windows phone 8 - Wp8 maps bounding rectangle -

i'm trying create mapcontrol, , need split current boundingrectangle 25 pieces, , realized there no boundingrectangle in wp7 version.

how solve problem than? avoid using nokia maps if possible.

    private locationrectangle getmapbounds()     {         geocoordinate topleft = mapcontrol.convertviewportpointtogeocoordinate(new point(0, 0));         geocoordinate bottomright = mapcontrol.convertviewportpointtogeocoordinate(new point(mapcontrol.actualwidth, mapcontrol.actualheight));          if (topleft != null && bottomright != null)         {             return locationrectangle.createboundingrectangle(new[] { topleft, bottomright });         }          return null;     }