render method
Implementation
@override
void render(Rect area, Buffer buffer, RenderContext ctx) {
final h = height ?? 1;
final w = width ?? area.width;
final ax = area.x + (area.width - w) ~/ 2;
final ay = area.y + (area.height - h) ~/ 2;
ctx.draw(child, Rect(ax, ay, w, h));
}