org.eclipse.jface.text/src/org/eclipse/jface/text/source/VerticalRuler.java - platform/eclipse.platform.text - Git at Google

 /*******************************************************************************
  * Copyright (c) 2000, 2015 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.jface.text.source;


 import java.util.Iterator;

 import org.eclipse.swt.SWT;
 import org.eclipse.swt.custom.StyledText;
 import org.eclipse.swt.events.DisposeEvent;
 import org.eclipse.swt.events.DisposeListener;
 import org.eclipse.swt.events.MouseEvent;
 import org.eclipse.swt.events.MouseListener;
 import org.eclipse.swt.events.PaintEvent;
 import org.eclipse.swt.events.PaintListener;
 import org.eclipse.swt.graphics.Font;
 import org.eclipse.swt.graphics.GC;
 import org.eclipse.swt.graphics.Image;
 import org.eclipse.swt.graphics.Point;
 import org.eclipse.swt.graphics.Rectangle;
 import org.eclipse.swt.widgets.Canvas;
 import org.eclipse.swt.widgets.Composite;
 import org.eclipse.swt.widgets.Control;
 import org.eclipse.swt.widgets.Display;

 import org.eclipse.jface.util.Util;

 import org.eclipse.jface.text.BadLocationException;
 import org.eclipse.jface.text.IDocument;
 import org.eclipse.jface.text.IRegion;
 import org.eclipse.jface.text.ITextListener;
 import org.eclipse.jface.text.ITextViewer;
 import org.eclipse.jface.text.ITextViewerExtension5;
 import org.eclipse.jface.text.IViewportListener;
 import org.eclipse.jface.text.JFaceTextUtil;
 import org.eclipse.jface.text.Position;
 import org.eclipse.jface.text.Region;
 import org.eclipse.jface.text.TextEvent;


 /**
  * A vertical ruler which is connected to a text viewer. Single column standard
  * implementation of {@link org.eclipse.jface.text.source.IVerticalRuler}.
  * <p>
  * The same can be achieved by using <code>CompositeRuler</code> configured
  * with an <code>AnnotationRulerColumn</code>. Clients may use this class as
  * is.
  *
  * @see org.eclipse.jface.text.ITextViewer
  */
 public final class VerticalRuler implements IVerticalRuler, IVerticalRulerExtension {

 	/**
 	 * Internal listener class.
 	 */
 	class InternalListener implements IViewportListener, IAnnotationModelListener, ITextListener {

 		@Override
 		public void viewportChanged(int verticalPosition) {
 			if (verticalPosition != fScrollPos)
 				redraw();
 		}

 		@Override
 		public void modelChanged(IAnnotationModel model) {
 			update();
 		}

 		@Override
 		public void textChanged(TextEvent e) {
 			if (fTextViewer != null && e.getViewerRedrawState())
 				redraw();
 		}
 	}

 	/**
 	 * <code>true</code> if we're on a Mac, where "new GC(canvas)" is expensive.
 	 * @see <a href="https://bugs.eclipse.org/298936">bug 298936</a>
 	 * @since 3.6
 	 */
 	static final boolean IS_MAC_BUG_298936= Util.isMac();

 	/** The vertical ruler's text viewer */
 	private ITextViewer fTextViewer;
 	/** The ruler's canvas */
 	private Canvas fCanvas;
 	/** The vertical ruler's model */
 	private IAnnotationModel fModel;
 	/** Cache for the actual scroll position in pixels */
 	private int fScrollPos;
 	/** The buffer for double buffering */
 	private Image fBuffer;
 	/** The line of the last mouse button activity */
 	private int fLastMouseButtonActivityLine= -1;
 	/** The internal listener */
 	private InternalListener fInternalListener= new InternalListener();
 	/** The width of this vertical ruler */
 	private int fWidth;
 	/**
 	 * The annotation access of this vertical ruler
 	 * @since 3.0
 	 */
 	private IAnnotationAccess fAnnotationAccess;

 	/**
 	 * Constructs a vertical ruler with the given width.
 	 *
 	 * @param width the width of the vertical ruler
 	 */
 	public VerticalRuler(int width) {
 		this(width, null);
 	}

 	/**
 	 * Constructs a vertical ruler with the given width and the given annotation
 	 * access.
 	 *
 	 * @param width the width of the vertical ruler
 	 * @param annotationAcccess the annotation access
 	 * @since 3.0
 	 */
 	public VerticalRuler(int width, IAnnotationAccess annotationAcccess) {
 		fWidth= width;
 		fAnnotationAccess= annotationAcccess;
 	}

