/*
 * VectorGraphics2D: Vector export for Java(R) Graphics2D
 *
 * (C) Copyright 2010 Erich Seifert <dev[at]erichseifert.de>
 *
 * This file is part of VectorGraphics2D.
 *
 * VectorGraphics2D is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * VectorGraphics2D is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with VectorGraphics2D.  If not, see <http://www.gnu.org/licenses/>.
 */

package de.erichseifert.vectorgraphics2d;

import java.awt.Graphics;
import java.awt.GraphicsConfiguration;
import java.awt.GraphicsDevice;
import java.awt.GraphicsEnvironment;
import java.awt.HeadlessException;
import java.awt.Image;
import java.awt.Transparency;
import java.awt.image.BufferedImage;
import java.awt.image.ColorModel;
import java.awt.image.PixelGrabber;

import javax.swing.ImageIcon;

/**
 * Abstract class that contains utility functions for working with graphics.
 * For example, this includes font handling.
 */
public abstract class GraphicsUtils {
	/**
	 * Default constructor that prevents creation of class.
	 */
	protected GraphicsUtils() {
		throw new UnsupportedOperationException();
	}

	/**
	 * This method returns <code>true</code> if the specified image
	 * has transparent pixels.
	 * Taken from http://www.exampledepot.com/egs/java.awt.image/HasAlpha.html
	 * @param image
	 * @return <code>true</code> if the specified image has transparent pixels,
	 *         <code>false</code> otherwise
	 */
	public static boolean hasAlpha(Image image) {
		// If buffered image, the color model is readily available
		if (image instanceof BufferedImage) {
			BufferedImage bimage = (BufferedImage) image;
			return bimage.getColorModel().hasAlpha();
		}
		// Use a pixel grabber to retrieve the image's color model;
		// grabbing a single pixel is usually sufficient
		PixelGrabber pg = new PixelGrabber(image, 0, 0, 1, 1, false);
		try {
			pg.grabPixels();
		} catch (InterruptedException e) {
		}
		// Get the image's color model
		ColorModel cm = pg.getColorModel();
		return cm.hasAlpha();
	}

	/**
	 * This method returns a buffered image with the contents of an image.
	 * Taken from http://www.exampledepot.com/egs/java.awt.image/Image2Buf.html
	 * @param image Image ot be converted
	 * @return a buffered image with the contents of the specified image
	 */
	public static BufferedImage toBufferedImage(Image image) {
		if (image instanceof BufferedImage) {
			return (BufferedImage) image;
		}
		// This code ensures that all the pixels in the image are loaded
		image = new ImageIcon(image).getImage();
		// Determine if the image has transparent pixels
		boolean hasAlpha = hasAlpha(image);
		// Create a buffered image with a format that's compatible with the
		// screen
		BufferedImage bimage = null;
		GraphicsEnvironment ge = GraphicsEnvironment
			.getLocalGraphicsEnvironment();
		try {
			// Determine the type of transparency of the new buffered image
			int transparency = Transparency.OPAQUE;
			if (hasAlpha) {
				transparency = Transparency.BITMASK;
			}
			// Create the buffered image
			GraphicsDevice gs = ge.getDefaultScreenDevice();
			GraphicsConfiguration gc = gs.getDefaultConfiguration();
			bimage = gc.createCompatibleImage(
					image.getWidth(null), image.getHeight(null), transparency);
		} catch (HeadlessException e) {
			// The system does not have a screen
			bimage = null;
		}
		if (bimage == null) {
			// Create a buffered image using the default color model
			int type = BufferedImage.TYPE_INT_RGB;
			if (hasAlpha) {
				type = BufferedImage.TYPE_INT_ARGB;
			}
			bimage = new BufferedImage(
					image.getWidth(null), image.getHeight(null), type);
		}
		// Copy image to buffered image
		Graphics g = bimage.createGraphics();
		// Paint the image onto the buffered image
		g.drawImage(image, 0, 0, null);
		g.dispose();
		return bimage;
	}
}