/*
 * NQPhotoAlbum.java       Version 1.0       09/25/2002
 *
 * Copyright (c) 2002 Jim Effinger. All Rights Reserved.
 *
 * End User License Agreement:
 * 1. You may NOT modify or distribute this file or it's compiled class files.
 * 2. You are granted a non-exclusive license to use this software on any Web site.
 * 3. THIS SOFTWARE IS MADE AVAILABLE TO YOU WITH NO WARRANTIES.
 *
 * Contact: admin@nilqualm.com
 */

/* If you want to make improvements to this software, then you must change
 * the class names, method names, and variable names. Also, you must remove
 * or replace all comments with your own, including my copyright notice and
 * EULA. In other words, feel free to use this as a learning tool, but don't
 * modify MY software in any way.
 */

import java.awt.*;
import java.net.*;
import java.awt.event.*;
import java.applet.*;

/**
 * This class is the applet run by the browser. After initializing the
 * components and event listeners for the buttons, it's plan is to read
 * parameters from the html in order to display photos. Not all photos
 * are loaded into memory at once. Instead, they are loaded into memory
 * one at a time as the user clicks through them.
 */
public class NQPhotoAlbum extends Applet {

	//Applet components
	private Panel buttonPanel = new Panel();            //defaults to FlowLayout
	private Panel picturePanel = new Panel();           //defaults to FlowLayout
	private PhotoCanvas canvas = new PhotoCanvas();     //image observer
	private Button bck = new Button("Back");            //looping backward
	private Button fwd = new Button("Next");            //looping forward
	private Button fit = new Button("Fit Image");       //optimize image on canvas
	private Label showing = new Label("     Showing:"); //label for status
	private TextField txt = new TextField("None.", 10); //text for status

	//Other variables
	private Image[] photos;
	private String[] imageNames;
	private URL url;
	private int currIdx = -1;
	
	//Variables configured by PARAM tags in html
	private String numPhotosString;
	private int num_photos;
	private String image_loc;
	

	/** 
	 * Standard browsers can call this method
	 * to get information about the applet.
	 */
	public String getAppletInfo(){
		return new String("by Jim Effinger, version 1.0, Copyright (c) 2002.");
	}

	/**
	 * This method is used when the browser creates the Applet.
	 * Constructor-like code goes here.
	 */
	public void init() {
		
		//This line must come early in order to avoid errors.
		loadParameters();
		
		photos = new Image[num_photos];

		//Add all the GUI components
		setLayout(new BorderLayout(2,2) );
		add(picturePanel, BorderLayout.CENTER);
		add(buttonPanel, BorderLayout.SOUTH);
		canvas.setSize( getSize() );
		canvas.setBackground( Color.white );
		picturePanel.add(canvas);
		buttonPanel.add(bck);
		buttonPanel.add(fwd);
		buttonPanel.add(showing);
		showing.setBackground( Color.lightGray );
		buttonPanel.add(txt);
		buttonPanel.add(fit);
		txt.setBackground( Color.lightGray );
		txt.setEditable( false );
		setBackground( Color.lightGray ); //the applet's color
		
		//Add the button listeners
		bck.addMouseListener( new MouseAdapter(){
			public void mouseClicked(MouseEvent e) {
				showPreviousImage();
			}
		});
		
		fwd.addMouseListener( new MouseAdapter(){
			public void mouseClicked(MouseEvent e) {
				showNextImage();
			}
		});
		
		fit.addMouseListener( new MouseAdapter(){
			public void mouseClicked(MouseEvent e) {
				fitImage();
			}
		});

		//This line serves as a Welcome message.
		canvas.setText("Click the [Next] button to begin.");
	}
	
	/**
	 * This method is used when the browser starts the Applet
	 * either after stopping for some reason, or initially after
	 * the applet is initialized.
	 */
	public void start() {
		//make the canvas fit perfectly in the white region.
		canvas.setSize( picturePanel.getSize() );
	}
	
	/**
	 * Stop method is used usually when the browser looses focus.
	 */
	public void stop() {
	}
	
	/**
	 * Destroy method is used when the applet is refreshed or when the user
	 * quits the browser session. Don't normally put code here.
	 */
	public void destroy() {
	}
	
	/**
	 * This is where the applet draws things on itself. Buttons and
	 * text fields, etc will repaint themselves automatically. In this
	 * software, the PhotoCanvas class is a Canvas component that we
	 * use to "paint" the images. Thus, we may not place any code here.
	 */
	public void paint(Graphics g) {
	}
	

