In a glass-half-full kind of way, Brooklyn has become a bright spot for city retail, with average asking rents on ground-floor spaces up in seven of the 16 shopping corridors.

The market has been hopping where there are more apartments, according to the Real Estate Board of New York’s summer retail report.

The drop in asking rents are taking place in mature neighborhoods where rents had climbed over the past decade. Those are now slipping as building owners become more realistic as retailers suffer from the impact of online shopping.

The average asking rents still rose in three of the five Williamsburg strips. The hot North Fourth Street rose a whopping 34 percent, to $197 per square foot, as vacancies emerged at newly developed properties and at those closer to Bedford Avenue.

Along North Sixth Street, as highlighted by The Post in October, rents went up 8 percent, to $251 per square foot. Along Bedford Avenue from North Eighth Street to North 12th Street by McCarren Park, rents increased 3 percent, to $168 per square foot.

Rents, however, fell 11 percent, to $351 per square foot, on Bedford between Grand and North 8th streets.

In Prospect Heights, Flatbush Avenue between Fifth Avenue and Grand Army Plaza rose 9 percent, to $118 per foot — its third year-over-year jump.

Other corridors saw asking rents fall because more expensive and better­ located storefronts were leased up — leaving cheaper ones languishing for the moment.

Rents on Court Street between Atlantic Avenue and Carroll Street dropped by 31 percent, to $103 per square foot. On Smith Street, also between Atlantic and Carroll, rents fell 32 percent, to $101 per foot. And on Montague Street between Hicks Street and Cadman Plaza, the average asking rents fell 27 percent, to $110 per foot.

Landlords and retailers are wondering about the shutdown of the L train between Brooklyn and Manhattan. The subway line is expected to close in April 2019 and last 15 months while repairs are made to the line’s Canarsie Tunnel, which runs under the East River and was flooded during Hurricane Sandy.

Orin Wilf of Skyline Developers has made a choice. After a year of thinking about what to build, Wilf has hired Morris Adjmi Architects to design a luxury rental with a unique facade for the vacant site at 12 W. 55th St.

The upcoming 24-story building will have more than 100 apartments in a design inspired by the pre-war architecture on the block ­between Fifth and Sixth avenues. Wilf is the owner of the Rockefeller Townhouses at 20 W. 55th St. and 13-15 W. 54th St., housing his offices and Michael’s restaurant.

The new structure will step back six times from West 55th Street, allowing light, air and views, plus 11,500 square feet for a retailer flagship.

Adjmi was responsible for the Meatpacking District’s glass-topped Samsung space at 837 Washington St.