Method enableGPSDisplay

src/gui/map/map_editor.cpp:3537–3622

void MapEditorController::enableGPSDisplay(bool enable)
{
	if (enable)
	{
		gps_display->startUpdates();
		
		// Create gps_track_recorder if we can determine a template track filename
		constexpr int gps_track_draw_update_interval = 10 * 1000; // in milliseconds
		if (! window->currentPath().isEmpty())
		{
			// Find or create a template for the track with a specific name
			QString gpx_file_path =
				QFileInfo(window->currentPath()).absoluteDir().canonicalPath()
				+ QLatin1Char('/')
				+ QFileInfo(window->currentPath()).completeBaseName()
				+ QLatin1String(" - GPS-")
				+ QDate::currentDate().toString(Qt::ISODate)
				+ QLatin1String(".gpx");
			
			bool new_template = true;  // Indicates that we really add a new template.
			TemplateTrack* track = nullptr;
			int template_index = 0;
			for ( ; template_index < map->getNumTemplates(); ++template_index)
			{
				auto* temp = map->getTemplate(template_index);
				if (temp->getTemplatePath() == gpx_file_path)
				{
					// There is a template for this track.
					new_template = false;
					track = qobject_cast<TemplateTrack*>(temp);
					break;
				}
			}
			
			// Derive new visibility from previous/default one.
			auto visibility = main_view->getTemplateVisibility(track);
			visibility.opacity = std::max(0.5, visibility.opacity);
			visibility.visible = true;
			
			if (!track)
			{
				if (!new_template)
				{
					// Need to replace the template at template_index
					map->deleteTemplate(template_index);
				}
				track = new TemplateTrack(gpx_file_path, map);
				// This will set the state to 'Loaded', so we need to reset it
				// to `Unloaded` to allow for loading the file when it becomes
				// visible for the first time.
				track->configureForGPSTrack();
				if (QFileInfo::exists(gpx_file_path))
				{
					track->unloadTemplateFile();
					track->loadTemplateFile();
				}
				map->addTemplate(template_index, std::unique_ptr<Template>{track});
				// When the map is saved, the new track must be saved even if it is empty.