159 lines
4.2 KiB
Java
159 lines
4.2 KiB
Java
//******************************************************************************
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//
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// File: ImagePanel.java
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// Package: edu.rit.swing
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// Unit: Class edu.rit.swing.ImagePanel
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//
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// This Java source file is copyright (C) 2013 by Alan Kaminsky. All rights
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// reserved. For further information, contact the author, Alan Kaminsky, at
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// ark@cs.rit.edu.
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//
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// This Java source file is part of the Parallel Java 2 Library ("PJ2"). PJ2 is
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// free software; you can redistribute it and/or modify it under the terms of
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// the GNU General Public License as published by the Free Software Foundation;
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// either version 3 of the License, or (at your option) any later version.
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//
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// PJ2 is distributed in the hope that it will be useful, but WITHOUT ANY
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// WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
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// A PARTICULAR PURPOSE. See the GNU General Public License for more details.
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//
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// A copy of the GNU General Public License is provided in the file gpl.txt. You
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// may also obtain a copy of the GNU General Public License on the World Wide
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// Web at http://www.gnu.org/licenses/gpl.html.
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//
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//******************************************************************************
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package edu.rit.swing;
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import java.awt.Dimension;
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import java.awt.Graphics;
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import java.awt.Graphics2D;
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import java.awt.Insets;
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import java.awt.RenderingHints;
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import java.awt.geom.AffineTransform;
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import java.awt.image.RenderedImage;
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import javax.swing.JPanel;
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/**
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* Class ImagePanel provides a GUI component that displays an image. If the
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* image is larger than the panel, the image is scaled to fit completely inside
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* the panel. The image is displayed centered in the panel.
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*
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* @author Alan Kaminsky
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* @version 30-Jun-2006
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*/
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public class ImagePanel
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extends JPanel
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{
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// Hidden data members.
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private RenderedImage myImage;
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// Exported constructors.
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/**
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* Construct a new image panel. The image panel initially displays no image.
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*/
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public ImagePanel()
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{
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setOpaque (true);
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}
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// Exported operations.
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/**
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* Specify the image to display in this image panel.
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*
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* @param theImage Image, or null to display no image.
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*/
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public void setImage
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(RenderedImage theImage)
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{
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myImage = theImage;
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repaint();
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}
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/**
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* Get the image being displayed in this image panel.
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*
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* @return Image, or null if no image is being displayed.
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*/
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public RenderedImage getImage()
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{
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return myImage;
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}
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// Hidden operations.
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/**
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* Paint this image panel in the given graphics context.
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*
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* @param g Graphics context.
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*/
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protected void paintComponent
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(Graphics g)
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{
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super.paintComponent (g);
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if (myImage == null) return;
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// Get a new 2-D graphics context.
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Graphics2D g2d = (Graphics2D) g.create();
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// Turn on antialiasing.
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g2d.setRenderingHint
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(RenderingHints.KEY_ANTIALIASING,
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RenderingHints.VALUE_ANTIALIAS_ON);
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// Get drawing area.
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Dimension panelSize = getSize();
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Insets panelInsets = getInsets();
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double panelWidth =
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panelSize.getWidth() - panelInsets.left - panelInsets.right;
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double panelHeight =
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panelSize.getHeight() - panelInsets.top - panelInsets.bottom;
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// Get image area.
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double imageWidth = myImage.getWidth();
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double imageHeight = myImage.getHeight();
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// Compute scale factor along each dimension.
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double xscale = Math.min (panelWidth / imageWidth, 1.0);
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double yscale = Math.min (panelHeight / imageHeight, 1.0);
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// Set up transformation so image area is centered within drawing area.
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AffineTransform transform = new AffineTransform();
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if (xscale < yscale)
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{
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transform.translate
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(panelInsets.left,
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panelInsets.top + (panelHeight - xscale * imageHeight) / 2.0);
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transform.scale (xscale, xscale);
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}
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else if (xscale > yscale)
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{
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transform.translate
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(panelInsets.left + (panelWidth - yscale * imageWidth) / 2.0,
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panelInsets.top);
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transform.scale (yscale, yscale);
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}
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else
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{
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transform.translate
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(panelInsets.left + (panelWidth - xscale * imageWidth) / 2.0,
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panelInsets.top + (panelHeight - yscale * imageHeight) / 2.0);
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transform.scale (xscale, yscale);
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}
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// Draw image.
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g2d.drawRenderedImage (myImage, transform);
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// Dispose of graphics context.
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g2d.dispose();
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}
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}
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