JavaFX：如何在按钮中显示富文本？

Question

In JavaFX-8 ( Edit: I realized I'm using jdk-9.0.1, might be a difference?) , I want a component with the functionality of a Button but where its label can be set as rich text. So far I've tried:

1. Using a TextFlow alone and with other components (Pane, StackPane) and CSS styling to add background color and border. This did not work because I could not get the text to be centered vertically in the component when I had set the component's preferred width and height.

2. The same as above but using vertical padding to center the text. This did not work because I could not set the height of the button. If I set a maximum width the text would wrap, but on wrapping, because the padding is constant size, the overall height of the component would increase instead of the text simply taking up more space or being clipped to fit (and appended with "..." like in a Button).

3. A button with no text and using its setGraphic method to set its graphic node to a TextFlow of my choosing. This did not work becuase the TextFlow isn't clipped to fit within the button. Instead, if it is to large, it is displayed outside the borders of the button. Edit: It does not seem possible to center the graphic vertically either. This is only done when the Button has text as well as graphic, but then it does not wrap instead.

4. I also noticed that a Button does have a TextFlow child, but unfortunately it seems I can't set it as I can only return it using Button's getChildrenUnmodifiable method.

Is there some other way to accomplish this, or is there some reasonable way to make one of the approaches I've already tried work?

To summarize, some important things I need:

• Ability to use component like a button.
• Display rich text in the component (with optional vertical centering).
• Easily set and change the rich text or parts of it.
• Allow the rich text to be clipped when it does no longer fit.
• Somehow set component size so it doesn't resize if text becomes large.

---

Per request, an MCVE where #3 does not work for me:

import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.layout.VBox;
import javafx.scene.text.Text;
import javafx.scene.text.TextFlow;
import javafx.stage.Stage;

public class TestWindow extends Application {

    public static void main(String[] args) {
        launch(args);
    }

    @Override
    public void start(Stage primaryStage) throws Exception {
        VBox mainLayout = new VBox();

        Text t = new Text(
                "Lorem ipsum dolor sit amet, consectetur adipiscing elit. Duis blandit dolor non dui porttitor, sit amet commodo ipsum condimentum. Proin quis tincidunt massa.");
        TextFlow a = new TextFlow(t);
        a.setTextAlignment(TextAlignment.CENTER);

        Button b = new Button();
        b.setGraphic(a);
        b.setAlignment(Pos.CENTER);
        b.setPrefSize(300, 100);

        mainLayout.getChildren().addAll(b);

        Scene scene = new Scene(mainLayout);
        primaryStage.setScene(scene);
        primaryStage.show();
    }

}

This code produces the following results

When running the program

After resizing window

If the button has some text, if it is for instance created with a single space

Button b = new Button(" ");

The text does not wrap at all

Answer 1

Partial Solution

I have not been able to find a solution that allows both centering the text and clipping it if it is too large. For now, my workaround is to only center the text.

It is possible to center a TextFlow vertically by setting its maxHeight to something small. Using the MCVE for #3 in the question, it is enough to add a.setMaxHeight(0); . This will center the text since the TextFlow will no longer expand to take up all available space.