+ // we're going to round the canvas size to an integer number of pixels, so round the
+ // tl-br rectangle accordingly - otherwise we see the jittering described in bug 2152666
+ br[0] -= (pw*(br[0]-tl[0]) - round_to_int(pw*(br[0]-tl[0]))) / pw;
+ br[1] -= (ph*(br[1]-tl[1]) - round_to_int(ph*(br[1]-tl[1]))) / ph;
+