ImprovedFormattedTextField.java

package com.clearlyspam23.GLE.debug;

import javax.swing.JFormattedTextField;
import javax.swing.JTextField;
import javax.swing.KeyStroke;
import javax.swing.SwingUtilities;
import javax.swing.event.DocumentEvent;
import javax.swing.event.DocumentListener;
import java.awt.Color;
import java.awt.event.FocusAdapter;
import java.awt.event.FocusEvent;
import java.awt.event.KeyEvent;
import java.text.Format;
import java.text.ParseException;

/**
 * <p>Extension of {@code JFormattedTextField} which solves some of the usability issues</p>
 */
public class ImprovedFormattedTextField extends JFormattedTextField {

  private static final Color ERROR_BACKGROUND_COLOR = new Color( 255, 215, 215 );
  private static final Color ERROR_FOREGROUND_COLOR = null;

  private Color fBackground, fForeground;

  /**
   * Create a new {@code ImprovedFormattedTextField} instance which will use {@code aFormat} for the
   * validation of the user input.
   *
   * @param aFormat The format. May not be {@code null}
   */
  public ImprovedFormattedTextField( Format aFormat ) {
    //use a ParseAllFormat as we do not want to accept user input which is partially valid
    super( new ParseAllFormat( aFormat ) );
    setFocusLostBehavior( JFormattedTextField.COMMIT_OR_REVERT );
    updateBackgroundOnEachUpdate();
    //improve the caret behavior
    //see also http://tips4java.wordpress.com/2010/02/21/formatted-text-field-tips/
    addFocusListener( new MousePositionCorrectorListener() );
  }

  /**
   * Create a new {@code ImprovedFormattedTextField} instance which will use {@code aFormat} for the
   * validation of the user input. The field will be initialized with {@code aValue}.
   *
   * @param aFormat The format. May not be {@code null}
   * @param aValue  The initial value
   */
  public ImprovedFormattedTextField( Format aFormat, Object aValue ) {
    this( aFormat );
    setValue( aValue );
  }

  private void updateBackgroundOnEachUpdate() {
    getDocument().addDocumentListener( new DocumentListener() {
      @Override
      public void insertUpdate( DocumentEvent e ) {
        updateBackground();
      }

      @Override
      public void removeUpdate( DocumentEvent e ) {
        updateBackground();
      }

      @Override
      public void changedUpdate( DocumentEvent e ) {
        updateBackground();
      }
    } );
  }

  /**
   * Update the background color depending on the valid state of the current input. This provides
   * visual feedback to the user
   */
  private void updateBackground() {
    boolean valid = validContent();
    if ( ERROR_BACKGROUND_COLOR != null ) {
      setBackground( valid ? fBackground : ERROR_BACKGROUND_COLOR );
    }
    if ( ERROR_FOREGROUND_COLOR != null ) {
      setForeground( valid ? fForeground : ERROR_FOREGROUND_COLOR );
    }
  }

  @Override
  public void updateUI() {
    super.updateUI();
    fBackground = getBackground();
    fForeground = getForeground();
  }

  private boolean validContent() {
    AbstractFormatter formatter = getFormatter();
    if ( formatter != null ) {
      try {
        formatter.stringToValue( getText() );
        return true;
      } catch ( ParseException e ) {
        return false;
      }
    }
    return true;
  }

  @Override
  public void setValue( Object value ) {
    boolean validValue = true;
    //before setting the value, parse it by using the format
    try {
      AbstractFormatter formatter = getFormatter();
      if ( formatter != null ) {
        formatter.valueToString( value );
      }
    } catch ( ParseException e ) {
      validValue = false;
      updateBackground();
    }
    //only set the value when valid
    if ( validValue ) {
      int old_caret_position = getCaretPosition();
      super.setValue( value );
      setCaretPosition( Math.min( old_caret_position, getText().length() ) );
    }
  }

  @Override
  protected boolean processKeyBinding( KeyStroke ks, KeyEvent e, int condition, boolean pressed ) {
    //do not let the formatted text field consume the enters. This allows to trigger an OK button by
    //pressing enter from within the formatted text field
    if ( validContent() ) {
      return super.processKeyBinding( ks, e,
                                      condition, pressed ) && ks != KeyStroke.getKeyStroke( KeyEvent.VK_ENTER, 0 );
    }
    else {
      return super.processKeyBinding( ks, e,
                                      condition, pressed );
    }
  }

  private static class MousePositionCorrectorListener extends FocusAdapter {
    @Override
    public void focusGained( FocusEvent e ) {
      /* After a formatted text field gains focus, it replaces its text with its
       * current value, formatted appropriately of course. It does this after
       * any focus listeners are notified. We want to make sure that the caret
       * is placed in the correct position rather than the dumb default that is
        * before the 1st character ! */
      final JTextField field = ( JTextField ) e.getSource();
      final int dot = field.getCaret().getDot();
      final int mark = field.getCaret().getMark();
      if ( field.isEnabled() && field.isEditable() ) {
        SwingUtilities.invokeLater( new Runnable() {
          @Override
          public void run() {
            // Only set the caret if the textfield hasn't got a selection on it
            if ( dot == mark ) {
              field.getCaret().setDot( dot );
            }
          }
        } );
      }
    }
  }
}