// Program to calculate values of capacitors

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

// Main class begins here
public class CapacitorApplet extends JApplet implements ActionListener
{ int digit1=0; // initialisation of digit1 combo to 0
  int digit2=0; // initialisation of digit2 combo to 0
  int digit3=0; // initialisation of digit3 combo to 0
  static float pvalue=0; // value float for picofarads (pF)
  static float nvalue; // value float for nanofarads (nF)
  static float uvalue; // value float for microfarads (uF)
  float multiplier=0; // multiplier float for multiplier digit
  static JTextField myTextField;  // Text field for value
  static JTextField myTextField1; // Text field for kvalue
  static JTextField myTextField2; // Text field for mvalue
  JButton calcButton; // Button to calculate values
  aboutProgramWindow aboutWindow;

  public void init()
  { Container c = getContentPane();
    c.setLayout(new FlowLayout());
    c.setBackground(Color.white);
    // Combo box values for number of bands
    String[] digits = { "0", "1", "2", "3", "4", "5", "6", "7", "8", "9" };
    String[] multDigits = { "0", "1", "2", "3", "4", "5", "6" };

    // Program Title
    JTextField title = new JTextField("Capacitor Calculator");
    title.setFont(new Font("Verdana", Font.BOLD, 32));
    title.setEditable(false);
    title.setBorder(BorderFactory.createEmptyBorder(0,0,0,0));
    title.setBackground(Color.white);
    c.add(title);

    // Digits text
    JTextField digitText = new JTextField("Digits: ");
    digitText.setFont(new Font("Verdana", Font.BOLD, 14));
    digitText.setEditable(false);
    digitText.setBorder(BorderFactory.createEmptyBorder(0,0,0,0));
    digitText.setBackground(Color.white);
    c.add(digitText);

    // Create the 1st combo box, select 0
    JComboBox digitList1 = new JComboBox(digits);
    digitList1.setSelectedIndex(0);
    digitList1.addActionListener(new ActionListener()
    { public void actionPerformed(ActionEvent e)
      { JComboBox cb = (JComboBox)e.getSource();
        digit1 = (int)cb.getSelectedIndex();
      }
    });
    c.add(digitList1);

    // Create the 2nd combo box, select 0
    JComboBox digitList2 = new JComboBox(digits);
    digitList2.setSelectedIndex(0);
    digitList2.addActionListener(new ActionListener()
    { public void actionPerformed(ActionEvent e)
      { JComboBox cb = (JComboBox)e.getSource();
        digit2 = (int)cb.getSelectedIndex();
      }
    });
    c.add(digitList2);

    // Create the 3rd combo box, select 0
    JComboBox digitList3 = new JComboBox(multDigits);
    digitList3.setSelectedIndex(0);
    digitList3.addActionListener(new ActionListener()
    { public void actionPerformed(ActionEvent e)
      { JComboBox cb = (JComboBox)e.getSource();
        digit3 = (int)cb.getSelectedIndex();
      }
    });
    c.add(digitList3);


    // Button to perform calculations
    JButton myButton = new JButton("Calculate");
    myButton.addActionListener(new calculateButtonHandler());
    c.add(myButton);

    // About Button
    JButton aboutButton = new JButton("About");
    aboutButton.addActionListener(this);
	c.add(aboutButton);

	aboutWindow = new aboutProgramWindow(getAppletContext());
    aboutWindow.pack();

    // Create the 1st text field, for value in pF
    myTextField = new JTextField("           0 pF");
    myTextField.setFont(new Font("Courier", Font.PLAIN, 12));
    myTextField.setEditable(false);
    myTextField.setBackground(Color.white);
    c.add(myTextField);

    // Create the 2nd text field, for value in nF
    myTextField1 = new JTextField("          0 nF");
    myTextField1.setFont(new Font("Courier", Font.PLAIN, 12));
    myTextField1.setEditable(false);
    myTextField1.setBackground(Color.white);
    c.add(myTextField1);

    // Create the 3rd text field, for value in uF
    myTextField2 = new JTextField("          0 uF");
    myTextField2.setFont(new Font("Courier", Font.PLAIN, 12));
    myTextField2.setEditable(false);
    myTextField2.setBackground(Color.white);
    c.add(myTextField2);
  }

  public void destroy()
  { aboutWindow.setVisible(false);
    aboutWindow = null;
  }

  public void actionPerformed(ActionEvent event)
  { aboutWindow.setVisible(true);
  }

  // Performed when calculate button is pressed
  class calculateButtonHandler implements ActionListener
  { public void actionPerformed(ActionEvent e)
    { pvalue = 0; // make sure values are reset
      multiplier = 0; // make sure multiplier is reset
      switch (digit3) // Switch to do the multiplications from digit 3
      { case 0:
          multiplier = 1;       break;
        case 1:
          multiplier = 10;      break;
        case 2:
          multiplier = 100;     break;
        case 3:
          multiplier = 1000;    break;
        case 4:
          multiplier = 10000;   break;
        case 5:
          multiplier = 100000;  break;
        case 6:
          multiplier = 1000000; break;
        default:
          multiplier = 1;
      }
      // Do the maths
      pvalue = (digit1 * 10) + digit2;
      pvalue = (pvalue * multiplier);
      nvalue = (pvalue / 1000f);
      uvalue = (pvalue / 1000000f);

      // Write the pvalue to textfield
      StringBuffer sb = new StringBuffer("               ");
      sb.insert(14, (CapacitorApplet.pvalue+" pF"));
      CapacitorApplet.myTextField.setText(sb.toString());

      // Write the nvalue to textfield1
      StringBuffer sb1 = new StringBuffer("              ");
      sb1.insert(14, (CapacitorApplet.nvalue+" nF"));
      CapacitorApplet.myTextField1.setText(sb1.toString());

      // Write the uvalue to textfield2
      StringBuffer sb2 = new StringBuffer("              ");
      sb2.insert(14, (CapacitorApplet.uvalue+" uF"));
      CapacitorApplet.myTextField2.setText(sb2.toString());
    }
  }
}

class aboutProgramWindow extends JFrame //implements ActionListener
{ TextField aboutField;
  AppletContext appletContext;
  public aboutProgramWindow(AppletContext appletContext)
  { super("About this Applet!");

    this.appletContext = appletContext;

    Container contentPane = getContentPane();
    contentPane.setLayout(new BoxLayout(contentPane, BoxLayout.Y_AXIS));

    contentPane.setBackground(Color.white);


    JLabel label1 = new JLabel("  Capacitor Calculator Applet Produced by Electro-Dan  ");
    label1.setFont(new Font("Verdana", Font.ITALIC, 16));
    label1.setAlignmentX(Component.CENTER_ALIGNMENT);
    contentPane.add(label1);
    JLabel label2 = new JLabel("Free to use and distribute but do not modify without consent");
    label2.setFont(new Font("Verdana", Font.BOLD, 12));
    label2.setAlignmentX(Component.CENTER_ALIGNMENT);
    contentPane.add(label2);
    JLabel label3 = new JLabel("http://jump.to/electro-dan");
    label3.setFont(new Font("Verdana", Font.BOLD, 12));
    label3.setAlignmentX(Component.CENTER_ALIGNMENT);
    contentPane.add(label3);

    addWindowListener(new WindowAdapter()
    { public void windowClosing(WindowEvent event)
      { setVisible(false);
      }
	});
  }
}