core/plugins/org.eclipse.dltk.ui/src/org/eclipse/dltk/internal/ui/BrowserInformationControl.java - dltk/org.eclipse.dltk.core - Git at Google

 /*******************************************************************************
  * Copyright (c) 2000, 2017 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.dltk.internal.ui;

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

 import org.eclipse.core.runtime.Assert;
 import org.eclipse.core.runtime.ListenerList;
 import org.eclipse.dltk.internal.ui.text.HTML2TextReader;
 import org.eclipse.dltk.ui.text.completion.HTMLPrinter;
 import org.eclipse.jface.action.ToolBarManager;
 import org.eclipse.jface.resource.JFaceResources;
 import org.eclipse.jface.text.AbstractInformationControl;
 import org.eclipse.jface.text.IDelayedInputChangeProvider;
 import org.eclipse.jface.text.IInformationControlCreator;
 import org.eclipse.jface.text.IInformationControlExtension2;
 import org.eclipse.jface.text.IInputChangedListener;
 import org.eclipse.jface.text.TextPresentation;
 import org.eclipse.swt.SWT;
 import org.eclipse.swt.SWTError;
 import org.eclipse.swt.browser.Browser;
 import org.eclipse.swt.browser.LocationListener;
 import org.eclipse.swt.browser.ProgressAdapter;
 import org.eclipse.swt.browser.ProgressEvent;
 import org.eclipse.swt.custom.StyleRange;
 import org.eclipse.swt.graphics.Color;
 import org.eclipse.swt.graphics.Font;
 import org.eclipse.swt.graphics.GC;
 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.widgets.Composite;
 import org.eclipse.swt.widgets.Display;
 import org.eclipse.swt.widgets.Menu;
 import org.eclipse.swt.widgets.Shell;
 import org.eclipse.swt.widgets.Slider;

 /**
  * Displays HTML information in a {@link org.eclipse.swt.browser.Browser}
  * widget.
  * <p>
  * This {@link IInformationControlExtension2} expects {@link #setInput(Object)}
  * to be called with an argument of type {@link BrowserInformationControlInput}.
  * </p>
  * <p>
  * Moved into this package from
  * <code>org.eclipse.jface.internal.text.revisions</code>.
  * </p>
  * <p>
  * This class may be instantiated; it is not intended to be subclassed.
  * </p>
  * <p>
  * Current problems:
  * <ul>
  * <li>the size computation is too small</li>
  * <li>focusLost event is not sent - see
  * https://bugs.eclipse.org/bugs/show_bug.cgi?id=84532</li>
  * </ul>
  * </p>
  *
  * @since 3.2
  */
 public class BrowserInformationControl extends AbstractInformationControl
 		implements IInformationControlExtension2, IDelayedInputChangeProvider {

 	/**
 	 * 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 {
 				Browser browser = new Browser(parent, SWT.NONE);
 				browser.dispose();
 				fgIsAvailable = true;

 				Slider sliderV = new Slider(parent, SWT.VERTICAL);
 				Slider sliderH = new Slider(parent, SWT.HORIZONTAL);
 				int width = sliderV.computeSize(SWT.DEFAULT, SWT.DEFAULT).x;
 				int height = sliderH.computeSize(SWT.DEFAULT, SWT.DEFAULT).y;
 				fgScrollBarSize = new Point(width, height);
 				sliderV.dispose();
 				sliderH.dispose();
 			} catch (SWTError er) {
 				fgIsAvailable = false;
 			} finally {
 				fgAvailabilityChecked = true;
 			}
 		}

 		return fgIsAvailable;
 	}

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

 	private static final int MIN_HEIGHT = 50;

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

 	private static boolean fgAvailabilityChecked = false;

 	/**
 	 * Cached scroll bar width and height
 	 *
 	 * @since 3.4
 	 */
 	private static Point fgScrollBarSize;

 	/** The control's browser widget */
 	private Browser fBrowser;

 	/** Tells whether the browser has content */
 	private boolean fBrowserHasContent;

 	/**
 	 * Text layout used to approximate size of content when rendered in browser
 	 */
 	private TextLayout fTextLayout;

 	/** Bold text style */
 	private TextStyle fBoldStyle;

 	private BrowserInformationControlInput fInput;

 	/**
 	 * <code>true</code> iff the browser has completed loading of the last input
 	 * set via {@link #setInformation(String)}.
 	 *
 	 * @since 3.4
 	 */
 	private boolean fCompleted = false;

 	/**
 	 * The listener to be notified when a delayed location changing event
 	 * happened.
 	 *
 	 * @since 3.4
 	 */
 	private IInputChangedListener fDelayedInputChangeListener;

