Current state

public/legacy/assets/plugins/retina.js

@@ -0,0 +1,146 @@
+(function() {
+  var root = (typeof exports == 'undefined' ? window : exports);
+
+  var config = {
+    // Ensure Content-Type is an image before trying to load @2x image
+    // https://github.com/imulus/retinajs/pull/45)
+    check_mime_type: true,
+
+    // Resize high-resolution images to original image's pixel dimensions
+    // https://github.com/imulus/retinajs/issues/8
+    force_original_dimensions: true
+ };
+
+  root.Retina = Retina;
+
+  function Retina() {}
+
+  Retina.configure = function(options) {
+    if (options === null) options = {};
+    for (var prop in options) config[prop] = options[prop];
+  };
+
+  Retina.init = function(context) {
+    if (context === null) context = root;
+
+    var existing_onload = context.onload || function(){};
+
+    context.onload = function() {
+      var images = document.getElementsByTagName("img"), retinaImages = [], i, image;
+      for (i = 0; i < images.length; i++) {
+        image = images[i];
+        retinaImages.push(new RetinaImage(image));
+      }
+      existing_onload();
+    };
+  };
+
+  Retina.isRetina = function(){
+    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)";
+
+    if (root.devicePixelRatio > 1)
+      return true;
+
+    if (root.matchMedia && root.matchMedia(mediaQuery).matches)
+      return true;
+
+    return false;
+  };
+
+
+  root.RetinaImagePath = RetinaImagePath;
+
+  function RetinaImagePath(path, at_2x_path) {
+    this.path = path;
+    if (typeof at_2x_path !== "undefined" && at_2x_path !== null) {
+      this.at_2x_path = at_2x_path;
+      this.perform_check = false;
+    } else {
+      this.at_2x_path = path.replace(/\.\w+$/, function(match) { return "@2x" + match; });
+      this.perform_check = true;
+    }
+  }
+
+  RetinaImagePath.confirmed_paths = [];
+
+  RetinaImagePath.prototype.is_external = function() {
+    return !!(this.path.match(/^https?\:/i) && !this.path.match('//' + document.domain) );
+  };
+
+  RetinaImagePath.prototype.check_2x_variant = function(callback) {
+    var http, that = this;
+    if (this.is_external()) {
+      return callback(false);
+    } else if (!this.perform_check && typeof this.at_2x_path !== "undefined" && this.at_2x_path !== null) {
+      return callback(true);
+    } else if (this.at_2x_path in RetinaImagePath.confirmed_paths) {
+      return callback(true);
+    } else {
+      http = new XMLHttpRequest();
+      http.open('HEAD', this.at_2x_path);
+      http.onreadystatechange = function() {
+        if (http.readyState != 4) {
+          return callback(false);
+        }
+
+        if (http.status >= 200 && http.status <= 399) {
+          if (config.check_mime_type) {
+            var type = http.getResponseHeader('Content-Type');
+            if (type === null || !type.match(/^image/i)) {
+              return callback(false);
+            }
+          }
+
+          RetinaImagePath.confirmed_paths.push(that.at_2x_path);
+          return callback(true);
+        } else {
+          return callback(false);
+        }
+      };
+      http.send();
+    }
+  };
+
+
+
+  function RetinaImage(el) {
+    this.el = el;
+    this.path = new RetinaImagePath(this.el.getAttribute('src'), this.el.getAttribute('data-at2x'));
+    var that = this;
+    this.path.check_2x_variant(function(hasVariant) {
+      if (hasVariant) that.swap();
+    });
+  }
+
+  root.RetinaImage = RetinaImage;
+
+  RetinaImage.prototype.swap = function(path) {
+    if (typeof path == 'undefined') path = this.path.at_2x_path;
+
+    var that = this;
+    function load() {
+      if (! that.el.complete) {
+        setTimeout(load, 5);
+      } else {
+        if (config.force_original_dimensions) {
+          that.el.setAttribute('width', that.el.offsetWidth);
+          that.el.setAttribute('height', that.el.offsetHeight);
+        }
+
+        that.el.setAttribute('src', path);
+      }
+    }
+    load();
+  };
+
+
+
+
+  if (Retina.isRetina()) {
+    Retina.init(root);
+  }
+
+})();