[core] switch to vector-tile library for decoding Mapbox vector tiles

3 files changed, 62 insertions, 252 deletions

diff --git a/src/mbgl/tile/vector_tile.cpp b/src/mbgl/tile/vector_tile.cpp
index 0e13b78a7d..e2e700b7b7 100644
--- a/src/mbgl/tile/vector_tile.cpp
+++ b/src/mbgl/tile/vector_tile.cpp
@@ -3,16 +3,13 @@
 #include <mbgl/tile/tile_loader_impl.hpp>
 #include <mbgl/renderer/tile_parameters.hpp>
 
-#include <memory>
-
 namespace mbgl {
 
 VectorTile::VectorTile(const OverscaledTileID& id_,
                        std::string sourceID_,
                        const TileParameters& parameters,
                        const Tileset& tileset)
-    : GeometryTile(id_, sourceID_, parameters),
-      loader(*this, id_, parameters, tileset) {
+    : GeometryTile(id_, sourceID_, parameters), loader(*this, id_, parameters, tileset) {
 }
 
 void VectorTile::setNecessity(Necessity necessity) {
diff --git a/src/mbgl/tile/vector_tile_data.cpp b/src/mbgl/tile/vector_tile_data.cpp
index 5eb199f482..bb8392f6d9 100644
--- a/src/mbgl/tile/vector_tile_data.cpp
+++ b/src/mbgl/tile/vector_tile_data.cpp
@@ -3,170 +3,78 @@
 
 namespace mbgl {
 
-Value parseValue(protozero::pbf_reader data) {
-    Value value;
-    while (data.next()) {
-        switch (data.tag()) {
-        case 1: // string_value
-            value = data.get_string();
-            break;
-        case 2: // float_value
-            value = static_cast<double>(data.get_float());
-            break;
-        case 3: // double_value
-            value = data.get_double();
-            break;
-        case 4: // int_value
-            value = data.get_int64();
-            break;
-        case 5: // uint_value
-            value = data.get_uint64();
-            break;
-        case 6: // sint_value
-            value = data.get_sint64();
-            break;
-        case 7: // bool_value
-            value = data.get_bool();
-            break;
-        default:
-            data.skip();
-            break;
-        }
-    }
-    return value;
+VectorTileFeature::VectorTileFeature(const mapbox::vector_tile::layer& layer,
+                                     const protozero::data_view& view)
+    : feature(view, layer) {
 }
 
-VectorTileFeature::VectorTileFeature(protozero::pbf_reader feature_pbf, std::shared_ptr<VectorTileLayerData> layerData_)
-    : layerData(std::move(layerData_)) {
-    while (feature_pbf.next()) {
-        switch (feature_pbf.tag()) {
-        case 1: // id
-            id = { feature_pbf.get_uint64() };
-            break;
-        case 2: // tags
-            tags_iter = feature_pbf.get_packed_uint32();
-            break;
-        case 3: // type
-            type = static_cast<FeatureType>(feature_pbf.get_enum());
-            break;
-        case 4: // geometry
-            geometry_iter = feature_pbf.get_packed_uint32();
-            break;
-        default:
-            feature_pbf.skip();
-            break;
-        }
+FeatureType VectorTileFeature::getType() const {
+    switch (feature.getType()) {
+    case mapbox::vector_tile::GeomType::POINT:
+        return FeatureType::Point;
+    case mapbox::vector_tile::GeomType::LINESTRING:
+        return FeatureType::LineString;
+    case mapbox::vector_tile::GeomType::POLYGON:
+        return FeatureType::Polygon;
+    default:
+        return FeatureType::Unknown;
     }
 }
 
 optional<Value> VectorTileFeature::getValue(const std::string& key) const {
-    auto keyIter = layerData->keysMap.find(key);
-    if (keyIter == layerData->keysMap.end()) {
-        return optional<Value>();
-    }
-
-    auto start_itr = tags_iter.begin();
-    const auto & end_itr = tags_iter.end();
-    while (start_itr != end_itr) {
-        auto tag_key = static_cast<uint32_t>(*start_itr++);
-
-        if (layerData->keysMap.size() <= tag_key) {
-            throw std::runtime_error("feature referenced out of range key");
-        }
-
-        if (start_itr == end_itr) {
-            throw std::runtime_error("uneven number of feature tag ids");
-        }
-
-        auto tag_val = static_cast<uint32_t>(*start_itr++);;
-        if (layerData->values.size() <= tag_val) {
-            throw std::runtime_error("feature referenced out of range value");
-        }
-
-        if (tag_key == keyIter->second) {
-            return layerData->values[tag_val];
-        }
-    }
-
-    return optional<Value>();
+    return feature.getValue(key);
 }
 