 	/**
 	 * The listeners to be notified when the input changed.
 	 *
 	 * @since 3.4
 	 */
 	private ListenerList<IInputChangedListener> fInputChangeListeners = new ListenerList<>(
 			ListenerList.IDENTITY);

 	/**
 	 * The symbolic name of the font used for size computations, or
 	 * <code>null</code> to use dialog font.
 	 *
 	 * @since 3.4
 	 */
 	private final String fSymbolicFontName;

 	/**
 	 * Creates a browser information control with the given shell as parent.
 	 *
 	 * @param parent
 	 *            the parent shell
 	 * @param symbolicFontName
 	 *            the symbolic name of the font used for size computations
 	 * @param resizable
 	 *            <code>true</code> if the control should be resizable
 	 * @since 3.4
 	 */
 	public BrowserInformationControl(Shell parent, String symbolicFontName,
 			boolean resizable) {
 		super(parent, resizable);
 		fSymbolicFontName = symbolicFontName;
 		create();
 	}

 	/**
 	 * Creates a browser information control with the given shell as parent.
 	 *
 	 * @param parent
 	 *            the parent shell
 	 * @param symbolicFontName
 	 *            the symbolic name of the font used for size computations
 	 * @param statusFieldText
 	 *            the text to be used in the optional status field or
 	 *            <code>null</code> if the status field should be hidden
 	 * @since 3.4
 	 */
 	public BrowserInformationControl(Shell parent, String symbolicFontName,
 			String statusFieldText) {
 		super(parent, statusFieldText);
 		fSymbolicFontName = symbolicFontName;
 		create();
 	}

 	/**
 	 * Creates a browser information control with the given shell as parent.
 	 *
 	 * @param parent
 	 *            the parent shell
 	 * @param symbolicFontName
 	 *            the symbolic name of the font used for size computations
 	 * @param toolBarManager
 	 *            the manager or <code>null</code> if toolbar is not desired
 	 * @since 3.4
 	 */
 	public BrowserInformationControl(Shell parent, String symbolicFontName,
 			ToolBarManager toolBarManager) {
 		super(parent, toolBarManager);
 		fSymbolicFontName = symbolicFontName;
 		create();
 	}

 	@Override
 	public IInformationControlCreator getInformationPresenterControlCreator() {
 		return parent -> new BrowserInformationControl(parent,
 				fSymbolicFontName, true);
 	}

 	@Override
 	protected void createContent(Composite parent) {
 		fBrowser = new Browser(parent, SWT.NONE);
 		fBrowser.setJavascriptEnabled(false);

 		Display display = getShell().getDisplay();
 		fBrowser.setForeground(
 				display.getSystemColor(SWT.COLOR_INFO_FOREGROUND));
 		fBrowser.setBackground(
 				display.getSystemColor(SWT.COLOR_INFO_BACKGROUND));

 		fBrowser.addProgressListener(new ProgressAdapter() {
 			@Override
 			public void completed(ProgressEvent event) {
 				fCompleted = true;
 			}
 		});

 		fBrowser.addOpenWindowListener(event -> event.required = true);

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

 		createTextLayout();
 	}

 	/**
 	 * {@inheritDoc}
 	 *
 	 * @deprecated use {@link #setInput(Object)}
 	 */
 	@Override
 	@Deprecated
 	public void setInformation(final String content) {
 		setInput(new BrowserInformationControlInput(null) {
 			@Override
 			public String getHtml() {
 				return content;
 			}

 			@Override
 			public String getInputName() {
 				return ""; //$NON-NLS-1$
 			}

 			@Override
 			public Object getInputElement() {
 				return content;
 			}
 		});
 	}

 	/**
 	 * {@inheritDoc} This control can handle {@link String} and
 	 * {@link BrowserInformationControlInput}.
 	 */
 	@Override
 	public void setInput(Object input) {
 		Assert.isLegal(input == null || input instanceof String
 				|| input instanceof BrowserInformationControlInput);

 		if (input instanceof String) {
 			setInformation((String) input);
 			return;
 		}

 		fInput = (BrowserInformationControlInput) input;

 		String content = null;
 		if (fInput != null)
 			content = fInput.getHtml();

 		fBrowserHasContent = content != null && content.length() > 0;

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

 		boolean RTL = (getShell().getStyle() & SWT.RIGHT_TO_LEFT) != 0;
 		boolean resizable = isResizable();

