Re: ConTeXt unofficial test suite stub

From: Hans Hagen <pragma@wxs.nl>
To: mailing list for ConTeXt users <ntg-context@ntg.nl>
Cc: Marco Pessotto <melmothx@gmail.com>
Subject: Re: ConTeXt unofficial test suite stub
Date: Wed, 17 Oct 2012 19:05:24 +0200	[thread overview]
Message-ID: <507EE554.4060706@wxs.nl> (raw)
In-Reply-To: <87y5j52g0r.fsf@universe.krase.net>

On 17-10-2012 18:57, Marco Pessotto wrote:
> Marco Patzer <homerow@lavabit.com> writes:
>
>>> Looking at the diffs, many of the differences are really tiny, but
>>> differences exist nevertheless. It will take me some time to sort out
>>> which ones are just tiny space shifting, and which ones give really
>>> different output.
>>
>> That's why I use a header for each test file. You can specify
>> “sensitivity=low|medium|high”, this sets a predefined tolerance for
>> the page difference. I don't see any other option. There is no
>> single value which is sensitive enough, for instance to detect if a
>> footnote is subscripted or not and at the same time tolerant enough
>> not to always mark a fifty page document as “failed”.
>
> I'm not sure that exists a “fuzzy” algorithm for the tolerance. From my
> testing, a minimal shift, say, to the right, on a full page will
> generate a lot of noise, because each glyph will be “doubled”. I'm
> generating, with the visual diffs, a script to launch two PDF viewers and
> eventually promote the generated to the new reference.
>
> I guess there is no shortcuts to the manual ispection of the diffs.

vertical shifts are probably more an issue; for horizontal shifts you 
can use a threshold of .1em because that catches spaces and distances 
etc but ignores differences in fonts.

Hans

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