 	@Override
 	public Control getControl() {
 		return fCanvas;
 	}

 	@Override
 	public Control createControl(Composite parent, ITextViewer textViewer) {

 		fTextViewer= textViewer;

 		fCanvas= new Canvas(parent, SWT.NO_BACKGROUND);

 		fCanvas.addPaintListener(new PaintListener() {
 			@Override
 			public void paintControl(PaintEvent event) {
 				if (fTextViewer != null)
 					doubleBufferPaint(event.gc);
 			}
 		});

 		fCanvas.addDisposeListener(new DisposeListener() {
 			@Override
 			public void widgetDisposed(DisposeEvent e) {
 				handleDispose();
 				fTextViewer= null;
 			}
 		});

 		fCanvas.addMouseListener(new MouseListener() {
 			@Override
 			public void mouseUp(MouseEvent event) {
 			}

 			@Override
 			public void mouseDown(MouseEvent event) {
 				fLastMouseButtonActivityLine= toDocumentLineNumber(event.y);
 			}

 			@Override
 			public void mouseDoubleClick(MouseEvent event) {
 				fLastMouseButtonActivityLine= toDocumentLineNumber(event.y);
 			}
 		});

 		if (fTextViewer != null) {
 			fTextViewer.addViewportListener(fInternalListener);
 			fTextViewer.addTextListener(fInternalListener);
 		}

 		return fCanvas;
 	}

 	/**
 	 * Disposes the ruler's resources.
 	 */
 	private void handleDispose() {

 		if (fTextViewer != null) {
 			fTextViewer.removeViewportListener(fInternalListener);
 			fTextViewer.removeTextListener(fInternalListener);
 			fTextViewer= null;
 		}

 		if (fModel != null)
 			fModel.removeAnnotationModelListener(fInternalListener);

 		if (fBuffer != null) {
 			fBuffer.dispose();
 			fBuffer= null;
 		}
 	}


 	/**
 	 * Double buffer drawing.
 	 *
 	 * @param dest the GC to draw into
 	 */
 	private void doubleBufferPaint(GC dest) {

 		Point size= fCanvas.getSize();

 		if (size.x <= 0 || size.y <= 0)
 			return;

 		if (fBuffer != null) {
 			Rectangle r= fBuffer.getBounds();
 			if (r.width != size.x || r.height != size.y) {
 				fBuffer.dispose();
 				fBuffer= null;
 			}
 		}
 		if (fBuffer == null)
 			fBuffer= new Image(fCanvas.getDisplay(), size.x, size.y);

 		GC gc= new GC(fBuffer);
 		gc.setFont(fTextViewer.getTextWidget().getFont());
 		try {
 			gc.setBackground(fCanvas.getBackground());
 			gc.fillRectangle(0, 0, size.x, size.y);

 			if (fTextViewer instanceof ITextViewerExtension5)
 				doPaint1(gc);
 			else
 				doPaint(gc);

 		} finally {
 			gc.dispose();
 		}

 		dest.drawImage(fBuffer, 0, 0);
 	}

 	/**
 	 * Returns the document offset of the upper left corner of the
 	 * widgets view port, possibly including partially visible lines.
 	 *
 	 * @return the document offset of the upper left corner including partially visible lines
 	 * @since 2.0
 	 */
 	private int getInclusiveTopIndexStartOffset() {

 		StyledText textWidget= fTextViewer.getTextWidget();
 		if (textWidget != null && !textWidget.isDisposed()) {
 			int top= JFaceTextUtil.getPartialTopIndex(fTextViewer);
 			try {
 				IDocument document= fTextViewer.getDocument();
 				return document.getLineOffset(top);
 			} catch (BadLocationException x) {
 			}
 		}

 		return -1;
 	}


 	/**
 	 * Draws the vertical ruler w/o drawing the Canvas background.
 	 *
 	 * @param gc  the GC to draw into
 	 */
 	protected void doPaint(GC gc) {

 		if (fModel == null || fTextViewer == null)
 			return;

 		IAnnotationAccessExtension annotationAccessExtension= null;
 		if (fAnnotationAccess instanceof IAnnotationAccessExtension)
 			annotationAccessExtension= (IAnnotationAccessExtension) fAnnotationAccess;

 		StyledText styledText= fTextViewer.getTextWidget();
 		IDocument doc= fTextViewer.getDocument();

 		int topLeft= getInclusiveTopIndexStartOffset();
 		int bottomRight= fTextViewer.getBottomIndexEndOffset();
 		int viewPort= bottomRight - topLeft;