 		// The default "overflow:auto" would not result in a predictable width
 		// for the client area
 		// and the re-wrapping would cause visual noise
 		String[] styles = null;
 		if (RTL && resizable)
 			styles = new String[] { "direction:rtl;", "overflow:scroll;", //$NON-NLS-1$ //$NON-NLS-2$
 					"word-wrap:break-word;" }; //$NON-NLS-1$
 		else if (RTL && !resizable)
 			styles = new String[] { "direction:rtl;", "overflow:hidden;", //$NON-NLS-1$ //$NON-NLS-2$
 					"word-wrap:break-word;" }; //$NON-NLS-1$
 		else if (!resizable)
 			// XXX: In IE, "word-wrap: break-word;" causes bogus wrapping even
 			// in non-broken words :-(see e.g. Javadoc of String).
 			// Re-check whether we really still need this now that the Javadoc
 			// Hover header already sets this style.
 			styles = new String[] {
 					"overflow:hidden;"/* , "word-wrap: break-word;" */ }; //$NON-NLS-1$
 		else
 			styles = new String[] { "overflow:scroll;" }; //$NON-NLS-1$

 		StringBuffer buffer = new StringBuffer(content);
 		HTMLPrinter.insertStyles(buffer, styles);
 		content = buffer.toString();

 		/*
 		 * XXX: Should add some JavaScript here that shows something like
 		 * "(continued...)" or "..." at the end of the visible area when the
 		 * page overflowed with "overflow:hidden;".
 		 */

 		fCompleted = false;
 		fBrowser.setText(content);

 		for (IInputChangedListener listener : fInputChangeListeners)
 			listener.inputChanged(fInput);
 	}

 	@Override
 	public void setVisible(boolean visible) {
 		Shell shell = getShell();
 		if (shell.isVisible() == visible)
 			return;

 		if (!visible) {
 			super.setVisible(false);
 			setInput(null);
 			return;
 		}

 		/*
 		 * The Browser widget flickers when made visible while it is not
 		 * completely loaded. The fix is to delay the call to setVisible until
 		 * either loading is completed (see ProgressListener in constructor), or
 		 * a timeout has been reached.
 		 */
 		final Display display = shell.getDisplay();

 		// Make sure the display wakes from sleep after timeout:
 		display.timerExec(100, () -> fCompleted = true);

 		while (!fCompleted) {
 			// Drive the event loop to process the events required to load the
 			// browser widget's contents:
 			if (!display.readAndDispatch()) {
 				display.sleep();
 			}
 		}

 		shell = getShell();
 		if (shell == null || shell.isDisposed())
 			return;

 		/*
 		 * Avoids flickering when replacing hovers, especially on Vista in
 		 * ON_CLICK mode. Causes flickering on GTK. Carbon does not care.
 		 */
 		if ("win32".equals(SWT.getPlatform())) //$NON-NLS-1$
 			shell.moveAbove(null);

 		super.setVisible(true);
 	}

 	@Override
 	public void setSize(int width, int height) {
 		fBrowser.setRedraw(false); // avoid flickering
 		try {
 			super.setSize(width, height);
 		} finally {
 			fBrowser.setRedraw(true);
 		}
 	}

 	/**
 	 * 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
 		String symbolicFontName = fSymbolicFontName == null
 				? JFaceResources.DIALOG_FONT
 				: fSymbolicFontName;
 		Font font = JFaceResources.getFont(symbolicFontName);
 		fTextLayout.setFont(font);
 		fTextLayout.setWidth(-1);
 		font = JFaceResources.getFontRegistry().getBold(symbolicFontName);
 		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(""); //$NON-NLS-1$
 	}

 	@Override
 	protected void handleDispose() {
 		if (fTextLayout != null) {
 			fTextLayout.dispose();
 			fTextLayout = null;
 		}
 		fBrowser = null;

 		super.handleDispose();
 	}

 	@Override
 	public Point computeSizeHint() {
 		Point sizeConstraints = getSizeConstraints();
 		Rectangle trim = computeTrim();
 		int height = trim.height;

 		// FIXME: The HTML2TextReader does not render <p> like a browser.
 		// Instead of inserting an empty line, it just adds a single line break.
 		// Furthermore, the indentation of <dl><dd> elements is too small (e.g
 		// with a long @see line)
 		TextPresentation presentation = new TextPresentation();
 		HTML2TextReader reader = new HTML2TextReader(
 				new StringReader(fInput.getHtml()), presentation);
 		String text;
 		try {
 			text = reader.getString();
 		} catch (IOException e) {
 			text = ""; //$NON-NLS-1$
 		}

 		fTextLayout.setText(text);
 		fTextLayout.setWidth(sizeConstraints == null ? SWT.DEFAULT
 				: sizeConstraints.x - trim.width);
 		Iterator<StyleRange> iter = presentation.getAllStyleRangeIterator();
 		while (iter.hasNext()) {
 			StyleRange sr = iter.next();
 			if (sr.fontStyle == SWT.BOLD)
 				fTextLayout.setStyle(fBoldStyle, sr.start,
 						sr.start + sr.length - 1);
 		}

