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https://github.com/robotpy/pynivision

Archived obsolete python wrappers for NI Vision (nivision)
https://github.com/robotpy/pynivision

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Archived obsolete python wrappers for NI Vision (nivision)

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README 

        
**Note**: This repository is no longer maintained by the RobotPy project. 

The successor to this project can be found at https://github.com/chrisjbillington/pynivision



********************************************

  Python Wrappers for NI Vision (nivision)

********************************************



:Author: Peter Johnson, FRC Team 294

:Copyright: Copyright |copy| 2012 Peter Johnson



About

=======



`NI Vision`_ is a `National Instruments`_ image/vision processing library.

It is available for multiple platforms including Windows and the

CompactRIO.  This project makes the functionality of NI Vision available

in the `Python`_ programming language.



.. _NI Vision: http://www.ni.com/vision/

.. _National Instruments: http://www.ni.com/

.. _Python: http://www.python.org/



Features

==========



*  Full wrapping of all structures, enumerations, and functions.

*  All functions raise a ``nivision.ImaqError`` exception if an error occurs,

   rather than relying on nonzero or NULL return values.

*  Output parameters are returned as a tuple (in parameter order).  If the

   function additionally returns a value, this is returned as the first

   element of the tuple, followed by the output parameters.

*  Count/size/length parameters that specify the length of an array are

   handled implicitly by using Python's ``len()`` function.  This includes

   return values (which are returned as a sized array).

*  Additional Pythonic helper functions (see Documentation_).

*  Automatic memory management of Image and other data types (see

   Documentation_).



Usage

=======



Read a JPEG file and print its dimensions (width and height)::



    import nivision

    img = nivision.imaqCreateImage(nivision.IMAQ_IMAGE_RGB)

    nivision.Priv_ReadJPEGString(img, open('example.jpg', 'rb').read())

    print(nivision.imaqGetImageSize(img))



Requirements

==============



An installed and licensed version of `NI Vision`_.  Only the 2011 version has

been tested.



The wrappers currently require ctypes, so this library is currently not usable

on platforms that don't have ctypes.  Unfortunately this includes `RobotPy`_ as

of this writing, but this is being worked on.



.. _RobotPy: https://github.com/robotpy/robotpy



The wrappers have only been tested on Python 3.x.



Installation

==============



On the robot, this will be installed automatically as of RobotPy 2015.0.1. Otherwise,

you can install it via pip:



    pip install pynivision



Run ``install.bat`` or ``python setup.py install``.



Documentation

===============



The "NI Vision for LabWindows/CVI Function Reference" help file

(NIVisionCVI.chm) is currently the best "complete" reference.  However, the

Python wrappers deviate from the C library in several important ways (see

Features_).



A few helper functions are provided due to the use of in/out parameters.



*  ``imaqGetCores()``: Returns the number of cores available to NI Vision.

*  ``imaqSetCores(customNumCores)``: Sets the number of cores available to NI

   Vision.

*  ``imaqUseMaxAvailableCores()``: Configures NI Vision to use the maximum

   number of available processor cores.



``imaqDispose()`` is automatically called when the corresponding Python object

is garbage collected for ``Image`` and all other structures/arrays returned

by imaq functions.  It is still ok to explicitly call ``imaqDispose()`` on

these objects (but be careful, as the underlying object will be immediately

freed even though the Python object is still accessible).



Implementation

================



Most of the wrapper code is generated by the ``gen_wrap.py`` script.

Hand-written Python code in ``ctypes_core_prefix.py`` and

``ctypes_core_suffix.py`` complements the automatically generated code.  The

``gen_wrap.py`` script creates ``nivision/core.py`` which includes the contents

of the prefix and suffix Python files.



The ``gen_wrap.py`` script reads an ``.ini`` file for Pythonic customizations

to the wrappers such as automatic disposal and handling of sized values as

arrays.  The .ini file used is automatically determined by the nivision

version in use (or can alternatively be specified on the command line).



As ``Priv_ReadJPEGString_C`` is not exported on current Windows distributions of

``nivissvc.dll``, a custom implementation that uses GDI+ has been written in

``nivision/private.py`` and ``nivision/gdiplus.py``.



License

=========



Copyright |copy| 2012 Peter Johnson.



Permission is hereby granted, free of charge, to any person obtaining a copy

of this software and associated documentation files (the "Software"), to deal

in the Software without restriction, including without limitation the rights

to use, copy, modify, merge, publish, distribute, sublicense, and/or sell

copies of the Software, and to permit persons to whom the Software is

furnished to do so, subject to the following conditions:



The above copyright notice and this permission notice shall be included in

all copies or substantial portions of the Software.



THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE

AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,

OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN

THE SOFTWARE.



.. |copy| unicode:: 0xA9 .. copyright sign



.. vim: tw=80 et ts=3 sw=3 ft=rst fenc=utf-8