-std::unordered_map<std::string,Value> VectorTileFeature::getProperties() const {
-    std::unordered_map<std::string,Value> properties;
-    auto start_itr = tags_iter.begin();
-    const auto & end_itr = tags_iter.end();
-    while (start_itr != end_itr) {
-        auto tag_key = static_cast<uint32_t>(*start_itr++);
-        if (start_itr == end_itr) {
-            throw std::runtime_error("uneven number of feature tag ids");
-        }
-        auto tag_val = static_cast<uint32_t>(*start_itr++);
-        properties[layerData->keys.at(tag_key)] = layerData->values.at(tag_val);
-    }
-    return properties;
+std::unordered_map<std::string, Value> VectorTileFeature::getProperties() const {
+    return feature.getProperties();
 }
 
 optional<FeatureIdentifier> VectorTileFeature::getID() const {
-    return id;
+    return feature.getID();
 }
 
 GeometryCollection VectorTileFeature::getGeometries() const {
-    uint8_t cmd = 1;
-    uint32_t length = 0;
-    int32_t x = 0;
-    int32_t y = 0;
-    const float scale = float(util::EXTENT) / layerData->extent;
-
-    GeometryCollection lines;
-
-    lines.emplace_back();
-    GeometryCoordinates* line = &lines.back();
-
-    auto g_itr = geometry_iter.begin();
-    while (g_itr != geometry_iter.end()) {
-        if (length == 0) {
-            auto cmd_length = static_cast<uint32_t>(*g_itr++);
-            cmd = cmd_length & 0x7;
-            length = cmd_length >> 3;
-        }
-
-        --length;
-
-        if (cmd == 1 || cmd == 2) {
-            x += protozero::decode_zigzag32(static_cast<uint32_t>(*g_itr++));
-            y += protozero::decode_zigzag32(static_cast<uint32_t>(*g_itr++));
-
-            if (cmd == 1 && !line->empty()) { // moveTo
-                lines.emplace_back();
-                line = &lines.back();
-            }
+    const float scale = float(util::EXTENT) / feature.getExtent();
+    auto lines = feature.getGeometries<GeometryCollection>(scale);
+    if (feature.getVersion() >= 2 || feature.getType() != mapbox::vector_tile::GeomType::POLYGON) {
+        return lines;
+    } else {
+        return fixupPolygons(lines);
+    }
+}
 
-            line->emplace_back(::round(x * scale), ::round(y * scale));
+VectorTileLayer::VectorTileLayer(std::shared_ptr<const std::string> data_,
+                                 const protozero::data_view& view)
+    : data(std::move(data_)), layer(view) {
+}
 
-        } else if (cmd == 7) { // closePolygon
-            if (!line->empty()) {
-                line->push_back((*line)[0]);
-            }
+std::size_t VectorTileLayer::featureCount() const {
+    return layer.featureCount();
+}
 
-        } else {
-            throw std::runtime_error("unknown command");
-        }
-    }
+std::unique_ptr<GeometryTileFeature> VectorTileLayer::getFeature(std::size_t i) const {
+    return std::make_unique<VectorTileFeature>(layer, layer.getFeature(i));
+}
 
-    if (layerData->version >= 2 || type != FeatureType::Polygon) {
-        return lines;
-    }
+std::string VectorTileLayer::getName() const {
+    return layer.getName();
+}
 
-    return fixupPolygons(lines);
+VectorTileData::VectorTileData(std::shared_ptr<const std::string> data_) : data(std::move(data_)) {
 }
 
-VectorTileData::VectorTileData(std::shared_ptr<const std::string> data_)
-    : data(std::move(data_)) {
+std::unique_ptr<GeometryTileData> VectorTileData::clone() const {
+    return std::make_unique<VectorTileData>(data);
 }
 
 const GeometryTileLayer* VectorTileData::getLayer(const std::string& name) const {
     if (!parsed) {
-        parse();
+        // We're parsing this lazily so that we can construct VectorTileData objects on the main
+        // thread without incurring the overhead of parsing immediately.
+        for (const auto& pair : mapbox::vector_tile::buffer(*data).getLayers()) {
+            layers.emplace(pair.first, VectorTileLayer{ data, pair.second });
+        }
+        parsed = true;
     }
 
     auto it = layers.find(name);
@@ -177,71 +85,7 @@ const GeometryTileLayer* VectorTileData::getLayer(const std::string& name) const
 }
 
 std::vector<std::string> VectorTileData::layerNames() const {
-    if (!parsed) {
-        parse();
-    }
-
-    std::vector<std::string> names;
-    names.reserve(layers.size());
-    for (auto const& layer : layers) {
-        names.emplace_back(layer.first);
-    }
-    return names;
-}
-
-void VectorTileData::parse() const {
-    parsed = true;
-    layers.clear();
-    protozero::pbf_reader tile_pbf(*data);
-    while (tile_pbf.next(3)) {
-        VectorTileLayer layer(tile_pbf.get_message(), data);
-        layers.emplace(layer.name, std::move(layer));
-    }
-}
-
-VectorTileLayerData::VectorTileLayerData(std::shared_ptr<const std::string> pbfData) :
-    data(std::move(pbfData))
-{}
-
-VectorTileLayer::VectorTileLayer(protozero::pbf_reader layer_pbf, std::shared_ptr<const std::string> pbfData)
-    : data(std::make_shared<VectorTileLayerData>(std::move(pbfData)))
-{
-    while (layer_pbf.next()) {
-        switch (layer_pbf.tag()) {
-        case 1: // name
-            name = layer_pbf.get_string();
-            break;
-        case 2: // feature
-            features.push_back(layer_pbf.get_message());
-            break;
-        case 3: // keys
-            {
-                auto iter = data->keysMap.emplace(layer_pbf.get_string(), data->keysMap.size());
-                data->keys.emplace_back(std::reference_wrapper<const std::string>(iter.first->first));
-            }
-            break;
-        case 4: // values
-            data->values.emplace_back(parseValue(layer_pbf.get_message()));
-            break;
-        case 5: // extent
-            data->extent = layer_pbf.get_uint32();
-            break;
-        case 15: // version
-            data->version = layer_pbf.get_uint32();
-            break;
-        default:
-            layer_pbf.skip();
-            break;
-        }
-    }
-}
-
-std::unique_ptr<GeometryTileFeature> VectorTileLayer::getFeature(std::size_t i) const {
-    return std::make_unique<VectorTileFeature>(features.at(i), data);
-}
-
-std::string VectorTileLayer::getName() const {
-    return name;
+    return mapbox::vector_tile::buffer(*data).layerNames();
 }
 
