getSymbolSize function
Returns the rendered ink size (width, height) of an FSW symbol key
(e.g. S2e748), measured in the Sutton SignWriting Line font at size 30.
Mirrors Python signwriting.visualizer.visualize.get_symbol_size. Sizes
are precomputed (see tool/generate_sizes.py) so this works without a font
renderer. Returns (0, 0) for keys that have no existing ISWA glyph.
Implementation
Tuple2<int, int> getSymbolSize(String symbol) {
final id = key2id(symbol);
final i = id * 2;
if (id < 0 || i + 1 >= _sizes.length) return const Tuple2(0, 0);
return Tuple2(_sizes[i], _sizes[i + 1]);
}