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//******************************************************************************
//
// File: ImagePanel.java
// Package: edu.rit.swing
// Unit: Class edu.rit.swing.ImagePanel
//
// This Java source file is copyright (C) 2006 by Alan Kaminsky. All rights
// reserved. For further information, contact the author, Alan Kaminsky, at
// ark@cs.rit.edu.
//
// This Java source file is part of the Parallel Java Library ("PJ"). PJ 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 3 of the License, or (at your option) any later version.
//
// PJ 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.
//
// Linking this library statically or dynamically with other modules is making a
// combined work based on this library. Thus, the terms and conditions of the
// GNU General Public License cover the whole combination.
//
// As a special exception, the copyright holders of this library give you
// permission to link this library with independent modules to produce an
// executable, regardless of the license terms of these independent modules, and
// to copy and distribute the resulting executable under terms of your choice,
// provided that you also meet, for each linked independent module, the terms
// and conditions of the license of that module. An independent module is a
// module which is not derived from or based on this library. If you modify this
// library, you may extend this exception to your version of the library, but
// you are not obligated to do so. If you do not wish to do so, delete this
// exception statement from your version.
//
// A copy of the GNU General Public License is provided in the file gpl.txt. You
// may also obtain a copy of the GNU General Public License on the World Wide
// Web at http://www.gnu.org/licenses/gpl.html.
//
//******************************************************************************
package edu.rit.swing;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Insets;
import java.awt.RenderingHints;
import java.awt.geom.AffineTransform;
import java.awt.image.RenderedImage;
import javax.swing.JPanel;
/**
* Class ImagePanel provides a GUI component that displays an image. If the
* image is larger than the panel, the image is scaled to fit completely inside
* the panel. The image is displayed centered in the panel.
*
* @author Alan Kaminsky
* @version 30-Jun-2006
*/
public class ImagePanel
extends JPanel
{
// Hidden data members.
private RenderedImage myImage;
// Exported constructors.
/**
* Construct a new image panel. The image panel initially displays no image.
*/
public ImagePanel()
{
setOpaque (true);
}
// Exported operations.
/**
* Specify the image to display in this image panel.
*
* @param theImage Image, or null to display no image.
*/
public void setImage
(RenderedImage theImage)
{
myImage = theImage;
repaint();
}
/**
* Get the image being displayed in this image panel.
*
* @return Image, or null if no image is being displayed.
*/
public RenderedImage getImage()
{
return myImage;
}
// Hidden operations.
/**
* Paint this image panel in the given graphics context.
*
* @param g Graphics context.
*/
protected void paintComponent
(Graphics g)
{
super.paintComponent (g);
if (myImage == null) return;
// Get a new 2-D graphics context.
Graphics2D g2d = (Graphics2D) g.create();
// Turn on antialiasing.
g2d.setRenderingHint
(RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
// Get drawing area.
Dimension panelSize = getSize();
Insets panelInsets = getInsets();
double panelWidth =
panelSize.getWidth() - panelInsets.left - panelInsets.right;
double panelHeight =
panelSize.getHeight() - panelInsets.top - panelInsets.bottom;
// Get image area.
double imageWidth = myImage.getWidth();
double imageHeight = myImage.getHeight();
// Compute scale factor along each dimension.
double xscale = Math.min (panelWidth / imageWidth, 1.0);
double yscale = Math.min (panelHeight / imageHeight, 1.0);
// Set up transformation so image area is centered within drawing area.
AffineTransform transform = new AffineTransform();
if (xscale < yscale)
{
transform.translate
(panelInsets.left,
panelInsets.top + (panelHeight - xscale * imageHeight) / 2.0);
transform.scale (xscale, xscale);
}
else if (xscale > yscale)
{
transform.translate
(panelInsets.left + (panelWidth - yscale * imageWidth) / 2.0,
panelInsets.top);
transform.scale (yscale, yscale);
}
else
{
transform.translate
(panelInsets.left + (panelWidth - xscale * imageWidth) / 2.0,
panelInsets.top + (panelHeight - yscale * imageHeight) / 2.0);
transform.scale (xscale, yscale);
}
// Draw image.
g2d.drawRenderedImage (myImage, transform);
// Dispose of graphics context.
g2d.dispose();
}
}
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