 		Rectangle bounds = fTextLayout.getBounds(); // does not return minimum
 													// width, see
 													// https://bugs.eclipse.org/bugs/show_bug.cgi?id=217446
 		int lineCount = fTextLayout.getLineCount();
 		int textWidth = 0;
 		for (int i = 0; i < lineCount; i++) {
 			Rectangle rect = fTextLayout.getLineBounds(i);
 			int lineWidth = rect.x + rect.width;
 			if (i == 0)
 				lineWidth += fInput.getLeadingImageWidth();
 			textWidth = Math.max(textWidth, lineWidth);
 		}
 		bounds.width = textWidth;
 		fTextLayout.setText(""); //$NON-NLS-1$

 		int minWidth = bounds.width;
 		height = height + bounds.height;

 		// Add some air to accommodate for different browser renderings
 		minWidth += 15;
 		height += 15;

 		// Apply max size constraints
 		if (sizeConstraints != null) {
 			if (sizeConstraints.x != SWT.DEFAULT)
 				minWidth = Math.min(sizeConstraints.x, minWidth + trim.width);
 			if (sizeConstraints.y != SWT.DEFAULT)
 				height = Math.min(sizeConstraints.y, height);
 		}

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

 		return new Point(width, height);
 	}

 	@Override
 	public Rectangle computeTrim() {
 		Rectangle trim = super.computeTrim();
 		if (isResizable()) {
 			boolean RTL = (getShell().getStyle() & SWT.RIGHT_TO_LEFT) != 0;
 			if (RTL) {
 				trim.x -= fgScrollBarSize.x;
 			}
 			trim.width += fgScrollBarSize.x;
 			trim.height += fgScrollBarSize.y;
 		}
 		return trim;
 	}

 	/**
 	 * Adds the listener to the collection of listeners who will be notified
 	 * when the current location has changed or is about to change.
 	 *
 	 * @param listener
 	 *            the location listener
 	 * @since 3.4
 	 */
 	public void addLocationListener(LocationListener listener) {
 		fBrowser.addLocationListener(listener);
 	}

 	@Override
 	public void setForegroundColor(Color foreground) {
 		super.setForegroundColor(foreground);
 		fBrowser.setForeground(foreground);
 	}

 	@Override
 	public void setBackgroundColor(Color background) {
 		super.setBackgroundColor(background);
 		fBrowser.setBackground(background);
 	}

 	@Override
 	public boolean hasContents() {
 		return fBrowserHasContent;
 	}

 	/**
 	 * Adds a listener for input changes to this input change provider. Has no
 	 * effect if an identical listener is already registered.
 	 *
 	 * @param inputChangeListener
 	 *            the listener to add
 	 * @since 3.4
 	 */
 	public void addInputChangeListener(
 			IInputChangedListener inputChangeListener) {
 		Assert.isNotNull(inputChangeListener);
 		fInputChangeListeners.add(inputChangeListener);
 	}

 	/**
 	 * Removes the given input change listener from this input change provider.
 	 * Has no effect if an identical listener is not registered.
 	 *
 	 * @param inputChangeListener
 	 *            the listener to remove
 	 * @since 3.4
 	 */
 	public void removeInputChangeListener(
 			IInputChangedListener inputChangeListener) {
 		fInputChangeListeners.remove(inputChangeListener);
 	}

 	@Override
 	public void setDelayedInputChangeListener(
 			IInputChangedListener inputChangeListener) {
 		fDelayedInputChangeListener = inputChangeListener;
 	}

 	/**
 	 * Tells whether a delayed input change listener is registered.
 	 *
 	 * @return <code>true</code> iff a delayed input change listener is
 	 *         currently registered
 	 * @since 3.4
 	 */
 	public boolean hasDelayedInputChangeListener() {
 		return fDelayedInputChangeListener != null;
 	}

 	/**
 	 * Notifies listeners of a delayed input change.
 	 *
 	 * @param newInput
 	 *            the new input, or <code>null</code> to request cancellation
 	 * @since 3.4
 	 */
 	public void notifyDelayedInputChange(Object newInput) {
 		if (fDelayedInputChangeListener != null)
 			fDelayedInputChangeListener.inputChanged(newInput);
 	}

 	@Override
 	public String toString() {
 		String style = (getShell().getStyle() & SWT.RESIZE) == 0 ? "fixed" //$NON-NLS-1$
 				: "resizeable"; //$NON-NLS-1$
 		return super.toString() + " -  style: " + style; //$NON-NLS-1$
 	}

