[core] offline region definition - add support for arbitrary geometries

2 files changed, 149 insertions, 69 deletions

diff --git a/platform/default/mbgl/storage/offline.cpp b/platform/default/mbgl/storage/offline.cpp
index 598a0b182b..e1ec0acb31 100644
--- a/platform/default/mbgl/storage/offline.cpp
+++ b/platform/default/mbgl/storage/offline.cpp
@@ -1,8 +1,10 @@
 #include <mbgl/storage/offline.hpp>
-#include <mbgl/util/tile_cover.hpp>
 #include <mbgl/util/tileset.hpp>
 #include <mbgl/util/projection.hpp>
 
+#include <mapbox/geojson.hpp>
+#include <mapbox/geojson/rapidjson.hpp>
+
 #include <rapidjson/document.h>
 #include <rapidjson/stringbuffer.h>
 #include <rapidjson/writer.h>
@@ -11,6 +13,8 @@
 
 namespace mbgl {
 
+// OfflineTilePyramidRegionDefinition
+
 OfflineTilePyramidRegionDefinition::OfflineTilePyramidRegionDefinition(
     std::string styleURL_, LatLngBounds bounds_, double minZoom_, double maxZoom_, float pixelRatio_)
     : styleURL(std::move(styleURL_)),
@@ -24,87 +28,100 @@ OfflineTilePyramidRegionDefinition::OfflineTilePyramidRegionDefinition(
     }
 }
 
-std::vector<CanonicalTileID> OfflineTilePyramidRegionDefinition::tileCover(style::SourceType type, uint16_t tileSize, const Range<uint8_t>& zoomRange) const {
-    const Range<uint8_t> clampedZoomRange = coveringZoomRange(type, tileSize, zoomRange);
 
-    std::vector<CanonicalTileID> result;
-
-    for (uint8_t z = clampedZoomRange.min; z <= clampedZoomRange.max; z++) {
-        for (const auto& tile : util::tileCover(bounds, z)) {
-            result.emplace_back(tile.canonical);
-        }
-    }
-
-    return result;
-}
+// OfflineGeometryRegionDefinition
 
-uint64_t OfflineTilePyramidRegionDefinition::tileCount(style::SourceType type, uint16_t tileSize, const Range<uint8_t>& zoomRange) const {
-    
-    const Range<uint8_t> clampedZoomRange = coveringZoomRange(type, tileSize, zoomRange);
-    unsigned long result = 0;;
-    for (uint8_t z = clampedZoomRange.min; z <= clampedZoomRange.max; z++) {
-        result +=  util::tileCount(bounds, z);
+OfflineGeometryRegionDefinition::OfflineGeometryRegionDefinition(std::string styleURL_, Geometry<double> geometry_, double minZoom_, double maxZoom_, float pixelRatio_)
+    : styleURL(styleURL_)
+    , geometry(std::move(geometry_))
+    , minZoom(minZoom_)
+    , maxZoom(maxZoom_)
+    , pixelRatio(pixelRatio_) {
+    if (minZoom < 0 || maxZoom < 0 || maxZoom < minZoom || pixelRatio < 0 ||
+        !std::isfinite(minZoom) || std::isnan(maxZoom) || !std::isfinite(pixelRatio)) {
+        throw std::invalid_argument("Invalid offline region definition");
     }
-
-    return result;
-}
-
-Range<uint8_t> OfflineTilePyramidRegionDefinition::coveringZoomRange(style::SourceType type, uint16_t tileSize, const Range<uint8_t>& zoomRange) const {
-    double minZ = std::max<double>(util::coveringZoomLevel(minZoom, type, tileSize), zoomRange.min);
-    double maxZ = std::min<double>(util::coveringZoomLevel(maxZoom, type, tileSize), zoomRange.max);
-
-    assert(minZ >= 0);
-    assert(maxZ >= 0);
-    assert(minZ < std::numeric_limits<uint8_t>::max());
-    assert(maxZ < std::numeric_limits<uint8_t>::max());
-    return { static_cast<uint8_t>(minZ), static_cast<uint8_t>(maxZ) };
 }
 
 OfflineRegionDefinition decodeOfflineRegionDefinition(const std::string& region) {
     rapidjson::GenericDocument<rapidjson::UTF8<>, rapidjson::CrtAllocator> doc;
     doc.Parse<0>(region.c_str());
 
