IN Java Graphics2D, how can text be center aligned on a Rectangle?

Question

Im In this code, I have a window with a blue box in one of the corners.

I need to get text center aligned on this box.

public class drawComponent extends JComponent {
public void paintComponent(Graphics g){ //called on window update
    int clueHeightDiff= 0;
    int gap = 5;
    int border = 10;
    Font font = new Font("Ariel", Font.PLAIN, 30);
Color blue = new Color(0,0,255);
Color white = new Color(255,255,255);

int winH = Jeopardy.window.getBounds().getSize().height;
int winW = Jeopardy.window.getBounds().getSize().width;
int width = (winW - ((2 * border) + (5 * gap))) / 6 ;
int height = ((winH - ((4*border) + (5 * gap) + clueHeightDiff ))) / 6;
int clueHeight = height + clueHeightDiff;
int Fx = border + (5* width) + (5*gap);
int foY = border + (2*gap) + (2*height) + clueHeightDiff;
Rectangle F2 = new Rectangle(Fx,foY, width , height);
Graphics2D g2f2 = (Graphics2D) g;
g2f2.draw(F2);
g2f2.fill(F2);
g2f2.setColor(blue);
FontMetrics metrics = g2f2.getFontMetrics(font);
    int height = metrics.getHeight();
    int width = metrics.stringWidth(text);
    Dimension size = new Dimension(width+2, height+2);

Given the X and Y bounds of this box, I need the text to fit comfortably inside. I just can't find a way to do this effectively, as according to the documentation, stringwidth() returns the value of only the first character.

You mean something like [this](http://stackoverflow.com/questions/14284754/java-center-text-in-rectangle/14287270#14287270) — MadProgrammer, Mar 25 '15 at 05:04
Beware, painting is performed from within the context of the component, that is, 0x0 is the top/left corner of the component, regardless of where it's positioned within it's parent container, you shouldn't be calculating positions relative to other components — MadProgrammer, Mar 25 '15 at 05:05
@MadProgrammer Im not calculating positions relative to other components... I have widths of borders and gaps between 36 of these squares. This is only a small excerpt of the program, as the whole thing presents a window like this: (http://imgur.com/vwhgLmd) — cd3, Mar 25 '15 at 05:11
That's not what `Jeopardy.window.getBounds().getSize().height;` seems to be suggesting...Depending on what you are trying to achieve the, width/height values should be calculated from the component it self, as windows can have other artifacts that can affect their size and not reflect the size of the viewable area. — MadProgrammer, Mar 25 '15 at 05:15
That's code to get the dimensions of the JFrame, passed from another class. It's set up so the boxes scale according to window size. — cd3, Mar 25 '15 at 05:25
Yep, which, if you've setup the layout correctly, the component will already do. The width and height properties of the component will give you the available painting area for the component itself — MadProgrammer, Mar 25 '15 at 05:26

score 4 · Accepted Answer · answered Mar 25 '15 at 05:13

FontMetrics#stringwidth will, generally, return the amount of pixels required to render the text

In the box

import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.FontMetrics;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Rectangle;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

public class Test {

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

    public Test() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                    ex.printStackTrace();
                }

                JFrame frame = new JFrame("Testing");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.add(new TestPane(new Rectangle(150, 150, 50, 50)));
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class TestPane extends JPanel {

        private Rectangle boxIn;

        public TestPane(Rectangle boxIn) {
            this.boxIn = boxIn;
        }

        @Override
        public Dimension getPreferredSize() {
            return new Dimension(200, 200);
        }

        @Override
        protected void paintComponent(Graphics g) {
            super.paintComponent(g);
            Graphics2D g2d = (Graphics2D) g.create();
            String text = "Hello";
            FontMetrics fm = g2d.getFontMetrics();

            int x = boxIn.x + ((boxIn.width - fm.stringWidth(text)) / 2);
            int y = boxIn.y + (((boxIn.height - fm.getHeight()) / 2) + fm.getAscent());

            g2d.setColor(Color.BLUE);
            g2d.fill(boxIn);
            g2d.setColor(Color.WHITE);
            g2d.drawString(text, x, y);

            g2d.dispose();
        }

    }

}

You can also use TextLayout, which is a little more complictated, but provides you with a bounding box, representing the area that would required to render the text. This is more useful for attributed text, but can still be useful

Not in of itself, it can be used in conjunction with a `LineBreakMeasurer`, demonstrated [here](http://docs.oracle.com/javase/tutorial/2d/text/drawmulstring.html) — MadProgrammer, Mar 25 '15 at 05:28

IN Java Graphics2D, how can text be center aligned on a Rectangle?

1 Answers1

Linked