inline void group_attribute_collector::operator() (group_symbolizer const& sym)
{
// find all column names referenced in the group symbolizer
std::set<std::string> group_columns;
attribute_collector column_collector(group_columns);
expression_attributes<std::set<std::string> > rk_attr(group_columns);
// get columns from symbolizer repeat key
expression_ptr repeat_key = get<mapnik::expression_ptr>(sym, keys::repeat_key);
if (repeat_key)
{
boost::apply_visitor(rk_attr, *repeat_key);
}
// get columns from child rules and symbolizers
group_symbolizer_properties_ptr props = get<group_symbolizer_properties_ptr>(sym, keys::group_properties);
if (props) {
for (auto const& rule : props->get_rules())
{
// note that this recurses down on to the symbolizer
// internals too, so we get all free variables.
column_collector(*rule);
// still need to collect repeat key columns
if (rule->get_repeat_key())
{
boost::apply_visitor(rk_attr, *(rule->get_repeat_key()));
}
}
}
// get indexed column names
int start = get<value_integer>(sym, keys::start_column);
int end = start + get<value_integer>(sym, keys::num_columns);
for (auto const& col_name : group_columns)
{
if (expand_index_columns_ && col_name.find('%') != std::string::npos)
{
// Note: ignore column name if it is '%' by itself.
// '%' is a special case to access the index value itself,
// rather than acessing indexed columns from data source.
if (col_name.size() > 1)
{
// Indexed column name. add column name for each index value.
for (int col_idx = start; col_idx < end; ++col_idx)
{
std::string col_idx_str;
if (mapnik::util::to_string(col_idx_str,col_idx))
{
std::string col_idx_name = col_name;
boost::replace_all(col_idx_name, "%", col_idx_str);
names_.insert(col_idx_name);
}
}
}
}
else
{
// This is not an indexed column, or we are ignoring indexes.
// Insert the name as is.
names_.insert(col_name);
}
}
}
void render_group_symbolizer(group_symbolizer const& sym,
feature_impl & feature,
attributes const& vars,
proj_transform const& prj_trans,
box2d<double> const& clipping_extent,
renderer_common & common,
render_thunk_list_dispatch & render_thunks)
{
// find all column names referenced in the group rules and symbolizers
std::set<std::string> columns;
group_attribute_collector column_collector(columns, false);
column_collector(sym);
auto props = get<group_symbolizer_properties_ptr>(sym, keys::group_properties);
// create a new context for the sub features of this group
context_ptr sub_feature_ctx = std::make_shared<mapnik::context_type>();
// populate new context with column names referenced in the group rules and symbolizers
for (auto const& col_name : columns)
{
sub_feature_ctx->push(col_name);
}
// keep track of the sub features that we'll want to symbolize
// along with the group rules that they matched
std::vector< std::pair<group_rule_ptr, feature_ptr> > matches;
// create a copied 'virtual' common renderer for processing sub feature symbolizers
// create an empty detector for it, so we are sure we won't hit anything
virtual_renderer_common virtual_renderer(common);
// keep track of which lists of render thunks correspond to
// entries in the group_layout_manager.
std::list<render_thunk_list> layout_thunks;
// layout manager to store and arrange bboxes of matched features
group_layout_manager layout_manager(props->get_layout());
layout_manager.set_input_origin(common.width_ * 0.5, common.height_ * 0.5);
// run feature or sub feature through the group rules & symbolizers
// for each index value in the range
value_integer start = get<value_integer>(sym, keys::start_column);
value_integer end = start + get<value_integer>(sym, keys::num_columns);
for (value_integer col_idx = start; col_idx < end; ++col_idx)
{
// create sub feature with indexed column values
feature_ptr sub_feature = feature_factory::create(sub_feature_ctx, col_idx);
// copy the necessary columns to sub feature
for(auto const& col_name : columns)
{
if (col_name.find('%') != std::string::npos)
{
if (col_name.size() == 1)
{
// column name is '%' by itself, so give the index as the value
sub_feature->put(col_name, col_idx);
}
else
{
// indexed column
std::string col_idx_str;
if (mapnik::util::to_string(col_idx_str,col_idx))
{
std::string col_idx_name = col_name;
boost::replace_all(col_idx_name, "%", col_idx_str);
sub_feature->put(col_name, feature.get(col_idx_name));
}
}
}
else
{
// non-indexed column
sub_feature->put(col_name, feature.get(col_name));
}
}
// add a single point geometry at pixel origin
double x = common.width_ / 2.0, y = common.height_ / 2.0, z = 0.0;
common.t_.backward(&x, &y);
prj_trans.forward(x, y, z);
// note that we choose a point in the middle of the screen to
// try to ensure that we don't get edge artefacts due to any
// symbolizers with avoid-edges set: only the avoid-edges of
// the group symbolizer itself should matter.
