Add utils for work with dom file like objects.

src/uxbox/util/dom/files.cljs

@@ -0,0 +1,35 @@
+;; This Source Code Form is subject to the terms of the Mozilla Public
+;; License, v. 2.0. If a copy of the MPL was not distributed with this
+;; file, You can obtain one at http://mozilla.org/MPL/2.0/.
+;;
+;; Copyright (c) 2016 Andrey Antukh <niwi@niwi.nz>
+
+(ns uxbox.util.dom.files
+  "A interop helpers for work with files."
+  (:require [beicon.core :as rx]
+            [cuerdas.core :as str]))
+
+(defn- read-as-dataurl
+  [file]
+  (rx/create
+   (fn [sick]
+     (let [fr (js/FileReader.)]
+       (aset fr "onload" #(sick (rx/end (.-result fr))))
+       (.readAsDataURL fr file))
+     (constantly nil))))
+
+(defn- retrieve-image-size
+  [data]
+  (println "data:" data)
+  (rx/create
+   (fn [sick]
+     (let [img (js/Image.)]
+       (aset img "onload" #(sick (rx/end [(.-width img) (.-height img)])))
+       (set! (.-src img) data))
+     (constantly nil))))
+
+(defn get-image-size
+  "Get the real image size."
+  [file]
+  (->> (read-as-dataurl file)
+       (rx/flat-map retrieve-image-size)))