fillRect method
Implementation
void fillRect(Rect rect, Cell cell) {
final clipped = rect.intersect(area);
if (clipped.isEmpty) return;
for (var dy = 0; dy < clipped.height; dy++) {
for (var dx = 0; dx < clipped.width; dx++) {
set(clipped.x + dx, clipped.y + dy, cell);
}
}
}