Java tutorial
/******************************************************************************* * Copyright (c) 2008 Tran Nam Quang. * All rights reserved. This program and the accompanying materials * are made available under the terms of the Eclipse Public License v1.0 * which accompanies this distribution, and is available at * http://www.eclipse.org/legal/epl-v10.html * * Contributors: * Tran Nam Quang - initial API and implementation *******************************************************************************/ package net.sourceforge.docfetcher.view; import java.io.File; import java.util.ArrayList; import java.util.List; import net.sourceforge.docfetcher.Const; import net.sourceforge.docfetcher.enumeration.Font; import net.sourceforge.docfetcher.enumeration.Icon; import net.sourceforge.docfetcher.enumeration.Msg; import net.sourceforge.docfetcher.enumeration.Pref; import net.sourceforge.docfetcher.model.Document; import net.sourceforge.docfetcher.model.RootScope; import net.sourceforge.docfetcher.parse.HTMLParser; import net.sourceforge.docfetcher.parse.ParseException; import net.sourceforge.docfetcher.parse.Parser; import net.sourceforge.docfetcher.parse.ParserRegistry; import net.sourceforge.docfetcher.parse.TextParser; import net.sourceforge.docfetcher.util.Event; import net.sourceforge.docfetcher.util.UtilFile; import net.sourceforge.docfetcher.util.UtilGUI; import org.apache.lucene.analysis.Analyzer; import org.apache.lucene.analysis.Token; import org.apache.lucene.search.Query; import org.apache.lucene.search.highlight.Formatter; import org.apache.lucene.search.highlight.Highlighter; import org.apache.lucene.search.highlight.NullFragmenter; import org.apache.lucene.search.highlight.QueryScorer; import org.apache.lucene.search.highlight.TokenGroup; import org.eclipse.swt.SWT; import org.eclipse.swt.SWTError; import org.eclipse.swt.browser.ProgressAdapter; import org.eclipse.swt.browser.ProgressEvent; import org.eclipse.swt.custom.StackLayout; import org.eclipse.swt.custom.StyleRange; import org.eclipse.swt.custom.StyledText; import org.eclipse.swt.events.DisposeEvent; import org.eclipse.swt.events.DisposeListener; import org.eclipse.swt.events.SelectionAdapter; import org.eclipse.swt.events.SelectionEvent; import org.eclipse.swt.graphics.Color; import org.eclipse.swt.graphics.Point; import org.eclipse.swt.layout.FormData; import org.eclipse.swt.layout.FormLayout; import org.eclipse.swt.widgets.Composite; import org.eclipse.swt.widgets.Control; import org.eclipse.swt.widgets.Display; import org.eclipse.swt.widgets.Text; import org.eclipse.swt.widgets.ToolBar; import org.eclipse.swt.widgets.ToolItem; /** * @author Tran Nam Quang */ public class PreviewPanel extends Composite { private Composite previewPanel; private StackLayout layout; private Control lastTopControl; private Composite textViewerContainer; private StyledText textViewer; private BrowserProvider browserProvider = new BrowserProvider(); private ToolBar generalToolBar; private ToolBar textToolBar; private Composite browserToolBar; private Text occurrenceCounter; private ToolItem upBt; private ToolItem downBt; private Color highlightColor; /** Whether this preview panel is enabled or not. */ private boolean isActive; /** The currently displayed file. */ private File file; /** The parser that has been used to parse the currently displayed file. */ private Parser parser; /** The query used to obtain the results. */ private Query query; /** * A list of pairs of start indices and lengths that indicate which * characters to highlight in the text-only preview. */ private int[] ranges = new int[0]; private Composite previewBar; public PreviewPanel(Composite parent) { super(parent, SWT.NONE); previewBar = UtilGUI.createCompositeWithBorder(this, true); occurrenceCounter = new Text(previewBar, SWT.BORDER | SWT.SINGLE | SWT.CENTER | SWT.READ_ONLY); occurrenceCounter.setBackground(UtilGUI.getColor(SWT.COLOR_WIDGET_BACKGROUND)); occurrenceCounter.setToolTipText(Msg.occurrence_count.value()); occurrenceCounter.setVisible(false); textToolBar = new ToolBar(previewBar, SWT.FLAT); textToolBar.setVisible(false); upBt = new ToolItem(textToolBar, SWT.FLAT); upBt.setImage(Icon.ARROW_UP.getImage()); upBt.setToolTipText(Msg.prev_occurrence.value()); upBt.setEnabled(false); downBt = new ToolItem(textToolBar, SWT.FLAT); downBt.setImage(Icon.ARROW_DOWN.getImage()); downBt.setToolTipText(Msg.next_occurrence.value()); downBt.setEnabled(false); // Create browser toolbar browserToolBar = new Composite(previewBar, SWT.NONE); browserToolBar.setLayoutData(new FormData(5, 5)); // Without this, the toolbar height would be too large // Create general toolbar generalToolBar = new ToolBar(previewBar, SWT.FLAT); new ToolItem(generalToolBar, SWT.SEPARATOR); final ToolItem htmlPreviewBt = new ToolItem(generalToolBar, SWT.FLAT | SWT.CHECK); htmlPreviewBt.setImage(Icon.BROWSER.getImage()); htmlPreviewBt.setSelection(Pref.Bool.PreviewHTML.getValue()); htmlPreviewBt.setToolTipText(Msg.use_embedded_html_viewer.value()); // Toolbar layout FormDataFactory fdf = FormDataFactory.getInstance(); fdf.setMargin(0).top().bottom().right().applyTo(generalToolBar); // Change search term highlighting color when the corresponding preferences value has changed Pref.IntArray.HighlightColor.evtChanged.add(new Event.Listener<int[]>() { public void update(int[] eventData) { Color oldColor = highlightColor; highlightColor = null; // the following call creates a new color object if this is null setHighlighting(Pref.Bool.HighlightSearchTerms.getValue()); if (oldColor != null) oldColor.dispose(); } }); // Toggle search term highlighting when the corresponding preferences value has changed Pref.Bool.HighlightSearchTerms.evtChanged.add(new Event.Listener<Boolean>() { public void update(Boolean eventData) { setHighlighting(eventData); } }); // Dispose of search term highlighting color on shutdown (it is created lazily) addDisposeListener(new DisposeListener() { public void widgetDisposed(DisposeEvent arg0) { if (highlightColor != null) highlightColor.dispose(); } }); upBt.addSelectionListener(new SelectionAdapter() { public void widgetSelected(SelectionEvent e) { Point sel = textViewer.getSelection(); int searchStart = Math.min(sel.x, sel.y); int tokenStart = -1; int tokenEnd = -1; int tokenIndex = 0; for (int i = 0; i < ranges.length - 1; i = i + 2) { if (ranges[i] + ranges[i + 1] <= searchStart) { tokenStart = ranges[i]; tokenEnd = ranges[i] + ranges[i + 1]; tokenIndex = (i / 2) + 1; } else break; } if (tokenStart == -1) return; textViewer.setSelection(tokenStart, tokenEnd); occurrenceCounter.setText(Integer.toString(tokenIndex) + "/" + //$NON-NLS-1$ Integer.toString(ranges.length / 2)); scrollToMiddle((tokenStart + tokenEnd) / 2); } }); downBt.addSelectionListener(new SelectionAdapter() { public void widgetSelected(SelectionEvent e) { Point sel = textViewer.getSelection(); int searchStart = Math.max(sel.x, sel.y); int tokenStart = -1; int tokenEnd = -1; int tokenIndex = 0; for (int i = 0; i < ranges.length - 1; i = i + 2) { if (ranges[i] >= searchStart) { tokenStart = ranges[i]; tokenEnd = tokenStart + ranges[i + 1]; tokenIndex = (i / 2) + 1; break; } } if (tokenStart == -1) return; textViewer.setSelection(tokenStart, tokenEnd); occurrenceCounter.setText(Integer.toString(tokenIndex) + "/" + //$NON-NLS-1$ Integer.toString(ranges.length / 2)); scrollToMiddle((tokenStart + tokenEnd) / 2); } }); htmlPreviewBt.addSelectionListener(new SelectionAdapter() { public void widgetSelected(SelectionEvent e) { Pref.Bool.PreviewHTML.setValue(htmlPreviewBt.getSelection()); if (parser instanceof HTMLParser) // Only refresh