 	/**
 	 * @return the current browser input or <code>null</code>
 	 */
 	public BrowserInformationControlInput getInput() {
 		return fInput;
 	}

 	@Override
 	public Point computeSizeConstraints(int widthInChars, int heightInChars) {
 		if (fSymbolicFontName == null)
 			return null;

 		GC gc = new GC(fBrowser);
 		Font font = fSymbolicFontName == null ? JFaceResources.getDialogFont()
 				: JFaceResources.getFont(fSymbolicFontName);
 		gc.setFont(font);
 		int width = gc.getFontMetrics().getAverageCharWidth();
 		int height = gc.getFontMetrics().getHeight();
 		gc.dispose();

 		return new Point(widthInChars * width, heightInChars * height);
 	}

 }
	/*******************************************************************************
	* Copyright (c) 2000, 2017 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.dltk.internal.ui;

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

	import org.eclipse.core.runtime.Assert;
	import org.eclipse.core.runtime.ListenerList;
	import org.eclipse.dltk.internal.ui.text.HTML2TextReader;
	import org.eclipse.dltk.ui.text.completion.HTMLPrinter;
	import org.eclipse.jface.action.ToolBarManager;
	import org.eclipse.jface.resource.JFaceResources;
	import org.eclipse.jface.text.AbstractInformationControl;
	import org.eclipse.jface.text.IDelayedInputChangeProvider;
	import org.eclipse.jface.text.IInformationControlCreator;
	import org.eclipse.jface.text.IInformationControlExtension2;
	import org.eclipse.jface.text.IInputChangedListener;
	import org.eclipse.jface.text.TextPresentation;
	import org.eclipse.swt.SWT;
	import org.eclipse.swt.SWTError;
	import org.eclipse.swt.browser.Browser;
	import org.eclipse.swt.browser.LocationListener;
	import org.eclipse.swt.browser.ProgressAdapter;
	import org.eclipse.swt.browser.ProgressEvent;
	import org.eclipse.swt.custom.StyleRange;
	import org.eclipse.swt.graphics.Color;
	import org.eclipse.swt.graphics.Font;
	import org.eclipse.swt.graphics.GC;
	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.widgets.Composite;
	import org.eclipse.swt.widgets.Display;
	import org.eclipse.swt.widgets.Menu;
	import org.eclipse.swt.widgets.Shell;
	import org.eclipse.swt.widgets.Slider;

	/**
	* Displays HTML information in a {@link org.eclipse.swt.browser.Browser}
	* widget.
	* <p>
	* This {@link IInformationControlExtension2} expects {@link #setInput(Object)}
	* to be called with an argument of type {@link BrowserInformationControlInput}.
	* </p>
	* <p>
	* Moved into this package from
	* <code>org.eclipse.jface.internal.text.revisions</code>.
	* </p>
	* <p>
	* This class may be instantiated; it is not intended to be subclassed.
	* </p>
	* <p>
	* Current problems:
	* <ul>
	* <li>the size computation is too small</li>
	* <li>focusLost event is not sent - see
	* https://bugs.eclipse.org/bugs/show_bug.cgi?id=84532</li>
	* </ul>
	* </p>
	*
	* @since 3.2
	*/
	public class BrowserInformationControl extends AbstractInformationControl
	implements IInformationControlExtension2, IDelayedInputChangeProvider {

	/**
	* 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 {
	Browser browser = new Browser(parent, SWT.NONE);
	browser.dispose();
	fgIsAvailable = true;

	Slider sliderV = new Slider(parent, SWT.VERTICAL);
	Slider sliderH = new Slider(parent, SWT.HORIZONTAL);
	int width = sliderV.computeSize(SWT.DEFAULT, SWT.DEFAULT).x;
	int height = sliderH.computeSize(SWT.DEFAULT, SWT.DEFAULT).y;
	fgScrollBarSize = new Point(width, height);
	sliderV.dispose();
	sliderH.dispose();
	} catch (SWTError er) {
	fgIsAvailable = false;
	} finally {
	fgAvailabilityChecked = true;
	}
	}

	return fgIsAvailable;
	}

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

	private static final int MIN_HEIGHT = 50;

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

	private static boolean fgAvailabilityChecked = false;

	/**
	* Cached scroll bar width and height
	*
	* @since 3.4
	*/
	private static Point fgScrollBarSize;

	/** The control's browser widget */
	private Browser fBrowser;

	/** Tells whether the browser has content */
	private boolean fBrowserHasContent;

	/**
	* Text layout used to approximate size of content when rendered in browser
	*/
	private TextLayout fTextLayout;

