fix: preserve window size throughout the application using screen man…

src/main/java/no/ntnu/idatt1005/group03/UI/AboutUsScreen.java

@@ -1,7 +1,6 @@
 package no.ntnu.idatt1005.group03.UI;
 
 import javafx.geometry.Pos;
-import javafx.scene.Scene;
 import javafx.scene.control.Button;
 import javafx.scene.control.ScrollPane;
 import javafx.scene.image.Image;
@@ -50,12 +49,12 @@ public void start(Stage stage) {
     ScrollPane scrollPane = wrapInScrollPane(content);
     layout.setCenter(scrollPane);
 
-    Scene scene = new Scene(layout, 625, 550);
-    scene.getStylesheets().add(getClass().getResource("/styles/app.css").toExternalForm());
-
-    stage.setTitle("About Us");
-    stage.setScene(scene);
-    stage.show();
+    ScreenManager.showRoot(
+            stage,
+            layout,
+            "About Us",
+            getClass().getResource("/styles/app.css").toExternalForm()
+    );
   }
 
   // --- UI COMPONENTS ---
@@ -91,4 +90,4 @@ private ScrollPane wrapInScrollPane(VBox content) {
     scrollPane.getStyleClass().add("dark-scroll-pane");
     return scrollPane;
   }
-}
+}

src/main/java/no/ntnu/idatt1005/group03/UI/AccountScreen.java

@@ -1,7 +1,6 @@
 package no.ntnu.idatt1005.group03.UI;
 
 import javafx.geometry.Pos;
-import javafx.scene.Scene;
 import javafx.scene.control.Button;
 import javafx.scene.layout.BorderPane;
 import javafx.stage.Stage;
@@ -62,13 +61,12 @@ public void start(Stage stage) {
 
     accountLayout.setCenter(mainContent);
 
-    Scene scene = new Scene(accountLayout, 450, 600);
-    // CONNECT TO CSS
-    scene.getStylesheets().add(getClass().getResource("/styles/app.css").toExternalForm());
-
-    stage.setTitle("Account");
-    stage.setScene(scene);
-    stage.show();
+    ScreenManager.showRoot(
+            stage,
+            accountLayout,
+            "Account",
+            getClass().getResource("/styles/app.css").toExternalForm()
+    );
   }
 
   private VBox createProfileSection() {
@@ -145,4 +143,4 @@ private VBox createLogoutSection() {
     VBox.setVgrow(logoutBox, Priority.ALWAYS);
     return logoutBox;
   }
-}
+}

src/main/java/no/ntnu/idatt1005/group03/UI/DonationScreen.java

@@ -1,7 +1,6 @@
 package no.ntnu.idatt1005.group03.UI;
 
 import javafx.geometry.Insets;
-import javafx.scene.Scene;
 import javafx.scene.control.Button;
 import javafx.scene.control.Label;
 import javafx.scene.control.TextField;
@@ -91,14 +90,12 @@ public void start(Stage stage) {
             donateButton,
             backButton);
 
-    Scene scene = new Scene(layout, 400, 330);
-
-    // CONNECT TO CSS
-    scene.getStylesheets().add(getClass().getResource("/styles/app.css").toExternalForm());
-
-    stage.setTitle("Donation");
-    stage.setScene(scene);
-    stage.show();
+    ScreenManager.showRoot(
+            stage,
+            layout,
+            "Donation",
+            getClass().getResource("/styles/app.css").toExternalForm()
+    );
   }
 
   private Label createOrgNameLabel() {
@@ -203,4 +200,4 @@ private Button createBackButton() {
     backButton.setOnAction(e -> ScreenManager.showHomeScreen());
     return backButton;
   }
-}
+}

src/main/java/no/ntnu/idatt1005/group03/UI/LoginScreen.java

@@ -1,6 +1,7 @@
 package no.ntnu.idatt1005.group03.UI;
 
 import javafx.application.Application;
+import javafx.application.Platform;
 import javafx.geometry.HPos;
 import javafx.geometry.Insets;
 import javafx.geometry.Pos;
@@ -32,8 +33,7 @@
  */
 public class LoginScreen extends Application { // homepage
 
-  private Scene scene1; // Sign Up
-  private Scene scene2; // Log In
+  private Scene authScene;
   private AuthController authController;
   private Stage stage;
   private Label signUpErrLabel;
@@ -51,6 +51,9 @@ public class LoginScreen extends Application { // homepage
    */
   @Override
   public void start(Stage primaryStage) {
+    boolean MaximizeOnStartup = primaryStage.getScene() == null;
+    String stylesheet = getClass().getResource("/styles/app.css").toExternalForm();
+
     this.stage = primaryStage;
     this.authController = new AuthController(new UserRepositoryDAO());
     this.favoriteController = new FavoriteController();
@@ -61,16 +64,27 @@ public void start(Stage primaryStage) {
     loginErrLabel = new Label();
     loginErrLabel.setTextFill(Color.RED);
 
-    scene1 = createScene1();
-    scene2 = createScene2();
+    if (primaryStage.getScene() == null) {
+      authScene = new Scene(createSignUpRoot());
+      authScene.getStylesheets().add(stylesheet);
+      primaryStage.setTitle("Log in screen");
+      primaryStage.setScene(authScene);
+      primaryStage.show();
+    } else {
+      authScene = primaryStage.getScene();
+      authScene.setRoot(createSignUpRoot());
+      authScene.getStylesheets().setAll(stylesheet);
+      primaryStage.setTitle("Log in screen");
+      primaryStage.show();
+    }
 
-    primaryStage.setTitle("Log in screen");
-    primaryStage.setScene(scene1);
-    primaryStage.show();
+    if (MaximizeOnStartup) {
+      Platform.runLater(() -> primaryStage.setMaximized(true));
+    }
   }
 