-    if (doc.HasParseError() ||
-        !doc.HasMember("style_url") || !doc["style_url"].IsString() ||
-        !doc.HasMember("bounds") || !doc["bounds"].IsArray() || doc["bounds"].Size() != 4 ||
-          !doc["bounds"][0].IsDouble() || !doc["bounds"][1].IsDouble() ||
-          !doc["bounds"][2].IsDouble() || !doc["bounds"][3].IsDouble() ||
-        !doc.HasMember("min_zoom") || !doc["min_zoom"].IsDouble() ||
-        (doc.HasMember("max_zoom") && !doc["max_zoom"].IsDouble()) ||
-        !doc.HasMember("pixel_ratio") || !doc["pixel_ratio"].IsDouble()) {
+    // validation
+
+    auto hasValidBounds = [&] {
+        return doc.HasMember("bounds") && doc["bounds"].IsArray() && doc["bounds"].Size() == 4
+               && doc["bounds"][0].IsDouble() && doc["bounds"][1].IsDouble()
+               && doc["bounds"][2].IsDouble() && doc["bounds"][3].IsDouble();
+    };
+
+    auto hasValidGeometry = [&] {
+        return doc.HasMember("geometry") && doc["geometry"].IsObject();
+    };
+
+    if (doc.HasParseError()
+        || !doc.HasMember("style_url") || !doc["style_url"].IsString()
+        || !(hasValidBounds() || hasValidGeometry())
+        || !doc.HasMember("min_zoom") || !doc["min_zoom"].IsDouble()
+        || (doc.HasMember("max_zoom") && !doc["max_zoom"].IsDouble())
+        || !doc.HasMember("pixel_ratio") || !doc["pixel_ratio"].IsDouble()) {
         throw std::runtime_error("Malformed offline region definition");
     }
 
+    // Common properties
+
     std::string styleURL { doc["style_url"].GetString(), doc["style_url"].GetStringLength() };
-    LatLngBounds bounds = LatLngBounds::hull(
-        LatLng(doc["bounds"][0].GetDouble(), doc["bounds"][1].GetDouble()),
-        LatLng(doc["bounds"][2].GetDouble(), doc["bounds"][3].GetDouble()));
     double minZoom = doc["min_zoom"].GetDouble();
     double maxZoom = doc.HasMember("max_zoom") ? doc["max_zoom"].GetDouble() : INFINITY;
     float pixelRatio = doc["pixel_ratio"].GetDouble();
+    
+    if (doc.HasMember("bounds")) {
+        return OfflineTilePyramidRegionDefinition{
+                styleURL,
+                LatLngBounds::hull(
+                         LatLng(doc["bounds"][0].GetDouble(), doc["bounds"][1].GetDouble()),
+                         LatLng(doc["bounds"][2].GetDouble(), doc["bounds"][3].GetDouble())),
+                minZoom, maxZoom, pixelRatio };
+    } else {
+        return OfflineGeometryRegionDefinition{
+                styleURL,
+                mapbox::geojson::convert<Geometry<double>>(doc["geometry"].GetObject()),
+                minZoom, maxZoom, pixelRatio };
+    };
 
-    return { styleURL, bounds, minZoom, maxZoom, pixelRatio };
 }
 
 std::string encodeOfflineRegionDefinition(const OfflineRegionDefinition& region) {
     rapidjson::GenericDocument<rapidjson::UTF8<>, rapidjson::CrtAllocator> doc;
     doc.SetObject();
 
-    doc.AddMember("style_url", rapidjson::StringRef(region.styleURL.data(), region.styleURL.length()), doc.GetAllocator());
+    // Encode common properties
+    region.match([&](auto& _region) {
+        doc.AddMember("style_url", rapidjson::StringRef(_region.styleURL.data(), _region.styleURL.length()), doc.GetAllocator());
+        doc.AddMember("min_zoom", _region.minZoom, doc.GetAllocator());
+        if (std::isfinite(_region.maxZoom)) {
+            doc.AddMember("max_zoom", _region.maxZoom, doc.GetAllocator());
+        }
 
-    rapidjson::GenericValue<rapidjson::UTF8<>, rapidjson::CrtAllocator> bounds(rapidjson::kArrayType);
-    bounds.PushBack(region.bounds.south(), doc.GetAllocator());
-    bounds.PushBack(region.bounds.west(), doc.GetAllocator());
-    bounds.PushBack(region.bounds.north(), doc.GetAllocator());
-    bounds.PushBack(region.bounds.east(), doc.GetAllocator());
-    doc.AddMember("bounds", bounds, doc.GetAllocator());
+        doc.AddMember("pixel_ratio", _region.pixelRatio, doc.GetAllocator());
+    });
 
