added inelegant capability to switch scenes

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

@@ -5,6 +5,14 @@ import java.util.logging.Level;
 import java.util.logging.Logger;
 import java.util.stream.Collectors;
 
+import javafx.application.Platform;
+import javafx.collections.FXCollections;
+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;
 import envoy.client.event.MessageCreationEvent;
@@ -17,12 +25,6 @@ import envoy.event.EventBus;
 import envoy.event.MessageStatusChangeEvent;
 import envoy.event.UserStatusChangeEvent;
 import envoy.util.EnvoyLog;
-import javafx.application.Platform;
-import javafx.collections.FXCollections;
-import javafx.fxml.FXML;
-import javafx.scene.control.*;
-import javafx.scene.input.KeyCode;
-import javafx.scene.input.KeyEvent;
 
 /**
  * Project: <strong>envoy-client</strong><br>
@@ -58,6 +60,8 @@ public final class ChatSceneController {
 
 	private Chat currentChat;
 
+	private Startup startup;
+
 	private static final EventBus	eventBus	= EventBus.getInstance();
 	private static final Logger		logger		= EnvoyLog.getLogger(ChatSceneController.class);
 
@@ -91,10 +95,11 @@ public final class ChatSceneController {
 		eventBus.register(UserStatusChangeEvent.class, e -> Platform.runLater(() -> userList.refresh()));
 	}
 
-	void initializeData(LocalDB localDB, Client client, WriteProxy writeProxy) {
-		this.localDB	= localDB;
-		this.client		= client;
-		this.writeProxy	= writeProxy;
+	void initializeData(Startup startup, LocalDB localDB, Client client, WriteProxy writeProxy) {
+		this.startup	= startup;
+		this.localDB		= localDB;
+		this.client			= client;
+		this.writeProxy		= writeProxy;
 
 		// TODO: handle offline mode
 		userList.setItems(FXCollections.observableList(localDB.getUser().getContacts().stream().collect(Collectors.toList())));
@@ -123,7 +128,10 @@ public final class ChatSceneController {
 	private void postButtonClicked() { postMessage(); }
 
 	@FXML
-	private void settingsButtonClicked() { logger.info("Settings Button clicked."); }
+	private void settingsButtonClicked() {
+		startup.changeScene("/fxml/SettingsScene.fxml", new VBox(), true);
+		Platform.runLater(() -> { ((SettingsSceneController) startup.getCurrentController()).initializeData(startup); });
+	}
 
 	@FXML
 	private void messageTextUpdated(KeyEvent e) {

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

@@ -7,25 +7,36 @@ import javafx.scene.control.*;
  * Project: <strong>envoy-client</strong><br>
  * File: <strong>SettingsSceneController.java</strong><br>
  * Created: <strong>10.04.2020</strong><br>
- * 
+ *
  * @author Kai S. K. Engelbart
  * @since Envoy Client v0.1-beta
  */
-public final class SettingsSceneController {
+public class SettingsSceneController {
 
+	private Startup					startup;
 	@FXML
-	private ListView<SettingsPane> settingsList;
+	private ListView<SettingsPane>	settingsList;
 
 	@FXML
 	private TitledPane titledPane;
 
+	/**
+	 * initializes the object needed to reset the 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; }
+
 	@FXML
 	private void initialize() {
 		settingsList.setCellFactory(listView -> new ListCell<>() {
 
 			@Override
-			protected void updateItem(SettingsPane item, boolean empty) { if (!empty && item != null) setGraphic(new Label(item.getTitle())); };
+			protected void updateItem(SettingsPane item, boolean empty) { if (!empty && item != null) setGraphic(new Label(item.getTitle())); }
 		});
+
+		// settingsList.getItems().add(new GeneralSettingsPane());
 	}
 
 	@FXML
@@ -34,4 +45,7 @@ public final class SettingsSceneController {
 		titledPane.setText(pane.getTitle());
 		titledPane.setContent(pane);
 	}
+
+	@FXML
+	private void backButtonClicked() { startup.restoreScene(false); }
 }

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

@@ -8,12 +8,14 @@ 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.image.Image;
 import javafx.scene.layout.GridPane;
+import javafx.scene.layout.Pane;
 import javafx.stage.Stage;
 
 import envoy.client.data.*;
@@ -40,6 +42,11 @@ public final class Startup extends Application {
 	private WriteProxy		writeProxy;
 	private Cache<Message>	cache;
 
+	private FXMLLoader	loader	= new FXMLLoader();
+	private Stage		stage;
+
+	private Scene previousScene;
+
 	private static final ClientConfig	config	= ClientConfig.getInstance();
 	private static final Logger			logger	= EnvoyLog.getLogger(Startup.class);
 
@@ -48,6 +55,7 @@ public final class Startup extends Application {
 	 */
 	@Override
 	public void start(Stage stage) throws Exception {
+		this.stage = stage;
 		try {
 			// Load the configuration from client.properties first
 			Properties properties = new Properties();
@@ -124,20 +132,67 @@ public final class Startup extends Application {
 				.forEach(u -> u.setStatus(UserStatus.OFFLINE));
 
 		// Prepare stage and load ChatScene
-		var	loader		= new FXMLLoader(getClass().getResource("/fxml/ChatScene.fxml"));
-		var	anchorPane	= loader.<GridPane>load();
-		var	chatScene	= new Scene(anchorPane);
+		changeScene("/fxml/ChatScene.fxml", new GridPane(), false);
+		Platform.runLater(() -> { ((ChatSceneController) loader.getController()).initializeData(this, localDB, client, writeProxy); });
 		stage.setTitle("Envoy");
 		stage.getIcons().add(new Image(getClass().getResourceAsStream("/icons/envoy_logo.png")));
-		stage.setScene(chatScene);
 
-		loader.<ChatSceneController>getController().initializeData(localDB, client, writeProxy);
 		stage.show();
 
 		// 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();
+				var	rootNode	= loader.<T>load(getClass().getResourceAsStream(fxmlLocation));
+				var	chatScene	= new Scene(rootNode);
+				previousScene = (savePrevious) ? stage.getScene() : null;
+				stage.setScene(chatScene);
+				stage.show();
+				// return loader.getController();
+			} catch (IOException e) {
+				new Alert(AlertType.ERROR, "The screen could not be updated due to reasons. (...bad programming...)");
+				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.
+	 *
+	 * @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
+				var temp = (storeCurrent) ? stage.getScene() : null;
+				stage.setScene(previousScene);
+				previousScene = temp;
+				stage.show();
+			}
+		});
+	}
+
 	/**
 	 * {@inheritDoc}
 	 */
@@ -159,4 +214,14 @@ public final class Startup extends Application {
 
 	@SuppressWarnings("javadoc")
 	public static void main(String[] args) { launch(args); }
+
+	/**
+	 * @return the controller of the current scene or a {@link NullPointerException}
+	 *         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();
+	}
 }