HelpTab.java

/*
 * PS3 Media Server, for streaming any medias to your PS3.
 * Copyright (C) 2008  A.Brochard
 *
 * 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; version 2
 * of the License only.
 *
 * 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., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 */
package net.pms.newgui;

import com.jgoodies.forms.builder.PanelBuilder;
import com.jgoodies.forms.layout.CellConstraints;
import com.jgoodies.forms.layout.FormLayout;
import java.awt.Color;
import java.awt.Desktop;
import java.awt.Dimension;
import java.io.File;
import java.io.IOException;
import java.net.URI;
import java.net.URISyntaxException;
import javax.swing.BorderFactory;
import javax.swing.JComponent;
import javax.swing.JEditorPane;
import javax.swing.JScrollPane;
import javax.swing.event.HyperlinkEvent;
import javax.swing.event.HyperlinkListener;
import javax.swing.text.html.HTMLDocument;
import javax.swing.text.html.HTMLEditorKit;
import javax.swing.text.html.StyleSheet;
import net.pms.PMS;
import net.pms.util.PropertiesUtil;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Sets up the panel for the help tab and loads its contents from a file.
 */
public class HelpTab {
	private static final Logger LOGGER = LoggerFactory.getLogger(HelpTab.class);

	private JEditorPane editorPane;

	/**
	 * Return the editor pane for the help tab containing the help contents.
	 * @return The editor pane for the help tab
	 */
	public JEditorPane getList() {
		return editorPane;
	}

	/**
	 * Set up the panel for the help tab and load its contents from a file.
	 * @return The component containing the help tab and its contents
	 */
	public JComponent build() {
		FormLayout layout = new FormLayout(
			"left:pref, 0:grow",
			"pref, fill:default:grow"
		);
		PanelBuilder builder = new PanelBuilder(layout);
		builder.opaque(true);
		CellConstraints cc = new CellConstraints();
		editorPane = new JEditorPane();
		editorPane.setEditable(false);
		editorPane.setContentType("text/html");
		editorPane.setBackground(Color.WHITE);
		HTMLEditorKit editorKit = new HTMLEditorKit();
		StyleSheet styleSheet = ((HTMLDocument) editorKit.createDefaultDocument()).getStyleSheet();
		buildStyleSheet(styleSheet);
		editorKit.setStyleSheet(styleSheet);
		editorPane.setEditorKit(editorKit);

		updateContents();

		// Enable internal anchor links
		editorPane.addHyperlinkListener(new HyperlinkListener() {
			@Override
			public void hyperlinkUpdate(HyperlinkEvent event) {
				try {
					if (event.getEventType() == HyperlinkEvent.EventType.ACTIVATED) {
						String urlString = event.getURL().toExternalForm();

						if (urlString.startsWith("http://") || urlString.startsWith("https://") || urlString.startsWith("ftp://")) {
							// Open external links in the desktop web browser
							URI uri = new URI(urlString);
							Desktop.getDesktop().browse(uri);
						} else {
							// Open anchor links in the editorPane
							editorPane.setPage(event.getURL());
						}
					}
				} catch (IOException | URISyntaxException e) {
					LOGGER.debug("Caught exception", e);
				}
			}
		});

		JScrollPane pane = new JScrollPane(editorPane, JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED, JScrollPane.HORIZONTAL_SCROLLBAR_AS_NEEDED);
		pane.setPreferredSize(new Dimension(500, 400));
		pane.setBorder(BorderFactory.createEmptyBorder());
		builder.add(pane, cc.xy(2, 2));

		return builder.getPanel();
	}

	/**
	 * Load the current help page in the editor pane.
	 */
	public void updateContents() {
		if (editorPane != null) {
			File documentationDir = new File(PropertiesUtil.getProjectProperties().get("project.documentation.dir"));
			String helpPage = PMS.getHelpPage();
			if (!documentationDir.exists()) {
				// Try to load help files from the source tree if not found to make it work while running from an IDE
				File sourceDocumentationDir = new File("src/main/external-resources/documentation");
				if (sourceDocumentationDir.exists()) {
					documentationDir = sourceDocumentationDir;
				}
			}
			File helpFile = new File(documentationDir, helpPage);
			if (helpFile.exists()) {
				try {
					// Display the HTML help file in the editor
					editorPane.setPage(helpFile.toURI().toURL());
				} catch (IOException e) {
					LOGGER.debug("Exception while trying to display help file: ", e);
				}
			} else {
				LOGGER.info("Couldn't find help file \"{}\". Help will not be available.", helpFile.getAbsolutePath());
			}
		}
	}

	/**
	 * This sets all sizes that should be relative to the font size in the HTML
	 * document. This is to respect the OS font size setting used for example
	 * on high DPI monitors.
	 *
	 * @param styleSheet the <code>StyleSheet</code> to modify
	 */
	public void buildStyleSheet(StyleSheet styleSheet) {
		int baseSize = editorPane.getFont().getSize();
		String rule = String.format(
			"body { font-size: %dpt; padding: %dpx; }",
			Math.round((double) baseSize * 7 / 6),
			Math.round((double) baseSize * 5 / 6)
		);
		styleSheet.addRule(rule);

		rule = String.format("h1 { font-size: %dpx; }", baseSize * 2);
		styleSheet.addRule(rule);

		rule = String.format("h2 { font-size: %dpx; }", Math.round(baseSize * 1.5));
		styleSheet.addRule(rule);

		rule = String.format("h3 { font-size: %dpx; }", Math.round(baseSize * 1.17));
		styleSheet.addRule(rule);

		rule = String.format("pre, tt { font-size: %dpt; }", baseSize);
		styleSheet.addRule(rule);

		rule = String.format("dd { margin-bottom: %dpx; }", Math.round((double) baseSize * 10 / 6));
		styleSheet.addRule(rule);
	}
}