scopesessions.org/js/jquery.blImageCenter.js
2015-02-03 04:36:49 +01:00

106 lines
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3.5 KiB
JavaScript
Executable file

/**
* bl-jquery-image-center jQuery Plugin
*
* @copyright Boxlight Media Ltd. 2012
* @license MIT License
* @description Centers an image by moving, cropping and filling spaces inside it's parent container. Call
* this on a set of images to have them fill their parent whilst maintaining aspect ratio
* @author Robert Cambridge
*
* Usage: See documentation at http://boxlight.github.com/bl-jquery-image-center
*/
(function($) {
$.fn.centerImage = function(method, callback) {
callback = callback || function() {};
var els = this;
var remaining = $(this).length;
method = method == 'inside';
// execute this on an individual image element once it's loaded
var fn = function(img) {
var $img = $(img);
var $div = $img.parent();
// parent CSS should be in stylesheet, but to reinforce:
$div.css({
overflow: 'hidden',
position: $div.css('position') == 'absolute' ? 'absolute' : 'relative'
});
// temporarily set the image size naturally so we can get the aspect ratio
$img.css({
'position': 'static',
'width': 'auto',
'height': 'auto',
'max-width': '100%',
'max-height': '100%'
});
// now resize
var div = { w: $div.width(), h: $div.height(), r: $div.width() / $div.height() };
var img = { w: $img.width(), h: $img.height(), r: $img.width() / $img.height() };
$img.css({
'max-width': 'none',
'max-height': 'none',
'width': Math.round((div.r > img.r) ^ method ? '100%' : div.h / img.h * img.w),
'height': Math.round((div.r < img.r) ^ method ? '100%' : div.w / img.w * img.h)
});
// now center - but portrait images need to be centered slightly above halfway (33%)
var div = { w: $div.width(), h: $div.height() };
var img = { w: $img.width(), h: $img.height() };
$img.css({
'position': 'absolute',
'left': Math.round((div.w - img.w) / 2),
'top': Math.round((div.h - img.h) / 3)
});
callbackWrapped(img)
};
var callbackWrapped = function(img) {
remaining--;
callback.apply(els, [ img, remaining ]);
};
// iterate through elements
return els.each(function(i) {
if (this.complete || this.readyState === 'complete') {
// loaded already? run fn
// when binding, we can tell whether image loaded or not.
// not if it's already failed though :(
(function(el) {
// use setTimeout to prevent browser locking up
setTimeout(function() { fn(el) }, 1);
})(this);
} else {
// not loaded? bind to load
(function(el) {
$(el)
.one('load', function() {
// use setTimeout to prevent browser locking up
setTimeout(function() {
fn(el);
}, 1);
})
.one('error', function() {
// the image did not load
callbackWrapped(el)
})
.end();
// IE9/10 won't always trigger the load event. fix it.
if (navigator.userAgent.indexOf("Trident/5") >= 0 || navigator.userAgent.indexOf("Trident/6")) {
el.src = el.src;
}
})(this);
}
});
};
// Alias functions which often better describe the use case
$.fn.imageCenterResize = function(callback) {
return $(this).centerImage('inside', callback);
};
$.fn.imageCropFill = function(callback) {
return $(this).centerImage('outside', callback);
};
})(jQuery);