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#include <mbgl/layout/merge_lines.hpp>
#include <mbgl/layout/symbol_feature.hpp>
#include <mbgl/util/hash.hpp>
namespace mbgl {
namespace util {
// Map of key -> index into features
using Index = std::unordered_map<size_t, size_t>;
size_t mergeFromRight(std::vector<SymbolFeature>& features,
Index& rightIndex,
Index::iterator left,
size_t rightKey,
GeometryCollection& geom) {
const size_t index = left->second;
rightIndex.erase(left);
rightIndex[rightKey] = index;
features[index].geometry[0].pop_back();
features[index].geometry[0].insert(
features[index].geometry[0].end(), geom[0].begin(), geom[0].end());
geom[0].clear();
return index;
}
size_t mergeFromLeft(std::vector<SymbolFeature>& features,
Index& leftIndex,
Index::iterator right,
size_t leftKey,
GeometryCollection& geom) {
const size_t index = right->second;
leftIndex.erase(right);
leftIndex[leftKey] = index;
geom[0].pop_back();
geom[0].insert(
geom[0].end(), features[index].geometry[0].begin(), features[index].geometry[0].end());
features[index].geometry[0].clear();
std::swap(features[index].geometry[0], geom[0]);
return index;
}
size_t getKey(const std::u16string& text, const GeometryCoordinate& coord) {
return util::hash(text, coord.x, coord.y);
}
void mergeLines(std::vector<SymbolFeature>& features) {
Index leftIndex;
Index rightIndex;
for (size_t k = 0; k < features.size(); k++) {
SymbolFeature& feature = features[k];
GeometryCollection& geometry = feature.geometry;
if (!feature.formattedText || geometry.empty() || geometry[0].empty()) {
continue;
}
// TODO: Key should include formatting options (see https://github.com/mapbox/mapbox-gl-js/issues/3645)
const size_t leftKey = getKey(feature.formattedText->rawText(), geometry[0].front());
const size_t rightKey = getKey(feature.formattedText->rawText(), geometry[0].back());
const auto left = rightIndex.find(leftKey);
const auto right = leftIndex.find(rightKey);
if (left != rightIndex.end() && right != leftIndex.end() && left->second != right->second) {
// found lines with the same text adjacent to both ends of the current line, merge all
// three
size_t j = mergeFromLeft(features, leftIndex, right, leftKey, geometry);
size_t i = mergeFromRight(features, rightIndex, left, rightKey, features[j].geometry);
leftIndex.erase(leftKey);
rightIndex.erase(rightKey);
rightIndex[getKey(feature.formattedText->rawText(), features[i].geometry[0].back())] = i;
} else if (left != rightIndex.end()) {
// found mergeable line adjacent to the start of the current line, merge
mergeFromRight(features, rightIndex, left, rightKey, geometry);
} else if (right != leftIndex.end()) {
// found mergeable line adjacent to the end of the current line, merge
mergeFromLeft(features, leftIndex, right, leftKey, geometry);
} else {
// no adjacent lines, add as a new item
leftIndex[leftKey] = k;
rightIndex[rightKey] = k;
}
}
}
} // end namespace util
} // end namespace mbgl
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