ImageFileViewer.java

import java.awt.*;
import java.awt.image.*;
import java.awt.event.*;
/**
 * JPG/PPM file viewer.
 *
 * Uses ImageCanvas to displayed the custom xxxFile implementations.
 *
 */
 class ImageFileViewer extends Frame implements WindowListener, ActionListener, MouseListener {

    // control buttons

    Button ExitButton;
    ImageCanvas canvas;

    public ImageFileViewer() {

	// constructor--initialize frame

	super("PPM/JPG File Viewer (Click on canvas to load image)");
	setup();
    }

    // initialize frame contents (buttons, etc.)

    public void setup() {

	Panel CanvasPanel;   // panel for drawing canvas
	Panel ButtonPanel;   // main button panel

	setSize(500,400);

	setLayout(new BorderLayout());

	this.setBackground(Color.gray);
	this.setForeground(Color.black);

	// initialize buttons, make frame responsible for actions

	ExitButton = new Button("Exit");
	ExitButton.addActionListener(this);

	// initialize canvas

	canvas = new ImageCanvas();
	canvas.addMouseListener(this);
	canvas.setSize(400, 300);
	canvas.setBackground(Color.black);
	canvas.setForeground(Color.white);

	ButtonPanel = new Panel();

	// buttons will be centered

	ButtonPanel.setLayout(new FlowLayout(FlowLayout.CENTER));

	// add buttons to button panel

	ButtonPanel.add(ExitButton);

	// add canvas to canvas panel centered

	CanvasPanel = new Panel();
	CanvasPanel.setLayout(new FlowLayout(FlowLayout.CENTER));
	CanvasPanel.add(canvas);

	// put main panels into the frame

	add("North", new Label(""));
	add("South", ButtonPanel);
	add("Center", CanvasPanel);

	// frame is hidden until you show it

	setVisible(true);

	// care about window events

	addWindowListener(this);
    }

    // under the new event handling model, you have to "implement" all
    // of these window operations if you're interested in any of them.
    // We only care about window close events.

    public void windowDeiconified(WindowEvent event) {
    }
    public void windowIconified(WindowEvent event) {
    }
    public void windowActivated(WindowEvent event) {
    }
    public void windowDeactivated(WindowEvent event) {
    }
    public void windowOpened(WindowEvent event) {
    }
    public void windowClosed(WindowEvent event) {
    }

    public void windowClosing(WindowEvent event) {

	// handle user closing frame

	setVisible(false); // hide frame first...
	dispose();         // release resources and destroy frame
	System.exit(0);    // exit program

    }

    public void mouseDragged(MouseEvent event) {

    }


    public void mousePressed(MouseEvent event) {

	// show file dialog for loading PPM when the user clicks...

	    FileDialog f = new FileDialog(this, "Open a JPG/PPM image file",
					  FileDialog.LOAD);
	    f.setFile("*.*");
	    f.show();
	    if (f.getFile() == null) {
		System.out.println("Image open cancelled.");
	    }
	    else {
              try {
                xxxFile file = null;
                String temp = (f.getDirectory()+f.getFile()).toLowerCase();

                temp = temp.substring(temp.lastIndexOf('.')+1,temp.length());
                if (temp.equals("jpg") || temp.equals("jpeg"))
                    file = new JPGFile(f.getDirectory() + f.getFile());
                else if (temp.equals("ppm") || temp.equals("pnm"))
                    file = new PPMFile(f.getDirectory() + f.getFile());

		setImage(file.getBytes(), file.getWidth(), file.getHeight());
              } catch (Exception e) { e.printStackTrace(); }
	    }


    }
    public void setImage(byte[] b, int w, int h) {
      canvas.readImage(b, w, h);
    }

    public void setImage(int[] b, int w, int h) {
      canvas.readImage(b, w, h);
    }
    public void setImage(double[] b, int w, int h) {
      canvas.readImage(b, w, h);
    }
    public void mouseReleased(MouseEvent event) {
    }
    public void mouseMoved(MouseEvent event) {
    }
    public void mouseEntered(MouseEvent event) {
    }
    public void mouseExited(MouseEvent event) {
    }
    public void mouseClicked(MouseEvent event) {
    }

    public void actionPerformed(ActionEvent event) {

	// handle pushbutton events--first get source of event

	Object source = event.getSource();

	if (source == ExitButton) {
	    setVisible(false); // hide frame first...
	    dispose();         // release resources and destroy frame
	    System.exit(0);    // exit program
	}
    }


}