org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/text/java/hover/BrowserInformationControl.java - jdt/eclipse.jdt.ui - Git at Google

 /*******************************************************************************
  * Copyright (c) 2000, 2006 IBM Corporation and others.
  * 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:
  *     IBM Corporation - initial API and implementation
  *******************************************************************************/

 package org.eclipse.jdt.internal.ui.text.java.hover;

 import java.io.IOException;
 import java.io.StringReader;
 import java.util.Iterator;

 import org.eclipse.core.runtime.ListenerList;

 import org.eclipse.swt.SWT;
 import org.eclipse.swt.SWTError;
 import org.eclipse.swt.browser.Browser;
 import org.eclipse.swt.browser.LocationAdapter;
 import org.eclipse.swt.browser.LocationEvent;
 import org.eclipse.swt.custom.StyleRange;
 import org.eclipse.swt.events.DisposeEvent;
 import org.eclipse.swt.events.DisposeListener;
 import org.eclipse.swt.events.FocusEvent;
 import org.eclipse.swt.events.FocusListener;
 import org.eclipse.swt.events.KeyEvent;
 import org.eclipse.swt.events.KeyListener;
 import org.eclipse.swt.graphics.Color;
 import org.eclipse.swt.graphics.Font;
 import org.eclipse.swt.graphics.FontData;
 import org.eclipse.swt.graphics.Point;
 import org.eclipse.swt.graphics.Rectangle;
 import org.eclipse.swt.graphics.TextLayout;
 import org.eclipse.swt.graphics.TextStyle;
 import org.eclipse.swt.layout.GridData;
 import org.eclipse.swt.layout.GridLayout;
 import org.eclipse.swt.widgets.Composite;
 import org.eclipse.swt.widgets.Display;
 import org.eclipse.swt.widgets.Event;
 import org.eclipse.swt.widgets.Label;
 import org.eclipse.swt.widgets.Listener;
 import org.eclipse.swt.widgets.Menu;
 import org.eclipse.swt.widgets.Shell;

 import org.eclipse.jface.text.IInformationControl;
 import org.eclipse.jface.text.IInformationControlExtension;
 import org.eclipse.jface.text.IInformationControlExtension3;
 import org.eclipse.jface.text.TextPresentation;

 import org.eclipse.jdt.internal.ui.JavaPlugin;
 import org.eclipse.jdt.internal.ui.text.HTML2TextReader;
 import org.eclipse.jdt.internal.ui.text.HTMLPrinter;
 import org.eclipse.jdt.internal.ui.text.IInformationControlExtension4;


 /**
  * Displays textual information in a {@link org.eclipse.swt.browser.Browser}
  * widget.
  *
  * <p>
  * This class may be instantiated; it is not intended to be subclassed.
  * </p>
  * <p>
  * Current problems:
  * - the size computation is too small
  * - focusLost event is not sent (see https://bugs.eclipse.org/bugs/show_bug.cgi?id=84532)
  * </p>
  *
  * @since 3.1
  */
 public class BrowserInformationControl implements IInformationControl, IInformationControlExtension, IInformationControlExtension3, IInformationControlExtension4,  DisposeListener {


 	/**
 	 * Tells whether the SWT Browser widget and hence this information
 	 * control is available.
 	 *
 	 * @param parent the parent component used for checking or <code>null</code> if none
 	 * @return <code>true</code> if this control is available
 	 */
 	public static boolean isAvailable(Composite parent) {
 		if (!fgAvailabilityChecked) {
 			try {
 				if (parent == null)
 					parent= JavaPlugin.getActiveWorkbenchShell();
 				if (parent == null)
 					return false; // don't store this value - try again later

 				Browser browser= new Browser(parent, SWT.NONE);
 				browser.dispose();
 				fgIsAvailable= true;
 			} catch (SWTError er) {
 				fgIsAvailable= false;
 			} finally {
 				fgAvailabilityChecked= true;
 			}
 		}

 		return fgIsAvailable;
 	}


 	/** Border thickness in pixels. */
 	private static final int BORDER= 1;

 	/**
 	 * Minimal size constraints.
 	 * @since 3.2
 	 */
 	private static final int MIN_WIDTH= 80;
 	private static final int MIN_HEIGHT= 80;


 	/**
 	 * Availability checking cache.
 	 */
 	private static boolean fgIsAvailable= false;
 	private static boolean fgAvailabilityChecked= false;

 	/** The control's shell */
 	private Shell fShell;
 	/** The control's browser widget */
 	private Browser fBrowser;
 	/** Tells whether the browser has content */
 	private boolean fBrowserHasContent;
 	/** The control width constraint */
 	private int fMaxWidth= -1;
 	/** The control height constraint */
 	private int fMaxHeight= -1;
 	private Font fStatusTextFont;
 	private Label fStatusTextField;
 	private String fStatusFieldText;
 	private boolean fHideScrollBars;
 	private Listener fDeactivateListener;
 	private ListenerList fFocusListeners= new ListenerList();
 	private Label fSeparator;
 	private String fInputText;
 	private TextLayout fTextLayout;

 	private TextStyle fBoldStyle;

