ImageDataFactory.java

package org.newdawn.slick.opengl;

import java.security.AccessController;
import java.security.PrivilegedAction;

import org.newdawn.slick.util.Log;

/**
 * A static utility to create the appropriate image data for a particular reference.
 *
 * @author kevin
 */
public class ImageDataFactory {
	/** True if we're going to use the native PNG loader - cached so it doesn't have
	 *  the security check repeatedly
	 */
	private static boolean usePngLoader = true;
	/** True if the PNG loader property has been checked */
	private static boolean pngLoaderPropertyChecked = false;
	
	/** The name of the PNG loader configuration property */
	private static final String PNG_LOADER = "org.newdawn.slick.pngloader";
	
	/**
	 * Check PNG loader property. If set the native PNG loader will
	 * not be used.
	 */
	private static void checkProperty() {
		if (!pngLoaderPropertyChecked) {
			pngLoaderPropertyChecked = true;

			try {
				AccessController.doPrivileged(new PrivilegedAction() {
		            public Object run() {
						String val = System.getProperty(PNG_LOADER);
						if ("false".equalsIgnoreCase(val)) {
							usePngLoader = false;
						}
						
						Log.info("Use Java PNG Loader = " + usePngLoader);
						return null;
		            }
				});
			} catch (Throwable e) {
				// ignore, security failure - probably an applet
			}
		}
	}
	
	/**
	 * Create an image data that is appropriate for the reference supplied
	 * 
	 * @param ref The reference to the image to retrieve
	 * @return The image data that can be used to retrieve the data for that resource
	 */
	public static LoadableImageData getImageDataFor(String ref) {
		LoadableImageData imageData;
		checkProperty();
		
		ref = ref.toLowerCase();
		
        if (ref.endsWith(".tga")) {
        	return new TGAImageData();
        } 
        if (ref.endsWith(".png")) {
        	CompositeImageData data = new CompositeImageData();
        	if (usePngLoader) {
        		data.add(new PNGImageData());
        	}
        	data.add(new ImageIOImageData());
        	
        	return data;
        } 
        
        return new ImageIOImageData();
	}
}