 		Point d= fCanvas.getSize();
 		fScrollPos= styledText.getTopPixel();

 		int topLine= -1, bottomLine= -1;
 		try {
 			IRegion region= fTextViewer.getVisibleRegion();
 			topLine= doc.getLineOfOffset(region.getOffset());
 			bottomLine= doc.getLineOfOffset(region.getOffset() + region.getLength());
 		} catch (BadLocationException x) {
 			return;
 		}

 		// draw Annotations
 		Rectangle r= new Rectangle(0, 0, 0, 0);
 		int maxLayer= 1;	// loop at least once though layers.

 		for (int layer= 0; layer < maxLayer; layer++) {
 			Iterator<Annotation> iter= fModel.getAnnotationIterator();
 			while (iter.hasNext()) {
 				IAnnotationPresentation annotationPresentation= null;
 				Annotation annotation= iter.next();

 				int lay= IAnnotationAccessExtension.DEFAULT_LAYER;
 				if (annotationAccessExtension != null)
 					lay= annotationAccessExtension.getLayer(annotation);
 				else if (annotation instanceof IAnnotationPresentation) {
 					annotationPresentation= (IAnnotationPresentation)annotation;
 					lay= annotationPresentation.getLayer();
 				}
 				maxLayer= Math.max(maxLayer, lay+1);	// dynamically update layer maximum
 				if (lay != layer)	// wrong layer: skip annotation
 					continue;

 				Position position= fModel.getPosition(annotation);
 				if (position == null)
 					continue;

 				if (!position.overlapsWith(topLeft, viewPort))
 					continue;

 				try {

 					int offset= position.getOffset();
 					int length= position.getLength();

 					int startLine= doc.getLineOfOffset(offset);
 					if (startLine < topLine)
 						startLine= topLine;

 					int endLine= startLine;
 					if (length > 0)
 						endLine= doc.getLineOfOffset(offset + length - 1);
 					if (endLine > bottomLine)
 						endLine= bottomLine;

 					startLine -= topLine;
 					endLine -= topLine;

 					r.x= 0;
 					r.y= JFaceTextUtil.computeLineHeight(styledText, 0, startLine, startLine)  - fScrollPos;

 					r.width= d.x;
 					int lines= endLine - startLine;

 					r.height= JFaceTextUtil.computeLineHeight(styledText, startLine, endLine + 1, (lines+1));

 					if (r.y < d.y && annotationAccessExtension != null)  // annotation within visible area
 						annotationAccessExtension.paint(annotation, gc, fCanvas, r);
 					else if (annotationPresentation != null)
 						annotationPresentation.paint(gc, fCanvas, r);

 				} catch (BadLocationException e) {
 				}
 			}
 		}
 	}

 	/**
 	 * Draws the vertical ruler w/o drawing the Canvas background. Uses
 	 * <code>ITextViewerExtension5</code> for its implementation. Will replace
 	 * <code>doPaint(GC)</code>.
 	 *
 	 * @param gc  the GC to draw into
 	 */
 	protected void doPaint1(GC gc) {

 		if (fModel == null || fTextViewer == null)
 			return;

 		IAnnotationAccessExtension annotationAccessExtension= null;
 		if (fAnnotationAccess instanceof IAnnotationAccessExtension)
 			annotationAccessExtension= (IAnnotationAccessExtension) fAnnotationAccess;

 		ITextViewerExtension5 extension= (ITextViewerExtension5) fTextViewer;
 		StyledText textWidget= fTextViewer.getTextWidget();

 		fScrollPos= textWidget.getTopPixel();
 		Point dimension= fCanvas.getSize();

 		// draw Annotations
 		Rectangle r= new Rectangle(0, 0, 0, 0);
 		int maxLayer= 1;	// loop at least once through layers.

 		for (int layer= 0; layer < maxLayer; layer++) {
 			Iterator<Annotation> iter= fModel.getAnnotationIterator();
 			while (iter.hasNext()) {
 				IAnnotationPresentation annotationPresentation= null;
 				Annotation annotation= iter.next();

 				int lay= IAnnotationAccessExtension.DEFAULT_LAYER;
 				if (annotationAccessExtension != null)
 					lay= annotationAccessExtension.getLayer(annotation);
 				else if (annotation instanceof IAnnotationPresentation) {
 					annotationPresentation= (IAnnotationPresentation)annotation;
 					lay= annotationPresentation.getLayer();
 				}
 				maxLayer= Math.max(maxLayer, lay+1);	// dynamically update layer maximum
 				if (lay != layer)	// wrong layer: skip annotation
 					continue;

 				Position position= fModel.getPosition(annotation);
 				if (position == null)
 					continue;

