Refactor barcode decoder to use Zxing's C++ version

By using the C++ version of Zxing, we can avoid having Java and Ant
as a dependency when running Video quality analysis on the bots.
This makes it far more easy to setup automation on new machines.

I also moved the scripts into the webrtc/ folder so it will be synced by default when building in Chrome (eliminating the need of a separate solution).

This CL also removes the need of the FFMPEG_HOME variable and replaces
its use with a command line flag to make the tool run smoothly on
Windows.

BUG=none
TEST=locally running the script on Windows, Mac and Linux.

Review URL: https://webrtc-codereview.appspot.com/1099007

git-svn-id: http://webrtc.googlecode.com/svn/trunk@3640 4adac7df-926f-26a2-2b94-8c16560cd09d

webrtc/tools/barcode_tools/helper_functions.py

@@ -0,0 +1,96 @@
+#!/usr/bin/env python
+# Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
+#
+# Use of this source code is governed by a BSD-style license
+# that can be found in the LICENSE file in the root of the source
+# tree. An additional intellectual property rights grant can be found
+# in the file PATENTS.  All contributing project authors may
+# be found in the AUTHORS file in the root of the source tree.
+
+import os
+import subprocess
+import sys
+
+_DEFAULT_PADDING = 4
+
+
+class HelperError(Exception):
+  """Exception raised for errors in the helper."""
+  pass
+
+
+def zero_pad(number, padding=_DEFAULT_PADDING):
+  """Converts an int into a zero padded string.
+
+  Args:
+    number(int): The number to convert.
+    padding(int): The number of chars in the output. Note that if you pass for
+      example number=23456 and padding=4, the output will still be '23456',
+      i.e. it will not be cropped. If you pass number=2 and padding=4, the
+      return value will be '0002'.
+  Return:
+    (string): The zero padded number converted to string.
+  """
+  return str(number).zfill(padding)
+
+
+def run_shell_command(cmd_list, fail_msg=None):
+  """Executes a command.
+
+  Args:
+    cmd_list(list): Command list to execute.
+    fail_msg(string): Message describing the error in case the command fails.
+
+  Return:
+    (string): The standard output from running the command.
+
+  Raise:
+    HelperError: If command fails.
+  """
+  process = subprocess.Popen(cmd_list, stdout=subprocess.PIPE,
+                             stderr=subprocess.PIPE)
+  output, error = process.communicate()
+  if process.returncode != 0:
+    if fail_msg:
+      print >> sys.stderr, fail_msg
+    raise HelperError('Failed to run %s: command returned %d and printed '
+                      '%s and %s' % (' '.join(cmd_list), process.returncode,
+                                     output, error))
+  return output.strip()
+
+
+def perform_action_on_all_files(directory, file_pattern, file_extension,
+                                start_number, action, **kwargs):
+  """Function that performs a given action on all files matching a pattern.
+
+  It is assumed that the files are named file_patternxxxx.file_extension, where
+  xxxx are digits. The file names start from
+  file_patern0..start_number>.file_extension.
+
+  Args:
+    directory(string): The directory where the files live.
+    file_pattern(string): The name pattern of the files.
+    file_extension(string): The files' extension.
+    start_number(int): From where to start to count frames.
+    action(function): The action to be performed over the files. Must return
+      False if the action failed, True otherwise.
+
+  Return:
+    (bool): Whether performing the action over all files was successful or not.
+  """
+  file_prefix = os.path.join(directory, file_pattern)
+  file_exists = True
+  file_number = start_number
+  errors = False
+
+  while file_exists:
+    zero_padded_file_number = zero_pad(file_number)
+    file_name = file_prefix + zero_padded_file_number + '.' + file_extension
+    if os.path.isfile(file_name):
+      if not action(file_name=file_name, **kwargs):
+        errors = True
+        break
+      file_number += 1
+    else:
+      file_exists = False
+  return not errors