	/** Bold text style */
	private TextStyle fBoldStyle;

	private BrowserInformationControlInput fInput;

	/**
	* <code>true</code> iff the browser has completed loading of the last input
	* set via {@link #setInformation(String)}.
	*
	* @since 3.4
	*/
	private boolean fCompleted = false;

	/**
	* The listener to be notified when a delayed location changing event
	* happened.
	*
	* @since 3.4
	*/
	private IInputChangedListener fDelayedInputChangeListener;

	/**
	* The listeners to be notified when the input changed.
	*
	* @since 3.4
	*/
	private ListenerList<IInputChangedListener> fInputChangeListeners = new ListenerList<>(
	ListenerList.IDENTITY);

	/**
	* The symbolic name of the font used for size computations, or
	* <code>null</code> to use dialog font.
	*
	* @since 3.4
	*/
	private final String fSymbolicFontName;

	/**
	* Creates a browser information control with the given shell as parent.
	*
	* @param parent
	* the parent shell
	* @param symbolicFontName
	* the symbolic name of the font used for size computations
	* @param resizable
	* <code>true</code> if the control should be resizable
	* @since 3.4
	*/
	public BrowserInformationControl(Shell parent, String symbolicFontName,
	boolean resizable) {
	super(parent, resizable);
	fSymbolicFontName = symbolicFontName;
	create();
	}

	/**
	* Creates a browser information control with the given shell as parent.
	*
	* @param parent
	* the parent shell
	* @param symbolicFontName
	* the symbolic name of the font used for size computations
	* @param statusFieldText
	* the text to be used in the optional status field or
	* <code>null</code> if the status field should be hidden
	* @since 3.4
	*/
	public BrowserInformationControl(Shell parent, String symbolicFontName,
	String statusFieldText) {
	super(parent, statusFieldText);
	fSymbolicFontName = symbolicFontName;
	create();
	}

	/**
	* Creates a browser information control with the given shell as parent.
	*
	* @param parent
	* the parent shell
	* @param symbolicFontName
	* the symbolic name of the font used for size computations
	* @param toolBarManager
	* the manager or <code>null</code> if toolbar is not desired
	* @since 3.4
	*/
	public BrowserInformationControl(Shell parent, String symbolicFontName,
	ToolBarManager toolBarManager) {
	super(parent, toolBarManager);
	fSymbolicFontName = symbolicFontName;
	create();
	}

	@Override
	public IInformationControlCreator getInformationPresenterControlCreator() {
	return parent -> new BrowserInformationControl(parent,
	fSymbolicFontName, true);
	}

	@Override
	protected void createContent(Composite parent) {
	fBrowser = new Browser(parent, SWT.NONE);
	fBrowser.setJavascriptEnabled(false);

	Display display = getShell().getDisplay();
	fBrowser.setForeground(
	display.getSystemColor(SWT.COLOR_INFO_FOREGROUND));
	fBrowser.setBackground(
	display.getSystemColor(SWT.COLOR_INFO_BACKGROUND));

	fBrowser.addProgressListener(new ProgressAdapter() {
	@Override
	public void completed(ProgressEvent event) {
	fCompleted = true;
	}
	});

	fBrowser.addOpenWindowListener(event -> event.required = true);

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

	createTextLayout();
	}

	/**
	* {@inheritDoc}
	*
	* @deprecated use {@link #setInput(Object)}
	*/
	@Override
	@Deprecated
	public void setInformation(final String content) {
	setInput(new BrowserInformationControlInput(null) {
	@Override
	public String getHtml() {
	return content;
	}

	@Override
	public String getInputName() {
	return ""; //$NON-NLS-1$
	}

	@Override
	public Object getInputElement() {
	return content;
	}
	});
	}

	/**
	* {@inheritDoc} This control can handle {@link String} and
	* {@link BrowserInformationControlInput}.
	*/
	@Override
	public void setInput(Object input) {
	Assert.isLegal(input == null \|\| input instanceof String
	\|\| input instanceof BrowserInformationControlInput);

	if (input instanceof String) {
	setInformation((String) input);
	return;
	}

	fInput = (BrowserInformationControlInput) input;

	String content = null;
	if (fInput != null)
	content = fInput.getHtml();

	fBrowserHasContent = content != null && content.length() > 0;

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

	boolean RTL = (getShell().getStyle() & SWT.RIGHT_TO_LEFT) != 0;
	boolean resizable = isResizable();

