+ Length xl_tmp = Length(a);
+ if (xl_tmp.value() < 0)
+ xl_tmp = Length(-xl_tmp.value(), xl_tmp.unit());
+ Length yb_tmp = Length(b);
+ if (yb_tmp.value() < 0)
+ yb_tmp = Length(-yb_tmp.value(), yb_tmp.unit());
+ Length xr_tmp = Length(c);
+ if (xr_tmp.value() < 0)
+ xr_tmp = Length(-xr_tmp.value(), xr_tmp.unit());
+ Length yt_tmp = Length(d);
+ if (yt_tmp.value() < 0)
+ yt_tmp = Length(-yt_tmp.value(), yt_tmp.unit());
+