added embeddedShutdown() that allows restarting an FXGL instance without the need to exit JavaFX, added sample, #1075

Author: AlmasB

fxgl-samples/src/main/java/sandbox/RestartableSample.java

@@ -0,0 +1,75 @@
+/*
+ * FXGL - JavaFX Game Library. The MIT License (MIT).
+ * Copyright (c) AlmasB (almaslvl@gmail.com).
+ * See LICENSE for details.
+ */
+
+package sandbox;
+
+import com.almasb.fxgl.app.GameApplication;
+import com.almasb.fxgl.dsl.FXGL;
+import javafx.application.Application;
+import javafx.scene.Parent;
+import javafx.scene.Scene;
+import javafx.scene.control.Button;
+import javafx.scene.layout.HBox;
+import javafx.scene.layout.Pane;
+import javafx.scene.layout.VBox;
+import javafx.stage.Stage;
+import sandbox.test3d.Model3DSample;
+
+import java.util.List;
+import java.util.function.Supplier;
+
+/**
+ * @author Almas Baimagambetov (almaslvl@gmail.com)
+ */
+public class RestartableSample extends Application {
+    @Override
+    public void start(Stage stage) throws Exception {
+        stage.setScene(new Scene(createContent()));
+        stage.show();
+    }
+
+    private Parent createContent() {
+        List<Supplier<GameApplication>> games = List.of(
+                SpriteSheetAnimationApp::new,
+                ScrollingBackgroundSample::new,
+                PlatformerSample::new,
+                TiledMapSample::new,
+                Model3DSample::new
+        );
+
+        var root = new VBox();
+        root.setPrefSize(1280, 720);
+
+        var hbox = new HBox(5);
+
+        for (int i = 0; i < games.size(); i++) {
+            var btn = new Button("game " + i);
+            var gameConstructor = games.get(i);
+
+            btn.setOnAction(e -> {
+                GameApplication.embeddedShutdown();
+
+                var pane = GameApplication.embeddedLaunch(gameConstructor.get());
+
+                root.getChildren().set(1, pane);
+            });
+
+            hbox.getChildren().add(btn);
+        }
+
+        root.getChildren().addAll(hbox, new Pane());
+        return root;
+    }
+
+    @Override
+    public void stop() throws Exception {
+        FXGL.getGameController().exit();
+    }
+
+    public static void main(String[] args) {
+        launch(args);
+    }
+}

fxgl/src/main/java/com/almasb/fxgl/app/GameApplication.java

@@ -8,6 +8,7 @@
 import com.almasb.fxgl.core.reflect.ReflectionUtils;
 import com.almasb.fxgl.core.util.Platform;
 import com.almasb.fxgl.dev.profiling.ProfilerService;
+import com.almasb.fxgl.dsl.FXGL;
 import com.almasb.fxgl.generated.BuildProperties;
 import com.almasb.fxgl.logging.*;
 
@@ -142,6 +143,19 @@ private void initLogger(ReadOnlyGameSettings settings) {
         log.debug("Logging settings\n" + settings);
     }
 
+    /**
+     * Shuts down currently running embedded FXGL instance.
+     * No-op if no FXGL instance is launched in embedded mode.
+     * After this call, another {@link #embeddedLaunch(GameApplication)} can be started.
+     * Note that after FXGL is no longer needed (no launch calls will be made),
+     * FXGL.getGameController().exit() should be called.
+     */
+    public static void embeddedShutdown() {
+        FXGL.extract$fxgl();
+
+        Logger.removeAllOutputs();
+    }
+
     /**
      * Initialize app settings.
      */

fxgl/src/main/kotlin/com/almasb/fxgl/dsl/FXGL.kt

@@ -92,6 +92,12 @@ class FXGL private constructor() { companion object {
         app = gameApp
     }
 
+    @JvmStatic
+    internal fun extract() {
+        if (this::engine.isInitialized)
+            engine.stopLoopAndExitServices()
+    }
+
     private val controller = object : GameController {
         override fun gotoIntro() {
             getWindowService().gotoIntro()