preview panel for HTML documents setFile(file, parser, query, true); } }); // Create preview panel, set up overall layout previewPanel = new Composite(this, SWT.BORDER); setLayout(new FormLayout()); fdf.reset().setMargin(0).top().left().right().applyTo(previewBar); fdf.top(previewBar).bottom().applyTo(previewPanel); previewPanel.setLayout(layout = new StackLayout()); textViewerContainer = new Composite(previewPanel, SWT.NONE); textViewerContainer.setLayout(FillLayoutFactory.getInst().margin(10).create()); textViewer = new StyledText(textViewerContainer, SWT.FULL_SELECTION | SWT.READ_ONLY | SWT.WRAP | SWT.MULTI | SWT.V_SCROLL); textViewerContainer.setBackground(textViewer.getBackground()); layout.topControl = textViewerContainer; textViewer.addSelectionListener(new SelectionAdapter() { public void widgetSelected(SelectionEvent e) { Point sel = textViewer.getSelection(); if (sel.x == sel.y) occurrenceCounter.setText(Integer.toString(ranges.length / 2)); } }); } /** * Vertically divides the text viewer into three segments of equal height * and scrolls the given caret offset into view so that it is always * displayed in the middle segment (either at the top or at bottom of it or * somewhere in between). */ private void scrollToMiddle(int caretOffset) { try { int lineIndexNow = textViewer.getLineAtOffset(caretOffset); int lineIndexTop = textViewer.getTopIndex(); int lineIndexBottom = textViewer.getLineIndex(textViewer.getClientArea().height); double dist = lineIndexBottom - lineIndexTop; int dist13 = (int) (dist / 3); int dist23 = (int) (2 * dist / 3); double lineIndexMiddleTop = lineIndexTop + dist / 3; double lineIndexMiddleBottom = lineIndexBottom - dist / 3; if (lineIndexNow < lineIndexMiddleTop) textViewer.setTopIndex(lineIndexNow - dist13); else if (lineIndexNow > lineIndexMiddleBottom) textViewer.setTopIndex(lineIndexNow - dist23); } catch (Exception e) { // textViewer.getLineAtOffset(..) can throw an IllegalArgumentException // See bug #2778204 } } /** * Enables or disables the preview panel. */ public void setActive(boolean active) { this.isActive = active; if (active) setFile(file, parser, query); else { // Set blank page showViewer(textViewerContainer); textViewer.setText(""); //$NON-NLS-1$ ranges = new int[0]; BrowserPanel browser = browserProvider.getBrowser(previewPanel, browserToolBar, ParserRegistry.getHTMLParser()); if (browser != null) // Is null on KDE desktops browser.setText("<html><head></head><body></body></html>"); //$NON-NLS-1$ } } /** * Sets the file to be displayed in the preview panel. The <tt>parser</tt> * parameter is the parser instance with which the file was parsed. This * method does nothing if the given file is null. */ public void setFile(File file, Parser parser, Query query) { setFile(file, parser, query, false); } /** * Sets the file to be displayed, using <tt>parser</tt> to extract the * text from the file on the disk. This method does nothing if the given * file is null. The <tt>force</tt> parameter specifies whether the * preview should be updated even if neither the file nor the search terms * have changed in the meantime. */ private void setFile(final File file, final Parser parser, final Query query, boolean force) { File lastFile = this.file; Query lastQuery = this.query; this.file = file; this.parser = parser; this.query = query; // Check input if (file == null) return; if (parser == null) // Allowed to be null if file is null, too throw new IllegalArgumentException(); if (!isActive) return; if (file.equals(lastFile) && !force) if (query != null && query.equals(lastQuery)) return; if (file.isDirectory()) throw new IllegalStateException("File expected for preview, got directory instead."); //$NON-NLS-1$ if (!file.exists()) { textViewer.setText(Msg.file_not_found.value()); showViewer(textViewerContainer); return; } // Use