[traffic] Calculate filter list for active MWMs

Signed-off-by: mvglasow <michael -at- vonglasow.com>

map/traffic_manager.cpp

@@ -266,12 +266,21 @@ void TrafficManager::UpdateViewport(ScreenBase const & screen)
   UpdateActiveMwms(screen.ClipRect(), m_lastDrapeMwmsByRect, m_activeDrapeMwms);
 }
 
+std::string TrafficManager::GetMwmFilters(std::set<MwmSet::MwmId> & mwms)
+{
+  std::vector<m2::RectD> rects;
+  for (auto mwmId : mwms)
+    rects.push_back(mwmId.GetInfo()->m_bordersRect);
+  return traffxml::FiltersToXml(rects);
+}
+
 // TODO make this work with multiple sources (e.g. Android)
 bool TrafficManager::Subscribe(std::set<MwmSet::MwmId> & mwms)
 {
   // TODO what if we’re subscribed already?
+  std::string filterList = GetMwmFilters(mwms);
   // TODO
-  LOG(LINFO, ("Would subscribe to", mwms));
+  LOG(LINFO, ("Would subscribe to:\n", filterList));
   m_subscriptionId = "placeholder_subscription_id";
   m_isPollNeeded = true; // would be false if we got a feed here
   return true;
@@ -280,9 +289,11 @@ bool TrafficManager::Subscribe(std::set<MwmSet::MwmId> & mwms)
 // TODO make this work with multiple sources (e.g. Android)
 bool TrafficManager::ChangeSubscription(std::set<MwmSet::MwmId> & mwms)
 {
-  // TODO what if we’re not subscribed yet?
+  if (!IsSubscribed())
+    return false;
+  std::string filterList = GetMwmFilters(mwms);
   // TODO
-  LOG(LINFO, ("Would change subscription", m_subscriptionId, "to", mwms));
+  LOG(LINFO, ("Would change subscription", m_subscriptionId, "to:\n", filterList));
   m_isPollNeeded = true; // would be false if we got a feed here
   return true;
 }
@@ -290,6 +301,7 @@ bool TrafficManager::ChangeSubscription(std::set<MwmSet::MwmId> & mwms)
 bool TrafficManager::SetSubscriptionArea()
 {
   std::set<MwmSet::MwmId> activeMwms;
+
   if (!IsSubscribed())
   {
     {

map/traffic_manager.hpp

@@ -183,6 +183,14 @@ private:
     traffic::TrafficInfo::Availability m_lastAvailability;
   };
 
+  /**
+   * @brief Returns a TraFF filter list for a set of MWMs.
+   *
+   * @param mwms The MWMs for which a filter list is to be created.
+   * @return A `filter_list` in XML format.
+   */
+  std::string GetMwmFilters(std::set<MwmSet::MwmId> & mwms);
+
   /**
    * @brief Subscribes to a traffic service.
    *

traffxml/traff_model.hpp

@@ -395,6 +395,22 @@ struct TraffMessage
 
 using TraffFeed = std::vector<TraffMessage>;
 
+// TODO Capabilities
+
+/*
+ * Filter: currently not implemented.
+ * We only use bbox, for which we have a suitable data type.
+ * min_road_class is not needed as we do not filter by road class.
+ */
+
+/*
+ * TraffSubscription: currently not implemented.
+ * We just store the ID as a string.
+ * Filters are only by bbox, not by min_road_class. The list is auto-generated from the list of
+ * active MWMs and changes exactly when the active MWM set changes, eliminating the need to store
+ * the full filter list.
+ */
+
 /**
  * @brief Guess the distance to the next point.
  *

traffxml/traff_model_xml.cpp

@@ -643,4 +643,16 @@ bool ParseTraff(pugi::xml_document const & document, TraffFeed & feed)
   }
   return result;
 }
+
+std::string FiltersToXml(std::vector<m2::RectD> & bboxRects)
+{
+  std::ostringstream os;
+  for (auto rect : bboxRects)
+    os << std::format("<filter bbox=\"{} {} {} {}\"/>\n",
+                      mercator::YToLat(rect.minY()),
+                      mercator::XToLon(rect.minX()),
+                      mercator::YToLat(rect.maxY()),
+                      mercator::XToLon(rect.maxX()));
+  return os.str();
+}
 }  // namespace openlr

traffxml/traff_model_xml.hpp

@@ -2,6 +2,11 @@
 
 #include "traffxml/traff_model.hpp"
 
+#include "geometry/rect2d.hpp"
+
+#include <string>
+#include <vector>
+
 namespace pugi
 {
 class xml_document;
@@ -11,4 +16,20 @@ class xml_node;
 namespace traffxml
 {
 bool ParseTraff(pugi::xml_document const & document, TraffFeed & feed);
+
+/**
+ * @brief Generates a list of XML `filter` elements from a vector of rects representing bboxes.
+ *
+ * The resulting string can be placed inside a TraFF XML `filter_list` element or can be passed as
+ * an extra to an Android intent.
+ *
+ * It will have one `filter` element for each element in `bboxRects`, although simplification may
+ * be applied to reduce the number of rects (currently not implemented).
+ *
+ * The `min_road_class` attribute is not used.
+ *
+ * @param bboxRects The rectangles, each of which represents a bounding box.
+ * @return A string of XML `filter` elements.
+ */
+std::string FiltersToXml(std::vector<m2::RectD> & bboxRects);
 }  // namespace traffxml