/usr/lib/python2.7/dist-packages/openalpr/openalpr.py is in python-openalpr 2.2.4-1build1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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import json
import platform
# We need to do things slightly differently for Python 2 vs. 3
# ... because the way str/unicode have changed to bytes/str
if platform.python_version_tuple()[0] == '2':
# Using Python 2
bytes = str
_PYTHON_3 = False
else:
# Assume using Python 3+
unicode = str
_PYTHON_3 = True
def _convert_to_charp(string):
# Prepares function input for use in c-functions as char*
if type(string) == unicode:
return string.encode("UTF-8")
elif type(string) == bytes:
return string
else:
raise TypeError("Expected unicode string values or ascii/bytes values. Got: %r" % type(string))
def _convert_from_charp(charp):
# Prepares char* output from c-functions into Python strings
if _PYTHON_3 and type(charp) == bytes:
return charp.decode("UTF-8")
else:
return charp
class Alpr():
def __init__(self, country, config_file, runtime_dir):
"""
Initializes an OpenALPR instance in memory.
:param country: The default region for license plates. E.g., "us" or "eu"
:param config_file: The path to the OpenALPR config file
:param runtime_dir: The path to the OpenALPR runtime data directory
:return: An OpenALPR instance
"""
country = _convert_to_charp(country)
config_file = _convert_to_charp(config_file)
runtime_dir = _convert_to_charp(runtime_dir)
try:
# Load the .dll for Windows and the .so for Unix-based
if platform.system().lower().find("windows") != -1:
self._openalprpy_lib = ctypes.cdll.LoadLibrary("openalprpy.dll")
elif platform.system().lower().find("darwin") != -1:
self._openalprpy_lib = ctypes.cdll.LoadLibrary("libopenalprpy.dylib")
else:
self._openalprpy_lib = ctypes.cdll.LoadLibrary("libopenalprpy.so")
except OSError as e:
nex = OSError("Unable to locate the OpenALPR library. Please make sure that OpenALPR is properly "
"installed on your system and that the libraries are in the appropriate paths.")
if _PYTHON_3:
nex.__cause__ = e;
raise nex
self._initialize_func = self._openalprpy_lib.initialize
self._initialize_func.restype = ctypes.c_void_p
self._initialize_func.argtypes = [ctypes.c_char_p, ctypes.c_char_p, ctypes.c_char_p]
self._dispose_func = self._openalprpy_lib.dispose
self._dispose_func.argtypes = [ctypes.c_void_p]
self._is_loaded_func = self._openalprpy_lib.isLoaded
self._is_loaded_func.argtypes = [ctypes.c_void_p]
self._is_loaded_func.restype = ctypes.c_bool
self._recognize_file_func = self._openalprpy_lib.recognizeFile
self._recognize_file_func.restype = ctypes.c_void_p
self._recognize_file_func.argtypes = [ctypes.c_void_p, ctypes.c_char_p]
self._recognize_array_func = self._openalprpy_lib.recognizeArray
self._recognize_array_func.restype = ctypes.c_void_p
self._recognize_array_func.argtypes = [ctypes.c_void_p, ctypes.POINTER(ctypes.c_ubyte), ctypes.c_uint]
self._free_json_mem_func = self._openalprpy_lib.freeJsonMem
self._set_country_func = self._openalprpy_lib.setCountry
self._set_country_func.argtypes = [ctypes.c_void_p, ctypes.c_char_p]
self._set_prewarp_func = self._openalprpy_lib.setPrewarp
self._set_prewarp_func.argtypes = [ctypes.c_void_p, ctypes.c_char_p]
self._set_default_region_func = self._openalprpy_lib.setDefaultRegion
self._set_default_region_func.argtypes = [ctypes.c_void_p, ctypes.c_char_p]
self._set_detect_region_func = self._openalprpy_lib.setDetectRegion
self._set_detect_region_func.argtypes = [ctypes.c_void_p, ctypes.c_bool]
self._set_top_n_func = self._openalprpy_lib.setTopN
self._set_top_n_func.argtypes = [ctypes.c_void_p, ctypes.c_int]
self._get_version_func = self._openalprpy_lib.getVersion
self._get_version_func.argtypes = [ctypes.c_void_p]
self._get_version_func.restype = ctypes.c_void_p
self.alpr_pointer = self._initialize_func(country, config_file, runtime_dir)
def unload(self):
"""
Unloads OpenALPR from memory.