	// The default "overflow:auto" would not result in a predictable width
	// for the client area
	// and the re-wrapping would cause visual noise
	String[] styles = null;
	if (RTL && resizable)
	styles = new String[] { "direction:rtl;", "overflow:scroll;", //$NON-NLS-1$ //$NON-NLS-2$
	"word-wrap:break-word;" }; //$NON-NLS-1$
	else if (RTL && !resizable)
	styles = new String[] { "direction:rtl;", "overflow:hidden;", //$NON-NLS-1$ //$NON-NLS-2$
	"word-wrap:break-word;" }; //$NON-NLS-1$
	else if (!resizable)
	// XXX: In IE, "word-wrap: break-word;" causes bogus wrapping even
	// in non-broken words :-(see e.g. Javadoc of String).
	// Re-check whether we really still need this now that the Javadoc
	// Hover header already sets this style.
	styles = new String[] {
	"overflow:hidden;"/* , "word-wrap: break-word;" */ }; //$NON-NLS-1$
	else
	styles = new String[] { "overflow:scroll;" }; //$NON-NLS-1$

	StringBuffer buffer = new StringBuffer(content);
	HTMLPrinter.insertStyles(buffer, styles);
	content = buffer.toString();

	/*
	* XXX: Should add some JavaScript here that shows something like
	* "(continued...)" or "..." at the end of the visible area when the
	* page overflowed with "overflow:hidden;".
	*/

	fCompleted = false;
	fBrowser.setText(content);

	for (IInputChangedListener listener : fInputChangeListeners)
	listener.inputChanged(fInput);
	}

	@Override
	public void setVisible(boolean visible) {
	Shell shell = getShell();
	if (shell.isVisible() == visible)
	return;

	if (!visible) {
	super.setVisible(false);
	setInput(null);
	return;
	}

	/*
	* The Browser widget flickers when made visible while it is not
	* completely loaded. The fix is to delay the call to setVisible until
	* either loading is completed (see ProgressListener in constructor), or
	* a timeout has been reached.
	*/
	final Display display = shell.getDisplay();

	// Make sure the display wakes from sleep after timeout:
	display.timerExec(100, () -> fCompleted = true);

	while (!fCompleted) {
	// Drive the event loop to process the events required to load the
	// browser widget's contents:
	if (!display.readAndDispatch()) {
	display.sleep();
	}
	}

	shell = getShell();
	if (shell == null \|\| shell.isDisposed())
	return;

	/*
	* Avoids flickering when replacing hovers, especially on Vista in
	* ON_CLICK mode. Causes flickering on GTK. Carbon does not care.
	*/
	if ("win32".equals(SWT.getPlatform())) //$NON-NLS-1$
	shell.moveAbove(null);

	super.setVisible(true);
	}

	@Override
	public void setSize(int width, int height) {
	fBrowser.setRedraw(false); // avoid flickering
	try {
	super.setSize(width, height);
	} finally {
	fBrowser.setRedraw(true);
	}
	}

	/**
	* 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
	String symbolicFontName = fSymbolicFontName == null
	? JFaceResources.DIALOG_FONT
	: fSymbolicFontName;
	Font font = JFaceResources.getFont(symbolicFontName);
	fTextLayout.setFont(font);
	fTextLayout.setWidth(-1);
	font = JFaceResources.getFontRegistry().getBold(symbolicFontName);
	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(""); //$NON-NLS-1$
	}

	@Override
	protected void handleDispose() {
	if (fTextLayout != null) {
	fTextLayout.dispose();
	fTextLayout = null;
	}
	fBrowser = null;

	super.handleDispose();
	}

	@Override
	public Point computeSizeHint() {
	Point sizeConstraints = getSizeConstraints();
	Rectangle trim = computeTrim();
	int height = trim.height;

	// FIXME: The HTML2TextReader does not render <p> like a browser.
	// Instead of inserting an empty line, it just adds a single line break.
	// Furthermore, the indentation of <dl><dd> elements is too small (e.g
	// with a long @see line)
	TextPresentation presentation = new TextPresentation();
	HTML2TextReader reader = new HTML2TextReader(
	new StringReader(fInput.getHtml()), presentation);
	String text;
	try {
	text = reader.getString();
	} catch (IOException e) {
	text = ""; //$NON-NLS-1$
	}

	fTextLayout.setText(text);
	fTextLayout.setWidth(sizeConstraints == null ? SWT.DEFAULT
	: sizeConstraints.x - trim.width);
	Iterator<StyleRange> iter = presentation.getAllStyleRangeIterator();
	while (iter.hasNext()) {
	StyleRange sr = iter.next();
	if (sr.fontStyle == SWT.BOLD)
	fTextLayout.setStyle(fBoldStyle, sr.start,
	sr.start + sr.length - 1);
	}

