odgi draw: add labels in the SVG output

src/algorithms/draw.cpp

@@ -1,4 +1,5 @@
 #include "draw.hpp"
+#include "split.hpp"
 
 namespace odgi {
 
@@ -98,15 +99,29 @@ void get_layout(const std::vector<double> &X,
 
 }
 
-
+struct label_info_t {
+    double x, y;
+    std::string content;
+    // Simple constructor for convenience
+    label_info_t(double x, double y, std::string content) : x(x), y(y), content(std::move(content)) {}
+};
+bool is_too_close(double x, double y, const std::string& content, double threshold, std::vector<label_info_t>& placed_labels) {
+    for (const auto& label : placed_labels) {
+        if (label.content == content && std::abs(label.x - x) < threshold && std::abs(label.y - y) < threshold) {
+            return true; // Found a label too close with the same content
+        }
+    }
+    return false;
+}
 void draw_svg(std::ostream &out,
               const std::vector<double> &X,
               const std::vector<double> &Y,
               const PathHandleGraph &graph,
               const double& scale,
               const double& border,
 			  const double& line_width,
-			  std::vector<algorithms::color_t>& node_id_to_color) {
+			  std::vector<algorithms::color_t>& node_id_to_color,
+              ska::flat_hash_map<handlegraph::nid_t, std::set<std::string>>& node_id_to_label_map) {
 
     std::vector<std::vector<handle_t>> weak_components;
     coord_range_2d_t rendered_range;
@@ -121,6 +136,8 @@ void draw_svg(std::ostream &out,
     double width = rendered_range.width();
     double height = rendered_range.height();
 
+    std::vector<label_info_t> placed_labels;
+
     out << std::setprecision(std::numeric_limits<double>::digits10 + 1);
     out << "<svg width=\"" << width << "\" height=\"" << height << "\" "
         << "viewBox=\"" << viewbox_x1 << " " << viewbox_y1
@@ -160,6 +177,29 @@ void draw_svg(std::ostream &out,
             } else {
                 highlights.push_back(handle);
             }
+
+            double x = (X[a] * scale) - x_off;
+            double y = (Y[a] * scale) + y_off;
+            // Check if this is a node with a label
+            if (node_id_to_label_map.count(graph.get_id(handle))){
+                // Collect the labels that can be put without overlapping identical ones
+                std::vector<std::string> labels;
+                for (auto text : node_id_to_label_map[graph.get_id(handle)]){
+                    if (!is_too_close(x, y, text, 30.0, placed_labels)) {
+                        labels.push_back(text);
+                    }
+                }
+                // Check if there is something to label
+                if (!labels.empty()){
+                    out << "<text font-family=\"Arial\" font-size=\"20\" fill=\"#000000\" stroke=\"#000000\" y=\"" << y << "\">";
+                    for (auto text : labels){
+                        out << "<tspan x=\"" << x << "\" dy=\"1.0em\">" << text << "</tspan>";
+                        placed_labels.emplace_back(x, y, text); // Record the label's placement
+                    }
+                    out << "</text>"
+                        << std::endl;
+                }
+            }
         }
 
         // color highlights

src/algorithms/draw.hpp

@@ -71,7 +71,8 @@ void draw_svg(std::ostream &out,
               const double& scale,
               const double& border,
 			  const double& line_width,
-			  std::vector<algorithms::color_t>& node_id_to_color);
+			  std::vector<algorithms::color_t>& node_id_to_color,
+              ska::flat_hash_map<handlegraph::nid_t, std::set<std::string>>& node_id_to_label_map);
 
 std::vector<uint8_t> rasterize(const std::vector<double> &X,
                                const std::vector<double> &Y,

src/subcommand/draw_main.cpp

@@ -117,6 +117,8 @@ int main_draw(int argc, char **argv) {
     // handle targets from BED
     std::vector<odgi::path_range_t> path_ranges;
     std::vector<algorithms::color_t> node_id_to_color;
+    ska::flat_hash_map<handlegraph::nid_t, std::set<std::string>> node_id_to_label_map; // To remember the unique node to label for each path range
+
     if (_path_bed_file && !args::get(_path_bed_file).empty()) {
         std::ifstream bed_in(args::get(_path_bed_file));
         std::string line;
@@ -137,6 +139,8 @@ int main_draw(int argc, char **argv) {
                 if (!path_range.name.empty()) {
                     auto vals = split(path_range.name, '#');
                     if (vals.size() == 2 && vals[1].length() == 6) {
+                        path_range.name = vals[0]; // Remove the color from the name
+
                         // Colors are given in RRGGBB in the BED file, but they are taken in BBGGRR, so we need to switch BB/RR
 
                         char temp = vals[1][0];
@@ -157,14 +161,18 @@ int main_draw(int argc, char **argv) {
                     }
                 }
 
-
-
-
-
+                bool first_handle_taken = path_range.name.empty(); // To avoid checking if there is no name to take
                 algorithms::for_handle_in_path_range(
                         graph, path_handle, path_range.begin.offset, path_range.end.offset,
                         [&](const handle_t& handle) {
-                            node_id_to_color[graph.get_id(handle)] = path_color;
+                            const auto node_id = graph.get_id(handle);
+                            node_id_to_color[node_id] = path_color;
+
+                            if (!first_handle_taken) {
+                                first_handle_taken = true;
+                                // The set automatically handles uniqueness of labels within the set.
+                                node_id_to_label_map[node_id].insert(path_range.name);
+                            }
                         });
             }
         }
@@ -216,7 +224,7 @@ int main_draw(int argc, char **argv) {
         // todo could be done with callbacks
         std::vector<double> X = layout.get_X();
         std::vector<double> Y = layout.get_Y();
-        algorithms::draw_svg(f, X, Y, graph, svg_scale, border_bp, _png_line_width, node_id_to_color);
+        algorithms::draw_svg(f, X, Y, graph, svg_scale, border_bp, _png_line_width, node_id_to_color, node_id_to_label_map);
         f.close();    
     }