Font Creator for j2game/PixEngine, made for Majoolwip.

FontCreator.java

package org.j2game.editor;

import java.awt.Color;
import java.awt.EventQueue;
import java.awt.Font;
import java.awt.FontMetrics;
import java.awt.Graphics2D;
import java.awt.GraphicsEnvironment;
import java.awt.Rectangle;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.font.FontRenderContext;
import java.awt.font.GlyphVector;
import java.awt.image.BufferedImage;
import java.io.File;

import javax.imageio.ImageIO;
import javax.swing.JButton;
import javax.swing.JComboBox;
import javax.swing.JFileChooser;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.border.EmptyBorder;
import javax.swing.filechooser.FileNameExtensionFilter;

public class FontCreator extends JFrame 
{

	/**
	 * 
	 */
	private static final long serialVersionUID = 1L;
	
	private JPanel contentPane;

	/**
	 * Launch the application.
	 */
	public static void main(String[] args)
	{
		EventQueue.invokeLater(new Runnable()
		{
			public void run()
			{
				try
				{
					FontCreator frame = new FontCreator();
					frame.setVisible(true);
				}
				catch (Exception ex)
				{
					ex.printStackTrace();
				}
			}
		});
	}

	/**
	 * Create the frame.
	 */
	public FontCreator()
	{
		final FontCreator component = this;
		
		try
		{
			UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
		}
		catch (Exception ex) {};
		
		setResizable(false);
		setTitle("Font Creator for j2game");
		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		setBounds(100, 100, 296, 136);
		setLocationRelativeTo(null);
		contentPane = new JPanel();
		contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
		setContentPane(contentPane);
		contentPane.setLayout(null);
		
		JLabel lblChooseFont = new JLabel("Choose Font:");
		lblChooseFont.setBounds(10, 11, 200, 14);
		contentPane.add(lblChooseFont);
		
		final JComboBox<String> fontComboBox = new JComboBox<>();
		fontComboBox.setEditable(true);
		fontComboBox.setBounds(10, 28, 200, 20);
		contentPane.add(fontComboBox);
		
		GraphicsEnvironment e = GraphicsEnvironment.getLocalGraphicsEnvironment();
	    Font[] fonts = e.getAllFonts();
		
		for (Font font : fonts)
		{
			fontComboBox.addItem(font.getName());
		}
		
		fontComboBox.setSelectedItem("Liberation Serif");
		
		JLabel lblFontSize = new JLabel("Font size:");
		lblFontSize.setBounds(220, 11, 60, 14);
		contentPane.add(lblFontSize);
		
		final JComboBox<Integer> sizeComboBox = new JComboBox<>();
		sizeComboBox.setEditable(true);
		sizeComboBox.setBounds(220, 28, 60, 20);
		contentPane.add(sizeComboBox);
		
		int[] sizes = { 8, 9, 10, 11, 12, 14, 16, 18, 20, 22, 24, 26, 28, 36, 48, 72 };
		
		for (int size : sizes)
		{
			sizeComboBox.addItem(size);
		}
		
		sizeComboBox.setSelectedItem(11);
		
		final JButton btnGenerate = new JButton("Create sprite!");
		btnGenerate.addActionListener(new ActionListener()
		{
			public void actionPerformed(ActionEvent arg0)
			{
				// Check if font and size are vaild
				String fontName = (String) fontComboBox.getSelectedItem();
				if (fontName == null || !existsFont(fontName))
				{
					return;
				}
				
				int fontSize = (int) sizeComboBox.getSelectedItem();
				if (fontSize < 8)
				{
					return;
				}
				
				// Create Font instance
				Font font = new Font(fontName, Font.PLAIN, fontSize);
				
				// Create an instance of Graphics2D
				BufferedImage img = new BufferedImage(1, 1, BufferedImage.TYPE_INT_RGB);
				Graphics2D gr = img.createGraphics();
				
				// Calculate width of sprite
				int width = 0;
				
				FontMetrics metrics = new JPanel().getFontMetrics(font);
				
				for (int c = 0; c < 256; c++)
				{
					width += metrics.charWidth((char) c) + 2;
				}
				
				// Calculate height of sprite
				int height = 0;
				
				FontRenderContext frc = gr.getFontRenderContext();
				
				StringBuffer buffer = new StringBuffer(256);
				for (int c = 0; c < 256; c++)
				{
					buffer.append((char) c);
				}
				
				GlyphVector vec = font.createGlyphVector(frc, buffer.toString());
		        Rectangle bounds = vec.getPixelBounds(null, 0, 0);
		        height = bounds.height + 1;
				
