https://writerslife.org/wp-content/themes/maxmag/js/retina.js?ver=35c79868b15870530e99d5eee093d443

1/*!
2 * Retina.js v1.3.0
3 *
4 * Copyright 2014 Imulus, LLC
5 * Released under the MIT license
6 *
7 * Retina.js is an open source script that makes it easy to serve
8 * high-resolution images to devices with retina displays.
9 */
10
11(function() {
12    var root = (typeof exports === 'undefined' ? window : exports);
13    var config = {
14        // An option to choose a suffix for 2x images
15        retinaImageSuffix : '@2x',
16
17        // Ensure Content-Type is an image before trying to load @2x image
18        // https://github.com/imulus/retinajs/pull/45)
19        check_mime_type: true,
20
21        // Resize high-resolution images to original image's pixel dimensions
22        // https://github.com/imulus/retinajs/issues/8
23        force_original_dimensions: true
24    };
25
26    function Retina() {}
27
28    root.Retina = Retina;
29
30    Retina.configure = function(options) {
31        if (options === null) {
32            options = {};
33        }
34
35        for (var prop in options) {
36            if (options.hasOwnProperty(prop)) {
37                config[prop] = options[prop];
38            }
39        }
40    };
41
42    Retina.init = function(context) {
43        if (context === null) {
44            context = root;
45        }
46
47        var existing_onload = context.onload || function(){};
48
49        context.onload = function() {
50            var images = document.getElementsByTagName('img'), retinaImages = [], i, image;
51            for (i = 0; i < images.length; i += 1) {
52                image = images[i];
53                if (!!!image.getAttributeNode('data-no-retina')) {
54                    retinaImages.push(new RetinaImage(image));
55                }
56            }
57            existing_onload();
58        };
59    };
60
61    Retina.isRetina = function(){
62        var mediaQuery = '(-webkit-min-device-pixel-ratio: 1.5), (min--moz-device-pixel-ratio: 1.5), (-o-min-device-pixel-ratio: 3/2), (min-resolution: 1.5dppx)';
63
64        if (root.devicePixelRatio > 1) {
65            return true;
66        }
67
68        if (root.matchMedia && root.matchMedia(mediaQuery).matches) {
69            return true;
70        }
71
72        return false;
73    };
74
75
76    var regexMatch = /\.\w+$/;
77    function suffixReplace (match) {
78        return config.retinaImageSuffix + match;
79    }
80
81    function RetinaImagePath(path, at_2x_path) {
82        this.path = path || '';
83        if (typeof at_2x_path !== 'undefined' && at_2x_path !== null) {
84            this.at_2x_path = at_2x_path;
85            this.perform_check = false;
86        } else {
87            if (undefined !== document.createElement) {
88                var locationObject = document.createElement('a');
89                locationObject.href = this.path;
90                locationObject.pathname = locationObject.pathname.replace(regexMatch, suffixReplace);
91                this.at_2x_path = locationObject.href;
92            } else {
93                var parts = this.path.split('?');
94                parts[0] = parts[0].replace(regexMatch, suffixReplace);
95                this.at_2x_path = parts.join('?');
96            }
97            this.perform_check = true;
98        }
99    }
100
101    root.RetinaImagePath = RetinaImagePath;
102
103    RetinaImagePath.confirmed_paths = [];
104
105    RetinaImagePath.prototype.is_external = function() {
106        return !!(this.path.match(/^https?\:/i) && !this.path.match('//' + document.domain) );
107    };
108
109    RetinaImagePath.prototype.check_2x_variant = function(callback) {
110        var http, that = this;
111        if (this.is_external()) {
112            return callback(false);
113        } else if (!this.perform_check && typeof this.at_2x_path !== 'undefined' && this.at_2x_path !== null) {
114            return callback(true);
115        } else if (this.at_2x_path in RetinaImagePath.confirmed_paths) {
116            return callback(true);
117        } else {
118            http = new XMLHttpRequest();
119            http.open('HEAD', this.at_2x_path);
120            http.onreadystatechange = function() {
121                if (http.readyState !== 4) {
122                    return callback(false);
123                }
124
125                if (http.status >= 200 && http.status <= 399) {
126                    if (config.check_mime_type) {
127                        var type = http.getResponseHeader('Content-Type');
128                        if (type === null || !type.match(/^image/i)) {
129                            return callback(false);
130                        }
131                    }
132
133                    RetinaImagePath.confirmed_paths.push(that.at_2x_path);
134                    return callback(true);
135                } else {
136                    return callback(false);
137                }
138            };
139            http.send();
140        }
141    };
142
143
144    function RetinaImage(el) {
145        this.el = el;
146        this.path = new RetinaImagePath(this.el.getAttribute('src'), this.el.getAttribute('data-at2x'));
147        var that = this;
148        this.path.check_2x_variant(function(hasVariant) {
149            if (hasVariant) {
150                that.swap();
151            }
152        });
153    }
154
155    root.RetinaImage = RetinaImage;
156
157    RetinaImage.prototype.swap = function(path) {
158        if (typeof path === 'undefined') {
159            path = this.path.at_2x_path;
160        }
161
162        var that = this;
163        function load() {
164            if (! that.el.complete) {
165                setTimeout(load, 5);
166            } else {
167                if (config.force_original_dimensions) {
168                    that.el.setAttribute('width', that.el.offsetWidth);
169                    that.el.setAttribute('height', that.el.offsetHeight);
170                }
171
172                that.el.setAttribute('src', path);
173            }
174        }
175        load();
176    };
177
178
179    if (Retina.isRetina()) {
180        Retina.init(root);
181    }
182})();