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Polyline6 support in the REST input

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This commit is contained in:
Lev Dragunov
2017-06-06 19:51:00 +03:00
parent 0d12d2fd28
commit 6b8f3c7fef
3 changed files with 49 additions and 47 deletions
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src/engine/polyline_compressor.cpp
+15 -42
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@@ -52,54 +52,27 @@ std::string encode(std::vector<int> &numbers)
}
return output;
}
}
std::vector<util::Coordinate> decodePolyline(const std::string &geometry_string)
{
// https://developers.google.com/maps/documentation/utilities/polylinealgorithm
auto decode_polyline_integer = [](auto &first, auto last) {
// varint coding parameters
const std::uint32_t bits_in_chunk = 5;
const std::uint32_t continuation_bit = 1 << bits_in_chunk;
const std::uint32_t chunk_mask = (1 << bits_in_chunk) - 1;
std::int32_t decode_polyline_integer(std::string::const_iterator &first, std::string::const_iterator last) {
// varint coding parameters
const std::uint32_t bits_in_chunk = 5;
const std::uint32_t continuation_bit = 1 << bits_in_chunk;
const std::uint32_t chunk_mask = (1 << bits_in_chunk) - 1;
std::uint32_t result = 0;
for (std::uint32_t value = continuation_bit, shift = 0;
(value & continuation_bit) && (shift < CHAR_BIT * sizeof(result) - 1) && first != last;
++first, shift += bits_in_chunk)
{
value = *first - 63; // convert ASCII coding [?..~] to an integer [0..63]
result |= (value & chunk_mask) << shift;
}
// change "zig-zag" sign coding to two's complement
result = ((result & 1) == 1) ? ~(result >> 1) : (result >> 1);
return static_cast<std::int32_t>(result);
};
auto polyline_to_coordinate = [](auto value) {
return static_cast<std::int32_t>(value * detail::POLYLINE_TO_COORDINATE);
};
std::vector<util::Coordinate> coordinates;
std::int32_t latitude = 0, longitude = 0;
std::string::const_iterator first = geometry_string.begin();
const std::string::const_iterator last = geometry_string.end();
while (first != last)
std::uint32_t result = 0;
for (std::uint32_t value = continuation_bit, shift = 0;
(value & continuation_bit) && (shift < CHAR_BIT * sizeof(result) - 1) && first != last;
++first, shift += bits_in_chunk)
{
const auto dlat = decode_polyline_integer(first, last);
const auto dlon = decode_polyline_integer(first, last);
latitude += dlat;
longitude += dlon;
coordinates.emplace_back(
util::Coordinate{util::FixedLongitude{polyline_to_coordinate(longitude)},
util::FixedLatitude{polyline_to_coordinate(latitude)}});
value = *first - 63; // convert ASCII coding [?..~] to an integer [0..63]
result |= (value & chunk_mask) << shift;
}
return coordinates;
// change "zig-zag" sign coding to two's complement
result = ((result & 1) == 1) ? ~(result >> 1) : (result >> 1);
return static_cast<std::int32_t>(result);
}
}
}
}