// This example is from the book _Java in a Nutshell_ by David Flanagan.
// Written by David Flanagan.  Copyright (c) 1996 O'Reilly & Associates.
// You may study, use, modify, and distribute this example for any purpose.
// This example is provided WITHOUT WARRANTY either expressed or implied.

import java.applet.*;
import java.awt.*;

public class Scribble extends Applet {
    private int last_x = 0;
    private int last_y = 0;
    private Color current_color = Color.black;
    private Button clear_button;
    private Choice color_choices;
    
    // Called to initialize the applet.
    public void init() {
        // Set the background color
        this.setBackground(Color.white);

        // Create a button and add it to the applet.
        // Also, set the button's colors
        clear_button = new Button("Clear");
        clear_button.setForeground(Color.black);
        clear_button.setBackground(Color.lightGray);
        this.add(clear_button);

        // Create a menu of colors and add it to the applet.
        // Also set the menus's colors and add a label.
        color_choices = new Choice();
        color_choices.addItem("black");
        color_choices.addItem("red");
        color_choices.addItem("yellow");
        color_choices.addItem("green");
        color_choices.setForeground(Color.black);
        color_choices.setBackground(Color.lightGray);
        this.add(new Label("Color: "));
        this.add(color_choices);
    }
    
    // Called when the user clicks the mouse to start a scribble
    public boolean mouseDown(Event e, int x, int y)
    {
        last_x = x; last_y = y;
        return true;
    }
    
    // Called when the user scribbles with the mouse button down
    public boolean mouseDrag(Event e, int x, int y)
    {
        Graphics g = this.getGraphics();
        g.setColor(current_color);
        g.drawLine(last_x, last_y, x, y);
        last_x = x;
        last_y = y;
        return true;
    }

    // Called when the user clicks the button or chooses a color
    public boolean action(Event event, Object arg) {
        // If the Clear button was clicked on, handle it.
        if (event.target == clear_button) {
            Graphics g = this.getGraphics();
            Rectangle r = this.bounds();
            g.setColor(this.getBackground());
            g.fillRect(r.x, r.y, r.width, r.height);
            return true;
        }
        // Otherwise if a color was chosen, handle that
        else if (event.target == color_choices) {
            String colorname = (String) arg;
            if (arg.equals("black")) current_color = Color.black;
            else if (arg.equals("red")) current_color = Color.red;
            else if (arg.equals("yellow")) current_color = Color.yellow;
            else if (arg.equals("green")) current_color = Color.green;
            return true;
        }
        // Otherwise, let the superclass handle it.
        else return super.action(event, arg);
    }

}