Re: Alternative pixel-based regtest checker

[Phil Holmes]

----- Original Message ----- 
From: <address@hidden>
To: "David Kastrup" <address@hidden>
Cc: <address@hidden>
Sent: Saturday, March 02, 2013 9:21 AM
Subject: Re: Alternative pixel-based regtest checker


> On 1 mars 2013, at 22:33, David Kastrup <address@hidden> wrote:
>
> > "Phil Holmes" <address@hidden> writes:
> >
> > > There's lots of improvements that could be made: parallelism, using
> > > something other than diff, but it basically works.
> > >
> > > Thoughts?
> >
> > CMP(1)                           User Commands 
> > CMP(1)
> >
> > NAME
> >       cmp - compare two files byte by byte
> >
> > SYNOPSIS
> >       cmp [OPTION]... FILE1 [FILE2 [SKIP1 [SKIP2]]]
> >
> > DESCRIPTION
> >       Compare two files byte by byte.
> >
> > --
> > David Kastrup
>
> As LilyPond is non deterministic, it does not draw stencils to the page in 
> the same order every time, which means (I think) that the same input can 
> generate two different PNG files.  So, a bytewise comparison may trigger 
> false positives.
>
> Cheers,
> MS


I know from my Windows pixel-based checker that, generally, the PNG files 
contain the same image, version after version (there are a few oddities with 
some text, which I'm used to).  I would have believed that identical images 
would only be produced by identical PNG files?

--
Phil Holmes