 } // namespace mbgl
diff --git a/src/mbgl/tile/vector_tile_data.hpp b/src/mbgl/tile/vector_tile_data.hpp
index 57b42ecd19..5ecb591273 100644
--- a/src/mbgl/tile/vector_tile_data.hpp
+++ b/src/mbgl/tile/vector_tile_data.hpp
@@ -1,5 +1,6 @@
 #include <mbgl/tile/geometry_tile_data.hpp>
 
+#include <mapbox/vector_tile.hpp>
 #include <protozero/pbf_reader.hpp>
 
 #include <unordered_map>
@@ -8,75 +9,43 @@
 
 namespace mbgl {
 
-class VectorTileLayer;
-
-using packed_iter_type = protozero::iterator_range<protozero::pbf_reader::const_uint32_iterator>;
-
-struct VectorTileLayerData {
-    VectorTileLayerData(std::shared_ptr<const std::string>);
-
-    // Hold a reference to the underlying pbf data that backs the lazily-built
-    // components of the owning VectorTileLayer and VectorTileFeature objects
-    std::shared_ptr<const std::string> data;
-
-    uint32_t version = 1;
-    uint32_t extent = 4096;
-    std::unordered_map<std::string, uint32_t> keysMap;
-    std::vector<std::reference_wrapper<const std::string>> keys;
-    std::vector<Value> values;
-};
-
 class VectorTileFeature : public GeometryTileFeature {
 public:
-    VectorTileFeature(protozero::pbf_reader, std::shared_ptr<VectorTileLayerData> layerData);
+    VectorTileFeature(const mapbox::vector_tile::layer&, const protozero::data_view&);
 
-    FeatureType getType() const override { return type; }
-    optional<Value> getValue(const std::string&) const override;
-    std::unordered_map<std::string,Value> getProperties() const override;
+    FeatureType getType() const override;
+    optional<Value> getValue(const std::string& key) const override;
+    std::unordered_map<std::string, Value> getProperties() const override;
     optional<FeatureIdentifier> getID() const override;
     GeometryCollection getGeometries() const override;
 
 private:
-    std::shared_ptr<VectorTileLayerData> layerData;
-    optional<FeatureIdentifier> id;
-    FeatureType type = FeatureType::Unknown;
-    packed_iter_type tags_iter;
-    packed_iter_type geometry_iter;
+    mapbox::vector_tile::feature feature;
 };
 
 class VectorTileLayer : public GeometryTileLayer {
 public:
-    VectorTileLayer(protozero::pbf_reader, std::shared_ptr<const std::string>);
+    VectorTileLayer(std::shared_ptr<const std::string> data, const protozero::data_view&);
 
-    std::size_t featureCount() const override { return features.size(); }
-    std::unique_ptr<GeometryTileFeature> getFeature(std::size_t) const override;
+    std::size_t featureCount() const override;
+    std::unique_ptr<GeometryTileFeature> getFeature(std::size_t i) const override;
     std::string getName() const override;
 
 private:
-    friend class VectorTileData;
-    friend class VectorTileFeature;
-
-    std::string name;
-    std::vector<protozero::pbf_reader> features;
-    std::shared_ptr<VectorTileLayerData> data;
+    std::shared_ptr<const std::string> data;
+    mapbox::vector_tile::layer layer;
 };
 
 class VectorTileData : public GeometryTileData {
 public:
     VectorTileData(std::shared_ptr<const std::string> data);
 
-    std::unique_ptr<GeometryTileData> clone() const override {
-        return std::make_unique<VectorTileData>(*this);
-    }
-
-    const GeometryTileLayer* getLayer(const std::string&) const override;
+    std::unique_ptr<GeometryTileData> clone() const override;
+    const GeometryTileLayer* getLayer(const std::string& name) const override;
 
     std::vector<std::string> layerNames() const;
 
 private:
-    void parse() const;
-
-private:
     std::shared_ptr<const std::string> data;
     mutable bool parsed = false;
     mutable std::unordered_map<std::string, VectorTileLayer> layers;