Externalized scene loading and management into SceneContext

src/main/java/envoy/client/ui/ChatSceneController.java

@@ -11,7 +11,6 @@ import javafx.fxml.FXML;
 import javafx.scene.control.*;
 import javafx.scene.input.KeyCode;
 import javafx.scene.input.KeyEvent;
-import javafx.scene.layout.VBox;
 
 import envoy.client.data.Chat;
 import envoy.client.data.LocalDB;
@@ -56,14 +55,13 @@ public final class ChatSceneController {
 	@FXML
 	private TextArea messageTextArea;
 
-	private LocalDB		localDB;
+	private LocalDB			localDB;
-	private Client		client;
+	private Client			client;
-	private WriteProxy	writeProxy;
+	private WriteProxy		writeProxy;
+	private SceneContext	sceneContext;
 
 	private Chat currentChat;
 
-	private Startup startup;
-
 	private static final Settings	settings	= Settings.getInstance();
 	private static final EventBus	eventBus	= EventBus.getInstance();
 	private static final Logger		logger		= EnvoyLog.getLogger(ChatSceneController.class);
@@ -97,11 +95,11 @@ public final class ChatSceneController {
 		eventBus.register(UserStatusChangeEvent.class, e -> Platform.runLater(() -> userList.refresh()));
 	}
 
-	void initializeData(Startup startup, LocalDB localDB, Client client, WriteProxy writeProxy) {
+	void initializeData(SceneContext sceneContext, LocalDB localDB, Client client, WriteProxy writeProxy) {
-		this.startup	= startup;
+		this.sceneContext	= sceneContext;
-		this.localDB	= localDB;
+		this.localDB		= localDB;
-		this.client		= client;
+		this.client			= client;
-		this.writeProxy	= writeProxy;
+		this.writeProxy		= writeProxy;
 
 		// TODO: handle offline mode
 		userList.setItems(FXCollections.observableList(localDB.getUser().getContacts().stream().collect(Collectors.toList())));
@@ -131,8 +129,12 @@ public final class ChatSceneController {
 
 	@FXML
 	private void settingsButtonClicked() {
-		startup.changeScene("/fxml/SettingsScene.fxml", new VBox(), true);
+		try {
-		Platform.runLater(() -> ((SettingsSceneController) startup.getCurrentController()).initializeData(startup));
+			sceneContext.load(SceneContext.SceneInfo.SETTINGS_SCENE);
+			sceneContext.<SettingsSceneController>getController().initializeData(sceneContext);
+		} catch (IOException e) {
+			e.printStackTrace();
+		}
 	}
 
 	@FXML

src/main/java/envoy/client/ui/SceneContext.java

@@ -0,0 +1,98 @@
+package envoy.client.ui;
+
+import java.io.IOException;
+import java.util.Stack;
+
+import javafx.fxml.FXMLLoader;
+import javafx.scene.Parent;
+import javafx.scene.Scene;
+import javafx.stage.Stage;
+
+import envoy.client.data.Settings;
+import envoy.client.event.ThemeChangeEvent;
+import envoy.event.EventBus;
+
+/**
+ * Project: <strong>envoy-client</strong><br>
+ * File: <strong>SceneContext.java</strong><br>
+ * Created: <strong>06.06.2020</strong><br>
+ * 
+ * @author Kai S. K. Engelbart
+ * @since Envoy Client v0.1-beta
+ */
+public final class SceneContext {
+
+	static enum SceneInfo {
+
+		CHAT_SCENE("/fxml/ChatScene.fxml"), SETTINGS_SCENE("/fxml/SettingsScene.fxml"), CONTACT_SEARCH_SCENE("/fxml/ContactSearchScene.fxml");
+
+		public final String path;
+
+		SceneInfo(String path) { this.path = path; }
+	}
+
+	private final Stage			stage;
+	private final FXMLLoader	loader		= new FXMLLoader();
+	private final Stack<Scene>	sceneStack	= new Stack<>();
+
+	private static final Settings settings = Settings.getInstance();
+
+	/**
+	 * Initializes the scene context.
+	 * 
+	 * @param stage the stage in which scenes will be displayed
+	 * @since Envoy Client v0.1-beta
+	 */
+	public SceneContext(Stage stage) {
+		this.stage = stage;
+		EventBus.getInstance().register(ThemeChangeEvent.class, theme -> applyCSS());
+	}
+
+	/**
+	 * Loads a new scene specified by a scene info.
+	 * 
+	 * @param sceneInfo specifies the scene to load
+	 * @throws IOException if the loading process fails
+	 * @since Envoy Client v0.1-beta
+	 */
+	public void load(SceneInfo sceneInfo) throws IOException {
+		loader.setRoot(null);
+		loader.setController(null);
+
+		final var	rootNode	= (Parent) loader.load(getClass().getResourceAsStream(sceneInfo.path));
+		final var	scene		= new Scene(rootNode);
+
+		sceneStack.push(scene);
+		stage.setScene(scene);
+		applyCSS();
+		stage.show();
+	}
+
+	/**
+	 * Removes the current scene and displays the previous one.
+	 * 
+	 * @since Envoy Client v0.1-beta
+	 */
+	public void pop() {
+		sceneStack.pop();
+		stage.setScene(sceneStack.peek());
+		applyCSS();
+		stage.show();
+	}
+
+	private void applyCSS() {
+		if (!sceneStack.isEmpty()) {
+			final var	styleSheets	= stage.getScene().getStylesheets();
+			final var	themeCSS	= "/css/" + (settings.isUsingDefaultTheme() ? settings.getCurrentThemeName() : "custom") + ".css";
+			styleSheets.clear();
+			styleSheets.addAll(getClass().getResource("/css/base.css").toExternalForm(), getClass().getResource(themeCSS).toExternalForm());
+		}
+	}
+
+	/**
+	 * @param <T> the type of the controller
+	 * @return the controller used by the current scene
+	 * @since Envoy Client v0.1-beta
+	 */
+	public <T> T getController() { return loader.getController(); }
+}