geometry::point<double> origin_pt(x,y);
sub_feature->set_geometry(origin_pt);
// get the layout for this set of properties
for (auto const& rule : props->get_rules())
{
if (util::apply_visitor(evaluate<feature_impl,value_type,attributes>(*sub_feature,common.vars_),
*(rule->get_filter())).to_bool())
{
// add matched rule and feature to the list of things to draw
matches.emplace_back(rule, sub_feature);
// construct a bounding box around all symbolizers for the matched rule
box2d<double> bounds;
render_thunk_list thunks;
render_thunk_extractor extractor(bounds, thunks, *sub_feature, common.vars_, prj_trans,
virtual_renderer, clipping_extent);
for (auto const& _sym : *rule)
{
// TODO: construct layout and obtain bounding box
util::apply_visitor(extractor, _sym);
}
// add the bounding box to the layout manager
layout_manager.add_member_bound_box(bounds);
layout_thunks.emplace_back(std::move(thunks));
break;
}
}
}
// create a symbolizer helper
std::list<box_element> box_elements;
for (size_t i = 0; i < matches.size(); ++i)
{
group_rule_ptr match_rule = matches[i].first;
feature_ptr match_feature = matches[i].second;
value_unicode_string rpt_key_value = "";
// get repeat key from matched group rule
expression_ptr rpt_key_expr = match_rule->get_repeat_key();
// if no repeat key was defined, use default from group symbolizer
if (!rpt_key_expr)
{
rpt_key_expr = get<expression_ptr>(sym, keys::repeat_key);
}
// evaluate the repeat key with the matched sub feature if we have one
if (rpt_key_expr)
{
rpt_key_value = util::apply_visitor(
evaluate<feature_impl,value_type,attributes>(*match_feature,common.vars_),
*rpt_key_expr).to_unicode();
}
box_elements.emplace_back(layout_manager.offset_box_at(i), rpt_key_value);
}
agg::trans_affine tr;
auto transform = get_optional<transform_type>(sym, keys::geometry_transform);
if (transform)
{
evaluate_transform(tr, feature, common.vars_, *transform, common.scale_factor_);
}
label_placement::placement_params params {
prj_trans, common.t_, tr, sym, feature, vars,
box2d<double>(0, 0, common.width_, common.height_), common.query_extent_,
common.scale_factor_, common.symbol_cache_ };
using traits = label_placement::group_symbolizer_traits;
text_placement_info_ptr placement_info = mapnik::get<text_placements_ptr>(
sym, keys::text_placements_)->get_placement_info(common.scale_factor_,
feature, vars, common.symbol_cache_);
group_layout_generator layout_generator(params,
*common.detector_, common.font_manager_,
*placement_info, box_elements);
const label_placement_enum placement_type =
layout_generator.get_text_props().label_placement;
label_placement::finder<traits>::apply(placement_type, layout_generator, params);
for (pixel_position const& pos : layout_generator.placements_)
{
size_t layout_i = 0;
for (auto const& thunks : layout_thunks)
{
pixel_position const& offset = layout_manager.offset_at(layout_i);
pixel_position render_offset = pos + offset;
render_thunks.render_list(thunks, render_offset);
++layout_i;
}
}
}