mapnik.go
func (m *Map) Resize(width, height int) {
	C.mapnik_map_resize(m.m, C.uint(width), C.uint(height))
	m.width = width
	m.height = height
}
func (m *Map) Resize(width, height int) {
	C.mapnik_map_resize(m.m, C.uint(width), C.uint(height))
	m.width = width
	m.height = height
}
// Resize changes the map size in pixel.
// Sizes larger than 16k pixels are ignored by Mapnik. Use NewSized
// to initialize larger maps.