the HTML browser if (file.getAbsolutePath().equals(Const.HELP_FILE) || Pref.Bool.PreviewHTML.getValue()) { final BrowserPanel browser = browserProvider.getBrowser(previewPanel, browserToolBar, parser); if (browser != null) { browser.addProgressListener(new ProgressAdapter() { public void completed(ProgressEvent event) { showViewer(browser); upBt.setEnabled(false); downBt.setEnabled(false); occurrenceCounter.setText("0"); //$NON-NLS-1$ } }); browser.setFile(file); return; } // Browser creation failed, go on to next code block } // Use text renderers showViewer(textViewerContainer); // Use monospace font for text files if (parser instanceof TextParser) { org.eclipse.swt.graphics.Font monoFont = Font.PREVIEW_MONO.getFont(); if (!textViewer.getFont().equals(monoFont)) textViewer.setFont(monoFont); } else { org.eclipse.swt.graphics.Font previewFont = Font.PREVIEW.getFont(); if (!textViewer.getFont().equals(previewFont)) textViewer.setFont(previewFont); } textViewer.setText(Msg.loading.value()); // display loading message new Thread() { // run in a thread because parsing the file takes some time public void run() { // Extract the raw text from the file String text; boolean fileParsed = true; try { text = parser.renderText(file); } catch (ParseException e) { text = Msg.cant_read_file.format(e.getMessage()); fileParsed = false; } catch (OutOfMemoryError e) { /* * We can get here if the user sets a high java heap space * value during indexing and then sets a lower value for * search only usage. */ text = Msg.out_of_jvm_memory.value(); fileParsed = false; } if (PreviewPanel.this.file != file) return; // Another preview request had been started while we were parsing /* * Create the message that will be displayed if the character limit * is reached. It is appended to the file contents later; if it * was appended here, some words in it might get highlighted. */ int maxLength = Pref.Int.PreviewLimit.getValue(); final String msg = "...\n\n\n[" //$NON-NLS-1$ + Msg.preview_limit_hint.format(new Object[] { maxLength, Pref.Int.PreviewLimit.name(), Const.USER_PROPERTIES_FILENAME }) + "]"; //$NON-NLS-1$ final boolean exceeded = text.length() > maxLength; if (text.length() > maxLength) text = text.substring(0, maxLength - msg.length()); final String fText = text; /* * Create StyleRange ranges (i.e. start-end integer pairs) for * search term highlighting. Only tokenize preview text if we're * not displaying any info messages and if there are tokens to * highlight. */ ranges = new int[0]; if (fileParsed && query != null) { final List<Integer> rangesList = new ArrayList<Integer>(); Analyzer analyzer = RootScope.analyzer; /* * A formatter is supposed to return formatted text, but * since we're only interested in the start and end offsets * of the search terms, we return null and store the offsets * in a list. */ Formatter nullFormatter = new Formatter() { public String highlightTerm(String originalText, TokenGroup tokenGroup) { for (int i = 0; i < tokenGroup.getNumTokens(); i++) { Token token = tokenGroup.getToken(i); if (tokenGroup.getScore(i) == 0) continue; int start = token.startOffset(); int end = token.endOffset(); rangesList.add(start); rangesList.add(end - start); } return null; } }; Highlighter highlighter = new Highlighter(nullFormatter, new QueryScorer(query, Document.contents)); highlighter.setMaxDocCharsToAnalyze(Integer.MAX_VALUE); highlighter.setTextFragmenter(new NullFragmenter()); try { /* * This has a return value, but we ignore it since we * only want the offsets. */ highlighter.getBestFragment(analyzer, Document.contents, fText); } catch (Exception e) { // We can do without the search term highlighting } // List to array (will be used by the method 'setHighlighting(..)') ranges = new int[rangesList.size()]; for (int i = 0; i < ranges.length; i++) ranges[i] = rangesList.get(i); } // Parsing