AlphaIcon.java

/**
 * AlphaIcon class written by Darryl from
 * https://tips4java.wordpress.com/2010/08/22/alpha-icons/
 *
 * Open licence code.
 */
package org.openpnp.gui;

import java.awt.AlphaComposite;
import java.awt.Component;
import java.awt.Graphics;
import java.awt.Graphics2D;

import javax.swing.Icon;

/**
 * An Icon wrapper that paints the contained icon with a specified transparency.
 * <P>
 * <B>Note:</B> This class is not suitable for wrapping an <CODE>ImageIcon</CODE>
 * that holds an animated image.  To show an animated ImageIcon with transparency,
 * use the companion class {@link AlphaImageIcon}.
 *
 * @version 1.0 08/16/10
 * @author Darryl
 */
public class AlphaIcon implements Icon {

  private Icon icon;
  private float alpha;

  /**
   * Creates an <CODE>AlphaIcon</CODE> with the specified icon and opacity.
   * The opacity <CODE>alpha</CODE> should be in the range 0.0F (fully transparent)
   * to 1.0F (fully opaque).
   *
   * @param icon the Icon to wrap
   * @param alpha the opacity
   */
  public AlphaIcon(Icon icon, float alpha) {
    this.icon = icon;
    this.alpha = alpha;
  }

  /**
   * Gets this <CODE>AlphaIcon</CODE>'s opacity
   * @return the opacity, in the range 0.0 to 1.0
   */
  public float getAlpha() {
    return alpha;
  }

  /**
   * Gets the icon wrapped by this <CODE>AlphaIcon</CODE>
   * @return the wrapped icon
   */
  public Icon getIcon() {
    return icon;
  }

  /**
   * Paints the wrapped icon with this <CODE>AlphaIcon</CODE>'s transparency.
   *
   * @param c The component to which the icon is painted
   * @param g the graphics context
   * @param x the X coordinate of the icon's top-left corner
   * @param y the Y coordinate of the icon's top-left corner
   */
  @Override
  public void paintIcon(Component c, Graphics g, int x, int y) {
    Graphics2D g2 = (Graphics2D) g.create();
    g2.setComposite(AlphaComposite.SrcAtop.derive(alpha));
    icon.paintIcon(c, g2, x, y);
    g2.dispose();
  }

  /**
   * Gets the width of the bounding rectangle of this <CODE>AlphaIcon</CODE>.
   * Returns the width of the wrapped icon.
   *
   * @return the width in pixels
   */
  @Override
  public int getIconWidth() {
    return icon.getIconWidth();
  }

  /**
   * Gets the height of the bounding rectangle of this <CODE>AlphaIcon</CODE>.
   ** Returns the height of the wrapped icon.
   * 
   * @return the height in pixels
   */
  @Override
  public int getIconHeight() {
    return icon.getIconHeight();
  }
}