Re: Why does -dbackend=svg -dcrop remove system-system-spacing?

[David Wright]

On Thu 07 Jan 2021 at 19:57:12 (-0500), Trevor Bača wrote:
> On Wed, Jan 6, 2021 at 2:29 PM David Wright wrote:
> > On Wed 06 Jan 2021 at 11:34:24 (-0500), Trevor Bača wrote:
> > > On Tue, Jan 5, 2021 at 11:31 PM David Wright wrote:
> > > > On Tue 05 Jan 2021 at 19:05:30 (-0500), Trevor Bača wrote:
> > > > > I love the functionality for cropped SVGs! (Added back in 2019, or
> > > > > around then?)
> > > > >
> > > > > Question: it appears that cropped multisystem SVGs remove all
> > > > > whitespace between systems. Is this supposed to happen?
> > > >
> > > > I think that removing all the margins is the functionality "crop" is
> > > > supposed to add to LP. To generate the equivalent cropped and packed
> > > > image without this facility would be quite tedious to do (unless
> > > > someone has a trick for doing it?).
> > > >
> > > > > %%% BEGIN %%%
> > > > > […]
> > > > > %%% END %%%
> > > > >
> > > > > Called with ...
> > > > >    lilypond -dbackend=svg -dcrop test.ly
> > > > > ... produces test.cropped.svg as attached here.
> > > > >
> > > > > Screenshot:
> > > > > […]
> > > > >
> > > > > Seems like cropping should be around the edges of the image (rather
> > > > > than between systems)?
> > > >
> > > > If you just want to crop the whole page image, you can do that easily
> > > > at the end of a normal run with the usual utilities. If you require
> > > > LP to set the entire score on a single page, just use a very long
> > > > custom page (as in NR §4.1.2: width, then length).
> > >
> > > I'm sorry; I don't understand.
> > >
> > > What I want Lily to do: remove whitespace from the *edges* of an SVG.
> >
> > As I said, you run LP as normal, and then trim to taste. So, taking
> > your example, I ran it with
> > $ lilypond-2.21.80-1.linux-64/bin/lilypond --svg -dno-point-and-click
> > Bača.ly
> > and then edited the first line of Bača.svg, resulting in Bača-trimmed.svg.
> > The end of the first line is modified from
> >  width="210.00mm" height="297.00mm" viewBox="0 0 119.5016 169.0094">
> > to
> >  width="192.00mm" height="297.00mm" viewBox="4.5 0 109.5016 169.0094">
> > which I did by inspection. As you use SVG files in your workflow,
> > I assume you can carry this out more easily and precisely¹ with some
> > particular tool. (I'm PDF-centric myself.) I only considered X because
> > I was inspecting the file on a landscape screen (and you didn't remove
> > the tagline anyway).
> >
> > > What Lily actually does when -dcrop is set: removes whitespace from the
> > > edges *and from between all systems* of an SVG.
> >
> > That's right, so that your file contains all the information,
> > unencumbered by margins, ready for some sort of further processing.
> > Obviously, I don't know what that will be in your case.
> >
> > It reminds me of those PNG files that you find in browsers' cache,
> > which have a strip or grid of little images that are used internally,
> > either as a toolbar, or displayed sequentially like a movie.
> >
> > > So my question is: is Lily supposed to remove whitespace from *between*
> > > systems when -d[c]rop is set?
> >
> > AIUI yes. But this is policy: I await pronouncements from higher-ups.
> >
> > ¹ I believe the modifications need to be kept proportional, in order
> >   to preserve the aspect ratio.
>
> I really appreciate the responses, but I'm even more confused than before.
> 
> When you ran ...
> 
> $ lilypond-2.21.80-1.linux-64/bin/lilypond --svg -dno-point-and-click Bača.ly
> 
> ... why didn't you include the -dcrop option?

[You need a fixed width font to make sense of text below.]

What running my command on your source produces might be represented by:

A   ┌────────────────────┐
    │⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱│
    │⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱│
    │⸱⸱⸱▒▒▒▒▒▒▒▒▒▒▒▒▒▒⸱⸱⸱│
    │⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱│
    │⸱⸱⸱▒▒▒▒▒▒▒▒▒▒▒▒▒▒⸱⸱⸱│
    │⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱│
    │⸱⸱⸱▒▒▒▒▒▒▒▒▒▒▒▒▒▒⸱⸱⸱│
    │⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱│
    │⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱│
    │⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱│
    │⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱│
    │⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱│
    │⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱│
    │⸱⸱⸱⸱⸱tttttttttt⸱⸱⸱⸱⸱│
    │⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱│
    └────────────────────┘

where ⸱ is white space, ▒ is music, and t is the tagline.

What my previous post also had attached to it was the result of
trimming off the whitespace from just the sides:

B   ┌──────────────┐
    │⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱│
    │⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱│
    │▒▒▒▒▒▒▒▒▒▒▒▒▒▒│
    │⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱│
    │▒▒▒▒▒▒▒▒▒▒▒▒▒▒│
    │⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱│
    │▒▒▒▒▒▒▒▒▒▒▒▒▒▒│
    │⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱│
    │⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱│
    │⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱│
    │⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱│
    │⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱│
    │⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱│
    │⸱⸱tttttttttt⸱⸱│
    │⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱│
    └──────────────┘

(I trimmed only the sides because the image was taller than
my screen, which made it difficult to inspect the entire
image in the Y direction.)

Then Niols posted inkscape command lines to produce:

C   ┌──────────────┐
    │▒▒▒▒▒▒▒▒▒▒▒▒▒▒│
    │⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱│
    │▒▒▒▒▒▒▒▒▒▒▒▒▒▒│
    │⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱│
    │▒▒▒▒▒▒▒▒▒▒▒▒▒▒│
    │⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱│
    │⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱│
    │⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱│
    │⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱│
    │⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱│
    │⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱│
    │⸱⸱tttttttttt⸱⸱│
    └──────────────┘

which might be improved by adding
\header { tagline = ##f }
to the source file and producing:

D   ┌──────────────┐
    │▒▒▒▒▒▒▒▒▒▒▒▒▒▒│
    │⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱│
    │▒▒▒▒▒▒▒▒▒▒▒▒▒▒│
    │⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱⸱│
    │▒▒▒▒▒▒▒▒▒▒▒▒▒▒│
    └──────────────┘

which is what I assume you actually want—just the music,
with the whitespace left untouched between the systems.

All of the images B, C and D can easily be produced with
widely-available utilities, and no involvement from LP.

To answer your question—why not use the -dcrop option—I think
we are in agreement that:

$ lilypond-2.21.80-1.linux-64/bin/lilypond --svg -dcrop Bača.ly

will produce the tightly packed:

E   ┌──────────────┐
    │▒▒▒▒▒▒▒▒▒▒▒▒▒▒│
    │▒▒▒▒▒▒▒▒▒▒▒▒▒▒│
    │▒▒▒▒▒▒▒▒▒▒▒▒▒▒│
    └──────────────┘

which is what you implied you didn't want (by saying "Is this
supposed to happen?" and "Seems like cropping should be …").

Cheers,
David.