IconManager

IconManager.java

package com.cmosis.iconlib;

import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import javax.imageio.ImageIO;
import javax.swing.Icon;
import javax.swing.ImageIcon;

public class IconManager
{
    private static IconManager instance;
    
    public static IconManager instance()
    {
        if (instance == null)
            instance = new IconManager();
        
        return instance;
    }
    
    private final Map<String, List<String>> iconNames = new HashMap<>();
    private final Map<String, BufferedImage> iconSheets = new HashMap<>();
    private final Map<String, BufferedImage> cache = new HashMap<>();
    
    private IconManager()
    {
    }
    
    public BufferedImage get(final String iconName)
    {
        final IconLocation location = IconLocation.fromString(iconName);
        
        if (cache.containsKey(location.toString()))
            return cache.get(location.toString());
        
        try
        {
            final List<String> names = getIconSheetNames(location.getSetName());
            final int index = names.indexOf(location.getIconName());
            
            if (index < 0)
                throw new IllegalStateException("Icon does not exist: " + location.toString());
            
            final BufferedImage image = getIconFromSheet(location, index);
            cache.put(location.toString(), image);
            return image;
        }
        catch (IOException ex)
        {
            throw new IllegalStateException("Icon does not exist" + location.toString(), ex);
        }
    }
    
    public Icon getIcon(final String iconName)
    {
        return new ImageIcon(get(iconName));
    }
    
    private BufferedImage getIconFromSheet(final IconLocation location, final int index) throws IOException
    {
        final BufferedImage source = getIconSheetImage(location.getSetName());
        
        final int tileWidth = source.getWidth() / 16;
        final int offsetX = (index % tileWidth) * 16;
        final int offsetY = (index / tileWidth) * 16;
        
        final BufferedImage image = new BufferedImage(16, 16, BufferedImage.TYPE_INT_ARGB);
        final Graphics g = image.createGraphics();
        g.drawImage(source, 0, 0, 16, 16, offsetX, offsetY, offsetX + 16, offsetY + 16, null);
        g.dispose();
        
        return image;
    }
    
    private BufferedImage getIconSheetImage(final String sheetName) throws IOException
    {
        if (iconSheets.containsKey(sheetName))
            return iconSheets.get(sheetName);
        
        final InputStream stream = getClass().getResourceAsStream(sheetName + ".png");
        final BufferedImage image = ImageIO.read(stream);
        
        iconSheets.put(sheetName, image);
        return image;
    }
    
    private List<String> getIconSheetNames(final String sheetName) throws IOException
    {
        if (iconNames.containsKey(sheetName))
            return iconNames.get(sheetName);
        
        final InputStream stream = getClass().getResourceAsStream(sheetName + ".txt");
        final BufferedReader reader = new BufferedReader(new InputStreamReader(stream));
        
        String line;
        List<String> names = new ArrayList<>();
        while ((line = reader.readLine()) != null)
            names.add(line);
        
        iconNames.put(sheetName, names);
        return names;
    }
}