-    doc.AddMember("min_zoom", region.minZoom, doc.GetAllocator());
-    if (std::isfinite(region.maxZoom)) {
-        doc.AddMember("max_zoom", region.maxZoom, doc.GetAllocator());
-    }
+    // Encode specific properties
+    region.match(
+            [&] (const OfflineTilePyramidRegionDefinition& _region) {
+                rapidjson::GenericValue<rapidjson::UTF8<>, rapidjson::CrtAllocator> bounds(rapidjson::kArrayType);
+                bounds.PushBack(_region.bounds.south(), doc.GetAllocator());
+                bounds.PushBack(_region.bounds.west(), doc.GetAllocator());
+                bounds.PushBack(_region.bounds.north(), doc.GetAllocator());
+                bounds.PushBack(_region.bounds.east(), doc.GetAllocator());
+                doc.AddMember("bounds", bounds, doc.GetAllocator());
+
+            },
+            [&] (const OfflineGeometryRegionDefinition& _region) {
+                doc.AddMember("geometry", mapbox::geojson::convert(_region.geometry, doc.GetAllocator()), doc.GetAllocator());
 
-    doc.AddMember("pixel_ratio", region.pixelRatio, doc.GetAllocator());
+            }
+    );
 
     rapidjson::StringBuffer buffer;
     rapidjson::Writer<rapidjson::StringBuffer> writer(buffer);
@@ -113,6 +130,9 @@ std::string encodeOfflineRegionDefinition(const OfflineRegionDefinition& region)
     return buffer.GetString();
 }
 
+
+// OfflineRegion
+
 OfflineRegion::OfflineRegion(int64_t id_,
                              OfflineRegionDefinition definition_,
                              OfflineRegionMetadata metadata_)
@@ -135,5 +155,4 @@ const OfflineRegionMetadata& OfflineRegion::getMetadata() const {
 int64_t OfflineRegion::getID() const {
     return id;
 }
-
 } // namespace mbgl
diff --git a/platform/default/mbgl/storage/offline_download.cpp b/platform/default/mbgl/storage/offline_download.cpp
index 179d2d5f57..118f3aad88 100644
--- a/platform/default/mbgl/storage/offline_download.cpp
+++ b/platform/default/mbgl/storage/offline_download.cpp
@@ -24,6 +24,63 @@ namespace mbgl {
 
 using namespace style;
 
+// Generic functions
+
+template <class RegionDefinition>
+Range<uint8_t> coveringZoomRange(const RegionDefinition& definition,
+                                 style::SourceType type, uint16_t tileSize, const Range<uint8_t>& zoomRange) {
+    double minZ = std::max<double>(util::coveringZoomLevel(definition.minZoom, type, tileSize), zoomRange.min);
+    double maxZ = std::min<double>(util::coveringZoomLevel(definition.maxZoom, type, tileSize), zoomRange.max);
+
+    assert(minZ >= 0);
+    assert(maxZ >= 0);
+    assert(minZ < std::numeric_limits<uint8_t>::max());
+    assert(maxZ < std::numeric_limits<uint8_t>::max());
+    return { static_cast<uint8_t>(minZ), static_cast<uint8_t>(maxZ) };
+}
+
+template <class Geometry, class Fn>
+void tileCover(const Geometry& geometry, uint8_t z, Fn&& fn) {
+    util::TileCover cover(geometry, z);
+    while (cover.hasNext()) {
+        fn(cover.next()->canonical);
+    }
+}
+
+
+template <class Fn>
+void tileCover(const OfflineRegionDefinition& definition, style::SourceType type,
+               uint16_t tileSize, const Range<uint8_t>& zoomRange, Fn&& fn) {
+    const Range<uint8_t> clampedZoomRange =
+            definition.match([&](auto& reg) { return coveringZoomRange(reg, type, tileSize, zoomRange); });
+
+    for (uint8_t z = clampedZoomRange.min; z <= clampedZoomRange.max; z++) {
+        definition.match(
+                [&](const OfflineTilePyramidRegionDefinition& reg){ tileCover(reg.bounds, z, fn); },
+                [&](const OfflineGeometryRegionDefinition& reg){ tileCover(reg.geometry, z, fn); }
+        );
+    }
+}
+
+uint64_t tileCount(const OfflineRegionDefinition& definition, style::SourceType type,
+                   uint16_t tileSize, const Range<uint8_t>& zoomRange) {
+
+    const Range<uint8_t> clampedZoomRange =
+            definition.match([&](auto& reg) { return coveringZoomRange(reg, type, tileSize, zoomRange); });
+
+    unsigned long result = 0;;
+    for (uint8_t z = clampedZoomRange.min; z <= clampedZoomRange.max; z++) {
+        result += definition.match(
+                [&](const OfflineTilePyramidRegionDefinition& reg){ return util::tileCount(reg.bounds, z); },
+                [&](const OfflineGeometryRegionDefinition& reg){ return util::tileCount(reg.geometry, z); }
+        );
+    }
+
+    return result;
+}
+
+// OfflineDownload
+
 OfflineDownload::OfflineDownload(int64_t id_,
                                  OfflineRegionDefinition&& definition_,
                                  OfflineDatabase& offlineDatabase_,
@@ -70,7 +127,8 @@ OfflineRegionStatus OfflineDownload::getStatus() const {
     }
 