 				IRegion widgetRegion= extension.modelRange2WidgetRange(new Region(position.getOffset(), position.getLength()));
 				if (widgetRegion == null)
 					continue;

 				int startLine= extension.widgetLineOfWidgetOffset(widgetRegion.getOffset());
 				if (startLine == -1)
 					continue;

 				int endLine= extension.widgetLineOfWidgetOffset(widgetRegion.getOffset() + Math.max(widgetRegion.getLength() -1, 0));
 				if (endLine == -1)
 					continue;

 				r.x= 0;
 				r.y= JFaceTextUtil.computeLineHeight(textWidget, 0, startLine, startLine)  - fScrollPos;

 				r.width= dimension.x;
 				int lines= endLine - startLine;

 				r.height= JFaceTextUtil.computeLineHeight(textWidget, startLine, endLine + 1, lines+1);

 				if (r.y < dimension.y && annotationAccessExtension != null)  // annotation within visible area
 					annotationAccessExtension.paint(annotation, gc, fCanvas, r);
 				else if (annotationPresentation != null)
 					annotationPresentation.paint(gc, fCanvas, r);
 			}
 		}
 	}

 	/**
 	 * Thread-safe implementation.
 	 * Can be called from any thread.
 	 */
 	@Override
 	public void update() {
 		if (fCanvas != null && !fCanvas.isDisposed()) {
 			Display d= fCanvas.getDisplay();
 			if (d != null) {
 				d.asyncExec(new Runnable() {
 					@Override
 					public void run() {
 						redraw();
 					}
 				});
 			}
 		}
 	}

 	/**
 	 * Redraws the vertical ruler.
 	 */
 	private void redraw() {
 		if (fCanvas != null && !fCanvas.isDisposed()) {
 			if (IS_MAC_BUG_298936) {
 				fCanvas.redraw();
 				fCanvas.update();
 			} else {
 				GC gc= new GC(fCanvas);
 				doubleBufferPaint(gc);
 				gc.dispose();
 			}
 		}
 	}

 	@Override
 	public void setModel(IAnnotationModel model) {
 		if (model != fModel) {

 			if (fModel != null)
 				fModel.removeAnnotationModelListener(fInternalListener);

 			fModel= model;

 			if (fModel != null)
 				fModel.addAnnotationModelListener(fInternalListener);

 			update();
 		}
 	}

 	@Override
 	public IAnnotationModel getModel() {
 		return fModel;
 	}

 	@Override
 	public int getWidth() {
 		return fWidth;
 	}

 	@Override
 	public int getLineOfLastMouseButtonActivity() {
 		IDocument doc= fTextViewer.getDocument();
 		if (doc == null || fLastMouseButtonActivityLine >= fTextViewer.getDocument().getNumberOfLines())
 			fLastMouseButtonActivityLine= -1;
 		return fLastMouseButtonActivityLine;
 	}

 	@Override
 	public int toDocumentLineNumber(int y_coordinate) {
 		if (fTextViewer == null  || y_coordinate == -1)
 			return -1;

 		StyledText text= fTextViewer.getTextWidget();
 		int line= text.getLineIndex(y_coordinate);

 		if (line == text.getLineCount() - 1) {
 			// check whether y_coordinate exceeds last line
 			if (y_coordinate > text.getLinePixel(line + 1))
 				return -1;
 		}

 		return widgetLine2ModelLine(fTextViewer, line);
 	}

 	/**
 	 * Returns the line of the viewer's document that corresponds to the given widget line.
 	 *
 	 * @param viewer the viewer
 	 * @param widgetLine the widget line
 	 * @return the corresponding line of the viewer's document
 	 * @since 2.1
 	 */
 	protected final static int widgetLine2ModelLine(ITextViewer viewer, int widgetLine) {

 		if (viewer instanceof ITextViewerExtension5) {
 			ITextViewerExtension5 extension= (ITextViewerExtension5) viewer;
 			return extension.widgetLine2ModelLine(widgetLine);
 		}

 		try {
 			IRegion r= viewer.getVisibleRegion();
 			IDocument d= viewer.getDocument();
 			return widgetLine += d.getLineOfOffset(r.getOffset());
 		} catch (BadLocationException x) {
 		}
 		return widgetLine;
 	}

 	@Override
 	public void setFont(Font font) {
 	}

 	@Override
 	public void setLocationOfLastMouseButtonActivity(int x, int y) {
 		fLastMouseButtonActivityLine= toDocumentLineNumber(y);
 	}

