SVG support

[rpatters1]

When the time comes to permit the specification of SMuFL glyphs for symbols in a systematic way, I would like to propose that anywhere a glyph can be supplied, alternatively an embedded SVG can be supplied.

I would further propose that these SVGs be specified in staff-spaces (with no explicit unit). If there are situations where the SVG is not tied to a staff, then in those cases they could be specified explicitly in millimeters or other fixed units.

From a json perspective, this would simply be a string node that contains the SVG. (For those that may not know, SVG itself is an xml format, but we would treat it as a blob that the consuming program validates and processes if it wants to.)

[adrianholovaty]

Interesting, would you mind sharing a specific use case (or two) for this?

[rpatters1]

This would allow interchange of Shape Definitions from Finale and Image classes from MuseScore. Both programs allow arbitrary shapes to be used as expressive markings and articulation markings. Both programs scale them to the staff size automatically.

Thinking further about this, in principal the SVG is just a string blob. But it might have to be encoded some way to avoid syntax conflicts with the embedded xml.
ChatGPT is recommending something like this:

{
  "svg": {
    "encoding": "base64",
    "mime": "image/svg+xml",
    "data": "PHN2ZyB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwv..."
  }
}

[rpatters1]

Other use cases in Finale are clefs, custom stems, fretboards, and spanner line endpoints (aka, "arrowheads"). Any of these can be arbitrary user-defined shapes. I'm not sure how many of them carry over into MuseScore.

[mscuthbert]

This is a good idea. And since these shapes can be reused we should put them in one place and reference them with id. Because many can also be scaled (smart shapes or meta shapes in Finale speak) putting x and y scales or absolute height/width on their point of use would make for the best compatibility. (Also enables things like interchange with Dorico graphic frames).

I can go either way on escaped-string vs base64 encoding for embedded SVG. Maybe closer to the latter so it's the same as png jpg etc.

[rpatters1]

Surely we want to specify the size in terms of staff spaces for scalable items. Otherwise, there could be an error-prone calculation each time the shape is assigned: one that is also potentially different each time.