and tokenizing done; display the results final boolean fFileParsed = fileParsed; Display.getDefault().syncExec(new Runnable() { public void run() { // Enable or disable up and down buttons upBt.setEnabled(ranges.length != 0); downBt.setEnabled(ranges.length != 0); textViewer.setText(fText); setHighlighting(fFileParsed && Pref.Bool.HighlightSearchTerms.getValue()); occurrenceCounter.setText(Integer.toString(ranges.length / 2)); if (exceeded) textViewer.append(msg); // character limit exceeded, append hint } }); } }.start(); } /** * Update the search term highlighting based on the current highlighting * preferences. */ private void setHighlighting(boolean highlight) { if (ranges.length != 0) { Color col = null; if (highlight) { if (highlightColor == null) { // lazy instantiation int[] rgb = Pref.IntArray.HighlightColor.getValue(); highlightColor = new Color(getDisplay(), rgb[0], rgb[1], rgb[2]); } col = highlightColor; } else { col = textViewer.getBackground(); // no highlighting } StyleRange style = new StyleRange(0, 0, null, col); StyleRange[] styles = new StyleRange[ranges.length / 2]; for (int i = 0; i < styles.length; i++) styles[i] = style; textViewer.setStyleRanges(ranges, styles); } else { textViewer.setStyleRange(null); } } /** * Bring the given viewer (either HTML viewer or text viewer) to the front. */ private void showViewer(Composite viewer) { layout.topControl = viewer; if (lastTopControl != layout.topControl) { FormDataFactory fdf = FormDataFactory.getInstance(); fdf.setMargin(0).top().bottom(); if (viewer == textViewerContainer) { browserToolBar.setVisible(false); browserToolBar.setLayoutData(new FormData(5, 5)); textToolBar.setVisible(true); fdf.right(generalToolBar).applyTo(textToolBar); occurrenceCounter.setVisible(true); fdf.right(textToolBar).minWidth(50).applyTo(occurrenceCounter); } else { browserToolBar.setVisible(true); fdf.height(5).top().bottom().left().right(generalToolBar).applyTo(browserToolBar); textToolBar.setVisible(false); textToolBar.setLayoutData(null); occurrenceCounter.setVisible(false); occurrenceCounter.setLayoutData(null); } previewBar.layout(); previewPanel.layout(); lastTopControl = viewer; } } /** * If the internal HTML viewer is available, this method displays the help * page in it and returns true. If not, it opens the help page in the * external HTML browser and returns false. */ public boolean showHelpPage() { parser = ParserRegistry.getHTMLParser(); final BrowserPanel browser = browserProvider.getBrowser(previewPanel, browserToolBar, parser); if (browser == null) { UtilFile.launch(Const.HELP_FILE); return false; } file = new File(Const.HELP_FILE); browser.addProgressListener(new ProgressAdapter() { public void completed(ProgressEvent event) { showViewer(browser); upBt.setEnabled(false); downBt.setEnabled(false); occurrenceCounter.setText("0"); //$NON-NLS-1$ } }); query = null; browser.setFile(file); return true; } } class BrowserProvider { private static boolean isBrowserAvailable = true; private BrowserPanel browser; /** * Returns an SWT browser for the given parent <tt>Composite</tt> and the * given HTML file only if several conditions are met: * <ul> * <li>An embedded browser must be available on the platform</li> * <li>The preferences must allow HTML preview</li> * <li>The given parser (with which the file was parsed) must be the * <tt>HTMLParser</tt>.</li> * </ul> * Returns null otherwise. */ public BrowserPanel getBrowser(Composite parent, Composite toolBar, Parser parser) { if (!isBrowserAvailable) return null; if (!(parser instanceof HTMLParser)) return null; try { if (browser == null) browser = new BrowserPanel(parent, toolBar); return browser; } catch (SWTError e) { isBrowserAvailable = false; if (browser != null) { browser.dispose(); browser = null; } return null; } } }