Metadata-Version: 2.1
Name: gphoto2
Version: 2.3.4
Summary: Python interface to libgphoto2
Home-page: https://github.com/jim-easterbrook/python-gphoto2
Author: Jim Easterbrook
Author-email: jim@jim-easterbrook.me.uk
License: GNU GPL
Platform: POSIX
Platform: MacOS
Classifier: Development Status :: 5 - Production/Stable
Classifier: Intended Audience :: Developers
Classifier: License :: OSI Approved :: GNU General Public License v3 or later (GPLv3+)
Classifier: Operating System :: MacOS
Classifier: Operating System :: MacOS :: MacOS X
Classifier: Operating System :: POSIX
Classifier: Operating System :: POSIX :: BSD :: FreeBSD
Classifier: Operating System :: POSIX :: BSD :: NetBSD
Classifier: Operating System :: POSIX :: Linux
Classifier: Programming Language :: Python :: 3
Classifier: Topic :: Multimedia
Classifier: Topic :: Multimedia :: Graphics
Classifier: Topic :: Multimedia :: Graphics :: Capture
License-File: LICENSE.txt

python-gphoto2 v\ 2.3.4
=======================

python-gphoto2 is a comprehensive Python interface (or binding) to libgphoto2_.
It is built using SWIG_ to automatically generate the interface code.
This gives direct access to nearly all the libgphoto2 functions_, but sometimes in a rather un-Pythonic manner.

Other Python bindings to libgphoto2_ are available:
piggyphoto_ uses ctypes_ (included in standard Python installations) to interface to the library.
The gphoto2 source tree includes some `Python bindings`_ which also use ctypes_.
`gphoto2-cffi`_ uses cffi_.

.. contents::
   :backlinks: top

Installation (binary wheel)
---------------------------

Since python-gphoto2 version 2.3.1 "binary wheels" are provided for many Linux and MacOS computers.
These include a recent version of the libgphoto2_ libraries, and pre-built Python interface modules, which makes installation quick and easy.
Use pip_'s ``--only-binary`` option to install one of these wheels::

    sudo pip3 install gphoto2 --only-binary :all:

If this fails it is most likely because none of the available wheels is compatible with your computer.
In this case you *must* install the dependencies listed below before installing python-gphoto2.
The installation process compiles and links the bindings with the libgphoto2_ installed on your computer.

Raspberry Pi
^^^^^^^^^^^^

Binary wheels for the Raspberry Pi are available from piwheels_.
You still need to install some system packages to use these::

    sudo apt install libexif12 libgphoto2-6 libgphoto2-port12 libltdl7
    sudo pip3 install gphoto2

Dependencies
------------

*   Python: http://python.org/ version 3.5 or greater
*   libgphoto2: http://www.gphoto.org/proj/libgphoto2/ version 2.5.0 or greater
*   build tools: pkg-config, C compiler & linker

In most cases you should use your operating system's package manager to install these.
Note that you need the "development headers" for libgphoto2_ and Python.
On some systems these are included in the base package, but on others they need to be installed separately.
Look for ``libgphoto2-dev`` or ``libgphoto2-devel`` or something similar.
Test your installation with the command ``pkg-config --cflags --libs libgphoto2 python3``.

Installation (source)
---------------------

There are several ways to install python-gphoto2, with varying levels of control over the installation process.
By far the easiest is to use your operating system's package manager, if you're lucky enough to be using a system that has python-gphoto2 available.
Note that this may not install the latest version.

Otherwise you can install it with pip_, or by downloading an archive, or by getting the source from GitHub_.
Make sure that you install the dependencies_ first.

Install with pip_
^^^^^^^^^^^^^^^^^

The easiest installation method is to use the pip_ command.
Note the use of ``--no-binary`` to prevent installation from a binary wheel::

    sudo pip3 install -v gphoto2 --no-binary :all:

This installation may take longer than you expect as the package's modules are compiled during installation.
The ``-v`` option increases pip_'s verbosity so you can see that it's doing something.

