144 lines
3.7 KiB
JavaScript
144 lines
3.7 KiB
JavaScript
(function() {
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var root = (typeof exports == 'undefined' ? window : exports);
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var config = {
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// Ensure Content-Type is an image before trying to load @2x image
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// https://github.com/imulus/retinajs/pull/45)
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check_mime_type: true
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};
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root.Retina = Retina;
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function Retina() {}
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Retina.configure = function(options) {
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if (options == null) options = {};
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for (var prop in options) config[prop] = options[prop];
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};
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Retina.init = function(context) {
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if (context == null) context = root;
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var existing_onload = context.onload || new Function;
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context.onload = function() {
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var images = document.getElementsByTagName("img"), retinaImages = [], i, image;
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for (i = 0; i < images.length; i++) {
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image = images[i];
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retinaImages.push(new RetinaImage(image));
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}
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existing_onload();
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}
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};
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Retina.isRetina = function(){
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var mediaQuery = "(-webkit-min-device-pixel-ratio: 1.5),\
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(min--moz-device-pixel-ratio: 1.5),\
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(-o-min-device-pixel-ratio: 3/2),\
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(min-resolution: 1.5dppx)";
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if (root.devicePixelRatio > 1)
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return true;
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if (root.matchMedia && root.matchMedia(mediaQuery).matches)
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return true;
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return false;
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};
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root.RetinaImagePath = RetinaImagePath;
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function RetinaImagePath(path, at_2x_path) {
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this.path = path;
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if (typeof at_2x_path !== "undefined" && at_2x_path !== null) {
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this.at_2x_path = at_2x_path;
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this.perform_check = false;
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} else {
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this.at_2x_path = path.replace(/\.\w+$/, function(match) { return "@2x" + match; });
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this.perform_check = true;
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}
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}
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RetinaImagePath.confirmed_paths = [];
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RetinaImagePath.prototype.is_external = function() {
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return !!(this.path.match(/^https?\:/i) && !this.path.match('//' + document.domain) )
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}
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RetinaImagePath.prototype.check_2x_variant = function(callback) {
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var http, that = this;
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if (this.is_external()) {
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return callback(false);
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} else if (!this.perform_check && typeof this.at_2x_path !== "undefined" && this.at_2x_path !== null) {
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return callback(true);
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} else if (this.at_2x_path in RetinaImagePath.confirmed_paths) {
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return callback(true);
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} else {
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http = new XMLHttpRequest;
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http.open('HEAD', this.at_2x_path);
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http.onreadystatechange = function() {
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if (http.readyState != 4) {
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return callback(false);
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}
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if (http.status >= 200 && http.status <= 399) {
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if (config.check_mime_type) {
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var type = http.getResponseHeader('Content-Type');
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if (type == null || !type.match(/^image/i)) {
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return callback(false);
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}
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}
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RetinaImagePath.confirmed_paths.push(that.at_2x_path);
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return callback(true);
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} else {
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return callback(false);
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}
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}
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http.send();
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}
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}
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function RetinaImage(el) {
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this.el = el;
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this.path = new RetinaImagePath(this.el.getAttribute('src'), this.el.getAttribute('data-at2x'));
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var that = this;
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this.path.check_2x_variant(function(hasVariant) {
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if (hasVariant) that.swap();
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});
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}
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root.RetinaImage = RetinaImage;
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RetinaImage.prototype.swap = function(path) {
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if (typeof path == 'undefined') path = this.path.at_2x_path;
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var that = this;
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function load() {
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if (! that.el.complete) {
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setTimeout(load, 5);
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} else {
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that.el.setAttribute('width', that.el.offsetWidth);
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that.el.setAttribute('height', that.el.offsetHeight);
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that.el.setAttribute('src', path);
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}
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}
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load();
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}
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if (Retina.isRetina()) {
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Retina.init(root);
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}
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})();
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