Update Readme in relation to initFileFn and readFileFn hooks

Author: evilaliv3

README.md

@@ -119,8 +119,10 @@ function, it will be passed a FlowFile, a FlowChunk and isTest boolean (Default:
 * `allowDuplicateUploads ` Once a file is uploaded, allow reupload of the same file. By default, if a file is already uploaded, it will be skipped unless the file is removed from the existing Flow object. (Default: `false`)
 * `prioritizeFirstAndLastChunk` Prioritize first and last chunks of all files. This can be handy if you can determine if a file is valid for your service from only the first or last chunk. For example, photo or video meta data is usually located in the first part of a file, making it easy to test support from only the first chunk. (Default: `false`)
 * `testChunks` Make a GET request to the server for each chunks to see if it already exists. If implemented on the server-side, this will allow for upload resumes even after a browser crash or even a computer restart. (Default: `true`)
-* `preprocess` Optional function to process each chunk before testing & sending. Function is passed the chunk as parameter, and should call the `preprocessFinished` method on the chunk when finished. (Default: `null`)
-* `generateUniqueIdentifier` Override the function that generates unique identifiers for each file.  (Default: `null`)
+* `preprocess` Optional function to process each chunk before testing & sending. To the function it will be passed the chunk as parameter, and should call the `preprocessFinished` method on the chunk when finished. (Default: `null`)
+* `initFileFn` Optional function to initialize the fileObject. To the function it will be passed a FlowFile and a FlowChunk arguments.
+* `readFileFn` Optional function wrapping reading operation from the original file. To the function it will be passed the FlowFile, the startByte and endByte, the fileType and the FlowChunk.
+* `generateUniqueIdentifier` Override the function that generates unique identifiers for each file. (Default: `null`)
 * `maxChunkRetries` The maximum number of retries for a chunk before the upload is failed. Valid values are any positive integer and `undefined` for no limit. (Default: `0`)
 * `chunkRetryInterval` The number of milliseconds to wait before retrying a chunk on a non-permanent error.  Valid values are any positive integer and `undefined` for immediate retry. (Default: `undefined`)
 * `progressCallbacksInterval` The time interval in milliseconds between progress reports. Set it

src/flow.js

@@ -917,7 +917,9 @@
      * @function
      */
     bootstrap: function () {
-      evalOpts(this.flowObj.opts.initFileFn, this.fileObj, this);
+      if (typeof this.flowObj.opts.initFileFn === "function") {
+        this.flowObj.opts.initFileFn(this);
+      }
 
       this.abort(true);
       this.error = false;
@@ -1047,15 +1049,20 @@
   /**
    * Default read function using the webAPI
    *
-   * @function webAPIFileRead(chunk, startByte, endByte, fileType)
+   * @function webAPIFileRead(fileObj, fileType, startByte, endByte, chunk)
    *
    */
-  function webAPIFileRead(chunk, startByte, endByte, fileType) {
-    var function_name = (chunk.fileObj.file.slice ? 'slice' :
-      (chunk.fileObj.file.mozSlice ? 'mozSlice' :
-        (chunk.fileObj.file.webkitSlice ? 'webkitSlice' :
-          'slice')));
-    chunk.readFinished(chunk.fileObj.file[function_name](startByte, endByte, fileType));
+  function webAPIFileRead(fileObj, fileType, startByte, endByte, chunk) {
+    var function_name = 'slice';
+
+    if (fileObj.file.slice)
+      function_name =  'slice';
+    else if (fileObj.file.mozSlice)
+      function_name = 'mozSlice';
+    else if (fileObj.file.webkitSlice)
+      function_name = 'webkitSlice';
+
+    chunk.readFinished(fileObj.file[function_name](startByte, endByte, fileType));
   }
 
 
@@ -1324,7 +1331,7 @@
       switch (this.readState) {
         case 0:
           this.readState = 1;
-          read(this, this.startByte, this.endByte, this.fileType);
+          read(this.fileObj, this.startByte, this.endByte, this.fileType, this);
           return;
         case 1:
           return;