Install a downloaded archive
^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Visit PyPI_ and download one of the zip or tar.gz files, then extract it and change to the new directory.
For example::

    tar xf gphoto2-2.3.0.tar.gz
    cd gphoto2-2.3.0

Python's setuptools_ are used to build and install python-gphoto2::

    pip3 wheel . -v
    sudo pip3 install gphoto2-*.whl

Install from GitHub_ (SWIG_ required)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

SWIG (http://swig.org/) should be installable via your operating system's package manager.
Note that this may be an older version of SWIG than the one used to generate the files on PyPI_.

To install the current development version, use git_ to "clone" the GitHub_ repository, then change to the new directory::

    git clone https://github.com/jim-easterbrook/python-gphoto2.git
    cd python-gphoto2

As before, Python's setuptools_ are used to build and install python-gphoto2, but now you have to run SWIG_ first to generate the files to be compiled.
The ``developer`` directory includes a script to run SWIG::

    python3 developer/build_swig.py system
    pip3 wheel . -v
    sudo pip3 install gphoto2-*.whl

See "`running SWIG`_" below for more detail.

Testing
-------

Since version 2.3.1 you can test your installation of python-gphoto2 by running it with the ``python3 -m gphoto2`` command::

    python3 -m gphoto2
    python-gphoto2 version: 2.3.1
    libgphoto2 version: ['2.5.27', 'standard camlibs (SKIPPING docupen)', 'gcc', 'ltdl', 'EXIF']
    libgphoto2_port version: ['0.12.0', 'iolibs: disk ptpip serial usb1 usbdiskdirect usbscsi vusb', 'gcc', 'ltdl', 'EXIF', 'USB', 'serial without locking']
    python-gphoto2 examples: /usr/lib64/python3.6/site-packages/gphoto2/examples

This shows the python-gphoto2 and libgphoto2 version numbers, and where the example programs have been installed.
Connect a digital camera to your computer, switch it on, and try one of the example programs::

    python3 /usr/lib64/python3.6/site-packages/gphoto2/examples/camera-summary.py

If this works then you're ready to start using python-gphoto2.

Reinstalling
^^^^^^^^^^^^

If you update or move your installation of libgphoto2_ the Python gphoto2 package may fail to import one of the libgphoto2 shared object files.
If this happens you need to rebuild and reinstall the Python gphoto2 package::

    sudo pip3 install -v -U --force-reinstall gphoto2

if you installed with pip_, or ::

    rm -rf build
    pip3 wheel . -v
    sudo pip3 install --force-reinstall gphoto2-*.whl

if you installed from source.

Using python-gphoto2
--------------------

The Python interface to libgphoto2_ should allow you to do anything you could do in a C program.
However, there are still bits missing and functions that cannot be called from Python.
Let me know if you run into any problems.

The following paragraphs show how the Python interfaces differ from C.
See the example programs for typical usage of the Python gphoto2 API.

"C" interface
^^^^^^^^^^^^^

These functions are as similar as possible to their libgphoto2_ equivalents.
Most of them return an error code which you must check.

Using SWIG_ to generate the Python interfaces automatically means that every function in libgphoto2_ *should* be available to Python.
You can show the documentation of a function with the ``pydoc`` command (or ``python -m pydoc`` if you installed gphoto2 with pip inside a virtual environment)::

   jim@firefly ~$ pydoc3 gphoto2.gp_camera_folder_list_files
   Help on built-in function gp_camera_folder_list_files in gphoto2:

   gphoto2.gp_camera_folder_list_files = gp_camera_folder_list_files(...)
       gp_camera_folder_list_files(camera, folder, context) -> int

       Parameters
       ----------
       camera: gphoto2.Camera
       folder: str
       context: gphoto2.Context (default=None)


       Lists the files in supplied `folder`.

       Parameters
       ----------
       * `camera` :
           a Camera
       * `folder` :
           a folder
       * `list` :
           a CameraList
       * `context` :
           a GPContext

       Returns
       -------
       a gphoto2 error code

       See also gphoto2.Camera.folder_list_files
   jim@firefly ~$

The first part of this text is the function signature and parameter list generated by SWIG.
(Note that ``context`` is optional - it's only needed if you need the callback functions that can be  associated with a context.)
The rest of the text is copied from the "doxygen" format documentation in the C source code.
(The online `API documentation`_ shows how it is intended to look.)
Note that this includes a ``list`` parameter that is not in the function signature.
In C this is an "output" parameter, a concept that doesn't really exist in Python.
The Python version of ``gp_camera_folder_list_files`` returns a sequence containing the integer error code and the ``list`` value.

