// SelectLayers enables/disables single layers. LayerSelector or SelectorFunc gets called for each layer.
func (m *Map) SelectLayers(selector LayerSelector) {
m.storeLayerStatus()
n := C.mapnik_map_layer_count(m.m)
for i := 0; i < int(n); i++ {
layerName := C.GoString(C.mapnik_map_layer_name(m.m, C.size_t(i)))
switch selector.Select(layerName) {
case Include:
C.mapnik_map_layer_set_active(m.m, C.size_t(i), 1)
case Exclude:
C.mapnik_map_layer_set_active(m.m, C.size_t(i), 0)
case Default:
}
}
}
func (m *Map) resetLayerStatus() {
if len(m.layerStatus) == 0 {
return // not stored
}
n := C.mapnik_map_layer_count(m.m)
if int(n) > len(m.layerStatus) {
// should not happen
return
}
for i := 0; i < int(n); i++ {
if m.layerStatus[i] {
C.mapnik_map_layer_set_active(m.m, C.size_t(i), 1)
} else {
C.mapnik_map_layer_set_active(m.m, C.size_t(i), 0)
}
}
m.layerStatus = nil
}