:return: None
"""
self._openalprpy_lib.dispose(self.alpr_pointer)
def is_loaded(self):
"""
Checks if OpenALPR is loaded.
:return: A bool representing if OpenALPR is loaded or not
"""
return self._is_loaded_func(self.alpr_pointer)
def recognize_file(self, file_path):
"""
This causes OpenALPR to attempt to recognize an image by opening a file on
disk.
:param file_path: The path to the image that will be analyzed
:return: An OpenALPR analysis in the form of a response dictionary
"""
file_path = _convert_to_charp(file_path)
ptr = self._recognize_file_func(self.alpr_pointer, file_path)
json_data = ctypes.cast(ptr, ctypes.c_char_p).value
json_data = _convert_from_charp(json_data)
response_obj = json.loads(json_data)
self._free_json_mem_func(ctypes.c_void_p(ptr))
return response_obj
def recognize_array(self, byte_array):
"""
This causes OpenALPR to attempt to recognize an image passed in as a byte array.
:param byte_array: This should be a string (Python 2) or a bytes object (Python 3)
:return: An OpenALPR analysis in the form of a response dictionary
"""
if type(byte_array) != bytes:
raise TypeError("Expected a byte array (string in Python 2, bytes in Python 3)")
pb = ctypes.cast(byte_array, ctypes.POINTER(ctypes.c_ubyte))
ptr = self._recognize_array_func(self.alpr_pointer, pb, len(byte_array))
json_data = ctypes.cast(ptr, ctypes.c_char_p).value
json_data = _convert_from_charp(json_data)
response_obj = json.loads(json_data)
self._free_json_mem_func(ctypes.c_void_p(ptr))
return response_obj
def get_version(self):
"""
This gets the version of OpenALPR
:return: Version information
"""
ptr = self._get_version_func(self.alpr_pointer)
version_number = ctypes.cast(ptr, ctypes.c_char_p).value
version_number = _convert_from_charp(version_number)
self._free_json_mem_func(ctypes.c_void_p(ptr))
return version_number
def set_top_n(self, topn):
"""
Sets the number of returned results when analyzing an image. For example,
setting topn = 5 returns the top 5 results.
:param topn: An integer that represents the number of returned results.
:return: None
"""
self._set_top_n_func(self.alpr_pointer, topn)
def set_country(self, country):
"""
This sets the country for detecting license plates. For example,
setting country to "us" for United States or "eu" for Europe.
:param country: A unicode/ascii string (Python 2/3) or bytes array (Python 3)
:return: None
"""
country = _convert_to_charp(country)
self._set_country_func(self.alpr_pointer, country)
def set_prewarp(self, prewarp):
"""
Updates the prewarp configuration used to skew images in OpenALPR before
processing.
:param prewarp: A unicode/ascii string (Python 2/3) or bytes array (Python 3)
:return: None
"""
prewarp = _convert_to_charp(prewarp)
self._set_prewarp_func(self.alpr_pointer, prewarp)
def set_default_region(self, region):
"""
This sets the default region for detecting license plates. For example,
setting region to "md" for Maryland or "fr" for France.
:param region: A unicode/ascii string (Python 2/3) or bytes array (Python 3)
:return: None
"""
region = _convert_to_charp(region)
self._set_default_region_func(self.alpr_pointer, region)
def set_detect_region(self, enabled):
"""
This allows OpenALPR to attempt to detect the region of a license plate
automatically. By default this is disabled, but you can enable it here.
:param enabled: A boolean representing whether or not auto-detection is enabled
:return: None
"""
self._set_detect_region_func(self.alpr_pointer, enabled)
def __del__(self):
if self.is_loaded():
self.unload()
def __enter__(self):
return self
def __exit__(self, exc_type, exc_val, exc_tb):
if self.is_loaded():
self.unload()
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