 	/**
 	 * Adds the given mouse listener.
 	 *
 	 * @param listener the listener to be added
 	 * @deprecated will be removed
 	 * @since 2.0
 	 */
 	@Deprecated
 	public void addMouseListener(MouseListener listener) {
 		if (fCanvas != null && !fCanvas.isDisposed())
 			fCanvas.addMouseListener(listener);
 	}

 	/**
 	 * Removes the given mouse listener.
 	 *
 	 * @param listener the listener to be removed
 	 * @deprecated will be removed
 	 * @since 2.0
 	 */
 	@Deprecated
 	public void removeMouseListener(MouseListener listener) {
 		if (fCanvas != null && !fCanvas.isDisposed())
 			fCanvas.removeMouseListener(listener);
 	}
 }
	/*******************************************************************************
	* Copyright (c) 2000, 2015 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.jface.text.source;


	import java.util.Iterator;

	import org.eclipse.swt.SWT;
	import org.eclipse.swt.custom.StyledText;
	import org.eclipse.swt.events.DisposeEvent;
	import org.eclipse.swt.events.DisposeListener;
	import org.eclipse.swt.events.MouseEvent;
	import org.eclipse.swt.events.MouseListener;
	import org.eclipse.swt.events.PaintEvent;
	import org.eclipse.swt.events.PaintListener;
	import org.eclipse.swt.graphics.Font;
	import org.eclipse.swt.graphics.GC;
	import org.eclipse.swt.graphics.Image;
	import org.eclipse.swt.graphics.Point;
	import org.eclipse.swt.graphics.Rectangle;
	import org.eclipse.swt.widgets.Canvas;
	import org.eclipse.swt.widgets.Composite;
	import org.eclipse.swt.widgets.Control;
	import org.eclipse.swt.widgets.Display;

	import org.eclipse.jface.util.Util;

	import org.eclipse.jface.text.BadLocationException;
	import org.eclipse.jface.text.IDocument;
	import org.eclipse.jface.text.IRegion;
	import org.eclipse.jface.text.ITextListener;
	import org.eclipse.jface.text.ITextViewer;
	import org.eclipse.jface.text.ITextViewerExtension5;
	import org.eclipse.jface.text.IViewportListener;
	import org.eclipse.jface.text.JFaceTextUtil;
	import org.eclipse.jface.text.Position;
	import org.eclipse.jface.text.Region;
	import org.eclipse.jface.text.TextEvent;


	/**
	* A vertical ruler which is connected to a text viewer. Single column standard
	* implementation of {@link org.eclipse.jface.text.source.IVerticalRuler}.
	* <p>
	* The same can be achieved by using <code>CompositeRuler</code> configured
	* with an <code>AnnotationRulerColumn</code>. Clients may use this class as
	* is.
	*
	* @see org.eclipse.jface.text.ITextViewer
	*/
	public final class VerticalRuler implements IVerticalRuler, IVerticalRulerExtension {

	/**
	* Internal listener class.
	*/
	class InternalListener implements IViewportListener, IAnnotationModelListener, ITextListener {

	@Override
	public void viewportChanged(int verticalPosition) {
	if (verticalPosition != fScrollPos)
	redraw();
	}

	@Override
	public void modelChanged(IAnnotationModel model) {
	update();
	}

	@Override
	public void textChanged(TextEvent e) {
	if (fTextViewer != null && e.getViewerRedrawState())
	redraw();
	}
	}

	/**
	* <code>true</code> if we're on a Mac, where "new GC(canvas)" is expensive.
	* @see <a href="https://bugs.eclipse.org/298936">bug 298936</a>
	* @since 3.6
	*/
	static final boolean IS_MAC_BUG_298936= Util.isMac();

	/** The vertical ruler's text viewer */
	private ITextViewer fTextViewer;
	/** The ruler's canvas */
	private Canvas fCanvas;
	/** The vertical ruler's model */
	private IAnnotationModel fModel;
	/** Cache for the actual scroll position in pixels */
	private int fScrollPos;
	/** The buffer for double buffering */
	private Image fBuffer;
	/** The line of the last mouse button activity */
	private int fLastMouseButtonActivityLine= -1;
	/** The internal listener */
	private InternalListener fInternalListener= new InternalListener();
	/** The width of this vertical ruler */
	private int fWidth;
	/**
	* The annotation access of this vertical ruler
	* @since 3.0
	*/
	private IAnnotationAccess fAnnotationAccess;

	/**
	* Constructs a vertical ruler with the given width.
	*
	* @param width the width of the vertical ruler
	*/
	public VerticalRuler(int width) {
	this(width, null);
	}

