cx_Freeze and OpenCV, fixing numpy imports and cascades as data files.

After all the problems found trying cx_Freeze in Mac to create the app in 32-bits (ref) I decided to bend like a bamboo in the wind, and move to OpenCV-64 bit.

Now, a couple of problems found:

When packaging the app with:

python2.7 setup.py bdist_dmg

An error would arise trying to execute it:

open build/exe.macosx-10.6-intel-2.7/capturebasic
"cx-freeze numpy.core.multiarray failed to import"

This error is solved by adding numpy in your setup.py, the reason behind is that even though OpenCv's Python wrapper uses numpy, cx_freeze fails to detect it in its dependency crawler.

setup.py then looks like:

from cx_Freeze import setup, Executable
setup(  name = "behave",
        version = "0.1",
        description = "Behave, face detection to help you",
        options = {'build_exe':
                    {'includes': ['numpy']}},
        executables = [Executable("capturebasic.py", )])

The second problem I encounter after that is that the cascades directory, where the xml files that the face detector algorithm uses, were not included in the cx_freeze app's directory.
The error you can find is similar to:

cv2.error: ../cascadedetect.cpp:1578: error: (-215) !empty() in function detectMultiScale

That is, instantiating "cv2.CascadeClassifier(path_to_xml_file)" will give no errors if you pass a wrong path, but when it is used later in the code to actually detect something, it will complain.

How to solve this? you need to add the cascade files in the project:

from cx_Freeze import setup, Executable
setup(  name = "behave",
        version = "0.1",
        description = "Behave, face detection to help you",
        options = {'build_exe':
                    {'includes': ['numpy'],
                    'include_files': ['cascades/haarcascade_frontalface_alt.xml']}},
        executables = [Executable("capturebasic.py", )])

One more step is required, since we are using those haarcascade files as data files inside cx_freeze, we need to tell the app where to find them, adding a function to our code:

def find_data_file(filename):
    if getattr(sys, 'frozen', False):
        # The application is frozen
        datadir = os.path.dirname(sys.executable)
    else:
        # The application is not frozen
        # Change this bit to match where you store your data files:
        datadir = os.path.dirname(__file__)

    return os.path.join(datadir, filename)

And using it any time we try to access the cascades we are using.
Inside the code it looks like:

self.face_classifier = classifiers.CascadeClassifier(
           find_data_file('cascades/haarcascade_frontalface_alt.xml'))

More information here:
http://cx-freeze.readthedocs.org/en/latest/faq.html#using-data-files