Re: GSoC Proposal - SVG Export

[Richard Shann]

On Fri, 2018-11-30 at 22:39 -0500, Étienne Beaulé wrote:
> Hello all!
> 
> I’m Étienne Beaulé and I’ve been making some changes to LilyPond. I
> am also the maintainer of the MediaWiki Score extension which allows
> embedded LilyPond on Wikipedia. I’m currently a bachelor student at
> the Université de Montréal studying computer science and mathematics,
> and Google Summer of Code caught my eye. I’d be interested in doing a
> project if a mentor is available.
> 
> # Improving SVG score output
> 
> ## Summary
> 
> Scalable Vector Graphics (SVG) is a vector graphics format designed
> for use on the internet. LilyPond (LY) is a program which translates
> musical notation syntax into a graphics format, such as SVG. This
> format is important for web publishing, and as a vector format, is
> advantageous over Portable Network Graphics (PNG) file, of which is
> _de facto_ used in this application.
> 
> LY already has SVG output, yet is somewhat broken in many factors.
> Namely in font handling with broken sky-lining #3778 and the use of
> musical symbols as text. Development in fixing these problems may
> offer changes in other backends. This project will focus on the use
> of musical symbols in SVG files and the positioning of text. I have
> previously submitted patches for text-positioning bugs.
> 
> ## Deliverables
> 
> * Self-contained musical SVG files
> * Functioning text sky-lining in SVG
> * Grouping of text for better placement in SVG
> 
> ## Timeline
> 
> _This is the hard part… Non-comprehensive_
> 
> * Analysis of incompatibilities between PostScript (PS) and SVG
> output
>   Important to have a grip on this to not introduce bugs and to keep
> commonalities between backends
> * Deprecation of SVG fonts - embed font into SVG
> 
> — —
> 
> * Reduce size of SVG by enumerating used glyphs
> * Merge glyph functions for text and symbols
> 
> — —
> 
> * Implement use of `<tspan>` tags and Cascading Style Sheets (CSS)
> for text handling
>   * Will require modification of PS backends
>   * Fix Horizontal Spacing of text
> * Fix SVG text sky-lining in conjunction with character size /
> spacing calculations
> 
> Thoughts?
It is probably a very small thing, but it would be good if you could
improve the SVG output with regard to the use of "current color" which
Lily outputs as the default foreground color rather than black. There
was a plea recently for this:
        
From:   d_l <address@hidden>
To:     address@hidden
Subject:        Request PATCH to ensure LilyPond SVG compatibility with
Scribus
Date:   Thu, 11 Oct 2018 06:56:34 -0700 (MST) (11/10/18 14:56:34)

and others earlier. Denemo has to work around this quirk - the problem
being the "current color" is frequently white, the same as the
background...

Richard