ImageButton.java

package apes.views.buttons;

import java.awt.Color;
import java.awt.Dimension;
import java.io.File;
import java.util.Observable;

import javax.swing.ImageIcon;
import javax.swing.JButton;

import apes.interfaces.LanguageObserver;
import apes.lib.Language;


/**
 * <p>
 * Creates a button with an icon on it. The button is stripped down so that all
 * that is visible is the icon. All buttons should have it's own button class
 * and extend this class which does the base job.
 * </p>
 * <p>
 * The reason all buttons are in a separate class and that this class does not
 * handle all cases (because it would have been easy), is because there may come
 * additional features for these buttons. And then doing it this way make it
 * more extensible.
 * </p>
 * 
 * @author Johan Andersson (johandy@student.chalmers.se)
 */
public abstract class ImageButton extends JButton implements LanguageObserver
{
  /**
   * Path to folder where buttons images are.
   */
  private String buttonPath;

  /**
   * Name of default image. This is used if an image is missing.
   */
  private static final String DEFAULT_ICON = "default";

  /**
   * Default extension for image button icons.
   */
  private static final String DEFAULT_EXTENSION = "png";

  /**
   * A language object.
   */
  private Language language;

  /**
   * Default operations for a button with an image on it.
   */
  public ImageButton()
  {
    this.language = Language.getInstance();

    setToolTipText(language.get(getDescription()));
    language.addObserver(this);

    // Set default button path.
    setButtonPath("images/buttons");

    // Default icon.
    ImageIcon icon = getButtonDefaultIcon();
    setIcon(icon);

    // Size of button should be same as size of image.
    int width = icon.getIconWidth();
    int height = icon.getIconHeight();

    setPreferredSize(new Dimension(width, height));

    // Remove border.
    setBorderPainted(false);

    // Remove filling.
    setContentAreaFilled(false);

    // Background color.
    setBackground(Color.GRAY);

    // Icon to use for rollover.
    setRolloverIcon(getButtonHoverIcon());

    // Icon to use for clicks.
    setPressedIcon(getButtonClickIcon());
  }

  /**
   * Returns the default button icon.
   * 
   * @return The default button icon.
   */
  private ImageIcon getButtonDefaultIcon()
  {
    return getButtonIcon(null);
  }

  /**
   * Returns the hover button icon. By standard should this image be named same
   * as the regular image but with "_hover" added to the end.
   * 
   * @return The hover button icon.
   */
  private ImageIcon getButtonHoverIcon()
  {
    return getButtonIcon("_hover");
  }

  /**
   * Returns the click button icon. By standard should this image be named same
   * as the regular image but with "_click" added to the end.
   * 
   * @return The click button icon.
   */
  private ImageIcon getButtonClickIcon()
  {
    return getButtonIcon("_click");
  }

  /**
   * Returns an ImageIcon object for an image.
   * 
   * @return An ImageIcon object for an image if it exist. If not, a default
   *         icon is returned.
   */
  private ImageIcon getButtonIcon(String postfix)
  {
    // File object for the image.
    File file = new File(getButtonIconPath(getImage() + postfix));

    // If there's no such file. Try with base file.
    if(!file.isFile())
    {
      file = new File(getButtonIconPath(getImage()));
    }

    // Return base image if it exists.
    if(file.isFile())
    {
      return new ImageIcon(file.getPath());
    }

    return new ImageIcon(getButtonIconPath(DEFAULT_ICON));
  }

  /**
   * Returns the path to the image given by name.
   * 
   * @param name The name of the image.
   * @return The path to the image.
   */
  private String getButtonIconPath(String name)
  {
    return getButtonPath() + "/" + name + "." + DEFAULT_EXTENSION;
  }

  /**
   * Returns the default buttons path.
   * 
   * @return Default buttons path.
   */
  public String getButtonPath()
  {
    return buttonPath;
  }

  /**
   * Sets the default buttons path to <code>buttonPath</code>.
   * 
   * @param buttonPath Path to the folder.
   */
  private void setButtonPath(String buttonPath)
  {
    this.buttonPath = buttonPath;
  }

  public void update(Observable o, Object arg)
  {
    setToolTipText(language.get(getDescription()));

    this.updateUI();
  }

  /**
   * Returns the name and name only of the image. If the image name is
   * <code>person_with_hat.png</code>, then this method should return
   * <code>person_with_hat</code>.
   * 
   * @return The name of the image without extension.
   */
  protected abstract String getImage();

  /**
   * Returns the description for that tells what this button does.
   * 
   * @return Description for tag for this button.
   */
  protected abstract String getDescription();
}