我有一个允许用户从文件系统中选择图像的方法。我的部分布局（包括工具栏和MenuBar）是在FXML中创建的，但主要的Image，ImageView，BorderPane和ScrollPane都是在主应用程序类中设置的。以前，我能够在适当的ImageView中显示所选图像，但现在它只是不可见。我测试了是否正确检索图像，并且确实可以在调试时检索其文件路径和宽度，但屏幕仍然没有显示图像。出了什么问题？
FXML：
<VBox prefHeight="600" prefWidth="800" xmlns="http://javafx.com/javafx/8.0.112" xmlns:fx="http://javafx.com/fxml/1">
<VBox alignment="TOP_CENTER">
<ToolBar minHeight="50.0" prefHeight="50.0" prefWidth="800.0" stylesheets="@style.css" GridPane.rowIndex="1">
<ImageView fitHeight="35.0" fitWidth="200.0" pickOnBounds="true" preserveRatio="true">
<Image url="@react-toolbar-logo.png" />
</ImageView>
</ToolBar>
<MenuBar fx:id="menuBar" prefHeight="0.0" prefWidth="0.0" />
</VBox>
</VBox>
主要应用类：
public class Main extends Application {
private Image mainImage;
private final Group selectionGroup = new Group();
@Override
public void start(Stage primaryStage) throws Exception {
// Basic stage settings
primaryStage.setTitle("Picture Viewer");
primaryStage.setResizable(true);
// Set task bar primary icon
primaryStage.getIcons().add(new javafx.scene.image.Image("main/react-app-icon.png"));
// Declare UI variables
final BorderPane borderPane = new BorderPane();
final ScrollPane scrollPane = new ScrollPane();
final Scene scene = new Scene(borderPane, 800, 600);
ImageView mainImageView = new ImageView();
// Select main layout file
FXMLLoader loader = new FXMLLoader(getClass().getResource("/main/scene.fxml"));
loader.setController(new MainController(primaryStage, selectionGroup, mainImage, mainImageView));
Parent root = loader.load();
// Add custom stylesheet URL
scene.getStylesheets().add("main/style.css");
// Set UI element properties
selectionGroup.getChildren().add(mainImageView);
scrollPane.setContent(selectionGroup);
scrollPane.setHbarPolicy(ScrollPane.ScrollBarPolicy.NEVER);
scrollPane.setVbarPolicy(ScrollPane.ScrollBarPolicy.NEVER);
// Show primary stage
// primaryStage.setScene(scene);
primaryStage.setScene(new Scene(root));
primaryStage.show();
}
public static void main(String[] args) {
launch(args);
}
}
主要控制器：
class MainController implements Initializable {
private Stage primaryStage;
private Group selectionGroup;
private Image mainImage;
private ImageView mainImageView;
MainController(Stage primaryStage, Group selectionGroup, Image mainImage, ImageView mainImageView) {
this.primaryStage = primaryStage;
this.selectionGroup = selectionGroup;
this.mainImage = mainImage;
this.mainImageView = mainImageView;
}
private boolean isAreaSelected = false;
private final AreaSelection areaSelection = new AreaSelection();
@FXML
private
MenuBar menuBar;
@Override
public void initialize(URL location, ResourceBundle resources) {
// Declare menus
final Menu menu1 = new Menu("File");
final Menu menu2 = new Menu("Options");
// Define menu 1 items
final MenuItem open = new MenuItem("Open");
final MenuItem clear = new MenuItem("Clear");
final MenuItem exit = new MenuItem("Exit");
// Define menu 2 items
// final MenuItem select = new MenuItem("Select Area");
final MenuItem crop = new MenuItem("Crop & Upload");
final MenuItem clearSelectionItem = new MenuItem("Clear Selection");
// Set menu items
menu1.getItems().addAll(open, clear, exit);
menu2.getItems().addAll(crop, clearSelectionItem);
// Set menu click events
setMenu1ClickEvents(primaryStage, open, clear, exit);
setMenu2ClickEvents(crop, clearSelectionItem);
// Instantiate menus
menuBar.getMenus().addAll(menu1, menu2);
}
private void setMenu1ClickEvents(Stage primaryStage, MenuItem open, MenuItem clear, MenuItem exit) {
// Open file system to select image
open.setOnAction(event -> {
FileChooser fileChooser = new FileChooser();
fileChooser.setTitle("Open Image File");
fileChooser.getExtensionFilters().addAll(
new FileChooser.ExtensionFilter("Image Files", "*.png", "*.jpg"));
File selectedFile = fileChooser.showOpenDialog(primaryStage);
if (selectedFile != null) {
clearSelection(selectionGroup);
this.mainImage = convertFileToImage(selectedFile);
System.out.println("selectedFile: " + selectedFile);
mainImageView.setImage(mainImage);
System.out.println("mainImage.getWidth(): " + mainImage.getWidth());
changeStageSizeImageDimensions(primaryStage, mainImage);
}
});
// Clear the current image
clear.setOnAction(event -> {
clearSelection(selectionGroup);
mainImageView.setImage(null);
System.gc();
});
// Exit the application
exit.setOnAction(event -> {
Platform.exit();
System.exit(0);
});
}
private void setMenu2ClickEvents(MenuItem crop, MenuItem clearSelectionItem) {
// Set menu 2 click events
crop.setOnAction(event -> {
if (isAreaSelected()) {
cropImage(areaSelection.selectArea(selectionGroup).getBoundsInParent(), mainImageView);
}
});
clearSelectionItem.setOnAction(event -> clearSelection(selectionGroup));
}
}
convertFileToImage：
private Image convertFileToImage(File imageFile) {
Image image = null;
try (FileInputStream fileInputStream = new FileInputStream(imageFile)) {
image = new Image(fileInputStream);
} catch (Exception e) {
e.printStackTrace();
}
return image;
}
答案 0 :(得分：1)
您永远不会显示您在Java代码中创建的ImageView或任何控件。
根据评论，您希望FXML的内容位于边框窗格的顶部，滚动窗格包含图像视图位于中心的组。
所以你应该这样做：
public class Main extends Application {
private Image mainImage;
private final Group selectionGroup = new Group();
@Override
public void start(Stage primaryStage) throws Exception {
// Basic stage settings
primaryStage.setTitle("Picture Viewer");
primaryStage.setResizable(true);
// Set task bar primary icon
primaryStage.getIcons().add(new javafx.scene.image.Image("main/react-app-icon.png"));
// Declare UI variables
final BorderPane borderPane = new BorderPane();
final ScrollPane scrollPane = new ScrollPane();
final Scene scene = new Scene(borderPane, 800, 600);
ImageView mainImageView = new ImageView();
// Select main layout file
FXMLLoader loader = new FXMLLoader(getClass().getResource("/main/scene.fxml"));
loader.setController(new MainController(primaryStage, selectionGroup, mainImage, mainImageView));
Parent root = loader.load();
// Add custom stylesheet URL
scene.getStylesheets().add("main/style.css");
// Set UI element properties
selectionGroup.getChildren().add(mainImageView);
scrollPane.setContent(selectionGroup);
scrollPane.setHbarPolicy(ScrollPane.ScrollBarPolicy.NEVER);
scrollPane.setVbarPolicy(ScrollPane.ScrollBarPolicy.NEVER);
borderPane.setCenter(scrollPane);
borderPane.setTop(root);
// Show primary stage
primaryStage.setScene(scene);
// primaryStage.setScene(new Scene(root));
primaryStage.show();
}
public static void main(String[] args) {
launch(args);
}
}