SearchField.java

package com.jbidwatcher.ui.util;

/**
 * A text field for search/filter interfaces. The extra functionality includes
 * <p/>
 * a placeholder string (when the user hasn't yet typed anything), and a button
 * <p/>
 * to clear the currently-entered text.
 *
 * @author Elliott Hughes
 */

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

//
// TODO: add a menu of recent searches.
// TODO: make recent searches persistent.

public class SearchField extends JTextField {
  private static final Border CANCEL_BORDER = new CancelBorder();
  private boolean sendsNotificationForEachKeystroke = false;
  private boolean showingPlaceholderText = false;
  private boolean armed = false;

  public SearchField(String placeholderText, int length) {
    super(length);
    addFocusListener(new PlaceholderText(placeholderText));
    initBorder();
    initKeyListener();
  }

  public SearchField(String placeholderText) {
    this(placeholderText, 15);
  }

  public SearchField() {
    this("Search");
  }

  private void initBorder() {
    setBorder(new CompoundBorder(getBorder(), CANCEL_BORDER));

    MouseInputListener mouseInputListener = new CancelListener();
    addMouseListener(mouseInputListener);
    addMouseMotionListener(mouseInputListener);
  }

  private void initKeyListener() {
    addKeyListener(new KeyAdapter() {
      public void keyReleased(KeyEvent e) {
        if (e.getKeyCode() == KeyEvent.VK_ESCAPE) {
          cancel();
        } else if (sendsNotificationForEachKeystroke) {
          maybeNotify();
        }
      }
    });
  }

  private void cancel() {
    setText("");
    postActionEvent();
  }

  private void maybeNotify() {
    if (showingPlaceholderText) {
      return;
    }
    postActionEvent();
  }

  public String getText() {
    if(showingPlaceholderText) return "";
    return super.getText();
  }

  public void setSendsNotificationForEachKeystroke(boolean eachKeystroke) {
    this.sendsNotificationForEachKeystroke = eachKeystroke;
  }

  /**
   * Draws the cancel button as a gray circle with a white cross inside.
   */
  static class CancelBorder extends EmptyBorder {
    private static final Color GRAY = new Color(0.7f, 0.7f, 0.7f);

    CancelBorder() {
      super(0, 0, 0, 15);
    }

    public void paintBorder(Component c, Graphics oldGraphics, int x, int y, int width, int height) {
      SearchField field = (SearchField) c;
      if (field.showingPlaceholderText || field.getText().length() == 0) {
        return;
      }

      Graphics2D g = (Graphics2D) oldGraphics;
      g.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);

      final int circleL = 14;
      final int circleX = x + width - circleL;
      final int circleY = y + (height - 1 - circleL) / 2;
      g.setColor(field.armed ? Color.GRAY : GRAY);
      g.fillOval(circleX, circleY, circleL, circleL);
      final int lineL = circleL - 8;
      final int lineX = circleX + 4;
      final int lineY = circleY + 4;
      g.setColor(Color.WHITE);
      g.drawLine(lineX, lineY, lineX + lineL, lineY + lineL);
      g.drawLine(lineX, lineY + lineL, lineX + lineL, lineY);
    }
  }

  /**
   * Handles a click on the cancel button by clearing the text and notifying
   * <p/>
   * any ActionListeners.
   */

  class CancelListener extends MouseInputAdapter {
    private boolean isOverButton(MouseEvent e) {
      // If the button is down, we might be outside the component
      // without having had mouseExited invoked.
      if (!contains(e.getPoint())) {
        return false;
      }
      // In lieu of proper hit-testing for the circle, check that
      // the mouse is somewhere in the border.
      Rectangle innerArea = SwingUtilities.calculateInnerArea(SearchField.this, null);
      return (!innerArea.contains(e.getPoint()));
    }

    public void mouseDragged(MouseEvent e) {
      arm(e);
    }

    public void mouseEntered(MouseEvent e) {
      arm(e);
    }

    public void mouseExited(MouseEvent e) {
      disarm();
    }

    public void mousePressed(MouseEvent e) {
      arm(e);
    }

    public void mouseReleased(MouseEvent e) {
      if (armed) {
        cancel();
      }
      disarm();
    }

    private void arm(MouseEvent e) {
      armed = (isOverButton(e) && SwingUtilities.isLeftMouseButton(e));
      repaint();
    }

    private void disarm() {
      armed = false;
      repaint();
    }
  }

  /**
   * Replaces the entered text with a gray placeholder string when the
   * <p/>
   * search field doesn't have the focus. The entered text returns when
   * <p/>
   * we get the focus back.
   */
  class PlaceholderText implements FocusListener {
    private String placeholderText;
    private String previousText = "";
    private Color previousColor;

    PlaceholderText(String placeholderText) {
      this.placeholderText = placeholderText;
      focusLost(null);
    }

    public void focusGained(FocusEvent e) {
      setForeground(previousColor);
      setText(previousText);
      showingPlaceholderText = false;
    }

    public void focusLost(FocusEvent e) {
      previousText = getText();
      previousColor = getForeground();
      if (previousText.length() == 0) {
        showingPlaceholderText = true;
        setForeground(Color.GRAY);
        setText(placeholderText);
      }
    }
  }
}