CameraPosition constructor
构造一个CameraPosition 对象
如果bearing
, target
, tilt
, 或者 zoom
为null时会返回AssertionError
Implementation
const CameraPosition({
this.bearing = 0.0,
@required this.target,
this.tilt = 0.0,
this.zoom = 10,
}) : assert(bearing != null),
assert(target != null),
assert(tilt != null),
assert(zoom != null);