	/**
	* Constructs a vertical ruler with the given width and the given annotation
	* access.
	*
	* @param width the width of the vertical ruler
	* @param annotationAcccess the annotation access
	* @since 3.0
	*/
	public VerticalRuler(int width, IAnnotationAccess annotationAcccess) {
	fWidth= width;
	fAnnotationAccess= annotationAcccess;
	}

	@Override
	public Control getControl() {
	return fCanvas;
	}

	@Override
	public Control createControl(Composite parent, ITextViewer textViewer) {

	fTextViewer= textViewer;

	fCanvas= new Canvas(parent, SWT.NO_BACKGROUND);

	fCanvas.addPaintListener(new PaintListener() {
	@Override
	public void paintControl(PaintEvent event) {
	if (fTextViewer != null)
	doubleBufferPaint(event.gc);
	}
	});

	fCanvas.addDisposeListener(new DisposeListener() {
	@Override
	public void widgetDisposed(DisposeEvent e) {
	handleDispose();
	fTextViewer= null;
	}
	});

	fCanvas.addMouseListener(new MouseListener() {
	@Override
	public void mouseUp(MouseEvent event) {
	}

	@Override
	public void mouseDown(MouseEvent event) {
	fLastMouseButtonActivityLine= toDocumentLineNumber(event.y);
	}

	@Override
	public void mouseDoubleClick(MouseEvent event) {
	fLastMouseButtonActivityLine= toDocumentLineNumber(event.y);
	}
	});

	if (fTextViewer != null) {
	fTextViewer.addViewportListener(fInternalListener);
	fTextViewer.addTextListener(fInternalListener);
	}

	return fCanvas;
	}

	/**
	* Disposes the ruler's resources.
	*/
	private void handleDispose() {

	if (fTextViewer != null) {
	fTextViewer.removeViewportListener(fInternalListener);
	fTextViewer.removeTextListener(fInternalListener);
	fTextViewer= null;
	}

	if (fModel != null)
	fModel.removeAnnotationModelListener(fInternalListener);

	if (fBuffer != null) {
	fBuffer.dispose();
	fBuffer= null;
	}
	}


	/**
	* Double buffer drawing.
	*
	* @param dest the GC to draw into
	*/
	private void doubleBufferPaint(GC dest) {

	Point size= fCanvas.getSize();

	if (size.x <= 0 \|\| size.y <= 0)
	return;

	if (fBuffer != null) {
	Rectangle r= fBuffer.getBounds();
	if (r.width != size.x \|\| r.height != size.y) {
	fBuffer.dispose();
	fBuffer= null;
	}
	}
	if (fBuffer == null)
	fBuffer= new Image(fCanvas.getDisplay(), size.x, size.y);

	GC gc= new GC(fBuffer);
	gc.setFont(fTextViewer.getTextWidget().getFont());
	try {
	gc.setBackground(fCanvas.getBackground());
	gc.fillRectangle(0, 0, size.x, size.y);

	if (fTextViewer instanceof ITextViewerExtension5)
	doPaint1(gc);
	else
	doPaint(gc);

	} finally {
	gc.dispose();
	}

	dest.drawImage(fBuffer, 0, 0);
	}

	/**
	* Returns the document offset of the upper left corner of the
	* widgets view port, possibly including partially visible lines.
	*
	* @return the document offset of the upper left corner including partially visible lines
	* @since 2.0
	*/
	private int getInclusiveTopIndexStartOffset() {

	StyledText textWidget= fTextViewer.getTextWidget();
	if (textWidget != null && !textWidget.isDisposed()) {
	int top= JFaceTextUtil.getPartialTopIndex(fTextViewer);
	try {
	IDocument document= fTextViewer.getDocument();
	return document.getLineOffset(top);
	} catch (BadLocationException x) {
	}
	}

	return -1;
	}



	/**
	* Draws the vertical ruler w/o drawing the Canvas background.
	*
	* @param gc the GC to draw into
	*/
	protected void doPaint(GC gc) {

	if (fModel == null \|\| fTextViewer == null)
	return;

	IAnnotationAccessExtension annotationAccessExtension= null;
	if (fAnnotationAccess instanceof IAnnotationAccessExtension)
	annotationAccessExtension= (IAnnotationAccessExtension) fAnnotationAccess;

	StyledText styledText= fTextViewer.getTextWidget();
	IDocument doc= fTextViewer.getDocument();

	int topLeft= getInclusiveTopIndexStartOffset();
	int bottomRight= fTextViewer.getBottomIndexEndOffset();
	int viewPort= bottomRight - topLeft;

