[core] Render::clearData clears fonts

CHANGELOG.md

@@ -6,7 +6,7 @@
 
 - [core] Add Renderer::clearData() ([#16323](https://github.com/mapbox/mapbox-gl-native/pull/16323))
 
-  The newly added `Renderer::clearData()` method allows to clear render data and thus save memory and make sure outdated tiles are not shown.
+  The newly added `Renderer::clearData()` method allows to clear render data and thus save memory and make sure outdated tiles are not shown. It clears data more agressively than `Renderer::reduceMemoryUse()` does, as it clears not only the cache but all orchestration data, including the data used by the currently rendered frame.
 
 ## maps-v1.4.1
 

src/mbgl/renderer/render_orchestrator.cpp

@@ -709,6 +709,7 @@ void RenderOrchestrator::clearData() {
     if (!patternAtlas->isEmpty()) patternAtlas = std::make_unique<PatternAtlas>();
 
     imageManager->clear();
+    glyphManager->evict(fontStacks(*layerImpls));
 }
 
 void RenderOrchestrator::onGlyphsError(const FontStack& fontStack, const GlyphRange& glyphRange, std::exception_ptr error) {

test/map/map.test.cpp

@@ -1349,42 +1349,44 @@ TEST(Map, TEST_REQUIRES_SERVER(ExpiredSpriteSheet)) {
 }
 
 namespace {
-constexpr auto styleJSON = R"STYLE({
-  "sources": {
-    "a": { "type": "vector", "tiles": [ "a/{z}/{x}/{y}" ] }
-  },
-  "layers": [{
-    "id": "a",
-    "type": "fill",
-    "source": "a",
-    "source-layer": "a"
-  }]
-})STYLE";
+
+int requestsCount = 0;
+auto makeResponse(const std::string& file, bool incrementCounter = false) {
+    return [file, incrementCounter](const Resource&) {
+        if (incrementCounter) ++requestsCount;
+        Response result;
+        result.data = std::make_shared<std::string>(util::read_file("test/fixtures/resources/" + file));
+        return result;
+    };
 }
 
+} // namespace
+
 TEST(Map, KeepRenderData) {
     MapTest<> test;
-    int requestsCount = 0;
-    test.fileSource->tileResponse = [&](const Resource&) {
-        ++requestsCount;
-        Response res;
-        res.noContent = true;
-        return res;
-    };
+
+    test.fileSource->tileResponse = makeResponse("vector.tile", true);
+    test.fileSource->glyphsResponse = makeResponse("glyphs.pbf", true);
+    // The resources below belong to style and requested on style re-load.
+    test.fileSource->styleResponse = makeResponse("style_vector.json");
+    test.fileSource->sourceResponse = makeResponse("source_vector.json");
+    test.fileSource->spriteJSONResponse = makeResponse("sprite.json");
+    test.fileSource->spriteImageResponse = makeResponse("sprite.png");
+
     test.map.jumpTo(CameraOptions().withZoom(10));
+    test.map.getStyle().loadURL("mapbox://streets");
     const int iterations = 3;
+    const int resourcesCount = 4 /*tiles*/ + 3 /*fonts*/;
     // Keep render data.
     for (int i = 1; i <= iterations; ++i) {
-        test.map.getStyle().loadJSON(styleJSON);
         test.frontend.render(test.map);
-        EXPECT_EQ(4, requestsCount);
+        EXPECT_EQ(resourcesCount, requestsCount);
     }
     requestsCount = 0;
     // Clear render data.
     for (int i = 1; i <= iterations; ++i) {
         test.frontend.getRenderer()->clearData();
-        test.map.getStyle().loadJSON(styleJSON);
         test.frontend.render(test.map);
-        EXPECT_EQ(4 * i, requestsCount);
+        EXPECT_EQ(resourcesCount * i, requestsCount);
     }
 }