[general] moving ios and android project under ./platform folder

test/map/prefetch.test.cpp

@@ -0,0 +1,90 @@
+#include <mbgl/test/util.hpp>
+#include <mbgl/test/stub_file_source.hpp>
+#include <mbgl/test/stub_map_observer.hpp>
+#include <mbgl/test/map_adapter.hpp>
+
+#include <mbgl/map/map_options.hpp>
+#include <mbgl/gfx/headless_frontend.hpp>
+#include <mbgl/style/style.hpp>
+#include <mbgl/util/image.hpp>
+#include <mbgl/util/io.hpp>
+#include <mbgl/util/run_loop.hpp>
+
+#include <algorithm>
+#include <string>
+#include <vector>
+
+using namespace mbgl;
+using namespace mbgl::style;
+using namespace std::literals::string_literals;
+using namespace std::chrono_literals;
+
+TEST(Map, PrefetchTiles) {
+    util::RunLoop runLoop;
+    std::shared_ptr<StubFileSource> fileSource = std::make_shared<StubFileSource>();
+
+    util::Timer emergencyShutoff;
+    emergencyShutoff.start(10s, 0s, [&] {
+        runLoop.stop();
+        FAIL() << "Did not stop rendering";
+    });
+
+    StubMapObserver observer;
+    observer.didFinishLoadingMapCallback = [&] () {
+        runLoop.stop();
+    };
+
+    HeadlessFrontend frontend { { 512, 512 }, 1 };
+    MapAdapter map(frontend, observer, fileSource,
+                MapOptions().withMapMode(MapMode::Continuous).withSize(frontend.getSize()));
+
+    std::vector<int> tiles;
+
+    fileSource->response = [&] (const Resource& res) -> optional<Response> {
+        static std::string tile = util::read_file("test/fixtures/map/prefetch/tile.png");
+
+        auto zoom = std::stoi(res.url);
+        tiles.push_back(zoom);
+
+        Response response;
+        response.data = std::make_shared<std::string>(tile);
+        return response;
+    };
+
+    auto checkTilesForZoom = [&](int zoom, const std::vector<int>& expected) {
+        tiles.clear();
+
+        // Force tile reloading.
+        map.getStyle().loadJSON(util::read_file("test/fixtures/map/prefetch/empty.json"));
+        map.getStyle().loadJSON(util::read_file("test/fixtures/map/prefetch/style.json"));
+        map.jumpTo(CameraOptions().withCenter(LatLng { 40.726989, -73.992857 }).withZoom(zoom)); // Manhattan
+        runLoop.run();
+
+        ASSERT_EQ(tiles.size(), expected.size());
+        ASSERT_TRUE(std::is_permutation(tiles.begin(), tiles.end(), expected.begin()));
+    };
+
+    // Check defaults, should be 4.
+    ASSERT_EQ(map.getPrefetchZoomDelta(), 4);
+    checkTilesForZoom(12, { 13, 13, 13, 13, 13, 13, 13, 13, 13, 9 });
+
+    // Setting it to 0 disables prefetching.
+    map.setPrefetchZoomDelta(0);
+
+    // No prefetching, raster tiles will use ideal
+    // tiles instead of the actual zoom level, that is
+    // why the zoom levels for non-prefetched tiles are
+    // not the same.
+    checkTilesForZoom(10, { 11, 11, 11, 11, 11, 11, 11, 11, 11 });
+
+    map.setPrefetchZoomDelta(5);
+    checkTilesForZoom(12, { 13, 13, 13, 13, 13, 13, 13, 13, 13, 8 });
+
+    // Should clamp at `minzoom`.
+    map.setPrefetchZoomDelta(20);
+    checkTilesForZoom(10, { 11, 11, 11, 11, 11, 11, 11, 11, 11, 0 });
+
+    // Disabled again.
+    map.setPrefetchZoomDelta(0);
+    checkTilesForZoom(13, { 14, 14, 14, 14, 14, 14, 14, 14, 14 });
+}