	Point d= fCanvas.getSize();
	fScrollPos= styledText.getTopPixel();

	int topLine= -1, bottomLine= -1;
	try {
	IRegion region= fTextViewer.getVisibleRegion();
	topLine= doc.getLineOfOffset(region.getOffset());
	bottomLine= doc.getLineOfOffset(region.getOffset() + region.getLength());
	} catch (BadLocationException x) {
	return;
	}

	// draw Annotations
	Rectangle r= new Rectangle(0, 0, 0, 0);
	int maxLayer= 1; // loop at least once though layers.

	for (int layer= 0; layer < maxLayer; layer++) {
	Iterator<Annotation> iter= fModel.getAnnotationIterator();
	while (iter.hasNext()) {
	IAnnotationPresentation annotationPresentation= null;
	Annotation annotation= iter.next();

	int lay= IAnnotationAccessExtension.DEFAULT_LAYER;
	if (annotationAccessExtension != null)
	lay= annotationAccessExtension.getLayer(annotation);
	else if (annotation instanceof IAnnotationPresentation) {
	annotationPresentation= (IAnnotationPresentation)annotation;
	lay= annotationPresentation.getLayer();
	}
	maxLayer= Math.max(maxLayer, lay+1); // dynamically update layer maximum
	if (lay != layer) // wrong layer: skip annotation
	continue;

	Position position= fModel.getPosition(annotation);
	if (position == null)
	continue;

	if (!position.overlapsWith(topLeft, viewPort))
	continue;

	try {

	int offset= position.getOffset();
	int length= position.getLength();

	int startLine= doc.getLineOfOffset(offset);
	if (startLine < topLine)
	startLine= topLine;

	int endLine= startLine;
	if (length > 0)
	endLine= doc.getLineOfOffset(offset + length - 1);
	if (endLine > bottomLine)
	endLine= bottomLine;

	startLine -= topLine;
	endLine -= topLine;

	r.x= 0;
	r.y= JFaceTextUtil.computeLineHeight(styledText, 0, startLine, startLine) - fScrollPos;

	r.width= d.x;
	int lines= endLine - startLine;

	r.height= JFaceTextUtil.computeLineHeight(styledText, startLine, endLine + 1, (lines+1));

	if (r.y < d.y && annotationAccessExtension != null) // annotation within visible area
	annotationAccessExtension.paint(annotation, gc, fCanvas, r);
	else if (annotationPresentation != null)
	annotationPresentation.paint(gc, fCanvas, r);

	} catch (BadLocationException e) {
	}
	}
	}
	}

	/**
	* Draws the vertical ruler w/o drawing the Canvas background. Uses
	* <code>ITextViewerExtension5</code> for its implementation. Will replace
	* <code>doPaint(GC)</code>.
	*
	* @param gc the GC to draw into
	*/
	protected void doPaint1(GC gc) {

	if (fModel == null \|\| fTextViewer == null)
	return;

	IAnnotationAccessExtension annotationAccessExtension= null;
	if (fAnnotationAccess instanceof IAnnotationAccessExtension)
	annotationAccessExtension= (IAnnotationAccessExtension) fAnnotationAccess;

	ITextViewerExtension5 extension= (ITextViewerExtension5) fTextViewer;
	StyledText textWidget= fTextViewer.getTextWidget();

	fScrollPos= textWidget.getTopPixel();
	Point dimension= fCanvas.getSize();

	// draw Annotations
	Rectangle r= new Rectangle(0, 0, 0, 0);
	int maxLayer= 1; // loop at least once through layers.

	for (int layer= 0; layer < maxLayer; layer++) {
	Iterator<Annotation> iter= fModel.getAnnotationIterator();
	while (iter.hasNext()) {
	IAnnotationPresentation annotationPresentation= null;
	Annotation annotation= iter.next();

	int lay= IAnnotationAccessExtension.DEFAULT_LAYER;
	if (annotationAccessExtension != null)
	lay= annotationAccessExtension.getLayer(annotation);
	else if (annotation instanceof IAnnotationPresentation) {
	annotationPresentation= (IAnnotationPresentation)annotation;
	lay= annotationPresentation.getLayer();
	}
	maxLayer= Math.max(maxLayer, lay+1); // dynamically update layer maximum
	if (lay != layer) // wrong layer: skip annotation
	continue;

	Position position= fModel.getPosition(annotation);
	if (position == null)
	continue;