	Rectangle bounds = fTextLayout.getBounds(); // does not return minimum
	// width, see
	// https://bugs.eclipse.org/bugs/show_bug.cgi?id=217446
	int lineCount = fTextLayout.getLineCount();
	int textWidth = 0;
	for (int i = 0; i < lineCount; i++) {
	Rectangle rect = fTextLayout.getLineBounds(i);
	int lineWidth = rect.x + rect.width;
	if (i == 0)
	lineWidth += fInput.getLeadingImageWidth();
	textWidth = Math.max(textWidth, lineWidth);
	}
	bounds.width = textWidth;
	fTextLayout.setText(""); //$NON-NLS-1$

	int minWidth = bounds.width;
	height = height + bounds.height;

	// Add some air to accommodate for different browser renderings
	minWidth += 15;
	height += 15;

	// Apply max size constraints
	if (sizeConstraints != null) {
	if (sizeConstraints.x != SWT.DEFAULT)
	minWidth = Math.min(sizeConstraints.x, minWidth + trim.width);
	if (sizeConstraints.y != SWT.DEFAULT)
	height = Math.min(sizeConstraints.y, height);
	}

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

	return new Point(width, height);
	}

	@Override
	public Rectangle computeTrim() {
	Rectangle trim = super.computeTrim();
	if (isResizable()) {
	boolean RTL = (getShell().getStyle() & SWT.RIGHT_TO_LEFT) != 0;
	if (RTL) {
	trim.x -= fgScrollBarSize.x;
	}
	trim.width += fgScrollBarSize.x;
	trim.height += fgScrollBarSize.y;
	}
	return trim;
	}

	/**
	* Adds the listener to the collection of listeners who will be notified
	* when the current location has changed or is about to change.
	*
	* @param listener
	* the location listener
	* @since 3.4
	*/
	public void addLocationListener(LocationListener listener) {
	fBrowser.addLocationListener(listener);
	}

	@Override
	public void setForegroundColor(Color foreground) {
	super.setForegroundColor(foreground);
	fBrowser.setForeground(foreground);
	}

	@Override
	public void setBackgroundColor(Color background) {
	super.setBackgroundColor(background);
	fBrowser.setBackground(background);
	}

	@Override
	public boolean hasContents() {
	return fBrowserHasContent;
	}

	/**
	* Adds a listener for input changes to this input change provider. Has no
	* effect if an identical listener is already registered.
	*
	* @param inputChangeListener
	* the listener to add
	* @since 3.4
	*/
	public void addInputChangeListener(
	IInputChangedListener inputChangeListener) {
	Assert.isNotNull(inputChangeListener);
	fInputChangeListeners.add(inputChangeListener);
	}

	/**
	* Removes the given input change listener from this input change provider.
	* Has no effect if an identical listener is not registered.
	*
	* @param inputChangeListener
	* the listener to remove
	* @since 3.4
	*/
	public void removeInputChangeListener(
	IInputChangedListener inputChangeListener) {
	fInputChangeListeners.remove(inputChangeListener);
	}

	@Override
	public void setDelayedInputChangeListener(
	IInputChangedListener inputChangeListener) {
	fDelayedInputChangeListener = inputChangeListener;
	}

	/**
	* Tells whether a delayed input change listener is registered.
	*
	* @return <code>true</code> iff a delayed input change listener is
	* currently registered
	* @since 3.4
	*/
	public boolean hasDelayedInputChangeListener() {
	return fDelayedInputChangeListener != null;
	}

	/**
	* Notifies listeners of a delayed input change.
	*
	* @param newInput
	* the new input, or <code>null</code> to request cancellation
	* @since 3.4
	*/
	public void notifyDelayedInputChange(Object newInput) {
	if (fDelayedInputChangeListener != null)
	fDelayedInputChangeListener.inputChanged(newInput);
	}

	@Override
	public String toString() {
	String style = (getShell().getStyle() & SWT.RESIZE) == 0 ? "fixed" //$NON-NLS-1$
	: "resizeable"; //$NON-NLS-1$
	return super.toString() + " - style: " + style; //$NON-NLS-1$
	}

	/**
	* @return the current browser input or <code>null</code>
	*/
	public BrowserInformationControlInput getInput() {
	return fInput;
	}

	@Override
	public Point computeSizeConstraints(int widthInChars, int heightInChars) {
	if (fSymbolicFontName == null)
	return null;

	GC gc = new GC(fBrowser);
	Font font = fSymbolicFontName == null ? JFaceResources.getDialogFont()
	: JFaceResources.getFont(fSymbolicFontName);
	gc.setFont(font);
	int width = gc.getFontMetrics().getAverageCharWidth();
	int height = gc.getFontMetrics().getHeight();
	gc.dispose();

	return new Point(widthInChars * width, heightInChars * height);
	}

	}