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Adding a new lens

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Robin Mills edited this page Oct 25, 2020 · 8 revisions

  1. Before changing the C++ code to recognise a lens, please consider using the "Configuration File" as documented in the man page: https://exiv2.org/manpage.html

  2. We will not accept a change to the C++ code without a test image. The procedure to create a test file is documented here: https://github.com/Exiv2/exiv2/wiki/Create-test-file

  3. Add a python script to test your change using your test image. Here's an example from a user: https://github.com/Exiv2/exiv2/issues/1368.. I explained the test harness to him here: https://github.com/Exiv2/exiv2/issues/1368#issuecomment-711407187

  4. Run the test suite before submitting your PR. This is documented in README.md.

  5. Until we release Exiv2 0.28, we will have two development branches - '0.27-maintenance' and 'master'. Please focus your PR on 0.27-maintenance and it will be ported to 'master'. Once Exiv2 v0.28 ships (mid 2021), please focus your PR on 'master'. It will not be back-ported to 0.27-maintenance.

Summary of new lens PR

Here is a typical python test. See https://github.com/Exiv2/exiv2/pull/992. The user provided a test python file tests/bugfixes/github/test_pr_992.py

# -*- coding: utf-8 -*-

import system_tests

class NikonSigmaLens_APO_MACRO_180_F35_EX_DG_HSM(metaclass=system_tests.CaseMeta):
    url = "https://github.com/Exiv2/exiv2/pull/992"
    
    filename = "$data_path/Sigma_APO_MACRO_180_F3.5_EX_DG_HSM.exv"
    commands = ["$exiv2 -pa --grep lensid/i $filename"]
    stderr = [""]
    stdout = [""
        """Exif.NikonLd3.LensIDNumber                   Byte        1  Sigma APO Macro 180mm F3.5 EX DG HSM
"""
]
    retval = [0]

The test file is test/data/Sigma_APO_MACRO_180_F3.5_EX_DG_HSM.exv. The tests executes the program exiv2 -pa --grep lensid/i foo.exv and compares the output to stdout. That's it.

In this case, there is only one exiv2 command being executed on a single file. Most tests are more involved. You'll notice that the variables, commands, stderr, stdout and retval are arrays to make it easy to execute several commands in a single test. The most common program to run is exiv2, however other programs from build/bin or system commands can be invoked. You may not pipe data between commands, however you can redefine stdin/stdout filter decode_output if required.

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