Most of the libgphoto2_ functions that use pointer parameters to return values in the C API have been adapted like this in the Python API.
(Unfortunately I've not found a way to persuade SWIG_ to include this extra return value in the documentation.
You should use ``pydoc`` to check the actual parameters expected by the Python function.)

For example, the C code:

.. code:: c

    #include "gphoto2.h"
    int error;
    Camera *camera;
    error = gp_camera_new(&camera);
    ...
    error = gp_camera_unref(camera);

has this Python equivalent:

.. code:: python

    import gphoto2 as gp
    error, camera = gp.gp_camera_new()
    ...

Note that the gp_camera_unref() call is not needed.
It is called automatically when the Python camera object is deleted.

Here is a complete example program (without any error checking):

.. code:: python

    import gphoto2 as gp
    error, camera = gp.gp_camera_new()
    error = gp.gp_camera_init(camera)
    error, text = gp.gp_camera_get_summary(camera)
    print('Summary')
    print('=======')
    print(text.text)
    error = gp.gp_camera_exit(camera)

"Object oriented" interface
^^^^^^^^^^^^^^^^^^^^^^^^^^^

This is the preferred way to use libgphoto2_ from Python.
Most of the libgphoto2_ functions have been added as methods of the appropriate GPhoto2 object.
This allows GPhoto2 to be used in a more "Pythonic" style.
For example, ``gp.gp_camera_init(camera)`` can be replaced by ``camera.init()``.
These methods also include error checking.
If an error occurs they raise a Python ``GPhoto2Error`` exception.

The example program can be re-written as follows:

.. code:: python

    import gphoto2 as gp
    camera = gp.Camera()
    camera.init()
    text = camera.get_summary()
    print('Summary')
    print('=======')
    print(str(text))
    camera.exit()

No additional error checking is required.

Error checking
^^^^^^^^^^^^^^

Most of the libgphoto2_ functions return an integer to indicate success or failure.
The Python interface includes a ``check_result()`` function to check these values and raise a ``GPhoto2Error`` exception if an error occurs.

This function also removes the error code from lists such as that returned by ``gp_camera_new()`` in the example.
Using this function the earlier example becomes:

.. code:: python

    import gphoto2 as gp
    camera = gp.check_result(gp.gp_camera_new())
    gp.check_result(gp.gp_camera_init(camera))
    text = gp.check_result(gp.gp_camera_get_summary(camera))
    print('Summary')
    print('=======')
    print(text.text)
    gp.check_result(gp.gp_camera_exit(camera))

There may be some circumstances where you don't want an exception to be raised when some errors occur.
You can "fine tune" the behaviour of the ``check_result()`` function by adjusting the ``error_severity`` variable:

.. code:: python

    import gphoto2 as gp
    gp.error_severity[gp.GP_ERROR] = logging.WARNING
    ...

In this case a warning message will be logged (using Python's standard logging module) but no exception will be raised when a ``GP_ERROR`` error occurs.
However, this is a "blanket" approach that treats all ``GP_ERROR`` errors the same.
It is better to test for particular error conditions after particular operations, as described below.

The ``GPhoto2Error`` exception object has two attributes that may be useful in an exception handler.
``GPhoto2Error.code`` stores the integer error generated by the library function and ``GPhoto2Error.string`` stores the corresponding error message.

For example, to wait for a user to connect a camera you could do something like this:

.. code:: python

    import gphoto2 as gp
    ...
    print('Please connect and switch on your camera')
    while True:
        try:
            camera.init()
        except gp.GPhoto2Error as ex:
            if ex.code == gp.GP_ERROR_MODEL_NOT_FOUND:
                # no camera, try again in 2 seconds
                time.sleep(2)
                continue
            # some other error we can't handle here
            raise
        # operation completed successfully so exit loop
        break
    # continue with rest of program
    ...

