Method copyLengths

src/core/virtual_path.cpp:767–835

This algorithm must (nearly) match VirtualPath::copy(). (It will always copy the length of the starting point, but VirtualPath::copy() might skip this point in some cases.)

// (It will always copy the length of the starting point, but
// VirtualPath::copy() might skip this point in some cases.)
void VirtualPath::copyLengths(
        const SplitPathCoord& first,
        const SplitPathCoord& last,
        std::vector<PathCoord::length_type>& out_lengths ) const
{
	Q_ASSERT(!empty());
	Q_ASSERT(first.path_coords == &path_coords);
	Q_ASSERT(last.path_coords == &path_coords);
	
	auto& flags  = coords.flags;
	
	// Handle first coordinate
	out_lengths.emplace_back(first.clen);
	
	bool after_curve_start = false;
	
	if (first.index == last.index)
	{
		after_curve_start = last.is_curve_end && last.param != first.param;
	}
	else 
	{
		after_curve_start = first.is_curve_start;
		
		auto stop_index = last.index;
		if (last.param == 0.0f)
		{
			stop_index -= last.is_curve_end ? 3 : 1;
		}
		
		auto index = first.index + 1;
		if (first.is_curve_start && index < stop_index)
		{
			after_curve_start = false;
			out_lengths.emplace_back(first.clen);
			out_lengths.emplace_back(first.clen);
			index += 2;
		}
		
		auto path_coord_index = first.path_coord_index;
		for (; index <= stop_index; ++index)
		{
			while (path_coords[path_coord_index].index < index)
				++path_coord_index;
			
			if (path_coords[path_coord_index].index == index)
			{
				// Normal node
				out_lengths.emplace_back(path_coords[path_coord_index].clen);
				after_curve_start = flags[index].isCurveStart();
			}
			else
			{
				// Control point
				out_lengths.emplace_back(out_lengths.back());
				after_curve_start = false;
			}
		}