 	/**
 	 * Creates a default information control with the given shell as parent. The given
 	 * information presenter is used to process the information to be displayed. The given
 	 * styles are applied to the created styled text widget.
 	 *
 	 * @param parent the parent shell
 	 * @param shellStyle the additional styles for the shell
 	 * @param style the additional styles for the styled text widget
 	 */
 	public BrowserInformationControl(Shell parent, int shellStyle, int style) {
 		this(parent, shellStyle, style, null);
 	}

 	/**
 	 * Creates a default information control with the given shell as parent. The given
 	 * information presenter is used to process the information to be displayed. The given
 	 * styles are applied to the created styled text widget.
 	 *
 	 * @param parent the parent shell
 	 * @param shellStyle the additional styles for the shell
 	 * @param style the additional styles for the styled text widget
 	 * @param statusFieldText the text to be used in the optional status field
 	 *                         or <code>null</code> if the status field should be hidden
 	 */
 	public BrowserInformationControl(Shell parent, int shellStyle, int style, String statusFieldText) {
 		fStatusFieldText= statusFieldText;

 		fShell= new Shell(parent, SWT.NO_FOCUS | SWT.ON_TOP | shellStyle);
 		Display display= fShell.getDisplay();
 		fShell.setBackground(display.getSystemColor(SWT.COLOR_BLACK));
 		fTextLayout= new TextLayout(display);

 		Composite composite= fShell;
 		GridLayout layout= new GridLayout(1, false);
 		int border= ((shellStyle & SWT.NO_TRIM) == 0) ? 0 : BORDER;
 		layout.marginHeight= border;
 		layout.marginWidth= border;
 		composite.setLayout(layout);

 		if (statusFieldText != null) {
 			composite= new Composite(composite, SWT.NONE);
 			layout= new GridLayout(1, false);
 			layout.marginHeight= 0;
 			layout.marginWidth= 0;
 			layout.verticalSpacing= 1;
 			layout.horizontalSpacing= 1;
 			composite.setLayout(layout);

 			GridData  gd= new GridData(GridData.FILL_BOTH);
 			composite.setLayoutData(gd);

 			composite.setForeground(display.getSystemColor(SWT.COLOR_INFO_FOREGROUND));
 			composite.setBackground(display.getSystemColor(SWT.COLOR_INFO_BACKGROUND));
 		}

 		// Browser field
 		fBrowser= new Browser(composite, SWT.NONE);
 		fHideScrollBars= (style & SWT.V_SCROLL) == 0 && (style & SWT.H_SCROLL) == 0;

 		GridData gd= new GridData(GridData.BEGINNING | GridData.FILL_BOTH);
 		fBrowser.setLayoutData(gd);

 		fBrowser.setForeground(display.getSystemColor(SWT.COLOR_INFO_FOREGROUND));
 		fBrowser.setBackground(display.getSystemColor(SWT.COLOR_INFO_BACKGROUND));
 		fBrowser.addKeyListener(new KeyListener() {

 			public void keyPressed(KeyEvent e)  {
 				if (e.character == 0x1B) // ESC
 					fShell.dispose();
 			}

 			public void keyReleased(KeyEvent e) {}
 		});
 		/*
 		 * XXX revisit when the Browser support is better
 		 * See https://bugs.eclipse.org/bugs/show_bug.cgi?id=107629. Choosing a link to a
 		 * non-available target will show an error dialog behind the ON_TOP shell that seemingly
 		 * blocks the workbench. Disable links completely for now.
 		 */
 		fBrowser.addLocationListener(new LocationAdapter() {
 			/*
 			 * @see org.eclipse.swt.browser.LocationAdapter#changing(org.eclipse.swt.browser.LocationEvent)
 			 */
 			public void changing(LocationEvent event) {
 				String location= event.location;
 				/*
 				 * Using the Browser.setText API triggers a location change to "about:blank" with
 				 * the mozilla widget. The Browser on carbon uses yet another kind of special
 				 * initialization URLs.
 				 * TODO remove this code once https://bugs.eclipse.org/bugs/show_bug.cgi?id=130314 is fixed
 				 */
 				if (!"about:blank".equals(location) && !("carbon".equals(SWT.getPlatform()) && location.startsWith("applewebdata:"))) //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
 					event.doit= false;
 			}
 		});

 		// Replace browser's built-in context menu with none
 		fBrowser.setMenu(new Menu(fShell, SWT.NONE));

 		// Status field
 		if (statusFieldText != null) {

 			fSeparator= new Label(composite, SWT.SEPARATOR | SWT.HORIZONTAL | SWT.LINE_DOT);
 			fSeparator.setLayoutData(new GridData(GridData.FILL_HORIZONTAL));

