biskuteri-cafe-JKomasto2/ImageWindow.java

import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JButton;
import javax.swing.ImageIcon;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.Dimension;
import java.awt.FontMetrics;
import java.awt.BorderLayout;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import java.awt.event.MouseListener;
import java.awt.event.MouseMotionListener;
import java.awt.event.MouseEvent;
import java.awt.event.MouseWheelListener;
import java.awt.event.MouseWheelEvent;
import java.awt.Image;
import java.net.URL;
import java.net.MalformedURLException;

class
ImageWindow extends JFrame {

	private Attachment[]
	attachments;

	private int
	offset;

//	 -	-%-	 -

	private ImageComponent
	display;

//	---%-@-%---

	public synchronized void
	showAttachments(Attachment[] attachments)
	{
		this.attachments = attachments;

		if (attachments.length == 0) {
			display.setImage(null);
			display.setNext(null);
			display.setPrev(null);
			display.repaint();
			return;
		}

		toImage(offset = 0);
	}

	public void
	toNextImage()
	{
		if (attachments.length == 0) return;
		assert offset < attachments.length - 1;
		toImage(++offset);
	}

	public void
	toPrevImage()
	{
		if (attachments.length == 0) return;
		assert offset > 0;
		toImage(--offset);
	}

//	 -	-%-	 -

	private synchronized void
	toImage(int offset)
	{
		int last = attachments.length  - 1;
		assert offset >= 0;
		assert offset < attachments.length;

		Attachment prev, curr, next;
		curr = attachments[offset];
		next = offset < last ? attachments[offset + 1] : null;
		prev = offset > 0 ? attachments[offset - 1] : null;

		display.setImage(curr.image);
		display.setNext(next != null ? next.image : null);
		display.setPrev(prev != null ? prev.image : null);

		if (!curr.type.equals("image"))
			display.setToolTipText(
				display.getToolTipText()
				+ "\n(Media is of type '" + curr.type + "')"
			);

		repaint();
	}

//	---%-@-%---

	ImageWindow()
	{
		setDefaultCloseOperation(DISPOSE_ON_CLOSE);
		setSize(600, 600);

		display = new ImageComponent(this);
		showAttachments(new Attachment[0]);
		setContentPane(display);
	}

}

class
ImageComponent extends JPanel
implements
	ActionListener,
	MouseListener, MouseMotionListener, MouseWheelListener {

	private ImageWindow
	primaire;

//	 -	-%-	 -

	private Image
	image, prevImage, nextImage;

	private JPanel
	buttonArea;

	private JButton
	prev, next, toggle;

	private boolean
	scaleImage;

	private int
	xOffset, yOffset, zoomLevel;

	private int
	dragX, dragY, xPOffset, yPOffset;

//	---%-@-%---

	public void
	setImage(Image image)
	{
		this.image = image;
		if (image != null) {
			Object p = image.getProperty("comment", this);
			String desc = p instanceof String ? (String)p : null;
			setToolTipText(desc);
		}
		xOffset = yOffset = xPOffset = yPOffset = 0;
		zoomLevel = 100;
	}

	public void
	setPrev(Image image)
	{
		prev.setEnabled(image != null);
		prev.setText(image == null ? "<" : "");
		prev.setIcon(toIcon(image));
	}

	public void
	setNext(Image image)
	{
		next.setEnabled(image != null);
		next.setText(image == null ? ">" : "");
		next.setIcon(toIcon(image));
	}

//	 -	-%-	 -

	public void
	actionPerformed(ActionEvent eA)
	{
		if (eA.getSource() == prev) primaire.toPrevImage();
		if (eA.getSource() == next) primaire.toNextImage();
		if (eA.getSource() == toggle) {
			scaleImage = !scaleImage;
			if (scaleImage) toggle.setText("Show unscaled");
			else toggle.setText("Show scaled to window");
			setImage(this.image);
			repaint();
		}
	}



	public void
	mousePressed(MouseEvent eM)
	{
		dragX = eM.getX();
		dragY = eM.getY();
	}

	public void
	mouseDragged(MouseEvent eM)
	{
		int dx = eM.getX() - dragX;
		int dy = eM.getY() - dragY;
		xPOffset = dx;
		yPOffset = dy;
		repaint();
	}

	public void
	mouseReleased(MouseEvent eM)
	{
		xOffset += xPOffset;
		yOffset += yPOffset;
		xPOffset = yPOffset = 0;
	}

	public void
	mouseWheelMoved(MouseWheelEvent eMw)
	{
		zoomLevel += 10 * -eMw.getUnitsToScroll();
		if (zoomLevel < 50) zoomLevel = 50;
		if (zoomLevel > 400) zoomLevel = 400;
		repaint();
	}


	public void
	mouseEntered(MouseEvent eM) { }

	public void
	mouseExited(MouseEvent eM) { }

	public void
	mouseClicked(MouseEvent eM) { }

	public void
	mouseMoved(MouseEvent eM) { }

//	 -	-%-	 -

	private static ImageIcon
	toIcon(Image image)
	{
		if (image == null) return null;
		return new ImageIcon(image);
	}

//	---%-@-%---

	private class
	Painter extends JPanel {

		protected void
		paintComponent(Graphics g)
		{
			if (image == null)
			{
				String str =
                    "(There are no images being displayed.)";
				FontMetrics fm = g.getFontMetrics();
				int x = (getWidth() - fm.stringWidth(str)) / 2;
				int y = (getHeight() + fm.getHeight()) / 2;
				g.drawString(str, x, y);
				return;
			}
			int wo = image.getWidth(this);
			int ho = image.getHeight(this);
			int wn, hn;
			if (wo > ho) {
				wn = scaleImage ? getWidth() : wo;
				hn = ho * wn / wo;
			}
			else {
				hn = scaleImage ? getHeight() : ho;
				wn = wo * hn / ho;
			}
			wn = wn * zoomLevel / 100;
			hn = hn * zoomLevel / 100;
			int x = (getWidth() - wn) / 2;
			int y = (getHeight() - hn) / 2;
			x += xOffset + xPOffset;
			y += yOffset + yPOffset;
			g.drawImage(image, x, y, wn, hn, this);
		}

	}

//	---%-@-%---

	ImageComponent(ImageWindow primaire)
	{
		this.primaire = primaire;

		Dimension BUTTON_SIZE = new Dimension(48, 48);

		setOpaque(false);
		scaleImage = true;
		zoomLevel = 100;

		prev = new JButton();
		toggle = new JButton("Show unscaled");
		next = new JButton();
		prev.setPreferredSize(BUTTON_SIZE);
		next.setPreferredSize(BUTTON_SIZE);
		prev.addActionListener(this);
		toggle.addActionListener(this);
		next.addActionListener(this);

		buttonArea = new JPanel();
		buttonArea.setOpaque(false);
		buttonArea.add(prev);
		buttonArea.add(toggle);
		buttonArea.add(next);

		setPrev(null);
		setNext(null);

		setLayout(new BorderLayout());
		add(buttonArea, BorderLayout.SOUTH);
		add(new Painter(), BorderLayout.CENTER);

		addMouseListener(this);
		addMouseMotionListener(this);
		addMouseWheelListener(this);
	}

}