Re: Text spanner shorten-pair

[Carl Sorensen]

 

 

From: Trevor Bača <address@hidden>
Date: Wednesday, February 13, 2019 at 6:43 AM
To: Carl Sorensen <address@hidden>
Cc: Andrew Bernard <address@hidden>, lilypond-user Mailinglist <address@hidden>
Subject: Re: Text spanner shorten-pair

 

 

 

On Tue, Feb 12, 2019 at 6:12 PM Carl Sorensen <address@hidden> wrote:

 

 

From: Trevor Bača <address@hidden>
Date: Tuesday, February 12, 2019 at 3:09 PM
To: Carl Sorensen <address@hidden>
Cc: Andrew Bernard <address@hidden>, lilypond-user Mailinglist <address@hidden>
Subject: Re: Text spanner shorten-pair

 

On Fri, Jan 25, 2019 at 11:38 AM Carl Sorensen <address@hidden> wrote:

 

Question: why are there two ways to move around the ends of spanners (padding vs. shortening)? I can't think of a reason that's motivated by music notation.

 

Padding is a minimum amount of blank space between two pieces of ink on the page.  When a pedal bracket is running into empty space, it doesn’t matter what the padding setting is, because there is no ink for it to move away from.  Padding says “don’t just avoid collisions; leave a minimum amount of empty space in addition to avoiding collisions”.  There’s no collision to avoid between a pedal bracket and its associated note column.

 

Ok, wow, this is actually hugely interesting. Thank you so much for the specificity of the first part of the answer: "Padding is a minimum amount of blank space between two pieces of ink on the page." That is actually genuinely new information to me about a small-but-pervasive concept in LilyPond. Right up until just now, I had assumed that padding meant "a minimum amount of blank space between TWO THINGS on the page (whether the things are visible or not)"; we are hugely concerned with the (frequently invisible) start- and stop-anchors of things when engraving objects in score; and I had incorrectly assumed that padding at the edges of, say, a piano pedal bracket would pad between the invisible start-anchor of the bracket (which you described earlier as some flavor of column) and the visible start of the bracket itself. This is apparently not the case.

 

I think that I was incorrect in saying “ink on the page”, although that is the intent of padding.  I should have said “between two bounding boxes”.  One way to make spanners respect padding would be to increase the vertical extent of the bounding box (but that comes with a cost of preventing markups from sitting above or below the bounding box.

 

This probably explains a small part of why I may have found the spacing behavior of piano pedal brackets flakey, to a certain extent, for well over a decade.

 

So my surprise here (that the Lily concept of "padding" won't pad between the invisible anchors of things that I'm always mentally tracking when I work), makes me think that this surprisingly-restricted (at least to me ;) model of padding is possibly a "mis-model" in the system, or maybe a not-yet-realized possibility for a more complete generalization of what spanners are.

 

I think that you have hit on an important fundamental that is not properly represented in LilyPond.  Spanners might be properly said to be anchored to note columns *regardless* of whether they have anything in them at a particular vertical location.  Maybe the spacing algorithms for spanners should assume a note-column with infinite vertical extents….

 

 

Thanks for your good thoughts about this.

 

Carl