 			// Status field label
 			fStatusTextField= new Label(composite, SWT.RIGHT);
 			fStatusTextField.setText(statusFieldText);
 			Font font= fStatusTextField.getFont();
 			FontData[] fontDatas= font.getFontData();
 			for (int i= 0; i < fontDatas.length; i++)
 				fontDatas[i].setHeight(fontDatas[i].getHeight() * 9 / 10);
 			fStatusTextFont= new Font(fStatusTextField.getDisplay(), fontDatas);
 			fStatusTextField.setFont(fStatusTextFont);
 			gd= new GridData(GridData.FILL_HORIZONTAL | GridData.HORIZONTAL_ALIGN_BEGINNING | GridData.VERTICAL_ALIGN_BEGINNING);
 			fStatusTextField.setLayoutData(gd);

 			fStatusTextField.setForeground(display.getSystemColor(SWT.COLOR_WIDGET_DARK_SHADOW));

 			fStatusTextField.setBackground(display.getSystemColor(SWT.COLOR_INFO_BACKGROUND));
 		}

 		addDisposeListener(this);
 		createTextLayout();
 	}

 	/**
 	 * Creates a default information control with the given shell as parent. The given
 	 * information presenter is used to process the information to be displayed. The given
 	 * styles are applied to the created styled text widget.
 	 *
 	 * @param parent the parent shell
 	 * @param style the additional styles for the browser widget
 	 */
 	public BrowserInformationControl(Shell parent,int style) {
 		this(parent, SWT.TOOL | SWT.NO_TRIM, style);
 	}

 	/**
 	 * Creates a default information control with the given shell as parent.
 	 * No information presenter is used to process the information
 	 * to be displayed. No additional styles are applied to the styled text widget.
 	 *
 	 * @param parent the parent shell
 	 */
 	public BrowserInformationControl(Shell parent) {
 		this(parent, SWT.NONE);
 	}


 	/*
 	 * @see IInformationControl#setInformation(String)
 	 */
 	public void setInformation(String content) {
 		fBrowserHasContent= content != null && content.length() > 0;

 		if (!fBrowserHasContent)
 			content= "<html><body ></html>"; //$NON-NLS-1$

 		fInputText= content;

 		int shellStyle= fShell.getStyle();
 		boolean RTL= (shellStyle & SWT.RIGHT_TO_LEFT) != 0;

 		String[] styles= null;
 		if (RTL && !fHideScrollBars)
 			styles= new String[] { "direction:rtl;", "word-wrap:break-word;" }; //$NON-NLS-1$ //$NON-NLS-2$
 		else if (RTL && fHideScrollBars)
 			styles= new String[] { "direction:rtl;", "overflow:hidden;", "word-wrap:break-word;" }; //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
 		else if (fHideScrollBars && true)
 			styles= new String[] { "overflow:hidden;", "word-wrap: break-word;" }; //$NON-NLS-1$ //$NON-NLS-2$

 		if (styles != null) {
 			StringBuffer buffer= new StringBuffer(content);
 			HTMLPrinter.insertStyles(buffer, styles);
 			content= buffer.toString();
 		}

 		fBrowser.setText(content);

 	}

 	/*
 	 * @see org.eclipse.jdt.internal.ui.text.IInformationControlExtension4#setStatusText(java.lang.String)
 	 * @since 3.2
 	 */
 	public void setStatusText(String statusFieldText) {
 		fStatusFieldText= statusFieldText;
 	}

 	/*
 	 * @see IInformationControl#setVisible(boolean)
 	 */
 	public void setVisible(boolean visible) {
 		if (fShell.isVisible() == visible)
 			return;

 		if (visible) {
 			if (fStatusTextField != null) {
 				boolean state= fStatusFieldText != null;
 				if (state)
 					fStatusTextField.setText(fStatusFieldText);
 				fStatusTextField.setVisible(state);
 				fSeparator.setVisible(state);
 			}
 		}

 		fShell.setVisible(visible);
 		if (!visible)
 			setInformation(""); //$NON-NLS-1$
 	}

 	/**
 	 * Creates and initializes the text layout used
 	 * to compute the size hint.
 	 *
 	 * @since 3.2
 	 */
 	private void createTextLayout() {
 		fTextLayout= new TextLayout(fBrowser.getDisplay());

 		// Initialize fonts
 		Font font= fBrowser.getFont();
 		fTextLayout.setFont(font);
 		fTextLayout.setWidth(-1);
 		FontData[] fontData= font.getFontData();
 		for (int i= 0; i < fontData.length; i++)
 			fontData[i].setStyle(SWT.BOLD);
 		font= new Font(fShell.getDisplay(), fontData);
 		fBoldStyle= new TextStyle(font, null, null);

 		// Compute and set tab width
 		fTextLayout.setText("    "); //$NON-NLS-1$
 		int tabWidth = fTextLayout.getBounds().width;
 		fTextLayout.setTabs(new int[] {tabWidth});

 		fTextLayout.setText(""); //$NON-NLS-1$
 	}

 	/*
 	 * @see IInformationControl#dispose()
 	 */
 	public void dispose() {
 		fTextLayout.dispose();
 		fTextLayout= null;
 		fBoldStyle.font.dispose();
 		fBoldStyle= null;
 		if (fShell != null && !fShell.isDisposed())
 			fShell.dispose();
 		else
 			widgetDisposed(null);
 	}

 	/*
 	 * @see org.eclipse.swt.events.DisposeListener#widgetDisposed(org.eclipse.swt.events.DisposeEvent)
 	 */
 	public void widgetDisposed(DisposeEvent event) {
 		if (fStatusTextFont != null && !fStatusTextFont.isDisposed())
 			fStatusTextFont.dispose();

 		fShell= null;
 		fBrowser= null;
 		fStatusTextFont= null;
 	}

 	/*
 	 * @see IInformationControl#setSize(int, int)
 	 */
 	public void setSize(int width, int height) {
 		fShell.setSize(Math.min(width, fMaxWidth), Math.min(height, fMaxHeight));
 	}

