inline bool encode_geometry(mapnik::geometry::linear_ring<std::int64_t> const& ring,
vector_tile::Tile_Feature & current_feature,
int32_t & start_x,
int32_t & start_y)
{
std::size_t ring_size = ring.size();
if (ring_size < 3)
{
return false;
}
unsigned line_to_length = static_cast<unsigned>(ring_size) - 1;
unsigned count = 0;
enum {
move_to = 1,
line_to = 2,
coords = 3
} status = move_to;
bool drop_last = false;
if (ring.size() > 2 && ring.front() == ring.back())
{
drop_last = true;
line_to_length -= 1;
if (line_to_length < 2)
{
return false;
}
}
for (auto const& pt : ring)
{
if (status == move_to)
{
status = line_to;
current_feature.add_geometry(9); // 1 | (move_to << 3)
}
else if (status == line_to)
{
status = coords;
current_feature.add_geometry(encode_length(line_to_length));
}
else if (drop_last && count == line_to_length + 1)
{
continue;
}
int32_t dx = pt.x - start_x;
int32_t dy = pt.y - start_y;
// Manual zigzag encoding.
current_feature.add_geometry(protozero::encode_zigzag32(dx));
current_feature.add_geometry(protozero::encode_zigzag32(dy));
start_x = pt.x;
start_y = pt.y;
++count;
}
current_feature.add_geometry(15); // close_path
return true;
}
inline bool encode_geometry(mapnik::geometry::point<std::int64_t> const& pt,
vector_tile::Tile_Feature & current_feature,
int32_t & start_x,
int32_t & start_y)
{
current_feature.add_geometry(9); // 1 | (move_to << 3)
int32_t dx = pt.x - start_x;
int32_t dy = pt.y - start_y;
// Manual zigzag encoding.
current_feature.add_geometry(protozero::encode_zigzag32(dx));
current_feature.add_geometry(protozero::encode_zigzag32(dy));
start_x = pt.x;
start_y = pt.y;
return true;
}
inline bool encode_geometry(mapnik::geometry::line_string<std::int64_t> const& line,
vector_tile::Tile_Feature & current_feature,
int32_t & start_x,
int32_t & start_y)
{
std::size_t line_size = line.size();
if (line_size <= 0)
{
return false;
}
unsigned line_to_length = static_cast<unsigned>(line_size) - 1;
enum {
move_to = 1,
line_to = 2,
coords = 3
} status = move_to;
for (auto const& pt : line)
{
if (status == move_to)
{
status = line_to;
current_feature.add_geometry(9); // 1 | (move_to << 3)
}
else if (status == line_to)
{
status = coords;
current_feature.add_geometry(encode_length(line_to_length));
}
int32_t dx = pt.x - start_x;
int32_t dy = pt.y - start_y;
// Manual zigzag encoding.
current_feature.add_geometry(protozero::encode_zigzag32(dx));
current_feature.add_geometry(protozero::encode_zigzag32(dy));
start_x = pt.x;
start_y = pt.y;
}
return true;
}
inline bool encode_geometry(mapnik::geometry::multi_point<std::int64_t> const& geom,
vector_tile::Tile_Feature & current_feature,
int32_t & start_x,
int32_t & start_y)
{
std::size_t geom_size = geom.size();
if (geom_size <= 0)
{
return false;
}
current_feature.add_geometry(1u | (geom_size << 3)); // move_to | (len << 3)
for (auto const& pt : geom)
{
int32_t dx = pt.x - start_x;
int32_t dy = pt.y - start_y;
// Manual zigzag encoding.
current_feature.add_geometry(protozero::encode_zigzag32(dx));
current_feature.add_geometry(protozero::encode_zigzag32(dy));
start_x = pt.x;
start_y = pt.y;
}
return true;
}
