source: josm/trunk/src/org/openstreetmap/josm/tools/ImageProvider.java@ 1180

// License: GPL. Copyright 2007 by Immanuel Scholz and others
package org.openstreetmap.josm.tools;

import java.awt.Cursor;
import java.awt.Graphics;
import java.awt.GraphicsConfiguration;
import java.awt.GraphicsEnvironment;
import java.awt.Image;
import java.awt.Point;
import java.awt.Toolkit;
import java.awt.Transparency;
import java.awt.image.BufferedImage;
import java.io.File;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.Arrays;
import java.util.Collection;
import java.util.HashMap;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;

import javax.swing.Icon;
import javax.swing.ImageIcon;

import org.openstreetmap.josm.Main;

/**
 * Helperclass to support the application with images.
 * @author imi
 */
public class ImageProvider {

    /**
     * Position of an overlay icon
     * @author imi
     */
    public static enum OverlayPosition {NORTHWEST, NORTHEAST, SOUTHWEST, SOUTHEAST}

    /**
     * The icon cache
     */
    private static Map<String, Image> cache = new HashMap<String, Image>();

    /**
     * Add here all ClassLoader whose ressource should be searched.
     * Plugin's class loaders are added by main.
     */
    public static final List<ClassLoader> sources = new LinkedList<ClassLoader>();

    /**
     * Return an image from the specified location.
     *
     * @param subdir    The position of the directory, e.g. "layer"
     * @param name      The icons name (without the ending of ".png")
     * @return The requested Image.
     */
    public static ImageIcon get(String subdir, String name) {
        ImageIcon icon = getIfAvailable(subdir, name);
        if (icon == null) {
            String ext = name.indexOf('.') != -1 ? "" : ".png";
            throw new NullPointerException("/images/"+subdir+name+ext+" not found");
        }
        return icon;
    }

    public static ImageIcon getIfAvailable(String subdir, String name)
    {
        return getIfAvailable((Collection<String>)null, null, subdir, name);
    }
    public static final ImageIcon getIfAvailable(String[] dirs, String id, String subdir, String name)
    {
        return getIfAvailable(Arrays.asList(dirs), id, subdir, name);
    }

    /**
     * Like {@link #get(String)}, but does not throw and return <code>null</code>
     * in case of nothing is found. Use this, if the image to retrieve is optional.
     */
    public static ImageIcon getIfAvailable(Collection<String> dirs, String id, String subdir, String name)
    {
        if (name == null)
            return null;
        if (subdir == null)
            subdir = "";
        else if (!subdir.equals(""))
            subdir += "/";
        String ext = name.indexOf('.') != -1 ? "" : ".png";
        String full_name = subdir+name+ext;
        String cache_name = full_name;
        /* cache separately */
        if(dirs != null && dirs.size() > 0)
            cache_name = "id:"+id+":"+full_name;

        Image img = cache.get(cache_name);
        if (img == null) {
            // getImageUrl() does a ton of "stat()" calls and gets expensive
            // and redundant when you have a whole ton of objects.  So,
            // index the cache by the name of the icon we're looking for
            // and don't bother to create a URL unless we're actually
            // creating the image.
            URL path = getImageUrl(full_name, dirs);
            if (path == null)
                return null;
            img = Toolkit.getDefaultToolkit().createImage(path);
            cache.put(cache_name, img);
        }

        return new ImageIcon(img);
    }

    private static URL getImageUrl(String path, String name)
    {
        if(path.startsWith("resource://"))
        {
            String p = path.substring("resource://".length());
            for (ClassLoader source : sources)
            {
                URL res;
                if ((res = source.getResource(p+name)) != null)
                    return res;
            }
        }
        else
        {
            try {
                File f = new File(path, name);
                if(f.exists())
                    return f.toURI().toURL();
            } catch (MalformedURLException e) {}
        }
        return null;
    }

    private static URL getImageUrl(String imageName, Collection<String> dirs)
    {
        URL u;
        // Try passed directories first
        if(dirs != null)
        {
            for (String name : dirs)
            {
                u = getImageUrl(name, imageName);
                if(u != null) return u;
            }
        }
        // Try user-preference directory
        u = getImageUrl(Main.pref.getPreferencesDir()+"images", imageName);
        if(u != null) return u;

        // Try plugins and josm classloader
        u = getImageUrl("resource://images/", imageName);
        if(u != null) return u;

        // Try all other ressource directories
        for (String location : Main.pref.getAllPossiblePreferenceDirs())
        {
            u = getImageUrl(location+"images", imageName);
            if(u != null) return u;
            u = getImageUrl(location, imageName);
            if(u != null) return u;
        }
        return null;
    }

    /**
     * Shortcut for get("", name);
     */
    public static ImageIcon get(String name) {
        return get("", name);
    }

    public static Cursor getCursor(String name, String overlay) {
        ImageIcon img = get("cursor",name);
        if (overlay != null)
            img = overlay(img, "cursor/modifier/"+overlay, OverlayPosition.SOUTHEAST);
        Cursor c = Toolkit.getDefaultToolkit().createCustomCursor(img.getImage(),
                name.equals("crosshair") ? new Point(10,10) : new Point(3,2), "Cursor");
        return c;
    }

    /**
     * @return an icon that represent the overlay of the two given icons. The
     * second icon is layed on the first relative to the given position.
     */
    public static ImageIcon overlay(Icon ground, String overlayImage, OverlayPosition pos) {
        GraphicsConfiguration conf = GraphicsEnvironment.getLocalGraphicsEnvironment().getDefaultScreenDevice().getDefaultConfiguration();
        int w = ground.getIconWidth();
        int h = ground.getIconHeight();
        ImageIcon overlay = ImageProvider.get(overlayImage);
        int wo = overlay.getIconWidth();
        int ho = overlay.getIconHeight();
        BufferedImage img = conf.createCompatibleImage(w,h, Transparency.TRANSLUCENT);
        Graphics g = img.createGraphics();
        ground.paintIcon(null, g, 0, 0);
        int x = 0, y = 0;
        switch (pos) {
        case NORTHWEST:
            x = 0;
            y = 0;
            break;
        case NORTHEAST:
            x = w-wo;
            y = 0;
            break;
        case SOUTHWEST:
            x = 0;
            y = h-ho;
            break;
        case SOUTHEAST:
            x = w-wo;
            y = h-ho;
            break;
        }
        overlay.paintIcon(null, g, x, y);
        return new ImageIcon(img);
    }

    static {
        try {
            sources.add(ClassLoader.getSystemClassLoader());
        } catch (SecurityException ex) {
            sources.add(ImageProvider.class.getClassLoader());
        }
    }
}