
}
$self[settings.effect](settings.effect_speed);

self.loaded = true;


var temp = $.grep(elements, function(element) {
return !element.loaded;
});
elements = $(temp);

if (settings.load) {
var elements_left = elements.length;
settings.load.call(self, elements_left, settings);
}
})
.attr("src", $self.attr("data-" + settings.data_attribute));
}
});


if (0 !== settings.event.indexOf("scroll")) {
$self.bind(settings.event, function() {
if (!self.loaded) {
$self.trigger("appear");
}
});
}
});


$window.bind("resize", function() {
update();
});


if ((/(?:iphone|ipod|ipad).*os 5/gi).test(navigator.appVersion)) {
$window.bind("pageshow", function(event) {
if (event.originalEvent && event.originalEvent.persisted) {
elements.each(function() {
$(this).trigger("appear");
});
}
});
}


$(document).ready(function() {
update();
});

return this;
};




$.belowthefold = function(element, settings) {
var fold;

if (settings.container === undefined || settings.container === window) {
fold = (window.innerHeight ? window.innerHeight : $window.height()) + $window.scrollTop();
} else {
fold = $(settings.container).offset().top + $(settings.container).height();
}

return fold <= $(element).offset().top - settings.threshold;
};

$.rightoffold = function(element, settings) {
var fold;

if (settings.container === undefined || settings.container === window) {
fold = $window.width() + $window.scrollLeft();
} else {
fold = $(settings.container).offset().left + $(settings.container).width();
}

return fold <= $(element).offset().left - settings.threshold;
};

$.abovethetop = function(element, settings) {
var fold;

if (settings.container === undefined || settings.container === window) {
fold = $window.scrollTop();
} else {
fold = $(settings.container).offset().top;
}

return fold >= $(element).offset().top + settings.threshold + $(element).height();
};

$.leftofbegin = function(element, settings) {
var fold;

if (settings.container === undefined || settings.container === window) {
fold = $window.scrollLeft();
} else {
fold = $(settings.container).offset().left;
}

return fold >= $(element).offset().left + settings.threshold + $(element).width();
};

$.inviewport = function(element, settings) {
return !$.rightoffold(element, settings) && !$.leftofbegin(element, settings) &&
!$.belowthefold(element, settings) && !$.abovethetop(element, settings);
};



$.extend($.expr[":"], {
"below-the-fold" : function(a) { return $.belowthefold(a, {threshold : 0}); },
"above-the-top" : function(a) { return !$.belowthefold(a, {threshold : 0}); },
"right-of-screen": function(a) { return $.rightoffold(a, {threshold : 0}); },
"left-of-screen" : function(a) { return !$.rightoffold(a, {threshold : 0}); },
"in-viewport" : function(a) { return $.inviewport(a, {threshold : 0}); },

"above-the-fold" : function(a) { return !$.belowthefold(a, {threshold : 0}); },
"right-of-fold" : function(a) { return $.rightoffold(a, {threshold : 0}); },
"left-of-fold" : function(a) { return !$.rightoffold(a, {threshold : 0}); }
});

})(jQuery, window, document);

Please excuse my ignorance - how can this be achieved?

Craig