add method
- PaletteEntry entry
Registers entry in the palette.
Throws a StateError if entry is already in another palette, or if an
entry with the same name is already registered to this palette.
Implementation
PaletteEntry add(PaletteEntry entry) {
if (entry._palette != null) {
throw StateError('This entry is registered in a different palette.');
}
// Ensured by the public `Palette` factory.
final name = entry.name!;
if (_index.containsKey(name)) {
throw StateError('A paint named "$name" is already registered.');
}
entry._palette = this;
_insert(entry);
_index[name] = entry;
return entry;
}