https://pja.org.pk/wp-content/themes/envision/lib/js/retina.js?ver=2.4

1/* ============================================================
2 * retina-replace.js v1.0
3 * http://github.com/leonsmith/retina-replace-js
4 * ============================================================
5 * Author: Leon Smith
6 * Twitter: @nullUK
7 *
8 * Licensed under the Apache License, Version 2.0 (the "License");
9 * you may not use this file except in compliance with the License.
10 * You may obtain a copy of the License at
11 *
12 * http://www.apache.org/licenses/LICENSE-2.0
13 *
14 * Unless required by applicable law or agreed to in writing, software
15 * distributed under the License is distributed on an "AS IS" BASIS,
16 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
17 * See the License for the specific language governing permissions and
18 * limitations under the License.
19 * ============================================================ */
20 (function($) {
21        "use strict";
22        
23        var retinaReplace = function(element, options) {
24                try {
25
26                    this.options = options;
27                    var $el = $(element);
28                    var is_image = $el.is('img');
29                    var normal_url = is_image ? $el.attr('src') : $el.backgroundImageUrl();
30                    var retina_url = $el.attr('data-at2x') ? $el.attr('data-at2x') : '';;
31
32                    if ( retina_url == '' ) {
33                        if ( $el.attr('data-retina-auto') ) {
34                            retina_url = this.options.generateUrl($el, normal_url);
35                        } else {
36                            return true;
37                        }
38                    }       
39
40
41                    $('<img/>').attr('src', retina_url).load(function() {
42
43                        if (is_image) {
44
45                            $el.css({ width: $el.width(), height: $el.height() });
46                            $el.attr('data-orginal-src', $el.attr('src'));
47                            $el.attr('src', $(this).attr('src'));
48
49                        } else {
50
51                            $el.backgroundImageUrl($(this).attr('src'));
52                            $el.backgroundSize($(this)[0].width, $(this)[0].height);
53                        
54                        }
55
56                        $el.attr('data-retina', 'complete');
57
58                    });
59                    
60                } catch (e) {}
61                        
62
63        }
64
65        retinaReplace.prototype = {
66                constructor: retinaReplace
67        }
68
69        $.fn.retinaReplace = function(option) {
70                // Finish if we arn't a retina device
71                return this.each(function() {
72                    var $this = $(this);
73                    var data = $this.data('retinaReplace');
74                    var options = $.extend({}, $.fn.retinaReplace.defaults, $this.data(), typeof option == 'object' && option);
75                    if (!data) { $this.data('retinaReplace', (data = new retinaReplace(this, options))); }
76                    if (typeof option == 'string') { data[option](); }
77                });
78        }
79        
80        $.fn.retinaReplace.defaults = {
81                suffix: '@2x', 
82                generateUrl: function(element, url) {
83                    if ( typeof url == 'undefined' ) {
84                        return '';
85                    }
86                    var dot_index = url.lastIndexOf('.');
87                    var extension = url.substr(dot_index + 1);
88                    var file = url.substr(0, dot_index);
89                    return file + this.suffix + '.' + extension;
90                }
91        }
92
93        $.fn.retinaReplace.Constructor = retinaReplace;
94
95        $.fn.backgroundImageUrl = function(url) {
96            return url ? this.each(function () { 
97                $(this).css("background-image", 'url("' + url + '")')
98            }) : $(this).css("background-image").replace(/url\(|\)|"|'/g, "");
99        }
100
101        $.fn.backgroundSize = function(retinaWidth, retinaHeight) {
102            var sizeValue = Math.floor(retinaWidth/2) + 'px ' + Math.floor(retinaHeight/2) + 'px';
103            $(this).css("background-size", sizeValue);
104            $(this).css("-webkit-background-size", sizeValue);
105        }
106
107        // Trigger replacement on elements that hav been marked up
108        var init = function(){
109            $(":not([data-at2x='']):visible").retinaReplace();
110        }
111
112
113        // Check is retina
114        var isRetina = function(){
115            var root = (typeof exports == 'undefined' ? window : exports);
116            var mediaQuery = "(-webkit-min-device-pixel-ratio: 1.5),\
117                            (min--moz-device-pixel-ratio: 1.5),\
118                            (-o-min-device-pixel-ratio: 3/2),\
119                            (min-resolution: 1.5dppx)";
120
121            if (root.devicePixelRatio > 1) {
122                return true;
123            }
124
125            if (root.matchMedia && root.matchMedia(mediaQuery).matches) {
126                return true;
127            }
128
129            //return true;
130            return false;
131        };
132
133
134        if ( isRetina() ) {
135            //$(init);
136            $('html').removeClass('no-retina').addClass('retina');
137            $(window).on('load', init );
138            $(window).smartresize( init );
139            $(window).bind( 'make@2x', init );
140        }
141
142
143})(window.jQuery);