 	/*
 	 * @see IInformationControl#setLocation(Point)
 	 */
 	public void setLocation(Point location) {
 		fShell.setLocation(location);
 	}

 	/*
 	 * @see IInformationControl#setSizeConstraints(int, int)
 	 */
 	public void setSizeConstraints(int maxWidth, int maxHeight) {
 		fMaxWidth= maxWidth;
 		fMaxHeight= maxHeight;
 	}

 	/*
 	 * @see IInformationControl#computeSizeHint()
 	 */
 	public Point computeSizeHint() {
 		TextPresentation presentation= new TextPresentation();
 		HTML2TextReader reader= new HTML2TextReader(new StringReader(fInputText), presentation);
 		String text;
 		try {
 			text= reader.getString();
 		} catch (IOException e) {
 			text= ""; //$NON-NLS-1$
 		}

 		fTextLayout.setText(text);
 		Iterator iter= presentation.getAllStyleRangeIterator();
 		while (iter.hasNext()) {
 			StyleRange sr= (StyleRange)iter.next();
 			if (sr.fontStyle == SWT.BOLD)
 				fTextLayout.setStyle(fBoldStyle, sr.start, sr.start + sr.length - 1);
 		}
 		Rectangle bounds= fTextLayout.getBounds();
 		int width= bounds.width;
 		int height= bounds.height;

 		width += 15;
 		height += 25;

 		if (fStatusFieldText != null && fSeparator != null) {
 			fTextLayout.setText(fStatusFieldText);
 			Rectangle statusBounds= fTextLayout.getBounds();
 			Rectangle separatorBounds= fSeparator.getBounds();
 			width= Math.max(width, statusBounds.width);
 			height= height + statusBounds.height + separatorBounds.height;
 		}

 		// Apply size constraints
 		if (fMaxWidth != SWT.DEFAULT)
 			width= Math.min(fMaxWidth, width);
 		if (fMaxHeight != SWT.DEFAULT)
 			height= Math.min(fMaxHeight, height);

 		// Ensure minimal size
 		width= Math.max(MIN_WIDTH, width);
 		height= Math.max(MIN_HEIGHT, height);

 		return new Point(width, height);
 	}

 	/*
 	 * @see org.eclipse.jface.text.IInformationControlExtension3#computeTrim()
 	 */
 	public Rectangle computeTrim() {
 		return fShell.computeTrim(0, 0, 0, 0);
 	}

 	/*
 	 * @see org.eclipse.jface.text.IInformationControlExtension3#getBounds()
 	 */
 	public Rectangle getBounds() {
 		return fShell.getBounds();
 	}

 	/*
 	 * @see org.eclipse.jface.text.IInformationControlExtension3#restoresLocation()
 	 */
 	public boolean restoresLocation() {
 		return false;
 	}

 	/*
 	 * @see org.eclipse.jface.text.IInformationControlExtension3#restoresSize()
 	 */
 	public boolean restoresSize() {
 		return false;
 	}

 	/*
 	 * @see IInformationControl#addDisposeListener(DisposeListener)
 	 */
 	public void addDisposeListener(DisposeListener listener) {
 		fShell.addDisposeListener(listener);
 	}

 	/*
 	 * @see IInformationControl#removeDisposeListener(DisposeListener)
 	 */
 	public void removeDisposeListener(DisposeListener listener) {
 		fShell.removeDisposeListener(listener);
 	}

 	/*
 	 * @see IInformationControl#setForegroundColor(Color)
 	 */
 	public void setForegroundColor(Color foreground) {
 		fBrowser.setForeground(foreground);
 	}

 	/*
 	 * @see IInformationControl#setBackgroundColor(Color)
 	 */
 	public void setBackgroundColor(Color background) {
 		fBrowser.setBackground(background);
 	}

 	/*
 	 * @see IInformationControl#isFocusControl()
 	 */
 	public boolean isFocusControl() {
 		return fBrowser.isFocusControl();
 	}

 	/*
 	 * @see IInformationControl#setFocus()
 	 */
 	public void setFocus() {
 		fShell.forceFocus();
 		fBrowser.setFocus();
 	}

 	/*
 	 * @see IInformationControl#addFocusListener(FocusListener)
 	 */
 	public void addFocusListener(final FocusListener listener) {
 		fBrowser.addFocusListener(listener);

 		/*
 		 * FIXME:	This is a workaround for bug https://bugs.eclipse.org/bugs/show_bug.cgi?id=84532
 		 * 			(Browser widget does not send focusLost event)
 		 */
 		if (fFocusListeners.isEmpty()) {
 			fDeactivateListener=  new Listener() {
 				public void handleEvent(Event event) {
 					Object[] listeners= fFocusListeners.getListeners();
 					for (int i = 0; i < listeners.length; i++)
 						((FocusListener)listeners[i]).focusLost(new FocusEvent(event));
 				}
 			};
 			fBrowser.getShell().addListener(SWT.Deactivate, fDeactivateListener);
 		}
 		fFocusListeners.add(listener);
 	}

 	/*
 	 * @see IInformationControl#removeFocusListener(FocusListener)
 	 */
 	public void removeFocusListener(FocusListener listener) {
 		fBrowser.removeFocusListener(listener);

