Java having difficulty centering textLayouts on a Graphics2d with various letters

Question

I'm having difficulty being able to vertical center textLayouts on a Graphics2d object. I'm using:

((intGraphics2dHeight / 2) + textLayout.getBounds().getHeight()) - textLayout.getDescent()

The result is the text is bouncing up and down.

Test strings are:

oaoaoa g oaoaoa
WWWWWW W WWWWWW
Prryrr P Prryrr

I'm probably not using texLayout correctly, but don't know how to fix it.

Answer 1

I'd suggest having a look at Working with Text APIs

A font represents the information necessary to render text

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.util.Arrays;
import java.util.StringJoiner;
import javax.swing.JFrame;
import javax.swing.JPanel;

public class Test {

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

    public Test() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                JFrame frame = new JFrame();
                frame.add(new TestPane());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class TestPane extends JPanel {

        public TestPane() {
        }

        @Override
        public Dimension getPreferredSize() {
            return new Dimension(500, 200);
        }

        private String[] texts = new String[]{
            "oaoaoa g oaoaoa",
            "WWWWWW W WWWWWW",
            "Prryrr P Prryrr"
        };

        @Override
        protected void paintComponent(Graphics g) {
            super.paintComponent(g);
            Graphics2D g2d = (Graphics2D) g.create();

            g2d.setColor(Color.RED);
            g2d.drawLine(getWidth() / 2, 0, getWidth() / 2, getHeight());
            g2d.drawLine(0, getHeight() / 2, getWidth(), getHeight() / 2);

            g2d.setColor(Color.BLACK);

            FontMetrics fm = g2d.getFontMetrics();

            int width = 0;
            for (String text : texts) {
                width += fm.stringWidth(text);
            }

            int xPos = (getWidth() - width) / 2;
            int yPos = ((getHeight() - fm.getHeight()) / 2) + fm.getAscent();

            int offset = 0;
            for (String text : texts) {
                g2d.drawString(text, xPos + offset, yPos);
                offset += fm.stringWidth(text);
            }

            g2d.dispose();
        }

    }
}

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.util.Arrays;
import java.util.StringJoiner;
import javax.swing.JFrame;
import javax.swing.JPanel;

public class Test {

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

    public Test() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                JFrame frame = new JFrame();
                frame.add(new TestPane());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class TestPane extends JPanel {

        public TestPane() {
        }

        @Override
        public Dimension getPreferredSize() {
            return new Dimension(500, 200);
        }

        private String[] texts = new String[]{
            "oaoaoa g oaoaoa",
            "WWWWWW W WWWWWW",
            "Prryrr P Prryrr"
        };

        @Override
        protected void paintComponent(Graphics g) {
            super.paintComponent(g);
            Graphics2D g2d = (Graphics2D) g.create();

            g2d.setColor(Color.RED);
            g2d.drawLine(getWidth() / 2, 0, getWidth() / 2, getHeight());
            g2d.drawLine(0, getHeight() / 2, getWidth(), getHeight() / 2);

            g2d.setColor(Color.BLACK);

            FontMetrics fm = g2d.getFontMetrics();

            int width = 0;
            for (String text : texts) {
                width += fm.stringWidth(text);
            }

            int xPos = (getWidth() - width) / 2;
            int yPos = ((getHeight() - fm.getHeight()) / 2) + fm.getAscent();

            int offset = 0;
            for (String text : texts) {
                g2d.drawString(text, xPos + offset, yPos);
                offset += fm.stringWidth(text);
            }

            g2d.dispose();
        }

    }
}

So, not seeing an issue, but since I have no context to your issue, I'm just guessing

Expanded Example using TextLayout

import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Rectangle;
import java.awt.RenderingHints;
import java.awt.Shape;
import java.awt.font.FontRenderContext;
import java.awt.font.GlyphVector;
import java.awt.font.TextLayout;
import java.util.HashMap;
import java.util.Map;
import javax.swing.JFrame;
import javax.swing.JPanel;

public class Test {

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

    public Test() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                JFrame frame = new JFrame();
                frame.add(new TestPane());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class TestPane extends JPanel {

        public TestPane() {
        }

        @Override
        public Dimension getPreferredSize() {
            return new Dimension(500, 200);
        }

        private String[] texts = new String[]{
            "oaoaoa g oaoaoa",
            "WWWWWW W WWWWWW",
            "Prryrr P Prryrr"
        };

        @Override
        protected void paintComponent(Graphics g) {
            super.paintComponent(g);
            Graphics2D g2d = (Graphics2D) g.create();
            g2d.setRenderingHint(RenderingHints.KEY_ALPHA_INTERPOLATION, RenderingHints.VALUE_ALPHA_INTERPOLATION_QUALITY);
            g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
            g2d.setRenderingHint(RenderingHints.KEY_COLOR_RENDERING, RenderingHints.VALUE_COLOR_RENDER_QUALITY);
            g2d.setRenderingHint(RenderingHints.KEY_DITHERING, RenderingHints.VALUE_DITHER_ENABLE);
            g2d.setRenderingHint(RenderingHints.KEY_FRACTIONALMETRICS, RenderingHints.VALUE_FRACTIONALMETRICS_ON);
            g2d.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BILINEAR);
            g2d.setRenderingHint(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY);
            g2d.setRenderingHint(RenderingHints.KEY_STROKE_CONTROL, RenderingHints.VALUE_STROKE_PURE);

            g2d.setColor(Color.RED);
            g2d.drawLine(getWidth() / 2, 0, getWidth() / 2, getHeight());
            g2d.drawLine(0, getHeight() / 2, getWidth(), getHeight() / 2);

            g2d.setColor(Color.BLACK);

            Font font = g2d.getFont();

            FontRenderContext frc = g2d.getFontRenderContext();
            Map<String, GlyphVector> vectors = new HashMap<>();
            double width = 0;
            for (String text : texts) {
                GlyphVector gv = font.createGlyphVector(frc, text);
                vectors.put(text, gv);
                width += gv.getVisualBounds().getWidth();
            }

            int xPos = (int) ((getWidth() - width) / 2.0);

            for (String text : texts) {
                xPos = render(g2d, text, xPos);
            }

            g2d.dispose();
        }

        protected int render(Graphics2D g2d, String text, int xOffset) {
            Font font = g2d.getFont();
            FontRenderContext frc = g2d.getFontRenderContext();

            int xPos = xOffset;
            for (char character : text.toCharArray()) {
                String value = Character.toString(character);
                // Create an layout of the text
                TextLayout tl = new TextLayout(value, font, frc);
                // Generate a shape of the layout
                Shape shape = tl.getOutline(null);
                // Align the shape to the center
                Rectangle rect = shape.getBounds();

                Graphics2D gCopy = (Graphics2D) g2d.create();
                int yPos = (getHeight() / 2) + (rect.height / 2);
                gCopy.translate(xPos, yPos);
                gCopy.fill(shape);
                gCopy.dispose();

                xPos += (int) (rect.getWidth());
            }
            return xPos;
        }

    }
}