本文整理汇总了C++中mapnik::Map::layers方法的典型用法代码示例。如果您正苦于以下问题：C++ Map::layers方法的具体用法？C++ Map::layers怎么用？C++ Map::layers使用的例子？那么, 这里精选的方法代码示例或许可以为您提供帮助。您也可以进一步了解该方法所在类mapnik::Map的用法示例。
在下文中一共展示了Map::layers方法的3个代码示例，这些例子默认根据受欢迎程度排序。您可以为喜欢或者感觉有用的代码点赞，您的评价将有助于系统推荐出更棒的C++代码示例。
示例1: render_layer_for_grid
void render_layer_for_grid(mapnik::Map const& map,
mapnik::grid & grid,
unsigned layer_idx,
boost::python::list const& fields,
double scale_factor,
unsigned offset_x,
unsigned offset_y)
{
std::vector<mapnik::layer> const& layers = map.layers();
std::size_t layer_num = layers.size();
if (layer_idx >= layer_num) {
std::ostringstream s;
s << "Zero-based layer index '" << layer_idx << "' not valid, only '"
<< layer_num << "' layers are in map\n";
throw std::runtime_error(s.str());
}
// convert python list to std::set
boost::python::ssize_t num_fields = boost::python::len(fields);
for(boost::python::ssize_t i=0; i<num_fields; i++) {
boost::python::extract<std::string> name(fields[i]);
if (name.check())
{
grid.add_field(name());
}
else
{
std::stringstream s;
s << "list of field names must be strings";
throw mapnik::value_error(s.str());
}
}
// copy field names
std::set<std::string> attributes = grid.get_fields();
// todo - make this a static constant
std::string known_id_key = "__id__";
if (attributes.find(known_id_key) != attributes.end())
{
attributes.erase(known_id_key);
}
std::string join_field = grid.get_key();
if (known_id_key != join_field &&
attributes.find(join_field) == attributes.end())
{
attributes.insert(join_field);
}
mapnik::grid_renderer<mapnik::grid> ren(map,grid,scale_factor,offset_x,offset_y);
mapnik::layer const& layer = layers[layer_idx];
ren.apply(layer,attributes);
}示例2: render_layer2
void render_layer2(const mapnik::Map& map,
mapnik::image_32& image,
unsigned layer_idx)
{
std::vector<mapnik::layer> const& layers = map.layers();
std::size_t layer_num = layers.size();
if (layer_idx >= layer_num) {
std::ostringstream s;
s << "Zero-based layer index '" << layer_idx << "' not valid, only '"
<< layer_num << "' layers are in map\n";
throw std::runtime_error(s.str());
}
python_unblock_auto_block b;
mapnik::layer const& layer = layers[layer_idx];
mapnik::agg_renderer<mapnik::image_32> ren(map,image,1.0,0,0);
std::set<std::string> names;
ren.apply(layer,names);
}示例3: render_layer2
void render_layer2(mapnik::Map const& map,
mapnik::image_any& image,
unsigned layer_idx,
double scale_factor,
unsigned offset_x,
unsigned offset_y)
{
std::vector<mapnik::layer> const& layers = map.layers();
std::size_t layer_num = layers.size();
if (layer_idx >= layer_num) {
std::ostringstream s;
s << "Zero-based layer index '" << layer_idx << "' not valid, only '"
<< layer_num << "' layers are in map\n";
throw std::runtime_error(s.str());
}
python_unblock_auto_block b;
mapnik::layer const& layer = layers[layer_idx];
std::set<std::string> names;
mapnik::util::apply_visitor(agg_renderer_visitor_4(map, scale_factor, offset_x, offset_y, layer, names), image);
}