activeValue method
The value of a value-attribute at the current selection, or null when the selection is not uniformly covered by it.
Implementation
Object? activeValue(UInlineAttr attr) {
final TextSelection sel = selection;
if (!sel.isValid) return null;
if (pending.containsKey(attr)) return pending[attr];
final int probe = sel.isCollapsed ? sel.start - 1 : sel.start;
if (probe < 0) return null;
for (final UStyleSpan sp in spans) {
if (sp.attr == attr && probe >= sp.start && probe < sp.end) return sp.value;
}
return null;
}