/*
 * ImagePanel.java
 *
 * Copyright (C) 2007  Scott Carpenter (scottc at movingtofreedom dot org)
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see http://www.gnu.org/licenses/.
 *
 * Created on November 9, 2007, 4:07 PM
 *
 */

package PicHelper;

import java.io.*;
import java.awt.*;
import javax.swing.*;
import javax.imageio.*;

public class ImagePanel extends JPanel {

	private Image image;
	private Image scaledImage;
	private int imageWidth = 0;
	private int imageHeight = 0;

	// private long paintCount = 0;

	// constructor
	public ImagePanel() {
		super();
	}

	public void loadImage(String file) throws IOException {
		loadImage(new File(file));
	}
	
	public void loadImage(File file) throws IOException {
		image = ImageIO.read(file);
		// might be a situation where image isn't fully loaded, and
		// should check for that before setting...
		imageWidth = image.getWidth(this);
		imageHeight = image.getHeight(this);
		setScaledImage();
	}

	// e.g., containing frame might call this from formComponentResized
	public void scaleImage() {
		setScaledImage();
	}

	// override paintComponent
	public void paintComponent(Graphics g) {
		super.paintComponent(g);
		if (scaledImage != null) {
			// System.out.println("ImagePanel paintComponent " + ++paintCount);
			g.drawImage(scaledImage, 0, 0, this);
		}
	}
	
	public Dimension getPreferredSize() {
		setScaledImage();
		return new Dimension(scaledImage.getWidth(null), scaledImage.getHeight(null));
	}

	private void setScaledImage() {
		if (image != null) {

			// use floats so division below won't round
			float iw = imageWidth;
			float ih = imageHeight;
			float pw = super.getWidth(); // panel width
			float ph = super.getHeight(); // panel height

			if (pw < iw || ph < ih) {

				/*
				 * compare some ratios and then decide which side of image to
				 * anchor to panel and scale the other side (this is all based
				 * on empirical observations and not at all grounded in theory)
				 */

				// System.out.println("pw/ph=" + pw/ph + ", iw/ih=" + iw/ih);

				if ((pw / ph) > (iw / ih)) {
					iw = -1;
					ih = ph;
				} else {
					iw = pw;
					ih = -1;
				}

				// prevent errors if panel is 0 wide or high
				if (iw == 0) {
					iw = -1;
				}
				if (ih == 0) {
					ih = -1;
				}

				scaledImage = image.getScaledInstance(new Float(iw).intValue(),
						new Float(ih).intValue(), Image.SCALE_DEFAULT);

			} else {
				scaledImage = image;
			}

			// System.out.println("iw = " + iw + ", ih = " + ih + ", pw = " + pw
			// + ", ph = " + ph);
		}
	}

}