src/main/java/envoy/client/ui/Startup.java

@@ -8,23 +8,16 @@ import java.util.logging.Level;
 import java.util.logging.Logger;
 
 import javafx.application.Application;
-import javafx.application.Platform;
-import javafx.fxml.FXMLLoader;
-import javafx.scene.Scene;
 import javafx.scene.control.Alert;
 import javafx.scene.control.Alert.AlertType;
-import javafx.scene.layout.GridPane;
-import javafx.scene.layout.Pane;
 import javafx.stage.Stage;
 
 import envoy.client.data.*;
-import envoy.client.event.ThemeChangeEvent;
 import envoy.client.net.Client;
 import envoy.client.net.WriteProxy;
 import envoy.data.Message;
 import envoy.data.User;
 import envoy.data.User.UserStatus;
-import envoy.event.EventBus;
 import envoy.exception.EnvoyException;
 import envoy.util.EnvoyLog;
 
@@ -43,20 +36,14 @@ public final class Startup extends Application {
 	private WriteProxy		writeProxy;
 	private Cache<Message>	cache;
 
-	private FXMLLoader	loader	= new FXMLLoader();
+	private static final ClientConfig	config	= ClientConfig.getInstance();
-	private Stage		stage;
+	private static final Logger			logger	= EnvoyLog.getLogger(Startup.class);
-	private Scene		previousScene;
-
-	private static final Settings		settings	= Settings.getInstance();
-	private static final ClientConfig	config		= ClientConfig.getInstance();
-	private static final Logger			logger		= EnvoyLog.getLogger(Startup.class);
 
 	/**
 	 * {@inheritDoc}
 	 */
 	@Override
 	public void start(Stage stage) throws Exception {
-		this.stage = stage;
 		try {
 			// Load the configuration from client.properties first
 			final Properties properties = new Properties();
@@ -133,72 +120,17 @@ public final class Startup extends Application {
 				.forEach(u -> u.setStatus(UserStatus.OFFLINE));
 
 		// Prepare stage and load ChatScene
-		changeScene("/fxml/ChatScene.fxml", new GridPane(), false);
+		final var sceneContext = new SceneContext(stage);
-		Platform.runLater(() -> { ((ChatSceneController) loader.getController()).initializeData(this, localDB, client, writeProxy); });
+		sceneContext.load(SceneContext.SceneInfo.CHAT_SCENE);
+		sceneContext.<ChatSceneController>getController().initializeData(sceneContext, localDB, client, writeProxy);
 		stage.setTitle("Envoy");
 		stage.getIcons().add(IconUtil.load("/icons/envoy_logo.png"));
 		stage.show();
-		// TODO: Add capability to change custom CSS. In case of switching to a default
-		// theme, no further action is required
-		EventBus.getInstance().register(ThemeChangeEvent.class, theme -> applyCSS());
 
 		// Relay unread messages from cache
 		if (cache != null && client.isOnline()) cache.relay();
 	}
 