 		/*
 		 * FIXME:	This is a workaround for bug https://bugs.eclipse.org/bugs/show_bug.cgi?id=84532
 		 * 			(Browser widget does not send focusLost event)
 		 */
 		fFocusListeners.remove(listener);
 		if (fFocusListeners.isEmpty()) {
 			fBrowser.getShell().removeListener(SWT.Deactivate, fDeactivateListener);
 			fDeactivateListener= null;
 		}
 	}

 	/*
 	 * @see IInformationControlExtension#hasContents()
 	 */
 	public boolean hasContents() {
 		return fBrowserHasContent;
 	}
 }
	/*******************************************************************************
	* Copyright (c) 2000, 2006 IBM Corporation and others.
	* 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:
	* IBM Corporation - initial API and implementation
	*******************************************************************************/

	package org.eclipse.jdt.internal.ui.text.java.hover;

	import java.io.IOException;
	import java.io.StringReader;
	import java.util.Iterator;

	import org.eclipse.core.runtime.ListenerList;

	import org.eclipse.swt.SWT;
	import org.eclipse.swt.SWTError;
	import org.eclipse.swt.browser.Browser;
	import org.eclipse.swt.browser.LocationAdapter;
	import org.eclipse.swt.browser.LocationEvent;
	import org.eclipse.swt.custom.StyleRange;
	import org.eclipse.swt.events.DisposeEvent;
	import org.eclipse.swt.events.DisposeListener;
	import org.eclipse.swt.events.FocusEvent;
	import org.eclipse.swt.events.FocusListener;
	import org.eclipse.swt.events.KeyEvent;
	import org.eclipse.swt.events.KeyListener;
	import org.eclipse.swt.graphics.Color;
	import org.eclipse.swt.graphics.Font;
	import org.eclipse.swt.graphics.FontData;
	import org.eclipse.swt.graphics.Point;
	import org.eclipse.swt.graphics.Rectangle;
	import org.eclipse.swt.graphics.TextLayout;
	import org.eclipse.swt.graphics.TextStyle;
	import org.eclipse.swt.layout.GridData;
	import org.eclipse.swt.layout.GridLayout;
	import org.eclipse.swt.widgets.Composite;
	import org.eclipse.swt.widgets.Display;
	import org.eclipse.swt.widgets.Event;
	import org.eclipse.swt.widgets.Label;
	import org.eclipse.swt.widgets.Listener;
	import org.eclipse.swt.widgets.Menu;
	import org.eclipse.swt.widgets.Shell;

	import org.eclipse.jface.text.IInformationControl;
	import org.eclipse.jface.text.IInformationControlExtension;
	import org.eclipse.jface.text.IInformationControlExtension3;
	import org.eclipse.jface.text.TextPresentation;

	import org.eclipse.jdt.internal.ui.JavaPlugin;
	import org.eclipse.jdt.internal.ui.text.HTML2TextReader;
	import org.eclipse.jdt.internal.ui.text.HTMLPrinter;
	import org.eclipse.jdt.internal.ui.text.IInformationControlExtension4;


	/**
	* Displays textual information in a {@link org.eclipse.swt.browser.Browser}
	* widget.
	*
	* <p>
	* This class may be instantiated; it is not intended to be subclassed.
	* </p>
	* <p>
	* Current problems:
	* - the size computation is too small
	* - focusLost event is not sent (see https://bugs.eclipse.org/bugs/show_bug.cgi?id=84532)
	* </p>
	*
	* @since 3.1
	*/
	public class BrowserInformationControl implements IInformationControl, IInformationControlExtension, IInformationControlExtension3, IInformationControlExtension4, DisposeListener {


	/**
	* Tells whether the SWT Browser widget and hence this information
	* control is available.
	*
	* @param parent the parent component used for checking or <code>null</code> if none
	* @return <code>true</code> if this control is available
	*/
	public static boolean isAvailable(Composite parent) {
	if (!fgAvailabilityChecked) {
	try {
	if (parent == null)
	parent= JavaPlugin.getActiveWorkbenchShell();
	if (parent == null)
	return false; // don't store this value - try again later

	Browser browser= new Browser(parent, SWT.NONE);
	browser.dispose();
	fgIsAvailable= true;
	} catch (SWTError er) {
	fgIsAvailable= false;
	} finally {
	fgAvailabilityChecked= true;
	}
	}

	return fgIsAvailable;
	}


	/** Border thickness in pixels. */
	private static final int BORDER= 1;

	/**
	* Minimal size constraints.
	* @since 3.2
	*/
	private static final int MIN_WIDTH= 80;
	private static final int MIN_HEIGHT= 80;


	/**
	* Availability checking cache.
	*/
	private static boolean fgIsAvailable= false;
	private static boolean fgAvailabilityChecked= false;

	/** The control's shell */
	private Shell fShell;
	/** The control's browser widget */
	private Browser fBrowser;
	/** Tells whether the browser has content */
	private boolean fBrowserHasContent;
	/** The control width constraint */
	private int fMaxWidth= -1;
	/** The control height constraint */
	private int fMaxHeight= -1;
	private Font fStatusTextFont;
	private Label fStatusTextField;
	private String fStatusFieldText;
	private boolean fHideScrollBars;
	private Listener fDeactivateListener;
	private ListenerList fFocusListeners= new ListenerList();
	private Label fSeparator;
	private String fInputText;
	private TextLayout fTextLayout;

	private TextStyle fBoldStyle;