   // -------- SCENE 1 (Sign Up) --------
-  private Scene createScene1() {
+  private GridPane createSignUpRoot() {
     GridPane root1 = createBaseGrid();
 
     Label nameLabel = new Label("Email address");
@@ -113,11 +127,11 @@ private Scene createScene1() {
     accountBox.setAlignment(Pos.CENTER);
     root1.add(accountBox, 1, 9, 3, 1);
 
-    return wrapInScene(root1);
+    return root1;
   }
 
   // -------- SCENE 2 (Log In) --------
-  private Scene createScene2() {
+  private GridPane createLoginRoot() {
     GridPane root2 = createBaseGrid();
 
     Label usernameLabel2 = new Label("Email address or username");
@@ -156,7 +170,7 @@ private Scene createScene2() {
 
     GridPane.setHalignment(forgot, HPos.CENTER);
 
-    return wrapInScene(root2);
+    return root2;
   }
 
   // -------- REUSABLE COMPONENTS --------
@@ -186,14 +200,14 @@ private void addHeader(GridPane grid, boolean isScene2) {
     signloginButton.getStyleClass().addAll("btn", isScene2 ? "btn-outline" : "btn-secondary", "btn-toggle");
     signloginButton.setOnAction(e -> {
       signUpErrLabel.setText("");
-      stage.setScene(scene1);
+      authScene.setRoot(createSignUpRoot());
     });
 
     Button loginButton = new Button("Log in");
     loginButton.getStyleClass().addAll("btn", isScene2 ? "btn-secondary" : "btn-outline", "btn-toggle");
     loginButton.setOnAction(e -> {
       loginErrLabel.setText("");
-      stage.setScene(scene2);
+      authScene.setRoot(createLoginRoot());
     });
 
     HBox buttonBox = new HBox(0); // 0px spacing
@@ -204,12 +218,6 @@ private void addHeader(GridPane grid, boolean isScene2) {
     grid.add(buttonBox, 1, 0, 3, 1);
   }
 
-  private Scene wrapInScene(GridPane root) {
-    Scene scene = new Scene(root, 450, 350);
-    scene.getStylesheets().add(getClass().getResource("/styles/app.css").toExternalForm());
-    return scene;
-  }
-
   // -------- ACTION LOGIC --------
 
   private void handleSignUp(String username, String email, String password, String confirmPassword) {
@@ -238,4 +246,4 @@ private void handleLogin(String usernameOrEmail, String password) {
       loginErrLabel.setText("Wrong username, email, or password.");
     }
   }
-}
+}

src/main/java/no/ntnu/idatt1005/group03/UI/OrganizationsScreen.java

@@ -1,7 +1,6 @@
 package no.ntnu.idatt1005.group03.UI;
 
 import javafx.geometry.Insets;
-import javafx.scene.Scene;
 import javafx.geometry.Pos;
 import javafx.scene.control.Button;
 import javafx.scene.control.Hyperlink;
@@ -87,12 +86,12 @@ public void start(Stage stage) {
     ScrollPane scrollPane = wrapInScrollPane(content);
     mainLayout.setCenter(scrollPane);
 
-    Scene scene = new Scene(mainLayout, 625, 550);
-    scene.getStylesheets().add(getClass().getResource("/styles/app.css").toExternalForm());
-
-    stage.setTitle("Organizations");
-    stage.setScene(scene);
-    stage.show();
+    ScreenManager.showRoot(
+            stage,
+            mainLayout,
+            "Organizations",
+            getClass().getResource("/styles/app.css").toExternalForm()
+    );
   }
 
   private Text createHeaderSection() {
@@ -211,4 +210,4 @@ private ScrollPane wrapInScrollPane(VBox content) {
     scrollPane.getStyleClass().add("transparent-scroll-pane");
     return scrollPane;
   }
-}
+}

src/main/java/no/ntnu/idatt1005/group03/UI/ScreenManager.java

@@ -1,5 +1,7 @@
 package no.ntnu.idatt1005.group03.UI;
 
+import javafx.scene.Parent;
+import javafx.scene.Scene;
 import javafx.stage.Stage;
 import no.ntnu.idatt1005.group03.Model.Organization;
 import no.ntnu.idatt1005.group03.Model.User;
@@ -55,6 +57,40 @@ public static User getCurrentUser() {
     return currentUser;
   }
 
+  public static void showScene(Stage stage, Scene scene, String title) {
+    Scene currentScene = stage.getScene();
+    stage.setTitle(title);
+    if (currentScene == null) {
+      stage.setScene(scene);
+      stage.show();
+    } else {
+      currentScene.setRoot(scene.getRoot());
+      currentScene.getStylesheets().setAll(scene.getStylesheets());
+    }
+  }
+
+  /**
+   * Shows a new root on the given stage while reusing the existing scene when possible.
+   *
+   * @param stage the stage to update
+   * @param root the root node to display
+   * @param title the window title
+   * @param stylesheet the stylesheet URL to apply
+   */
+  public static void showRoot(Stage stage, Parent root, String title, String stylesheet) {
+    Scene currentScene = stage.getScene();
+    stage.setTitle(title);
+    if (currentScene == null) {
+      Scene scene = new Scene(root);
+      scene.getStylesheets().add(stylesheet);
+      stage.setScene(scene);
+      stage.show();
+    } else {
+      currentScene.setRoot(root);
+      currentScene.getStylesheets().setAll(stylesheet);
+    }
+  }
+
   // Navigation Methods
   /**
    * Displays the home screen for the current user.
@@ -95,4 +131,4 @@ public static void logout() {
     currentUser = null;
     new LoginScreen().start(mainStage);
   }
-}
+}