imagecanvas.java

这是linux下ssl vpn的实现程序

/*
 *  SSL-Explorer
 *
 *  Copyright (C) 2003-2006 3SP LTD. All Rights Reserved
 *
 *  This program is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU General Public License
 *  as published by the Free Software Foundation; either version 2 of
 *  the License, or (at your option) any later version.
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public
 *  License along with this program; if not, write to the Free Software
 *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */
			
package com.sslexplorer.vpn.client;

import java.awt.Canvas;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.MediaTracker;
import java.net.URL;
import java.awt.Toolkit;

/**
 * Simple component to draw an image. The image can be either centered in the container or
 *
 * @author $author$
 * @version $revision$
 */

public class ImageCanvas
    extends Canvas {

  /**
   * Centered in container
   */
  public final static int CENTERED = 0;

  /**
   * Resize to take up all space allocated to component
   */
  public final static int STRETCH = 1;

  //	Private instance variables
  private MediaTracker tracker;
  private Image image;
  private int scale;
  private int border;
  private Color borderColor;

  /**
   * <p>Construct a new image canvas</p>
   *
   */
  public ImageCanvas() {
    super();
  }

  /**
   * <p>Construct a new image canvas</p>
   *
   * @param iamge image
   *
   */
  public ImageCanvas(Image image) {
    super();
    setImage(image);
  }

  /**
   * <p>Construct a new image canvas given a <code>Class</code> from which the <code>Classloader</code> can
   * be determined, and the resource name. The image will be centered in the container.</p>
   *
   * @param cls name of image
   * @param scale scale
   *
   */
  public ImageCanvas(Class cls, String image) {
    super();
    setImage(loadImage(cls, image));
  }

  public void setImage(URL url) {
    setImage(Toolkit.getDefaultToolkit().getImage(url));
  }

  public static Image loadImage(Class clazz, String resource) {
    String path = resource;

    URL url = clazz.getResource(path);
    Image image = null;
    if (url != null) {
      return Toolkit.getDefaultToolkit().getImage(url);
    }
    else {
      return Toolkit.getDefaultToolkit().getImage(path);
    }
  }


  /**
   * Set the border width around the image
   *
   * @param border border
   */
  public void setBorder(int border) {
    this.border = border;
  }

  /**
   * Get the border width around the image
   *
   * @return border
   */
  public int getBorder() {
    return border;
  }

  /**
   * Get the border color
   *
   * @return border color
   */
  public Color getBorderColor() {
    return borderColor;
  }

  /**
   * Set the border color
   *
   * @param borderColor border color
   */
  public void setBorderColor(Color borderColor) {
    this.borderColor = borderColor;
  }

  /**
   * <p>Set the scale. Can be one of </p>
   *
   * <ul>
   *    <li><code>ImageCanvas.STRETCH</code></li>
   *    <li><code>ImageCanvas.CENTERED</code></li>
   * </ul>
   *
   * @param scale scale
   */
  public void setScale(int scale) {
    this.scale = scale;
    repaint();
  }

  /**
   * <p>Get the scale. Can be one of </p>
   *
   * <ul>
   *    <li><code>ImageCanvas.STRETCH</code></li>
   *    <li><code>ImageCanvas.CENTERED</code></li>
   * </ul>
   *
   * @return scale
   */
  public int getScale() {
    return scale;
  }

  /**
   * Set the image to display
   *
   * @param image
   */
  public void setImage(Image image) {
    //	Prompt a layout if the image size changes
    if ( (image == null && this.image != null) ||
        (image != null && this.image == null) ||
        (image != null && this.image != null && (
        image.getWidth(this) != this.image.getWidth(this) ||
        image.getHeight(this) != this.image.getHeight(this)))) {
      this.image = image;
      doLayout();
    }
    else {
      this.image = image;
    }
    repaint();
  }

  /**
   * Set the image to display
   *
   * @return image
   */
  public Image getImage() {
    return image;
  }

  /*
   * Prevent flicker
   * @see java.awt.Component#update(java.awt.Graphics)
   */
  public void update(Graphics g) {
    paint(g);
  }

  public void paint(Graphics g) {
    Dimension d = getSize();
    Dimension f = new Dimension(d.width - (border * 2), d.height - (border * 2));
    if (image != null) {
      if (scale == STRETCH) {
        g.drawImage(image, border, border, f.width, f.height, this);
      }
      else {
        int x = Math.max( (f.width - image.getWidth(this)) / 2, 0);
        int y = Math.max( (f.height - image.getHeight(this)) / 2, 0);
        g.drawImage(image, x + border, y + border, this);
      }
    }
  }

  public Dimension getPreferredSize() {
    if (image == null) {
      return new Dimension(border * 2, border * 2);
    }
    else {
      return new Dimension(image.getWidth(this) + (border * 2), image.getHeight(this) +
                           (border * 2));
    }
  }

  public Dimension getMinimumSize() {
    return getPreferredSize();
  }
}