	/**
	* Creates a default information control with the given shell as parent. The given
	* information presenter is used to process the information to be displayed. The given
	* styles are applied to the created styled text widget.
	*
	* @param parent the parent shell
	* @param shellStyle the additional styles for the shell
	* @param style the additional styles for the styled text widget
	*/
	public BrowserInformationControl(Shell parent, int shellStyle, int style) {
	this(parent, shellStyle, style, null);
	}

	/**
	* Creates a default information control with the given shell as parent. The given
	* information presenter is used to process the information to be displayed. The given
	* styles are applied to the created styled text widget.
	*
	* @param parent the parent shell
	* @param shellStyle the additional styles for the shell
	* @param style the additional styles for the styled text widget
	* @param statusFieldText the text to be used in the optional status field
	* or <code>null</code> if the status field should be hidden
	*/
	public BrowserInformationControl(Shell parent, int shellStyle, int style, String statusFieldText) {
	fStatusFieldText= statusFieldText;

	fShell= new Shell(parent, SWT.NO_FOCUS \| SWT.ON_TOP \| shellStyle);
	Display display= fShell.getDisplay();
	fShell.setBackground(display.getSystemColor(SWT.COLOR_BLACK));
	fTextLayout= new TextLayout(display);

	Composite composite= fShell;
	GridLayout layout= new GridLayout(1, false);
	int border= ((shellStyle & SWT.NO_TRIM) == 0) ? 0 : BORDER;
	layout.marginHeight= border;
	layout.marginWidth= border;
	composite.setLayout(layout);

	if (statusFieldText != null) {
	composite= new Composite(composite, SWT.NONE);
	layout= new GridLayout(1, false);
	layout.marginHeight= 0;
	layout.marginWidth= 0;
	layout.verticalSpacing= 1;
	layout.horizontalSpacing= 1;
	composite.setLayout(layout);

	GridData gd= new GridData(GridData.FILL_BOTH);
	composite.setLayoutData(gd);

	composite.setForeground(display.getSystemColor(SWT.COLOR_INFO_FOREGROUND));
	composite.setBackground(display.getSystemColor(SWT.COLOR_INFO_BACKGROUND));
	}

	// Browser field
	fBrowser= new Browser(composite, SWT.NONE);
	fHideScrollBars= (style & SWT.V_SCROLL) == 0 && (style & SWT.H_SCROLL) == 0;

	GridData gd= new GridData(GridData.BEGINNING \| GridData.FILL_BOTH);
	fBrowser.setLayoutData(gd);

	fBrowser.setForeground(display.getSystemColor(SWT.COLOR_INFO_FOREGROUND));
	fBrowser.setBackground(display.getSystemColor(SWT.COLOR_INFO_BACKGROUND));
	fBrowser.addKeyListener(new KeyListener() {

	public void keyPressed(KeyEvent e) {
	if (e.character == 0x1B) // ESC
	fShell.dispose();
	}

	public void keyReleased(KeyEvent e) {}
	});
	/*
	* XXX revisit when the Browser support is better
	* See https://bugs.eclipse.org/bugs/show_bug.cgi?id=107629. Choosing a link to a
	* non-available target will show an error dialog behind the ON_TOP shell that seemingly
	* blocks the workbench. Disable links completely for now.
	*/
	fBrowser.addLocationListener(new LocationAdapter() {
	/*
	* @see org.eclipse.swt.browser.LocationAdapter#changing(org.eclipse.swt.browser.LocationEvent)
	*/
	public void changing(LocationEvent event) {
	String location= event.location;
	/*
	* Using the Browser.setText API triggers a location change to "about:blank" with
	* the mozilla widget. The Browser on carbon uses yet another kind of special
	* initialization URLs.
	* TODO remove this code once https://bugs.eclipse.org/bugs/show_bug.cgi?id=130314 is fixed
	*/
	if (!"about:blank".equals(location) && !("carbon".equals(SWT.getPlatform()) && location.startsWith("applewebdata:"))) //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
	event.doit= false;
	}
	});

	// Replace browser's built-in context menu with none
	fBrowser.setMenu(new Menu(fShell, SWT.NONE));

	// Status field
	if (statusFieldText != null) {

	fSeparator= new Label(composite, SWT.SEPARATOR \| SWT.HORIZONTAL \| SWT.LINE_DOT);
	fSeparator.setLayoutData(new GridData(GridData.FILL_HORIZONTAL));

