The principles governing state law preemption of local ordinances are as follows: Under article XI, section 7 of the California Constitution, a city may make and enforce within its limits all local ordinances not in conflict with general state laws. (O'Connell v. City of Stockton (2007) 41 Cal.4th 1061, 1067 (O'Connell).) A conflict exists if the local ordinance "'"'"duplicates, contradicts, or enters an area fully occupied by general law, either expressly or by legislative implication."'"'" (O'Connell, at p. 1067.) "A local ordinance duplicates state law when it is 'coextensive' with state law." (O'Connell, supra, 41 Cal.4th at p. 1067.) In re Portnoy (1942) 21 Cal.2d 237, provided such an example, where a county ordinance imposed the same criminal prohibitions on gambling activities as found in the Penal Code. (Portnoy, at p. 240.)