-	/**
-	 * Changes the scene of the stage.
-	 *
-	 * @param <T>          the type of the layout to use
-	 * @param fxmlLocation the location of the fxml file
-	 * @param layout       the layout to use
-	 * @param savePrevious if true, the previous stage will be stored in this
-	 *                     instance of Startup, else the variable storing it will be
-	 *                     set to null
-	 * @since Envoy Client v0.1-beta
-	 */
-	public <T extends Pane> void changeScene(String fxmlLocation, T layout, boolean savePrevious) {
-		Platform.runLater(() -> {
-			try {
-				// Clearing the loader so that a new Scene can be initialised
-				loader = new FXMLLoader();
-				final var	rootNode	= loader.<T>load(getClass().getResourceAsStream(fxmlLocation));
-				final var	scene		= new Scene(rootNode);
-				previousScene = savePrevious ? stage.getScene() : null;
-				// Setting the visual appearance
-				stage.setScene(scene);
-				applyCSS();
-				stage.show();
-			} catch (final IOException e) {
-				new Alert(AlertType.ERROR, "The screen could not be updated due to reasons. (...bad programming...)");
-				System.err.println("input: FXMLLocation: " + fxmlLocation);
-				e.printStackTrace();
-				logger.severe("Something happened (while loading the new scene from " + fxmlLocation + ")");
-			}
-		});
-	}
-
-	/**
-	 * Changes the visual scene back to the saved value. The currently active scene
-	 * can be saved, but must not be.
-	 *
-	 * @param storeCurrent the old scene to store, if wanted. Can be null
-	 * @since Envoy Client v0.1-beta
-	 */
-	public void restoreScene(boolean storeCurrent) {
-		Platform.runLater(() -> {
-			if (previousScene == null) throw new IllegalStateException("Someone tried restoring a null scene. (Something happened)");
-			else {
-				// switching previous and current
-				final var temp = storeCurrent ? stage.getScene() : null;
-				stage.setScene(previousScene);
-				applyCSS();
-				previousScene = temp;
-				stage.show();
-			}
-		});
-	}
-
 	/**
 	 * {@inheritDoc}
 	 */
@@ -218,29 +150,11 @@ public final class Startup extends Application {
 	}
 
 	/**
-	 * @return the controller of the current scene or a {@link NullPointerException}
+	 * Starts the application.
-	 *         if there is none
-	 * @since Envoy Client v0.1-beta
-	 */
-	public Object getCurrentController() {
-		if (loader.getController() == null) throw new NullPointerException("Cannot deliver current controller as its undefined (duh!)");
-		else return loader.getController();
-	}
-
-	/**
-	 * Sets the CSS files used for each scene. Should be called when the theme
-	 * changes.
 	 * 
+	 * @param args the command line arguments are processed by the
+	 *             {@link ClientConfig}
 	 * @since Envoy Client v0.1-beta
 	 */
-	public void applyCSS() {
-		final var styleSheets = stage.getScene().getStylesheets();
-		styleSheets.clear();
-		styleSheets.add(getClass().getResource("/css/base.css").toExternalForm());
-		styleSheets.add(getClass().getResource("/css/" + (settings.isUsingDefaultTheme() ? settings.getCurrentThemeName() : "custom") + ".css")
-			.toExternalForm());
-	}
-
-	@SuppressWarnings("javadoc")
 	public static void main(String[] args) { launch(args); }
 }

src/main/java/envoy/client/ui/settings/SettingsSceneController.java

@@ -3,7 +3,7 @@ package envoy.client.ui.settings;
 import javafx.fxml.FXML;
 import javafx.scene.control.*;
 
-import envoy.client.ui.Startup;
+import envoy.client.ui.SceneContext;
 
 /**
  * Project: <strong>envoy-client</strong><br>
@@ -15,20 +15,19 @@ import envoy.client.ui.Startup;
  */
 public class SettingsSceneController {
 
-	private Startup					startup;
 	@FXML
-	private ListView<SettingsPane>	settingsList;
+	private ListView<SettingsPane> settingsList;
 
 	@FXML
 	private TitledPane titledPane;
 
+	private SceneContext sceneContext;
+
 	/**
-	 * initializes the object needed to reset the scene
+	 * @param sceneContext enables the user to return to the chat scene
-	 * 
-	 * @param startup the instance of startup that stores the stage
 	 * @since Envoy Client v0.1-beta
 	 */
-	public void initializeData(Startup startup) { this.startup = startup; }
+	public void initializeData(SceneContext sceneContext) { this.sceneContext = sceneContext; }
 
 	@FXML
 	private void initialize() {
@@ -54,5 +53,5 @@ public class SettingsSceneController {
 	}
 
 	@FXML
-	private void backButtonClicked() { startup.restoreScene(false); }
+	private void backButtonClicked() { sceneContext.pop(); }
 }