	// Status field label
	fStatusTextField= new Label(composite, SWT.RIGHT);
	fStatusTextField.setText(statusFieldText);
	Font font= fStatusTextField.getFont();
	FontData[] fontDatas= font.getFontData();
	for (int i= 0; i < fontDatas.length; i++)
	fontDatas[i].setHeight(fontDatas[i].getHeight() * 9 / 10);
	fStatusTextFont= new Font(fStatusTextField.getDisplay(), fontDatas);
	fStatusTextField.setFont(fStatusTextFont);
	gd= new GridData(GridData.FILL_HORIZONTAL \| GridData.HORIZONTAL_ALIGN_BEGINNING \| GridData.VERTICAL_ALIGN_BEGINNING);
	fStatusTextField.setLayoutData(gd);

	fStatusTextField.setForeground(display.getSystemColor(SWT.COLOR_WIDGET_DARK_SHADOW));

	fStatusTextField.setBackground(display.getSystemColor(SWT.COLOR_INFO_BACKGROUND));
	}

	addDisposeListener(this);
	createTextLayout();
	}

	/**
	* Creates a default information control with the given shell as parent. The given
	* information presenter is used to process the information to be displayed. The given
	* styles are applied to the created styled text widget.
	*
	* @param parent the parent shell
	* @param style the additional styles for the browser widget
	*/
	public BrowserInformationControl(Shell parent,int style) {
	this(parent, SWT.TOOL \| SWT.NO_TRIM, style);
	}

	/**
	* Creates a default information control with the given shell as parent.
	* No information presenter is used to process the information
	* to be displayed. No additional styles are applied to the styled text widget.
	*
	* @param parent the parent shell
	*/
	public BrowserInformationControl(Shell parent) {
	this(parent, SWT.NONE);
	}


	/*
	* @see IInformationControl#setInformation(String)
	*/
	public void setInformation(String content) {
	fBrowserHasContent= content != null && content.length() > 0;

	if (!fBrowserHasContent)
	content= "<html><body ></html>"; //$NON-NLS-1$

	fInputText= content;

	int shellStyle= fShell.getStyle();
	boolean RTL= (shellStyle & SWT.RIGHT_TO_LEFT) != 0;

	String[] styles= null;
	if (RTL && !fHideScrollBars)
	styles= new String[] { "direction:rtl;", "word-wrap:break-word;" }; //$NON-NLS-1$ //$NON-NLS-2$
	else if (RTL && fHideScrollBars)
	styles= new String[] { "direction:rtl;", "overflow:hidden;", "word-wrap:break-word;" }; //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
	else if (fHideScrollBars && true)
	styles= new String[] { "overflow:hidden;", "word-wrap: break-word;" }; //$NON-NLS-1$ //$NON-NLS-2$

	if (styles != null) {
	StringBuffer buffer= new StringBuffer(content);
	HTMLPrinter.insertStyles(buffer, styles);
	content= buffer.toString();
	}

	fBrowser.setText(content);

	}

	/*
	* @see org.eclipse.jdt.internal.ui.text.IInformationControlExtension4#setStatusText(java.lang.String)
	* @since 3.2
	*/
	public void setStatusText(String statusFieldText) {
	fStatusFieldText= statusFieldText;
	}

	/*
	* @see IInformationControl#setVisible(boolean)
	*/
	public void setVisible(boolean visible) {
	if (fShell.isVisible() == visible)
	return;

	if (visible) {
	if (fStatusTextField != null) {
	boolean state= fStatusFieldText != null;
	if (state)
	fStatusTextField.setText(fStatusFieldText);
	fStatusTextField.setVisible(state);
	fSeparator.setVisible(state);
	}
	}

	fShell.setVisible(visible);
	if (!visible)
	setInformation(""); //$NON-NLS-1$
	}

	/**
	* Creates and initializes the text layout used
	* to compute the size hint.
	*
	* @since 3.2
	*/
	private void createTextLayout() {
	fTextLayout= new TextLayout(fBrowser.getDisplay());

	// Initialize fonts
	Font font= fBrowser.getFont();
	fTextLayout.setFont(font);
	fTextLayout.setWidth(-1);
	FontData[] fontData= font.getFontData();
	for (int i= 0; i < fontData.length; i++)
	fontData[i].setStyle(SWT.BOLD);
	font= new Font(fShell.getDisplay(), fontData);
	fBoldStyle= new TextStyle(font, null, null);

	// Compute and set tab width
	fTextLayout.setText(" "); //$NON-NLS-1$
	int tabWidth = fTextLayout.getBounds().width;
	fTextLayout.setTabs(new int[] {tabWidth});

	fTextLayout.setText(""); //$NON-NLS-1$
	}

	/*
	* @see IInformationControl#dispose()
	*/
	public void dispose() {
	fTextLayout.dispose();
	fTextLayout= null;
	fBoldStyle.font.dispose();
	fBoldStyle= null;
	if (fShell != null && !fShell.isDisposed())
	fShell.dispose();
	else
	widgetDisposed(null);
	}

	/*
	* @see org.eclipse.swt.events.DisposeListener#widgetDisposed(org.eclipse.swt.events.DisposeEvent)
	*/
	public void widgetDisposed(DisposeEvent event) {
	if (fStatusTextFont != null && !fStatusTextFont.isDisposed())
	fStatusTextFont.dispose();

	fShell= null;
	fBrowser= null;
	fStatusTextFont= null;
	}

	/*
	* @see IInformationControl#setSize(int, int)
	*/
	public void setSize(int width, int height) {
	fShell.setSize(Math.min(width, fMaxWidth), Math.min(height, fMaxHeight));
	}

	/*
	* @see IInformationControl#setLocation(Point)
	*/
	public void setLocation(Point location) {
	fShell.setLocation(location);
	}

