JavaFX中Pane快照保存为BMP文件为空的问题求助

我已在同一个Pane上绘制了BarChart和LineChart两种图表，现在要实现一个保存按钮，点击后把包含坐标轴的图表图像保存为指定BMP文件。代码运行后会弹出成功提示并生成文件，但生成的文件是空的（0字节）。

原代码 #

@FXML // fx:id="graph"
private Pane graph; // Value injected by FXMLLoader

@FXML // fx:id="saveButton"
private Button saveButton; // Value injected by FXMLLoader

// ...

@FXML
void clickSave(ActionEvent event) {
    Stage yourStage = (Stage) saveButton.getScene().getWindow();

    FileChooser fileChooser = new FileChooser();
    fileChooser.setInitialDirectory(new File("Path\\With\\Spaces"));
    fileChooser.getExtensionFilters().add(new FileChooser.ExtensionFilter("BMP Files", "*.bmp"));

    // Show save dialog
    File file = fileChooser.showSaveDialog(yourStage);

    if (file != null) {
        if (!file.exists()) {
            try {
                Files.createFile(file.toPath());
            } catch (IOException e) {
                e.printStackTrace(); // Handle the exception
            }
        }

        WritableImage writableImage = graph.snapshot(new SnapshotParameters(), null);
        BufferedImage bufferedImage = SwingFXUtils.fromFXImage(writableImage, null);

        try {
            ImageIO.write(bufferedImage, "BMP", file);

            // Inform the user about the successful save
            Alert alert = new Alert(Alert.AlertType.INFORMATION);
            alert.setTitle("File Saved");
            alert.setHeaderText(null);
            alert.setContentText("The file has been saved successfully.");
            alert.showAndWait();
        } catch (IOException e) {
            e.printStackTrace();

            // Inform the user about the error
            Alert alert = new Alert(Alert.AlertType.ERROR);
            alert.setTitle("Error");
            alert.setHeaderText(null);
            alert.setContentText("An error occurred while saving the file.");
            alert.showAndWait();
        }
    }
}

修改后的代码（按@James_D建议调整后问题仍存在） #

@FXML
void clickSave(ActionEvent event) {
    Stage stage = (Stage) saveButton.getScene().getWindow();

    FileChooser fileChooser = new FileChooser();
    fileChooser.setInitialDirectory(new File("Path\\With\\Spaces"));
    fileChooser.getExtensionFilters().add(new FileChooser.ExtensionFilter("BMP Files", "*.bmp"));

    // Show save dialog
    File file = fileChooser.showSaveDialog(stage);

    if (file != null) {
        WritableImage writableImage = graph.snapshot(new SnapshotParameters(), null);
        BufferedImage bufferedImage = SwingFXUtils.fromFXImage(writableImage, null);

        try {
            ImageIO.write(bufferedImage, "BMP", file);

            if (!file.exists()) {
                Files.createFile(file.toPath());
            }

            // Inform the user about the successful save
            Alert alert = new Alert(Alert.AlertType.INFORMATION);
            alert.setTitle("File Saved");
            alert.setHeaderText(null);
            alert.setContentText("The file has been saved successfully.");
            alert.showAndWait();
        } catch (IOException e) {
            e.printStackTrace();

            // Inform the user about the error
            Alert alert = new Alert(Alert.AlertType.ERROR);
            alert.setTitle("Error");
            alert.setHeaderText(null);
            alert.setContentText("An error occurred while saving the file.");
            alert.showAndWait();
        }
    }
}

内容的提问来源于stack exchange，提问作者MrChickenNuggetBadman