Add Buffer creation convenience

lib/exif/ExifImage.js

@@ -9,6 +9,17 @@ var debug = require('debug')('exif');
 
 var DEFAULT_MAX_ENTRIES=128;
 
+function base64ToArrayBuffer(base64) {
+  base64 = base64.replace(/^data\:([^\;]+)\;base64,/gmi, '');
+  var binary = atob(base64);
+  var len = binary.length;
+  var view = new Uint8Array(new ArrayBuffer(len));
+  for (var i = 0; i < len; i++) {
+      view[i] = binary.charCodeAt(i);
+  }
+  return view.buffer;
+}
+
 /**
  * Represents an image with Exif information. When instantiating it you have to
  * provide an image and a callback function which is called once all metadata
@@ -107,7 +118,20 @@ function ExifImage (options, callback) {
 //    callback(new Error('You have to provide an image, it is pretty hard to extract Exif data from nothing...'));
     return;
   }
-
+
+  if (ops.hasOwnProperty('imageDataType')) {
+    switch (ops.imageDataType.toLowerCase()) {
+      case 'base64':
+        ops.image = new Buffer(base64ToArrayBuffer(ops.image));
+        break;
+      case 'arraybuffer':
+        ops.image = new Buffer(ops.image);
+        break;
+      default:
+        break;
+    }
+  } 
+
   if (typeof callback !== 'function') {
     throw new Error('You have to provide a callback function.');
   }