Provide getDataUrl method for previews

meteor-file.js

@@ -101,7 +101,35 @@ EJSON.addType("MeteorFile", MeteorFile.fromJSONValue);
 
 /************************ Client *********************************************/
 if (Meteor.isClient) {
+
+  /**
+   * Create a binary string out of an array of numbers (bytes), each varying
+   * from 0-255.
+   *
+   * @param {Array} bytes The array of numbers to transform into a binary str.
+   * @return {string} The byte array as a string.
+   */
+  function arrayToBinaryString(bytes) {
+    if (typeof bytes != typeof []) {
+      return null;
+    }
+    var i = bytes.length;
+    var bstr = new Array(i);
+    while (i--) {
+      bstr[i] = String.fromCharCode(bytes[i]);
+    }
+    return bstr.join('');
+  }
+
+  function toDataURL(contentType, uint8Array) {
+    return 'data:' + contentType + ';base64,' +
+        self.btoa(arrayToBinaryString(uint8Array));
+  }
+
   _.extend(MeteorFile.prototype, {
+    getDataUrl: function() {
+        return toDataURL(this.type, this.data);
+    },
     read: function (file, options, callback) {
       if (arguments.length == 2)
         callback = options;

package.js

@@ -4,9 +4,7 @@ Package.describe({
 
 Package.on_use(function (api) {
   api.use(["underscore", "ejson"], ["client", "server"]);
-  api.use(["handlebars", "spark"], "client");
   api.add_files(["meteor-file.js"], ["client", "server"]);
-  api.add_files("meteor-file-uploader.js", "client");
 
   if (typeof api.export !== 'undefined') {
     api.export("MeteorFile", ["client", "server"]);