Method setupAngleHelperFromEditedObjects

src/tools/edit_tool.cpp:127–245

void EditTool::setupAngleHelperFromEditedObjects()
{
	constexpr auto max_num_primary_directions = std::size_t(5);
	constexpr auto angle_window = (2 * M_PI) * 2 / 360.0;
	// Amount of all path length which has to be covered by an angle
	// to be classified as "primary angle"
	constexpr auto path_angle_threshold = qreal(1 / 5.0);
	
	angle_helper->clearAngles();
	
	std::unordered_set<qreal> primary_directions;
	for (const Object* object : editedObjects())
	{
		if (object->getType() == Object::Point)
		{
			primary_directions.insert(fmod_pos(object->asPoint()->getRotation(), M_PI / 2));
		}
		else if (object->getType() == Object::Text)
		{
			primary_directions.insert(fmod_pos(object->asText()->getRotation(), M_PI / 2));
		}
		else if (object->getType() == Object::Path)
		{
			const auto* path = object->asPath();
			// Maps angles to the path distance covered by them
			std::map<qreal, qreal> path_directions;
			
			// Collect segment directions, only looking at the first part
			auto& part = path->parts().front();
			auto path_length = part.path_coords.back().clen;
			for (auto c = part.first_index; c < part.last_index; c = part.nextCoordIndex(c))
			{
				if (!path->getCoordinate(c).isCurveStart())
				{
					auto segment = MapCoordF(path->getCoordinate(c + 1) - path->getCoordinate(c));
					auto angle = fmod_pos(-segment.angle(), M_PI / 2);
					auto length = segment.length();
					
					auto angle_it = path_directions.find(angle);
					if (angle_it != path_directions.end())
						angle_it->second += length;
					else
						path_directions.insert({angle, length});
				}
			}
			
			// Determine primary directions by moving a window over the collected angles
			// and determining maxima.
			// The iterators are the next angle which crosses the respective window border.
			auto angle_start = -angle_window;
			auto start_it = path_directions.begin();
			auto angle_end = qreal(0.0);
			auto end_it = path_directions.begin();
			
			auto length_increasing = true;
			auto cur_length = qreal(0.0);
			while (start_it != path_directions.end())
			{