// http://www-cs-faculty.stanford.edu/~eroberts/jtf/

import acm.program.*;
import acm.graphics.*;
import acm.util.RandomGenerator;

import javax.swing.*;
import java.awt.event.*;
import java.awt.Color;

static final void main(String[] args) {
  new SliderProgram().start(args);
}

static class SliderProgram extends GraphicsProgram {

  void init() {
    add(new JButton("Slide"), SOUTH);
    addActionListeners();
  }

  void actionPerformed(ActionEvent e) {
    final String cmd = e.getActionCommand();

    if (cmd.equals("Slide")) {
      final Slider slider = new Slider
        (rgen.nextInt(10, 50), rgen.nextInt(1, 10), rgen.nextColor());
      add(slider, 0, rgen.nextInt(getHeight() - 25));
      new Thread(slider).start();
    }
  }

  final RandomGenerator rgen = RandomGenerator.getInstance();
}

static class Slider extends GRect implements Runnable {

  Slider(int size, int pace, Color colour) {
    super(size<<1, size);
    step = pace;
    setColor(colour);
    setFilled(true);
  }

  void run() {
    for (int i = 0, ii = 1000/step; i != ii; ++i) {
      pause(DELAY);
      move(step, 0);
    }
  }

  final int step;
  static final int DELAY = 1000/60;
}