idea: merge consecutive paths with same fill?

[anthrotype]

while looking at some waved flags in noto-emoji, I noticed one where there are dozen (perhaps hundreds, I didn't count -- the svg is probably autotraced which may expain the big numbers) of consecutive paths that have the same fill.

Since in nanoemoji we convert each <path> elements to a glyph (to be used as a filled path in COLR PaintGlyph), and the total number of glyphIDs in a font is 65,636, we want to reduce the overall number of layers that each color glyph uses.

What if picosvg makes a single <path> out of two or more <path>s that have the same fill?
We could use skia-pathops to make a union of the paths..

[anthrotype]

I said consecutive (as in Z-order), but in theory they could be interspersed with other paths that have different fill but which do not overlap with the paths we're trying to union. Such that merging the latter while pushing the ones in between after the merged path wouldn't change the way they look.

[anthrotype]

this has become more urgent as we discovered Safar rejects SVG documents in OpenType SVG table if they contain more than 1000 elements in total, or if any element has more than 500 children.

For example, the Ecuador and the El Salvador's flags both contain more than 1000 elements each, but hundreds of them are consecutive <path> elements that share the same fill or stroke properties so they can be merged into single elements.