     result->requiredResourceCount++;
-    optional<Response> styleResponse = offlineDatabase.get(Resource::style(definition.styleURL));
+    optional<Response> styleResponse =
+            offlineDatabase.get(Resource::style(definition.match([](auto& reg){ return reg.styleURL; })));
     if (!styleResponse) {
         return *result;
     }
@@ -86,7 +144,7 @@ OfflineRegionStatus OfflineDownload::getStatus() const {
         auto handleTiledSource = [&] (const variant<std::string, Tileset>& urlOrTileset, const uint16_t tileSize) {
             if (urlOrTileset.is<Tileset>()) {
                 result->requiredResourceCount +=
-                    definition.tileCount(type, tileSize, urlOrTileset.get<Tileset>().zoomRange);
+                        tileCount(definition, type, tileSize, urlOrTileset.get<Tileset>().zoomRange);
             } else {
                 result->requiredResourceCount += 1;
                 const auto& url = urlOrTileset.get<std::string>();
@@ -96,7 +154,7 @@ OfflineRegionStatus OfflineDownload::getStatus() const {
                     optional<Tileset> tileset = style::conversion::convertJSON<Tileset>(*sourceResponse->data, error);
                     if (tileset) {
                         result->requiredResourceCount +=
-                            definition.tileCount(type, tileSize, (*tileset).zoomRange);
+                                tileCount(definition, type, tileSize, (*tileset).zoomRange);
                     }
                 } else {
                     result->requiredResourceCountIsPrecise = false;
@@ -116,7 +174,7 @@ OfflineRegionStatus OfflineDownload::getStatus() const {
             handleTiledSource(rasterSource.getURLOrTileset(), rasterSource.getTileSize());
             break;
         }
-        
+
         case SourceType::RasterDEM: {
             const auto& rasterDEMSource = *source->as<RasterDEMSource>();
             handleTiledSource(rasterDEMSource.getURLOrTileset(), rasterDEMSource.getTileSize());
@@ -161,7 +219,8 @@ void OfflineDownload::activateDownload() {
     status = OfflineRegionStatus();
     status.downloadState = OfflineRegionDownloadState::Active;
     status.requiredResourceCount++;
-    ensureResource(Resource::style(definition.styleURL), [&](Response styleResponse) {
+    ensureResource(Resource::style(definition.match([](auto& reg){ return reg.styleURL; })),
+                   [&](Response styleResponse) {
         status.requiredResourceCountIsPrecise = true;
 
         style::Parser parser;
@@ -207,7 +266,7 @@ void OfflineDownload::activateDownload() {
                 handleTiledSource(rasterSource.getURLOrTileset(), rasterSource.getTileSize());
                 break;
             }
-            
+
             case SourceType::RasterDEM: {
                 const auto& rasterDEMSource = *source->as<RasterDEMSource>();
                 handleTiledSource(rasterDEMSource.getURLOrTileset(), rasterDEMSource.getTileSize());
@@ -247,8 +306,9 @@ void OfflineDownload::activateDownload() {
         }
 
         if (!parser.spriteURL.empty()) {
-            queueResource(Resource::spriteImage(parser.spriteURL, definition.pixelRatio));
-            queueResource(Resource::spriteJSON(parser.spriteURL, definition.pixelRatio));
+            auto pixelRatio = definition.match([](auto& reg){ return reg.pixelRatio; });
+            queueResource(Resource::spriteImage(parser.spriteURL, pixelRatio));
+            queueResource(Resource::spriteJSON(parser.spriteURL, pixelRatio));
         }
 
         continueDownload();
@@ -296,11 +356,12 @@ void OfflineDownload::queueResource(Resource resource) {
 }
 
 void OfflineDownload::queueTiles(SourceType type, uint16_t tileSize, const Tileset& tileset) {
-    for (const auto& tile : definition.tileCover(type, tileSize, tileset.zoomRange)) {
+    tileCover(definition, type, tileSize, tileset.zoomRange, [&](const auto& tile) {
         status.requiredResourceCount++;
-        resourcesRemaining.push_back(
-            Resource::tile(tileset.tiles[0], definition.pixelRatio, tile.x, tile.y, tile.z, tileset.scheme));
-    }
+        resourcesRemaining.push_back(Resource::tile(
+            tileset.tiles[0], definition.match([](auto& def) { return def.pixelRatio; }), tile.x,
+            tile.y, tile.z, tileset.scheme));
+    });
 }
 
 void OfflineDownload::ensureResource(const Resource& resource,