399 lines
13 KiB
JavaScript
Executable File
399 lines
13 KiB
JavaScript
Executable File
/**
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* Dense - Device pixel ratio aware images
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*
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* @link http://dense.rah.pw
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* @license MIT
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*/
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/*
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* Copyright (C) 2013 Jukka Svahn
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*
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* Permission is hereby granted, free of charge, to any person obtaining a
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* copy of this software and associated documentation files (the "Software"),
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* to deal in the Software without restriction, including without limitation
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* the rights to use, copy, modify, merge, publish, distribute, sublicense,
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* and/or sell copies of the Software, and to permit persons to whom the
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* Software is furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
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* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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*/
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/**
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* @name jQuery
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* @class
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*/
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/**
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* @name fn
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* @class
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* @memberOf jQuery
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*/
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(function (factory)
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{
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'use strict';
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if (typeof define === 'function' && define.amd)
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{
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define(['jquery'], factory);
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}
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else
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{
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factory(window.jQuery || window.Zepto);
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}
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}(function ($)
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{
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'use strict';
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/**
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* An array of checked image URLs.
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*/
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var pathStack = [],
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/**
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* Methods.
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*/
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methods = {},
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/**
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* Regular expression to check whether the URL has a protocol.
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*
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* Is used to check whether the image URL is external.
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*/
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regexHasProtocol = /^([a-z]:)?\/\//i,
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/**
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* Regular expression that split extensions from the file.
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*
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* Is used to inject the DPR suffix to the name.
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*/
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regexSuffix = /\.\w+$/,
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/**
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* Device pixel ratio.
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*/
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devicePixelRatio;
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/**
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* Init is the default method responsible for rendering
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* a pixel-ratio-aware images.
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*
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* This method is used to select the images that
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* should display retina-size images on high pixel ratio
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* devices. Dense defaults to the init method if no
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* method is specified.
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*
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* When attached to an image, the correct image variation is
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* selected based on the device's pixel ratio. If the image element
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* defines <code>data-{ratio}x</code> attributes (e.g. data-1x, data-2x, data-3x),
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* the most appropriate of those is selected.
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*
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* If no data-ratio attributes are defined, the retina image is
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* constructed from the <code>src</code> attribute.
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* The searched high pixel ratio images follows
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* a <code>{imageName}_{ratio}x.{ext}</code> naming convention.
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* For an image found in /path/to/images/image.jpg, the 2x retina
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* image would be looked from /path/to/images/image_2x.jpg.
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*
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* When image is constructed from the src, the image existance is
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* verified using HTTP HEAD request, if <code>ping</code> option is
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* <code>true</code>. The check makes sure no HTTP error code is returned,
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* and that the received content-type is of an image. Vector image formats,
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* like svg, are skipped based on the file extension.
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*
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* This method can also be used to load image in semi-lazy fashion,
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* and avoid larger extra HTTP requests due to retina replacements.
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* The data-1x attribute can be used to supstitute the src, making
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* sure the browser doesn't try to download the normal image variation
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* before the JavaScript driven behaviour kicks in.
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*
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* Some classes are added to the selected elements while Dense is processing
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* the document. These classes include <code>dense-image</code>, <code>dense-loading</code>
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* and <code>dense-ready</code>. These classes can be used to style the images,
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* or hide them while they are being loaded.
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*
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* @param {Object} [options={}] Options
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* @param {Boolean} [options.ping=null] Check image existence. If the default <code>NULL</code> checks local images, <code>FALSE</code> disables checking and <code>TRUE</code> checks even external images cross-domain
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* @param {String} [options.dimensions=preserve] What to do with the image's <code>width</code> and <code>height</code> attributes. Either <code>update</code>, <code>remove</code> or <code>preserve</code>
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* @param {String} [options.glue=_] String that glues the retina "nx" suffix to the image. This option can be used to change the naming convention between the two commonly used practices, <code>image@2x.jpg</code> and <code>image_2x.jpg</code>
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* @param {Array} [options.skipExtensions=['svg']] Skipped image file extensions. There might be situations where you might want to exclude vector image formats
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* @return {Object} this
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* @method init
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* @memberof jQuery.fn.dense
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* @fires jQuery.fn.dense#denseRetinaReady.dense
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* @example
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* $('img').dense({
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* ping: false,
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* dimension: 'update'
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* });
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*/
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methods.init = function (options)
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{
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options = $.extend({
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ping: null,
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dimensions: 'preserve',
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glue: '_',
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skipExtensions: ['svg']
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}, options);
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this.each(function ()
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{
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var $this = $(this);
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if (!$this.is('img') || $this.hasClass('dense-image'))
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{
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return;
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}
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$this.addClass('dense-image dense-loading');
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var image = methods.getImageAttribute.call(this),
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originalImage = $this.attr('src'),
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ping = false,
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updateImage;
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if (!image)
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{
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if (!originalImage || devicePixelRatio === 1 || $.inArray(originalImage.split('.').pop().split(/[\?\#]/).shift(), options.skipExtensions) !== -1)
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{
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$this.removeClass('dense-image dense-loading');
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return;
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}
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image = originalImage.replace(regexSuffix, function (extension)
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{
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var pixelRatio = $this.attr('data-dense-cap') ? $this.attr('data-dense-cap') : devicePixelRatio;
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return options.glue + pixelRatio + 'x' + extension;
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});
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ping = options.ping !== false && $.inArray(image, pathStack) === -1 && (options.ping === true || !regexHasProtocol.test(image) || image.indexOf('//'+document.domain) === 0 || image.indexOf(document.location.protocol+'//'+document.domain) === 0);
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}
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updateImage = function ()
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{
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var readyImage = function ()
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{
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$this.removeClass('dense-loading').addClass('dense-ready').trigger('denseRetinaReady.dense');
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};
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$this.attr('src', image);
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if (options.dimensions === 'update')
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{
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$this.dense('updateDimensions').one('denseDimensionChanged', readyImage);
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}
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else
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{
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if (options.dimensions === 'remove')
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{
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$this.removeAttr('width height');
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}
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readyImage();
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}
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};
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if (ping)
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{
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$.ajax({
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url : image,
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type : 'HEAD'
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})
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.done(function (data, textStatus, jqXHR)
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{
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var type = jqXHR.getResponseHeader('Content-type');
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if (!type || type.indexOf('image/') === 0)
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{
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pathStack.push(image);
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updateImage();
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}
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});
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}
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else
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{
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updateImage();
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}
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});
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return this;
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};
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/**
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* Sets an image's width and height attributes to its native values.
