Tile key filter policy

To specify tiles that you want to download from a specific catalog, use the tile_key_filter_policy field of the CatalogSettings structure.

Example:

struct TileKeyFilterPolicy
{
    bool
    operator( )( const olp::geo::TileKey& tile_key ) const
    {
        return catalog_tile_keys.find( tile_key ) != catalog_tile_keys.end( );
    }

    std::set< olp::geo::TileKey > catalog_tile_keys;
};

...

olp::clientmap::datastore::CatalogSettings catalog_settings;
catalog_settings.tile_key_filter_policy = TileKeyFilterPolicy( );

Note: operator( ) must be of the CatalogSettings::TileKeyFilterPolicyType type.

If the tile key filter policy returns false for the requested tile, the tile is not loaded from the catalog and an empty tile data instance is created.