[core] Simulate tile buffer for annotation symbolsupstream/symbol-stencil-clip

This fixes an issue where symbols were clipped to their corresponding
tiles.

3 files changed, 25 insertions, 1 deletions

diff --git a/src/mbgl/annotation/annotation_manager.cpp b/src/mbgl/annotation/annotation_manager.cpp
index ada580eb84..41b82ba3bb 100644
--- a/src/mbgl/annotation/annotation_manager.cpp
+++ b/src/mbgl/annotation/annotation_manager.cpp
@@ -159,7 +159,14 @@ std::unique_ptr<AnnotationTileData> AnnotationManager::getTileData(const Canonic
 
     AnnotationTileLayer& pointLayer = tileData->layers.emplace(PointLayerID, PointLayerID).first->second;
 
-    symbolTree.query(bgi::intersects(LatLngBounds { tileID }),
+    // Simulate tile buffer by augmenting the bounds for each tile on a
+    // constant ratio i.e. 1/8:
+    static const double ratio = 1.0 / 8.0;
+    auto bounds = LatLngBounds { tileID };
+    auto offset = LatLng { (bounds.north() - bounds.south()) * ratio, (bounds.east() - bounds.west()) * ratio };
+    bounds.extend(LatLng { bounds.south() - offset.latitude, bounds.west() - offset.longitude });
+    bounds.extend(LatLng { bounds.north() + offset.latitude, bounds.east() + offset.longitude });
+    symbolTree.query(bgi::intersects(bounds),
         boost::make_function_output_iterator([&](const auto& val){
             val->updateLayer(tileID, pointLayer, state);
         }));
diff --git a/test/api/annotations.test.cpp b/test/api/annotations.test.cpp
index 6d6734a10f..de0301de75 100644
--- a/test/api/annotations.test.cpp
+++ b/test/api/annotations.test.cpp
@@ -55,6 +55,23 @@ TEST(Annotations, SymbolAnnotation) {
     EXPECT_EQ(features.size(), 1u);
 }
 
+TEST(Annotations, SymbolAnnotationAcrossTiles) {
+    AnnotationTest test;
+
+    test.map.setStyleJSON(util::read_file("test/fixtures/api/empty.json"));
+    test.map.addAnnotationIcon("default_marker", namedMarker("default_marker.png"));
+
+    for (int longitude = -5; longitude <= 5; ++longitude) {
+        for (int latitude = -5; latitude <= 5; ++latitude) {
+            test.map.addAnnotation(SymbolAnnotation { { double(latitude), double(longitude) }, "default_marker" });
+        }
+    }
+
+    test.map.setZoom(3.5);
+    test.map.setPitch(60);
+    test.checkRendering("symbol_annotation_across_tiles");
+}
+
 TEST(Annotations, LineAnnotation) {
     AnnotationTest test;
 
diff --git a/test/fixtures/annotations/symbol_annotation_across_tiles/expected.png b/test/fixtures/annotations/symbol_annotation_across_tiles/expected.png
new file mode 100644
index 0000000000..75ec43a7bb
--- /dev/null
+++ b/test/fixtures/annotations/symbol_annotation_across_tiles/expected.png