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*
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* Updates an img element's dimensions to the source image's
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* real values. This method is asynchronous, so you can not directly
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* return its values. Instead, use the 'dense-dimensions-updated'
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* event to detect when the action is done.
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*
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* @return {Object} this
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* @method updateDimensions
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* @memberof jQuery.fn.dense
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* @fires jQuery.fn.dense#denseDimensionChanged.dense
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* @example
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* var image = $('img').dense('updateDimensions');
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*/
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methods.updateDimensions = function ()
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{
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return this.each(function ()
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{
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var img, $this = $(this), src = $this.attr('src');
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if (src)
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{
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img = new Image();
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img.src = src;
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$(img).on('load.dense', function ()
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{
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$this.attr({
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width: img.width,
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height: img.height
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}).trigger('denseDimensionChanged.dense');
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});
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}
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});
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};
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/**
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* Gets device pixel ratio rounded up to the closest integer.
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*
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* @return {Integer} The pixel ratio
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* @method devicePixelRatio
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* @memberof jQuery.fn.dense
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* @example
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* var ratio = $(window).dense('devicePixelRatio');
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* alert(ratio);
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*/
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methods.devicePixelRatio = function ()
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{
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var pixelRatio = 1;
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if ($.type(window.devicePixelRatio) !== 'undefined')
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{
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pixelRatio = window.devicePixelRatio;
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}
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else if ($.type(window.matchMedia) !== 'undefined')
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{
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$.each([1.3, 2, 3, 4, 5, 6], function (key, ratio)
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{
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var mediaQuery = [
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'(-webkit-min-device-pixel-ratio: '+ratio+')',
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'(min-resolution: '+Math.floor(ratio*96)+'dpi)',
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'(min-resolution: '+ratio+'dppx)'
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].join(',');
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if (!window.matchMedia(mediaQuery).matches)
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{
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return false;
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}
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pixelRatio = ratio;
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});
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}
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return Math.ceil(pixelRatio);
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};
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/**
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* Gets an appropriate URL for the pixel ratio from the data attribute list.
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*
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* Selects the most appropriate <code>data-{ratio}x</code> attribute from
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* the given element's attributes. If the devices pixel ratio is greater
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* than the largest specified image, the largest one of the available is used.
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*
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* @return {String|Boolean} The attribute value
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* @method getImageAttribute
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* @memberof jQuery.fn.dense
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* @example
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* var image = $('<div data-1x="image.jpg" data-2x="image_2x.jpg" />').dense('getImageAttribute');
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* $('body').css('background-image', 'url(' + image + ')');
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*/
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methods.getImageAttribute = function ()
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{
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var $this = $(this).eq(0), image = false, url;
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for (var i = 1; i <= devicePixelRatio; i++)
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{
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url = $this.attr('data-' + i + 'x');
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if (url)
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{
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image = url;
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}
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}
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return image;
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};
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devicePixelRatio = methods.devicePixelRatio();
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/**
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* Dense offers few methods and options that can be used to both customize the
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* plugin's functionality and return resulting values. All interaction is done through
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* the <code>$.fn.dense()</code> method, that accepts a called method and its options
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* object as its arguments. Both arguments are optional, and either one can be omitted.
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*
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* @param {String} [method=init] The called method
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* @param {Object} [options={}] Options passed to the method
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* @class dense
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* @memberof jQuery.fn
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*/
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$.fn.dense = function (method, options)
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{
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if ($.type(method) !== 'string' || $.type(methods[method]) !== 'function')
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{
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options = method;
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method = 'init';
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}
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return methods[method].call(this, options);
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};
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/**
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* Initialize automatically when document is ready.
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*
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* Dense is initialized automatically if the body element
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* has a <code>dense-retina</code> class.
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*/
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$(function ()
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{
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$('body.dense-retina img').dense();
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});
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/**
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* This event is invoked when a retina image has finished loading.
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*
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* @event jQuery.fn.dense#denseRetinaReady.dense
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* @type {Object}
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*/
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/**
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* This event is invoked when an image's dimension values
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* have been updated by the <code>updateDimensions</code>
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* method.
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*
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* @event jQuery.fn.dense#denseDimensionChanged.dense
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* @type {Object}
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*/
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})); |