When just calling a single function like this, it's probably easier to test the error value directly instead of using Python exceptions:

.. code:: python

    import gphoto2 as gp
    ...
    print('Please connect and switch on your camera')
    while True:
        error = gp.gp_camera_init(camera)
        if error >= gp.GP_OK:
            # operation completed successfully so exit loop
            break
        if error != gp.GP_ERROR_MODEL_NOT_FOUND:
            # some other error we can't handle here
            raise gp.GPhoto2Error(error)
        # no camera, try again in 2 seconds
        time.sleep(2)
    # continue with rest of program
    ...

Logging
^^^^^^^

The libgphoto2_ library includes functions (such as ``gp_log()``) to output messages from its various functions.
These messages are mostly used for debugging purposes, and it can be helpful to see them when using libgphoto2_ from Python.
The Python interface includes a ``use_python_logging()`` function to connect libgphoto2_ logging to the standard Python logging system.
If you want to see the messages you should call ``use_python_logging()`` near the start of your program, as shown in the examples.
In normal use you probably don't want to see these messages (libgphoto2_ is rather verbose) so this could be controlled by a "verbose" or "debug" option in your application.

The libgphoto2_ logging messages have four possible severity levels, each of which is mapped to a suitable Python logging severity.
You can override this mapping by passing your own to ``use_python_logging()``:

.. code:: python

    import logging
    import gphoto2 as gp
    ...
    callback_obj = gp.check_result(gp.use_python_logging(mapping={
        gp.GP_LOG_ERROR   : logging.INFO,
        gp.GP_LOG_DEBUG   : logging.DEBUG,
        gp.GP_LOG_VERBOSE : logging.DEBUG - 3,
        gp.GP_LOG_DATA    : logging.DEBUG - 6}))
    ...

If you prefer to use your own logging system you can define a logging callback function in Python.
The function must take 3 or 4 parameters: ``level``, ``domain``, ``string`` and an optional ``data``.
The ``data`` parameter allows you to pass some user data to your callback function (e.g. to log which thread an error occurred in):
The callback function is installed with ``gp_log_add_func``:

.. code:: python

    import gphoto2 as gp
    ...
    def callback(level, domain, string, data=None):
        print('Callback: level =', level, ', domain =', domain, ', string =', string, 'data =', data)
    ...
    callback_obj1 = gp.check_result(gp.gp_log_add_func(gp.GP_LOG_VERBOSE, callback))
    callback_obj2 = gp.check_result(gp.gp_log_add_func(gp.GP_LOG_VERBOSE, callback, 123))
    ...

What to do if you have a problem
--------------------------------

If you find a problem in the Python gphoto2 interface (e.g. a segfault, a missing function, or a function without a usable return value) then please report it on the GitHub "issues" page (https://github.com/jim-easterbrook/python-gphoto2/issues) or email jim@jim-easterbrook.me.uk.

If your problem is more general, e.g. difficulty with capturing multiple images, then try doing what you want to do with the `gphoto2 command line program`_.
If the problem persists then it might be worth asking on the `gphoto-user mailing list`_.
Another reader of the mailing list may have the same camera model and already know what to do.

Notes on some gphoto2 functions
-------------------------------

gp_log_add_func / use_python_logging
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Since python-gphoto2 version 2.0.0 these functions return a sequence containing an error code and an object storing details of the callback.
The callback is automatically uninstalled when this object is deleted.

In earlier versions of python-gphoto2 these functions return an integer id that must be passed to ``gp_log_remove_func`` to uninstall the callback.

gp_context_set_idle_func / gp_context_set_progress_funcs / etc.
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

These functions are only usable since python-gphoto2 version 1.9.0.
They return a Python object which your program must store until the callback(s) are no longer required.
Deleting the returned object cancels the callback(s), so there is no need to do this yourself.
See the ``context_with_callbacks.py`` example for a convenient way to do this.

gp_file_get_data_and_size / CameraFile.get_data_and_size
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Since python-gphoto2 version 1.2.0 these functions return a ``FileData`` object that supports the `buffer protocol`_.
The data can be made accessible to Python by using a memoryview_ object.
This allows the data to be used without copying.
See the ``copy-data.py`` example for typical usage.