	/*
	* @see IInformationControl#setSizeConstraints(int, int)
	*/
	public void setSizeConstraints(int maxWidth, int maxHeight) {
	fMaxWidth= maxWidth;
	fMaxHeight= maxHeight;
	}

	/*
	* @see IInformationControl#computeSizeHint()
	*/
	public Point computeSizeHint() {
	TextPresentation presentation= new TextPresentation();
	HTML2TextReader reader= new HTML2TextReader(new StringReader(fInputText), presentation);
	String text;
	try {
	text= reader.getString();
	} catch (IOException e) {
	text= ""; //$NON-NLS-1$
	}

	fTextLayout.setText(text);
	Iterator iter= presentation.getAllStyleRangeIterator();
	while (iter.hasNext()) {
	StyleRange sr= (StyleRange)iter.next();
	if (sr.fontStyle == SWT.BOLD)
	fTextLayout.setStyle(fBoldStyle, sr.start, sr.start + sr.length - 1);
	}
	Rectangle bounds= fTextLayout.getBounds();
	int width= bounds.width;
	int height= bounds.height;

	width += 15;
	height += 25;

	if (fStatusFieldText != null && fSeparator != null) {
	fTextLayout.setText(fStatusFieldText);
	Rectangle statusBounds= fTextLayout.getBounds();
	Rectangle separatorBounds= fSeparator.getBounds();
	width= Math.max(width, statusBounds.width);
	height= height + statusBounds.height + separatorBounds.height;
	}

	// Apply size constraints
	if (fMaxWidth != SWT.DEFAULT)
	width= Math.min(fMaxWidth, width);
	if (fMaxHeight != SWT.DEFAULT)
	height= Math.min(fMaxHeight, height);

	// Ensure minimal size
	width= Math.max(MIN_WIDTH, width);
	height= Math.max(MIN_HEIGHT, height);

	return new Point(width, height);
	}

	/*
	* @see org.eclipse.jface.text.IInformationControlExtension3#computeTrim()
	*/
	public Rectangle computeTrim() {
	return fShell.computeTrim(0, 0, 0, 0);
	}

	/*
	* @see org.eclipse.jface.text.IInformationControlExtension3#getBounds()
	*/
	public Rectangle getBounds() {
	return fShell.getBounds();
	}

	/*
	* @see org.eclipse.jface.text.IInformationControlExtension3#restoresLocation()
	*/
	public boolean restoresLocation() {
	return false;
	}

	/*
	* @see org.eclipse.jface.text.IInformationControlExtension3#restoresSize()
	*/
	public boolean restoresSize() {
	return false;
	}

	/*
	* @see IInformationControl#addDisposeListener(DisposeListener)
	*/
	public void addDisposeListener(DisposeListener listener) {
	fShell.addDisposeListener(listener);
	}

	/*
	* @see IInformationControl#removeDisposeListener(DisposeListener)
	*/
	public void removeDisposeListener(DisposeListener listener) {
	fShell.removeDisposeListener(listener);
	}

	/*
	* @see IInformationControl#setForegroundColor(Color)
	*/
	public void setForegroundColor(Color foreground) {
	fBrowser.setForeground(foreground);
	}

	/*
	* @see IInformationControl#setBackgroundColor(Color)
	*/
	public void setBackgroundColor(Color background) {
	fBrowser.setBackground(background);
	}

	/*
	* @see IInformationControl#isFocusControl()
	*/
	public boolean isFocusControl() {
	return fBrowser.isFocusControl();
	}

	/*
	* @see IInformationControl#setFocus()
	*/
	public void setFocus() {
	fShell.forceFocus();
	fBrowser.setFocus();
	}

	/*
	* @see IInformationControl#addFocusListener(FocusListener)
	*/
	public void addFocusListener(final FocusListener listener) {
	fBrowser.addFocusListener(listener);

	/*
	* FIXME: This is a workaround for bug https://bugs.eclipse.org/bugs/show_bug.cgi?id=84532
	* (Browser widget does not send focusLost event)
	*/
	if (fFocusListeners.isEmpty()) {
	fDeactivateListener= new Listener() {
	public void handleEvent(Event event) {
	Object[] listeners= fFocusListeners.getListeners();
	for (int i = 0; i < listeners.length; i++)
	((FocusListener)listeners[i]).focusLost(new FocusEvent(event));
	}
	};
	fBrowser.getShell().addListener(SWT.Deactivate, fDeactivateListener);
	}
	fFocusListeners.add(listener);
	}

	/*
	* @see IInformationControl#removeFocusListener(FocusListener)
	*/
	public void removeFocusListener(FocusListener listener) {
	fBrowser.removeFocusListener(listener);

	/*
	* FIXME: This is a workaround for bug https://bugs.eclipse.org/bugs/show_bug.cgi?id=84532
	* (Browser widget does not send focusLost event)
	*/
	fFocusListeners.remove(listener);
	if (fFocusListeners.isEmpty()) {
	fBrowser.getShell().removeListener(SWT.Deactivate, fDeactivateListener);
	fDeactivateListener= null;
	}
	}

	/*
	* @see IInformationControlExtension#hasContents()
	*/
	public boolean hasContents() {
	return fBrowserHasContent;
	}
	}