net.sourceforge.squirrel_sql.fw.gui.ChooserPreviewer Maven / Gradle / Ivy

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package net.sourceforge.squirrel_sql.fw.gui;
/*
 * Copyright (C) 2001-2003 Colin Bell
 * [email protected]
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */
import java.awt.BorderLayout;
import java.awt.Component;
import java.awt.Dimension;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import java.io.File;
import java.io.FileReader;
import java.io.IOException;

import javax.swing.ImageIcon;
import javax.swing.JComponent;
import javax.swing.JFileChooser;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;

import net.sourceforge.squirrel_sql.fw.util.StringManager;
import net.sourceforge.squirrel_sql.fw.util.StringManagerFactory;
import net.sourceforge.squirrel_sql.fw.util.Utilities;
/**
 * This is a decorator class that can be used in a JFileChooser
 * to preview the contents of a text or image file. If the file name
 * has a suffix of jpg, jpeg, gif or png this class will attempt to render
 * it as an image, else it will render it as text.
 *
 * @author Colin Bell
 */
public class ChooserPreviewer extends JComponent
{
	/** Internationalized strings for this class. */
	private static final StringManager s_stringMgr =
		StringManagerFactory.getStringManager(ChooserPreviewer.class);

	/** Default number of bytes to read from file for preview. */
	private int DFT_BYTES_TO_READ = 2048;

	/**
	 * Empty panel. Used when cannot display anything in the
	 * preview panel.
	 */
	private final JPanel _emptyPnl = new JPanel();

	/** Text area to display the contents of a text file in. */
	private final JTextArea _textComponent = new JTextArea();

	/** Label to display the contents of an image file in. */
	private final JLabel _imageComponent = new JLabel();

	/** Component currently being displayed in the preview area. */
	private Component _currentComponent;

	/** Scrollpane for _currentComponent. */
	private JScrollPane _currentComponentSp;

	/** JFileChooser that this accessory belongs to. */
	private JFileChooser _chooser;

	/**
	 * Listener listening to JFileChooser for a change
	 * in the selected file.
	 */
	private ChooserListener _propChangeListener;

	/**
	 * Default ctor.
	 */
	public ChooserPreviewer()
	{
		super();
		createUserInterface();
	}

	/**
	 * This accessory is being added to a chooser. Add a listener
	 * to the chooser for when the selected file changes.
	 */
	public void addNotify()
	{
		super.addNotify();
		cleanup();
		Component parent = getParent();
		while (parent != null)
		{
			if (parent instanceof JFileChooser)
			{
				_chooser = (JFileChooser)parent;
				break;
			}
			parent = parent.getParent();
		}

		if (_chooser != null)
		{
			_propChangeListener = new ChooserListener();
			_chooser.addPropertyChangeListener(_propChangeListener);
		}
	}

	/**
	 * This accessory is being removed from a chooser. Remove
	 * the listener from the chooser.
	 */
	public void removeNotify()
	{
		super.removeNotify();
		cleanup();
	}

	/**
	 * Remove listener from the chooser.
	 */
	protected void cleanup()
	{
		if (_chooser != null && _propChangeListener != null)
		{
			_chooser.removePropertyChangeListener(_propChangeListener);
		}
		_propChangeListener = null;
		_chooser = null;
	}

	/**
	 * The file selected in the FileChooser has changed so display
	 * its contents in this previewer.
	 */
	protected void fileChanged()
	{
		Component componentToUse = _emptyPnl;

		File file = _chooser.getSelectedFile();
		if (file != null && file.isFile() && file.canRead())
		{
			String suffix = Utilities.getFileNameSuffix(file.getPath()).toLowerCase();
			if (suffix.equals("gif") || suffix.equals("jpg")
				|| suffix.equals("jpeg") || suffix.equals("png"))
			{
				componentToUse = readImageFile(file);
			}
			else
			{
				componentToUse = readTextFile(file);
			}
		}

		if (componentToUse != _currentComponent)
		{
			_currentComponentSp.setViewportView(componentToUse);
			_currentComponent = componentToUse;
		}
	}

	/**
	 * Read the image from the passed file and return it within
	 * a component.
	 *
	 * @param	file	The file to be read.
	 *
	 * @return	The image component.
	 */
	protected Component readImageFile(File file)
	{
		final ImageIcon icon = new ImageIcon(file.getPath());
		_imageComponent.setIcon(icon);
		return _imageComponent;
	}

	/**
	 * Read the first portion of the passed file
	 * and place them in the text component. If cannot
	 * read it then clear the text component.
	 *
	 * @param	file	The file to be read.
	 *
	 * @return	The text component
	 */
	protected Component readTextFile(File file)
	{
		StringBuffer buf = new StringBuffer(DFT_BYTES_TO_READ);
		if (file != null && file.isFile() && file.canRead())
		{
			try
			{
				FileReader rdr = new FileReader(file);
				try
				{
					char[] data = new char[DFT_BYTES_TO_READ];
					int count = rdr.read(data, 0, data.length);
					if (count != -1)
					{
						buf.append(data, 0, count);
					}
				}
				finally
				{
					rdr.close();
				}
			}
			catch (IOException ex)
			{
				buf = new StringBuffer(s_stringMgr.getString("ChooserPreviewer.error", ex.toString()));
			}
		}
		_textComponent.setText(buf.toString());
		_textComponent.setCaretPosition(0);
		return _textComponent;
	}

	/**
	 * Create the User Interface.
	 */
	private void createUserInterface()
	{
		_textComponent.setEditable(false);
		setLayout(new BorderLayout());
		_currentComponentSp = new JScrollPane(_textComponent);
		add(_currentComponentSp, BorderLayout.CENTER);
		setPreferredSize(new Dimension(250, 0));
	}

	/**
	 * Listener to the FileChooser that will preview the seleted file
	 * as it changes in the chooser.
	 */
	private class ChooserListener implements PropertyChangeListener
	{
		public void propertyChange(PropertyChangeEvent evt)
		{
			if (evt.getPropertyName().equals(JFileChooser.SELECTED_FILE_CHANGED_PROPERTY))
			{
				ChooserPreviewer.this.fileChanged();
			}
		}
	}
}