Glyph copy constructor about opentype.js HOT 3 CLOSED

Did a quick and dirty hack attempt to effect a copy using

window.copyGlyph = function(g) {
    var g2 = new Glyph(g);
    if(g.points) {
        g2.points = [];
        g.points.forEach(function(p) {
            g2.points.push({
                lastPointOfContour: p.lastPointOfContour,
                onCurve: p.onCurve,
                x: p.x,
                y: p.y
            });
        });
    }
    return g2;
}

but this does interesting things - even if I modify the x/y values of points, calling g.draw on the resulting glyph shows me the origin glyph, not the modified one

(the original problem was that modifying the glyph meant modifying every instance, since there is only one, so instead of too much modification, I now have too little =)

from opentype.js.

With a g.path = window.getGlyphPath(g.points) (an alias for the getPath function) before calling g.draw works. There's a patch in here somewhere, I can smell it.

from opentype.js.

Glyph.points is actually just stored once during parsing of TrueType fonts, but it's not used again when calling Glyph.path,
as that path is generated during parsing as well. But actually, now that variable fonts are implemented, those points are used for building the transformed path for TrueType fonts. Glyph.points and Glyph.path currenly have to be modified separately, which is something we need to remedy in the future. When setting the path, points shold be recalculated, and vice versa.

To answer your original question: There's currently no built-in way to duplicate a glyph. You need to do something like this:

new Glyph(Object.assign({}, glyph, {points: deepCloneOfPoints, path: deepCloneOfPath}));

[...glyph.points] and [...glyph.path] will not be enough, because they still hold references to the objects, in those arrays, you'll actually need a deep copy either by using a package made for that, or the quick-and-dirty JSON.parse(JSON.stringify(glyph.path))

from opentype.js.