[core] Fix flickering caused by regression in #7586

It should be safe to invoke GeometryTileWorker::setData multiple times without invoking GeometryTileWorker::setLayers. Therefore GeometryTileWorker::redoLayout() must not consume the layers.

3 files changed, 98 insertions, 4 deletions

diff --git a/test/src/mbgl/test/stub_tile_observer.hpp b/test/src/mbgl/test/stub_tile_observer.hpp
new file mode 100644
index 0000000000..43ae4d8360
--- /dev/null
+++ b/test/src/mbgl/test/stub_tile_observer.hpp
@@ -0,0 +1,22 @@
+#pragma once
+
+#include <mbgl/tile/tile_observer.hpp>
+
+using namespace mbgl;
+
+/**
+ * An implementation of TileObserver that forwards all methods to dynamically-settable lambas.
+ */
+class StubTileObserver : public TileObserver {
+public:
+    void onTileChanged(Tile& tile) override {
+        if (tileChanged) tileChanged(tile);
+    }
+
+    void onTileError(Tile& tile, std::exception_ptr error) override {
+        if (tileError) tileError(tile, error);
+    }
+
+    std::function<void (Tile&)> tileChanged;
+    std::function<void (Tile&, std::exception_ptr)> tileError;
+};
diff --git a/test/style/group_by_layout.test.cpp b/test/style/group_by_layout.test.cpp
index d74916cdc9..600ba6a0f1 100644
--- a/test/style/group_by_layout.test.cpp
+++ b/test/style/group_by_layout.test.cpp
@@ -12,7 +12,7 @@ TEST(GroupByLayout, Related) {
     std::vector<std::unique_ptr<Layer>> layers;
     layers.push_back(std::make_unique<LineLayer>("a", "source"));
     layers.push_back(std::make_unique<LineLayer>("b", "source"));
-    auto result = groupByLayout(std::move(layers));
+    auto result = groupByLayout(layers);
     ASSERT_EQ(1u, result.size());
     ASSERT_EQ(2u, result[0].size());
 }
@@ -21,7 +21,7 @@ TEST(GroupByLayout, UnrelatedType) {
     std::vector<std::unique_ptr<Layer>> layers;
     layers.push_back(std::make_unique<BackgroundLayer>("background"));
     layers.push_back(std::make_unique<CircleLayer>("circle", "source"));
-    auto result = groupByLayout(std::move(layers));
+    auto result = groupByLayout(layers);
     ASSERT_EQ(2u, result.size());
 }
 
@@ -30,7 +30,7 @@ TEST(GroupByLayout, UnrelatedFilter) {
     layers.push_back(std::make_unique<LineLayer>("a", "source"));
     layers.push_back(std::make_unique<LineLayer>("b", "source"));
     layers[0]->as<LineLayer>()->setFilter(EqualsFilter());
-    auto result = groupByLayout(std::move(layers));
+    auto result = groupByLayout(layers);
     ASSERT_EQ(2u, result.size());
 }
 
@@ -39,6 +39,6 @@ TEST(GroupByLayout, UnrelatedLayout) {
     layers.push_back(std::make_unique<LineLayer>("a", "source"));
     layers.push_back(std::make_unique<LineLayer>("b", "source"));
     layers[0]->as<LineLayer>()->setLineCap(LineCapType::Square);
-    auto result = groupByLayout(std::move(layers));
+    auto result = groupByLayout(layers);
     ASSERT_EQ(2u, result.size());
 }
diff --git a/test/tile/geojson_tile.test.cpp b/test/tile/geojson_tile.test.cpp
new file mode 100644
index 0000000000..920e946a2b
--- /dev/null
+++ b/test/tile/geojson_tile.test.cpp
@@ -0,0 +1,72 @@
+#include <mbgl/test/util.hpp>
+#include <mbgl/test/fake_file_source.hpp>
+#include <mbgl/test/stub_tile_observer.hpp>
+#include <mbgl/tile/geojson_tile.hpp>
+#include <mbgl/tile/tile_loader_impl.hpp>
+
+#include <mbgl/util/default_thread_pool.hpp>
+#include <mbgl/util/run_loop.hpp>
+#include <mbgl/map/transform.hpp>
+#include <mbgl/style/style.hpp>
+#include <mbgl/style/update_parameters.hpp>
+#include <mbgl/style/layers/circle_layer.hpp>
+#include <mbgl/annotation/annotation_manager.hpp>
+
+#include <memory>
+
+using namespace mbgl;
+using namespace mbgl::style;
+
+class GeoJSONTileTest {
+public:
+    FakeFileSource fileSource;
+    TransformState transformState;
+    util::RunLoop loop;
+    ThreadPool threadPool { 1 };
+    AnnotationManager annotationManager { 1.0 };
+    style::Style style { fileSource, 1.0 };
+    Tileset tileset { { "https://example.com" }, { 0, 22 }, "none" };
+
+    style::UpdateParameters updateParameters {
+        1.0,
+        MapDebugOptions(),
+        transformState,
+        threadPool,
+        fileSource,
+        MapMode::Continuous,
+        annotationManager,
+        style
+    };
+};
+
+TEST(GeoJSONTile, Issue7648) {
+    GeoJSONTileTest test;
+    GeoJSONTile tile(OverscaledTileID(0, 0, 0), "source", test.updateParameters);
+
+    test.style.addLayer(std::make_unique<CircleLayer>("circle", "source"));
+
+    StubTileObserver observer;
+    observer.tileChanged = [&] (const Tile&) {
+        // Once present, the bucket should never "disappear", which would cause
+        // flickering.
+        ASSERT_NE(nullptr, tile.getBucket(*test.style.getLayer("circle")));
+    };
+    tile.setObserver(&observer);
+
+    tile.setPlacementConfig({});
+
+    mapbox::geometry::feature_collection<int16_t> features;
+    features.push_back(mapbox::geometry::feature<int16_t> {
+        mapbox::geometry::point<int16_t>(0, 0)
+    });
+
+    tile.updateData(features);
+    while (!tile.isComplete()) {
+        test.loop.runOnce();
+    }
+
+    tile.updateData(features);
+    while (!tile.isComplete()) {
+        test.loop.runOnce();
+    }
+}