	IRegion widgetRegion= extension.modelRange2WidgetRange(new Region(position.getOffset(), position.getLength()));
	if (widgetRegion == null)
	continue;

	int startLine= extension.widgetLineOfWidgetOffset(widgetRegion.getOffset());
	if (startLine == -1)
	continue;

	int endLine= extension.widgetLineOfWidgetOffset(widgetRegion.getOffset() + Math.max(widgetRegion.getLength() -1, 0));
	if (endLine == -1)
	continue;

	r.x= 0;
	r.y= JFaceTextUtil.computeLineHeight(textWidget, 0, startLine, startLine) - fScrollPos;

	r.width= dimension.x;
	int lines= endLine - startLine;

	r.height= JFaceTextUtil.computeLineHeight(textWidget, startLine, endLine + 1, lines+1);

	if (r.y < dimension.y && annotationAccessExtension != null) // annotation within visible area
	annotationAccessExtension.paint(annotation, gc, fCanvas, r);
	else if (annotationPresentation != null)
	annotationPresentation.paint(gc, fCanvas, r);
	}
	}
	}

	/**
	* Thread-safe implementation.
	* Can be called from any thread.
	*/
	@Override
	public void update() {
	if (fCanvas != null && !fCanvas.isDisposed()) {
	Display d= fCanvas.getDisplay();
	if (d != null) {
	d.asyncExec(new Runnable() {
	@Override
	public void run() {
	redraw();
	}
	});
	}
	}
	}

	/**
	* Redraws the vertical ruler.
	*/
	private void redraw() {
	if (fCanvas != null && !fCanvas.isDisposed()) {
	if (IS_MAC_BUG_298936) {
	fCanvas.redraw();
	fCanvas.update();
	} else {
	GC gc= new GC(fCanvas);
	doubleBufferPaint(gc);
	gc.dispose();
	}
	}
	}

	@Override
	public void setModel(IAnnotationModel model) {
	if (model != fModel) {

	if (fModel != null)
	fModel.removeAnnotationModelListener(fInternalListener);

	fModel= model;

	if (fModel != null)
	fModel.addAnnotationModelListener(fInternalListener);

	update();
	}
	}

	@Override
	public IAnnotationModel getModel() {
	return fModel;
	}

	@Override
	public int getWidth() {
	return fWidth;
	}

	@Override
	public int getLineOfLastMouseButtonActivity() {
	IDocument doc= fTextViewer.getDocument();
	if (doc == null \|\| fLastMouseButtonActivityLine >= fTextViewer.getDocument().getNumberOfLines())
	fLastMouseButtonActivityLine= -1;
	return fLastMouseButtonActivityLine;
	}

	@Override
	public int toDocumentLineNumber(int y_coordinate) {
	if (fTextViewer == null \|\| y_coordinate == -1)
	return -1;

	StyledText text= fTextViewer.getTextWidget();
	int line= text.getLineIndex(y_coordinate);

	if (line == text.getLineCount() - 1) {
	// check whether y_coordinate exceeds last line
	if (y_coordinate > text.getLinePixel(line + 1))
	return -1;
	}

	return widgetLine2ModelLine(fTextViewer, line);
	}

	/**
	* Returns the line of the viewer's document that corresponds to the given widget line.
	*
	* @param viewer the viewer
	* @param widgetLine the widget line
	* @return the corresponding line of the viewer's document
	* @since 2.1
	*/
	protected final static int widgetLine2ModelLine(ITextViewer viewer, int widgetLine) {

	if (viewer instanceof ITextViewerExtension5) {
	ITextViewerExtension5 extension= (ITextViewerExtension5) viewer;
	return extension.widgetLine2ModelLine(widgetLine);
	}

	try {
	IRegion r= viewer.getVisibleRegion();
	IDocument d= viewer.getDocument();
	return widgetLine += d.getLineOfOffset(r.getOffset());
	} catch (BadLocationException x) {
	}
	return widgetLine;
	}

	@Override
	public void setFont(Font font) {
	}

	@Override
	public void setLocationOfLastMouseButtonActivity(int x, int y) {
	fLastMouseButtonActivityLine= toDocumentLineNumber(y);
	}

	/**
	* Adds the given mouse listener.
	*
	* @param listener the listener to be added
	* @deprecated will be removed
	* @since 2.0
	*/
	@Deprecated
	public void addMouseListener(MouseListener listener) {
	if (fCanvas != null && !fCanvas.isDisposed())
	fCanvas.addMouseListener(listener);
	}

	/**
	* Removes the given mouse listener.
	*
	* @param listener the listener to be removed
	* @deprecated will be removed
	* @since 2.0
	*/
	@Deprecated
	public void removeMouseListener(MouseListener listener) {
	if (fCanvas != null && !fCanvas.isDisposed())
	fCanvas.removeMouseListener(listener);
	}
	}