In earlier versions of python-gphoto2 these functions returned a ``bytes`` object containing a copy of the data in the ``CameraFile`` object.

gp_file_set_data_and_size / CameraFile.set_data_and_size
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Since python-gphoto2 version 2.1.0 these functions accept any `bytes-like object`_.
In earlier versions of python-gphoto2 these functions required a string and its length, and didn't work correctly anyway.

gp_file_append / CameraFile.append
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Since python-gphoto2 version 2.1.0 these functions accept any `bytes-like object`_.
In earlier versions of python-gphoto2 these functions required a string and its length.

gp_camera_file_read / Camera.file_read
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

The ``buf`` parameter can be any Python object that exposes a writeable buffer interface.
This allows you to read a file directly into a Python object without additional copying.
See the ``copy-chunks.py`` example which uses memoryview_ to expose a bytearray_.

gp_camera_wait_for_event / Camera.wait_for_event
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

These functions return both the event type and the event data.
The data you get depends on the type.
``GP_EVENT_FILE_ADDED`` and ``GP_EVENT_FOLDER_ADDED`` events return a ``CameraFilePath``, others return ``None`` or a text string.

Running SWIG_
-------------

SWIG_ is used to convert the ``.i`` interface definition files in ``src/gphoto2`` to ``.py`` and ``.c`` files.
These are then compiled to build the Python interface to libgphoto2_.
The files downloaded from PyPI_ include the SWIG_ generated files, but you may wish to regenerate them by running SWIG_ again (e.g. to test a new version of SWIG_ or of libgphoto2_).
You will also need to run SWIG_ if you have downloaded the python-gphoto2 sources from GitHub_ instead of using PyPI_.

The ``developer`` directory includes a script to run SWIG_.
It requires one parameter: the version to be swigged.
This can be ``system`` or a number triplet, e.g. ``2.5.27``::

    python3 developer/build_swig.py system

This builds the interface for the version of libgphoto2_ installed on your computer.
The interface files are created in directories with names like ``src/swig-gp2.5.18``.
This naming scheme allows for different versions of libgphoto2_.
The most appropriate version is chosen when the interface is built.

To build interfaces for multiple versions of libgphoto2_ (e.g. v2.5.10 as well as v2.5.0) you need to put those versions' source files in your working directory and then run ``python developer/build_swig.py`` again, specifying the version::

    python3 developer/build_swig.py 2.5.10

More information about this is in the file ``developer/README.txt``.

Licence
-------

| python-gphoto2 - Python interface to libgphoto2
| http://github.com/jim-easterbrook/python-gphoto2
| Copyright (C) 2014-22  Jim Easterbrook  jim@jim-easterbrook.me.uk

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see http://www.gnu.org/licenses/.

.. _API documentation: http://www.gphoto.org/doc/api/
.. _buffer protocol:   https://docs.python.org/2/c-api/buffer.html
.. _bytearray:         https://docs.python.org/2/library/functions.html#bytearray
.. _bytes-like object: https://docs.python.org/3/glossary.html#term-bytes-like-object
.. _cffi:              http://cffi.readthedocs.org/
.. _ctypes:            https://docs.python.org/2/library/ctypes.html
.. _functions:         http://www.gphoto.org/doc/api/
.. _git:               http://git-scm.com/
.. _GitHub:            https://github.com/jim-easterbrook/python-gphoto2
.. _gphoto2-cffi:      https://github.com/jbaiter/gphoto2-cffi
.. _gphoto2 command line program:
                       http://gphoto.org/doc/manual/using-gphoto2.html
.. _gphoto-user mailing list:
                       http://gphoto.org/mailinglists/
.. _libgphoto2:        http://www.gphoto.org/proj/libgphoto2/
.. _memoryview:        https://docs.python.org/2/library/stdtypes.html#memoryview
.. _Python bindings:
   http://sourceforge.net/p/gphoto/code/HEAD/tree/trunk/bindings/libgphoto2-python/
.. _piggyphoto:        https://github.com/alexdu/piggyphoto
.. _pip:               https://pip.pypa.io/
.. _piwheels:          https://www.piwheels.org/project/gphoto2/
.. _PyPI:              https://pypi.python.org/pypi/gphoto2/
.. _setuptools:        https://pypi.org/project/setuptools/
.. _SWIG:              http://swig.org/
.. _SWIG -builtin:     http://www.swig.org/Doc3.0/Python.html#Python_builtin_types