		        // Calculate offset of font due to wrong height of chars like '(', ')' or 'Q'		        
				int[] sizes = new int[256];
				
				for (int c = 0; c < 256; c++)
				{
		            GlyphVector gv = font.createGlyphVector(frc, String.valueOf((char) c));
		            sizes[c] = gv.getPixelBounds(null, 0, 0).height;
				}
				
				int total = 0;
				for (int size : sizes)
				{
					total += size;
				}
				
				int ratio = (total / sizes.length);
				fontSize = (fontSize + ratio) / 2;
				
				// Create sprite image and get the Graphics to draw 
				BufferedImage sprite = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
				Graphics2D graphics = sprite.createGraphics();
			    graphics.setColor(Color.MAGENTA);
			    graphics.fillRect(0, 0, width, height);
			    
			    // "Drawer" position
			    int x = 0, y = 0;
			    graphics.setFont(font);
			    
			    for (int c = 0; c < 256; c++)
				{
			    	y = 0;
			    	graphics.setColor(Color.BLUE);
			    	graphics.drawLine(x, y, x, y);
			    	x++;
			    	
			    	y = 1;
			    	graphics.setColor(Color.WHITE);
			    	graphics.drawString(String.valueOf((char) c), x, y + fontSize);
			    	x += metrics.charWidth((char) c);
			    	
			    	y = 0;
			    	graphics.setColor(Color.YELLOW);
			    	graphics.drawLine(x, y, x, y);
			    	x++;
				}
			    
			    // Save file dialog
			    JFileChooser fileChooser = new JFileChooser()
			    {
					/**
					 * 
					 */
					private static final long serialVersionUID = 1L;
					
					@Override
					public File getSelectedFile() 
					{
						File file = super.getSelectedFile();
						if (file == null)
						{
							return null;
						}
						
						String fileName = file.getName();
				        if (!fileName.endsWith(".png"))
				        {
				        	fileName += ".png";
				        }
				        
				        return new File(file.getParentFile(), fileName);
					}
					
					@Override
					public void approveSelection()
					{
						File file = getSelectedFile();
						if (file.exists() && getDialogType() == SAVE_DIALOG)
						{
							int result = JOptionPane.showConfirmDialog(this, "The file " + file.getName() + " already exists. Do you want to replace the existing file?", "Ovewrite file", JOptionPane.YES_NO_CANCEL_OPTION);
							switch (result)
							{
								case JOptionPane.YES_OPTION:
									super.approveSelection();
									return;
								case JOptionPane.NO_OPTION:
									return;
								case JOptionPane.CLOSED_OPTION:
									return;
								case JOptionPane.CANCEL_OPTION:
									cancelSelection();
									return;
							}
						}
						
						super.approveSelection();
					}
				};
				fileChooser.setDialogTitle("Save file");
				fileChooser.setFileFilter(new FileNameExtensionFilter("Portable Network Graphics (.png)", "png"));
				
			    int result = fileChooser.showSaveDialog(component);
			    if (result == JFileChooser.APPROVE_OPTION)
			    {
			        File file = fileChooser.getSelectedFile();
			        
			        try 
			        {
						ImageIO.write(sprite, "png", file);
					} 
			        catch (Exception ex) 
			        {
			        	JOptionPane.showMessageDialog(component, ex.getMessage(), ex.getClass().getCanonicalName(), JOptionPane.ERROR_MESSAGE);
						ex.printStackTrace();
						return;
					}
			        
			        JOptionPane.showMessageDialog(component, "Font successfully saved at " + file.getAbsolutePath(), "File saved", JOptionPane.INFORMATION_MESSAGE);
			    }
			}
		});
		btnGenerate.setFont(new Font(btnGenerate.getFont().getName(), btnGenerate.getFont().getStyle(), 12));
		btnGenerate.setBounds(10, 59, 270, 35);
		contentPane.add(btnGenerate);
		
		setVisible(true);
	}
	
	public int getPopularElement(int[] a)
	{
		int count = 1, tempCount;
		int popular = a[0];
		int temp = 0;
		
		for (int i = 0; i < (a.length - 1); i++)
		{
			temp = a[i];
			tempCount = 0;
			for (int j = 1; j < a.length; j++)
			{
				if (temp == a[j])
				{
					tempCount++;
				}
			}
			
			if (tempCount > count)
			{
				popular = temp;
				count = tempCount;
			}
		}
		
		return popular;
	}
	
	public static boolean existsFont(String fontName)
	{
		GraphicsEnvironment e = GraphicsEnvironment.getLocalGraphicsEnvironment();
	    Font[] fonts = e.getAllFonts();
		
		for (Font font : fonts)
		{
			if (font.getName().equals(fontName))
			{
				return true;
			}
		}
		
		return false;
	}
}

Finding this in 2022 while running through Majoolwip's game engine series. Amazing work!