在JavaFX中获取文本边界

Question

I am using JavaFX to produce bitmap previews of my music documents.

At certain points, within the paint process, I need to know the dimensions of a given string.

Upto now, I have used the following :

bounds = TextBuilder.create().text(string).font(m_Font).build().getLayoutBounds();

However, eclipse informs me that this is depreciated. It is so depreciated that the bounds object is empty (all set to zero).

How do I go about getting the bounds - width and height - of a single line string now ?

Please note that there are no on screen controls being used to display this stuff. Everything is generated in memory and "dumped" out to a png bitmap.

I have scavenged around on the net and have not found the answer ( or I missed it entirely ).

Any expert help available ?

Answer 1

As I mentioned in my comment, getLayoutBounds() is not deprecated and is perfectly valid to use. It's just the builder which is deprecated.

That said, I have created the following test application which produced seemingly correct output, using builders and creating objects directly:

import javafx.geometry.Bounds;
import javafx.scene.text.Text;
import javafx.scene.text.TextBuilder;
import javafx.stage.Stage;
import javafx.scene.text.Font;

public class stack extends javafx.application.Application {

    public static void main(String[] args)
    {
        // Builder
        Bounds b = TextBuilder.create().text("hello").build().getLayoutBounds();
        System.out.println(b.getHeight() + ", " + b.getWidth());

        b = TextBuilder.create().text("heeeeello").build().getLayoutBounds();
        System.out.println(b.getHeight() + ", " + b.getWidth());

        // No builder
        b = new Text("hello").getLayoutBounds();
        System.out.println(b.getHeight() + ", " + b.getWidth());

        b = new Text("heeeeello").getLayoutBounds();
        System.out.println(b.getHeight() + ", " + b.getWidth());

        // With bad font, zero sized
        Font my_font = new Font("i am not a font", 0);
        Text text = new Text("heeeeello");
        text.setFont(my_font);
        b = text.getLayoutBounds();
        System.out.println(b.getHeight() + ", " + b.getWidth());

        // With bad font, arbitrary size
        my_font = new Font("i am not a font", 20);
        text = new Text("heeeeello");
        text.setFont(my_font);
        b = text.getLayoutBounds();
        System.out.println(b.getHeight() + ", " + b.getWidth());
    }

    @Override
    public void start(Stage primaryStage) throws Exception {  }  
}

Output:

15.9609375, 25.91015625
15.9609375, 51.01171875

15.9609375, 25.91015625
15.9609375, 51.01171875

0.0, 0.0
26.6015625, 85.01953125

I would hypothesise that your font is screwing things up , possibly the size is set to zero or some other error.