Bug#851359: diffoscope: Improve support for comparing images

[Chris Lamb]

Hey Maria,

> […]

Looks great, please go ahead and rebase onto the experimental
branch :)

> >   a) We should rename this global variable to something that reflects
> >      this usage.

Thank for changing this. One thing I might fix up around here is that the
following code in main.py:

    Config().compute_visual_diffs = any((
        parsed_args.html_output,
        parsed_args.html_output_directory,
    ))

.. violates the abstraction layer. I would probably do this by returning
splitting presenters.formats.output_all into two methods, one returning
the presenters we *plan* to execute later, and one then acting on that.
Or something.

That way, we can define something like "supports_visual_diffs" in the
FORMATS dictionary, and simply check for any existence of that instead.
No need to do this to merge , mostly braindumping for myself... :)


Regards,

-- 
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     : :'  :     Chris Lamb
     `. `'`      lamby at debian.org / chris-lamb.co.uk
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