	/**
	 * This method gets information from the html file to allow
	 * the user to configure some of the applet behavior:
	 *
	 * NUM_PHOTOS is the number of photos that this applet will display.
	 * IMAGE_LOC is the folder containing the photos (images).
	 * IMAGEx is a place-holder for loading each image by name, where
	 *        x is a number from 1 to NUM_PHOTOS.
	 */
	private void loadParameters(){
		
		String param;
		
		//First get the number of photos to loop through
		num_photos = 1;
		numPhotosString = getParameter("NUM_PHOTOS");
		if (numPhotosString != null) {
			try{
				num_photos = Integer.parseInt( numPhotosString );
			}catch(Exception e){
				//defaults to 1 photo
			}
		}

		//Get the name of the subFolder containing the images.
		image_loc = getParameter("IMAGE_LOC");
		if (image_loc == null)
			image_loc = ".";
			//defaults to the codeBase folder (where the applet is)
		
		//Initialize the array of image file names to load.
		imageNames = new String[num_photos];
		
		//Then loop through the image name parameters.
		for (int i=0; i < num_photos; i++ )
		{
			param = new String("IMAGE" + String.valueOf(i+1));
			imageNames[i] = new String(getParameter(param));
		}
		
	}

	/**
	 *	Decrements the image index.
	 */
	public void showPreviousImage() {
		
		currIdx--;
		if (currIdx < 0)
			currIdx = num_photos - 1;
		
		displayPhoto(currIdx);
	}
	
	/**
	 *	Increments the image index.
	 */
	public void showNextImage() {
		
		currIdx++;
		if (currIdx == num_photos)
			currIdx = 0;
		
		displayPhoto(currIdx);
	}

	/**
	 * Loads image from Web folder, if necessary, then sets the canvas image.
	 */	
	private void displayPhoto(int idx){
		
		String path = "getImage not called";
		String text = "";

		try{

			//Only load image into memory if not already done.
			if (photos[idx] == null){
				canvas.setText("Loading image, please wait...");
				path = image_loc + "/" + imageNames[idx];
				photos[idx] = getImage(getCodeBase(), path );
			}

			//Update PhotoCanvas.
			canvas.setImage( photos[idx] );
			
			//Update the text field.			
			text = new String( idx + 1 + " of " + num_photos );
			txt.setText( text );
			
		}catch(Exception e){
			//This only works with the AppletViewer.exe utility
			e.printStackTrace();
		}
	}
	
	/**
	 * This method calculates the image size and the aspect ratio
	 * and compares it to the PhotoCanvas, then streches or compresses
	 * the image so that it fits optimally in the area available.
	 */
	public void fitImage(){
		
		float imgH=1, imgW=1, scrH=1, scrW=1;
		float imgRat=1, scrRat=1;
		float multiplier=1;
		int width=100, height=100;
		Image tempImage;

		//only perform if there is an image ready.
		if (currIdx >= 0 && photos[currIdx] != null){
			
			scrH = canvas.getSize().height;
			scrW = canvas.getSize().width;
			imgH = photos[currIdx].getHeight(canvas);
			imgW = photos[currIdx].getWidth(canvas);
	
			imgRat = imgW/imgH;
			scrRat = scrW/scrH;
			
			//This will fit to height
			if (imgRat <= scrRat){
				multiplier = scrH/imgH;
			}
			else{
				//fit to width
				multiplier = scrW/imgW;
			}

			width = (int)(imgW * multiplier);
			height = (int)(imgH * multiplier);
			
			//Generate the better image with smooth scaling.
			tempImage = photos[currIdx].getScaledInstance( 
				width, height, Image.SCALE_SMOOTH );
			
			//Display the better image.
			canvas.setImage(tempImage);

			//replace the old image in the array if not already done.
			if (width != imgW)
				photos[currIdx] = tempImage;
		}
	}

	
}

/*
 * This class is used to render text or images via setter methods.
 */
class PhotoCanvas extends Canvas {
	
	private String text;
	private Image image;
	
	/** Default constructor. Initializes private variables. */
	public PhotoCanvas(){
		text = new String();
	}

	/** Displays a string and sets the image to null. */
	public void setText(String text) {
		this.text = text;
		image = null;
		repaint();
	}
	
	/** Displays the image passed in and empties the text. */
	public void setImage(Image img){
		image = img;
		text = "";
		repaint();
	}


	/** Overrides the paint method for the Canvas object. */
	public void paint(Graphics g) {
		
		if (text.length() > 0){
			//display any text as necessary
			g.drawString(text, 20,20);
		}

		if (image != null){
			//keep the image on the canvas
			g.drawImage(image, 0, 0,this);
		}
	}
	
}